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Old guy44

compression ratio?

18 posts in this topic

So my "new" '63 catalina convertible is now in my driveway, 43,000 original miles! As one would expect for a car of that vintage which has spent a good share of its life sucking unleaded fuel the engine needs some serious help. It is presently the two barrel 389 single exhaust. While I have built numerous Chevy's  and the occasional Ford I have never built a Pontiac. I overhauled a ton of them as I was doing it professionally up until 1977.  As this car will be a daily driver the engine will be built for economy not performance. Does anyone out there know what compression ratio I can run and still use regular fuel? Also I am considering using an edelbrock throttle body injection, my thought is that it has much better fuel control than a carburetor. Has anyone tried one and how does it work? I am open to any suggestions as I am in unfamiliar territory here. 

I was going to find a 700R4 and put it behind the 389 but the "slim jim" still shifts great so the R4 can wait. I had forgotten how well those actually shifted new until the wrong person overhauled it the first time and over-torqued all the bolts tweaking the case.

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First off congrats on your new old Pontiac they are way cool cars. Just a couple things as far as unleaded fuel goes at only 43000 miles it more than likely has not been driven enough to have done much if any at all to have pounded the valve seats into oblivion yet. Chances are that most of the miles on it were put on it early in its life when real gas was all you could buy. Unless you are planning to drive it ten of thousands of miles a year,put some lead additive in the fuel and knock the timing back a couple degrees so it doesn't spark knock but if has the low compression engine that would be a non issue under hard acceleration will probably be OK. If you are planning to take engine apart anyway then would definitely put hardened valve seats in it for sure. would be more concerned about the ethanol in the gas  attacking the internals of the carburetor. If I am not mistaken it has a Rochester 2GC #7023063 with 1 7/16s throat size but could be #7023060 with 1 11/16s throat size on it unless it has been changed sometime in the past. Reason I say it is probably the 3063 is that particular carb is used with the single exhaust which would have been used in the "Economy package" from the factory. Just for my own curiosity would like to know for sure?Those are actually really good carbs rebuild kits with the updated parts (gaskets floats ect.) are widely available to make ethanol a non issue. Unless you just want to spend money on injection set up the results realistically would probably negligible compared to a well tuned carb in both fuel mileage and drivability . just my opinion. Sure others would argue that. You say is has the roto hydramatic (slim jim) trans in it they are generally known as a good transmissions they were also used in other applications besides GM. That being said Would suggest instead of 700R would used the 200R instead because it uses the BOP case would not need adapter plate to bolt up to the engine as you would with the 700R but could run into flex plate compatability issue but not 100% sure about that.also can depend what rear end ratio that is car now could have major impact on performance that is not necessarily good. The axle codes that identify the ratio in rear are different color paint markings at the ends of the axle tubes there also a code number that is stamped on the axle carrier itself the safe T trac is also identified by tag next oil filler plug. they have several different gear ratios available. If you could give me the numerical code that is stamped on it. I would be able to ID exactly what it is. the code is stamped at about the 7o clock position looking at the front of the axle on the carrier itself. As far as the compression ratios for the engine depending which 389 CID engine it is it could be anywhere from 7.6:1 to 11.5:1 the standard bore and stroke for 389 is 4 1/16 bore and a 3 3/4 stroke. The engine ID code is a 3 digit letter numerical code that is stamped into the engine block below the production # FYI there were 33 different engine combinations that were available in 1963. SURE do miss the old days. If you could give me the 3 digit code I will be able to tell exactly what it is from compression ratio to camshaft specs the letter in that code denotes which trans originally came in car and possibly the transmission ratio as well. One other thing they are only original once...........almost forgot it has been my experience that old cars that have really NEVER BEEN RUN HARD they tend to build up a ridge in the top of cylinder bores even at that low mileage when you start hammering on it the rods will stretch a little bit (normal) and the rings will hit the ridge and break top ring every time.

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First, Where is that number stamped on the block, I.E. front of block below right cylinder head or near transmission flange left side or ??? I have been a small block chevy man my entire life and know nothing about the small details of a Pontiac.

 Second, It is already cranking with at least one weak hole, growing up in the business your ears hear a lot. Depending on what I see when the heads come off it will be getting a rebore as I WILL be putting tens of thousands of miles on it. I am planning to make it my daily driver and at my age it will likely be my last personal car. That is the reason that I am asking how high I can go with the compression and still use regular fuel. putting a lot of compression into it to improve engine efficiency and then having to run premium fuel is just counter productive.

As the heads do need to come off and get the unleaded upgrade at the very least it will be getting rings bearings and a camshaft but my bet is that it will need a rebore. The primary cause of engine wear on the early ones was in the first 10 or so minutes of operation when the engine was cold and the choke was on dumping a ridiculously rich mixture into the cylinders washing all that precious oil off of the cylinder walls. Considering that the car spent its entire life in Indiana (cold weather) and the fact that it has averaged less than 1000 miles a year it must have spent a lot of time in the cold engine scenario. My bet is that the cylinders have an excessive amount of taper in them and a rebore will be a necessity. The amount of blow by that the engine has right now does nothing but strengthen that belief. So as I will probably be buying pistons I might as well get the optimum compression ratio whatever that may be. The couple of times that I built a small block chevy for economy we found that 9 was about as far as you could go and still run regular fuel BUT that was with LEADED regular. The unleaded factors in a variable that I have no experience with.

Finally the fuel injection. Yes, it is possible to get good economy with a carburetor. The last economy build I did was in a 66 Nova. Won't go into the particulars but the induction was an A series AFB on top of an Edelbrock streetmaster manifold. Neither of which is available anymore. That engine delivered 20 in town 29 on the highway and 19 towing a boat. But it took a lot of tweaking with metering rods and springs which on the AFB could be done by removing a couple of small plates on the top of the carb and did not require any disassembly and recurving the distributor a couple of times which did require removing the distributor and putting it on the distributor machine. Whereas with a fuel injection it can all be done with programming. In addition there is no way possible to get the same kind of control with a carburetor that you can get with an electronic fuel injection. Further the reliability and lack of maintenance with and FI and electronic ignition and spark control means a lot to an old f... that just does not get all that excited about an open hood anymore.

So we get back to the original question, how much compression can I put into that Indian and still run regular fuel?

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Posted (edited)

The engine I'D should be stamped on the block front of engine pass side just below cylinder head. As far as compression ratio depending what combo you use anywhere from 8.5 to 9.0 would be the range that depending on the tune should be OK for using regular gas but Cal. Uses different gas blends than they use here on east coast.Just to satisfy my own curiosity would like to know what the codes are rear axle,engine,carb# are. knew would have controversy over carb VS After market fuel injection but will save that for another time.......also grew up the business too since was able walk..

Edited by TWO LANE BLACK TOP

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Posted (edited)

FYI When doing cylinder heads on pontiac engines. Most machine shops do mostly Ford's and chevys and as a result they overlook certain nuances specific to Pontiac mainly when installing hardened valve seats most shops will use the valve seats that are designed for chevys They are thicker and as a result the valve stem heights will not be correct that is very critical on a Pontiac if stem heights are not exactly right the engine will not have a well balanced air flow into the cylinders and no matter what you do will have erratic idle and an exessively nolsey valve train. The only fix other than remachining heads is to use adjustable push rods.  Also lifter preload is very important too.incorrect valve stem heights have major impact on that as well. Alot of shops will also use chev style lifters although dementionaly the same the oil hole on the side of lifter on chev is higher up from bottom of the lifter.  then actual Pontiac lifter and with certain Pontiac cam shaft grinds the oil hole can come up above the lifter bosses at max lift will cause low oil pressure issues. Just something to be aware of....

Edited by TWO LANE BLACK TOP

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Just came in from the garage. Couldn't stand it had to pull the heads. The numbers on the block are 15H and 509395. I would have bet money that it needed a rebore and would have lost the bet. The front cylinders have .003 wear the rest are barely measurable. With effort I can hook a fingernail in the ridge at one point about 2:00 right bank and 10:00 left bank on the front cylinders, the rest have virtually no ridge. Interestingly enough as little wear as the cylinders have there is excessive camshaft wear. I knew that Chevy's of that era had soft camshafts but I never ran into it in a Pontiac. I don't see any obvious valve problems they are all the same color and the color is correct, but the wear I see on the cam I wonder if I have an almost flat lobe causing the low cylinder cranking and the limp at idle. I didn't crank the engine around to check all the lobes but since I am changing it anyway it doesn't matter.

I will keep the cylinder head information in mind but Larry over at valley head service is not your average machine shop and he has been doing this longer than I have. 

Don't know what era you grew up in but the first engine I ever overhauled was a flat head ford. the first overhead V8 I worked on I could not believe all the stuff I had to remove to get to the cylinder heads. Ahhhh nostalgia.

The carb is a 2GC Rochester 7023060, I will forward all the other numbers when I crawl under it some time in the not too distant future. The saga continues.

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Have ran into the soft camshaft issue before myself but is was mostly in nail head Buicks from the early 1960s also know that Chevrolet late 70s into real early 80s had cam issues as well. Guess it depends on the suppliers and QC issues during during different eras of production. Maybe more common problem than realize? the number 509395 is the production # of the engine think the last 4 digits should match the VIN on the car. The 15H indicates the particular engine combination which is 389 CID with 10.25 compression ratio. Rochester 2g with the number that you indicated above. camshaft profile #0 not sure exactly duration , lift , lobe separation on that is but can find out. also indicates dual valve springs. AC 45 sparkplugs also # on distributer should be1110996. Also indicates equipped with heavy duty starter. rated at 267 [email protected]  410 ft lbs [email protected]. with the roto hydramatic (slim jim) trans. Have done some flat heads and straight 8 packards among lots of other things including a Liberty aircraft engine that was in a boat. My dad was a master mechanic my first rebuild was a F head hurricane from a 1951 Willys jeep. definately don't make them like they used too that's for sure.

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Pontiac definitely operated under a different mind set than Chevrolet division. When Chevy's of that era had a 10.25 compression ratio in an engine it had at least one 4 barrel on it and generally two a a rump and thump camshaft, and definitely dual exhaust. I have the original owners manual for the car and under fuel requirements it lists all the engines and in the list there it is, "two barrel premium fuel engine", two barrel single exhaust and 10.25 compression ratio. That one really caught me off guard. I saw a two barrel and had visions of a compression ratio somewhere around 7 or 8. That does explain why as bad as the engine is it had a lot better throttle response than I ever expected. I have the engine on a stand in the garage. I don't have it disassembled yet but turning it over I looked at the camshaft and about a quarter of the lobes look like they are down to about half of the original lift, and one almost round. There is the idle limp. I don't remember ever seeing a camshaft that worn at any mileage and sure not at 43,000. Any suggestions on a cam grinder, the last engine I built I used a Racer Brown camshaft, yes it was that long ago. His shop was about 10 miles from my dads shop and while he was the benchmark of a grumpy old curmudgeon he would grind me anything I wanted and it always did everything he said it would do. 

Do you know if anyone still bends up all the pipes to put a dual exhaust on it or will I be taking it to the local muffler shop and have them bend everything up. I did a quick google search on Pontiac exhaust and came up dry.

While the engine is out and the car is on jack stands I will also be putting in new bushings on the front control arms. Those 54 year old bushings are looking pretty tired, new ball joints probably would not be a bad idea either since I will probably be driving it forever.

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Posted (edited)

Have heard of Racer Brown from what I understand that in the 1950s and early 60s his grinds were the hot tickets if you were racing Chevrolets and wanted to win. Have a good connection at COMP cams will custom grind anything you want. We used them all the time. With no problems.  Was building 9000 RPM NASCAR 18 degree modified engines. Also engines for other short track classes including 4 cylinder fords and Toyotas also straight 6cylinders for Sportsman class at our local track ( Bowman Gray Stadium)here in town and around the Southeast One of our guys also holds several land speed records.  Ran 206 MPH in a 1953 Studebaker that weighed 4300 lbs. in the East Coast Timing Association. Have also done some really NASTY street engines too that actually have good driveability. All told people running our stuff have won well over 100 races in the last 12 years. When the TV show (madhouse) aired in 2010 they had us portrayed on the show as like the mad scientist engine builders. We had been using our own secret custom spec grinds that COMP cams ground for us to use in the Modified engines for a few years. So COMP cams saw the show they reached out to us and made us a dealer. If you ever saw the show they gave us a 10ft by 6ft banner to put on the wall so when film crew was at the shop you could see it in the background. free advertising. Anyway getting back to the subject to insure that you get the optimum grind that you want. you need to know a couple things First and foremost once you decide what kind of combo you want weather high performance or fuel mileage and economy .You cant change your mind in the middle of your build or your results will be less than optimal. From what you have said I am assuming that smooth idle and good fuel mileage with good mid range power is your goal. they have some really good off the shelf Pontiac specific grinds. Not all of them are listed in most catalogs that you see everywhere summit racing jeggs etc. you also need to know rear end gear ratio most important weather you are using aftermarket fuel injection and which system you are going to use. the best grinds for Pontiac will be dual pattern. Intake will have one duration. Exhaust side will have more duration because of the shape of Pontiac exhaust port is on the restrictive side and a little more duration helps the evacuation of the exhaust be more efficient that in turn helps airflow thru the intake be more efficient especially with stock heads.Ideally exhaust flow should be right around 70% of what the intake flow is.Dual pattern cams help that. even in an economy type build. if you are going to rebuild the engine completely and use dished pistons to drop the compression ratio go ahead and line bore and square the decks up also Most of those old engines like that are not line bored and decked at the factory.Will greatly reduce internal friction caused by the parts working against each other will help fuel mileage and help in making it run sewing machine smooth. There are a couple more bottom end tricks. If interested I will let you know what they are. Sorry about being so long winded and giving way to much unnecessary information. Cant help myself sometimes. Go to COMP cams website and they will help you out with any kind of grind you want. Custom or otherwise no problem. Also would use local muffler shop can probably custom bend exactly right to the car while in their shop.

Edited by TWO LANE BLACK TOP

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Posted (edited)

I have been following this thread and I'd like to add my two cents. You mentioned getting a 700R4 transmission. I imagine that is for overdrive and mileage consideration. As Two Lane as already stated, the 700R4 is strictly a Chevy bolt pattern and will require and adaptor plate kit to go from the Pontiac (or BOP - Buick/Olds/Pontiac) bolt pattern to the Chevy. The alternative would be to find a 200-4R transmission. They were used in early 80s Trans Am and turbo Regals/Grand Nationals and other applications. You can find them if you look around. They have the BOP bolt pattern and they are only a couple of inches larger than the 350/400 transmission. You will have to have your drive shaft shortened and replaced though for the new tranny.

I am using a Melling cam and lifters in my 455, I don't recall the cam specs since it has been in the engine and in the car for over 13 years but it is close to a Ram Air II/III spec (since I also have a 4 bbl carb). Additional I am using a Melling high volume oil pump to go along with it to keep it well lubricated. I used ARP studs and fasteners for all the internals and bottom end to keep everything together. I still use the stock head bolts to keep everything outwardly stock appearing. I recommend a new weight and spring set with the distributor. This way you will get maximum vacuum and mechanical advance all in as soon as possible. I also recommend replacing your points and condenser with a breakerless unit from Pertronix. You will never have to set a dwell ever again. I also have a new double roller timing chain and gears to replace the stretched original timing chain.

One more thing for your overall rebuild. The late John Sawruck, Pontiac historian and professional engineer at Pontiac, use to lecture to us Pontiac faithful over and over was replacing all rubber hoses on the car, especially those that came in contact with gasoline or gas vapor with modern hose. The reason being that rubber hoses made back in the day were designed with the leaded fuel of the day in mind. Rubber lines have several enemies these days that try to break it down from the outside: time, UV/sun exposure, chemical exposure, road grim exposure. However gas formulas have changed significantly since your car was built. Today's unleaded gas contains between 0-15% ethanol. The ethanol starts breaking down the original rubber from the inside now. Today's modern rubber hose is designed to resist all of this. So it is best that you replace every rubber hose on the car while you have the opportunity to do so with modern equivalent available hose, especially the small one that runs from the fuel tank to the hard lines. I replaced mine and I found it about ready to split in half. You can get modern hoses with the correct OEM markings from many of the catalog vendors along with the period correct clamps if you are going for a totally original look too. The real key is this is a safety and reliability issue. We don't want a car breaking down or worse, catching fire.

As for an exhaust, you might contact Pypes Exhaust. While they are a performance minded exhaust company, they do have exhaust down turns for your car. They also have quieter mufflers if you still want to hear the radio! Have you considered headers or factory headers (RAM AIR/HO manifolds) to replace the stock log style exhaust manifolds to help improve exhaust flow (and your mileage)?

Lastly Walden Exhaust produces exact OEM reproduction exhausts, so if you choose to stay with a factory correct single exhaust or switch to a factory style dual exhaust, I suspect they will have what you need. Of course you can always go to Midas, Tuffy, or whomever else.

 

Edited by Frosty

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Two Lane and Frosty,

Thanks for the responses this old Chevy guy needs to learn to speak Pontiac. I will give Comp cams a call and see what they can do. Will it help to use your name? With regards to the cam I am not looking for mid range I am looking for something that runs between 1000 and 4000. the last economy build I did was in a '65 nova. we used a 307? truck block, it had a 3 7/8 bore and 3 1/4 stroke. The logic was that the slightly smaller bore meant that the flame did not have to travel as far across the cylinder and the slightly longer stroke gave it a little longer to burn. We used early 283 heads with the 1 3/4 intakes and 1.5 exhausts to keep port velocity up at lower RPM's. We used an Edelbrock streetmaster manifold, a single plane similar to the torquer but with smaller runners.  Topped it off with an A series AFB with primaries somewhere around one inch We used the 283 ram horn exhaust manifolds to maintain some exhaust back pressure and keep the cylinders from purging too completely  Racer ground us a camshaft that fit right into our path of logic. The engine ran surprisingly strong up to about 4500 rpm and then virtually shut off. It ran out of carburetor, manifold, cylinder heads and camshaft all at the same time. However it was built for mileage and it excelled beyond our expectations. 20 in town, 29 on the highway and 19 towing a boat. 

Hopefully I can find a combination that works on the Pontiac, I don't expect to match those results but hopefully I can get it into the mid to high teens in town. I am still picking brains to see what might work on the Pontiac but I haven't found anyone yet that has done a mileage build on a 389. I spoke at length to Edelbrock about the throttle body injection and they felt it would help highway mileage but not so sure about city, it is a relatively new offering and there is not a lot of information about how it works on the 389, and no information on what I am trying to accomplish. A lot of money for an experiment. I am leaning toward keeping the 12.25 compression ratio and working around it, premium fuel is only about 20c a gallon more. If I can get Comp cams to grind something that will trap as much cylinder pressure as possible at low to mid range rpm's it would give me a good starting point. I may just put the two barrel back on for now, if it is repairable. The only time I drove it the exhaust would burn your eyes and when I opened up the hood it reeked of gas fumes, running really fat. Any opinion about how the 389 likes a single plane manifold? What about an HEI or MSD? A hotter spark never hurt anything. 

With regards to the trans I will keep the slim jim. It only has a converter for stage one and stage two (first gear) and then it is direct drive stage three (second gear) and stage 4 (third gear). so cruising at any speed is a direct drive, just like a lock up converter.

 

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Two Lane,

Forgot to mention it but VERY IMPRESSIVE credentials! I was cruising around ebay and there are several old edelbrock torquers on there. It appears that they have the heat passage under the carburetor unlike all of the newer remakes. Further looking, as I am sure that you are aware, there is a 500 cfm version of the edelbrock performer. Might work on the 389? Also as I recall on the 307 economy small block we cleaned up the intake ports around the valve pockets to eliminate all the sharp edges and lightly polished the whole port to retard the formation of droplets. do you think that it would be worth the effort on the Pontiac?

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Old Guy, I would definite recommend doing a light porting and polishing on both the intake and exhaust ports. I would also recommend a 3-angle valve job to help the valves seal properly on any engine. Also porting to match the intake and exhaust gaskets/manifolds is good for any engine. I have done that with my 455. As for mileage, I get around 12-14 on the highway with my 4-bbl and 400TH combo with my 455 (its really a 462 - a 455 bored .030 over). Lucy is a 4500 lb car too. With the top down or a super heavy right foot, it can drop to 8 smiles per gallon. I have never measured city driving since I don't use mine as a daily driver. However, the 4-bbl carbs only open the bigger secondaries only when you need them.

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Posted (edited)

Whats up fellas Don't have a lot of time right now but will throw a couple things at you. As far as the cylinder heads go in the combustion chamber it will help to knock sharp edge down between the valves . Do not take any material out of it just dull the sharp edge.Reason to dull the edge it eliminates potential hot spot that will cause premature detonation. Around the edge of the combustion chamber you will notice when you run your finger around it has a slight convcave shape to it leave that alone it is like that on purpose to facilitate the flame travel around the cylinder into the center of it. You can just dull the edge again to not remove any material. Leave the combustion chamber itself rough. That is very important. On the intake port Do Not polish it want the intake ports rough. Reason for that is the rough surface is essential in keeping the atomized fuel suspended in the mixture as it travels thru the port also the rough uneven texture can actually help in maintaining air velocity by less friction between the surface of the port and the air. As a smooth even area actually has more surface area for the air to travel thru thereby causing more friction. Think of the surface of a golf ball. the dimples make it more aerodynamic as there less exposed surface area to the air thus less friction to slow it down.Unless there is any left over casting flashing left at the opening of the port. Leave it alone . Just to clarify rough ports keep the fuel suspended by the fact when the fuel droplits hit the sides of the port it doesn't give the fuel any where to cling too. smooth surface encourages fuel to puddle and stick to the surface. It is like when you see a drop of water on a glass surface it immediately beeds up into a single drops and little puddles . When put drop onto rough surface it doesn't really beed up it breaks up and spreads out. Same principle with fuel mixture. You can polish the exhaust port as long as don't remove any material. removing material from the exhaust port will hurt low end torque. A lot of people polish all that stuff up. Reallity is does more harm than good.When working the heads POWER GAINS are made by changing the shapes of ports Mainly among other things by raising the roof and working the short side radius at the top side of valve pocket. Not by making them look shiny and trick. In street applications bigger is not always better maintaining velocity is most important. As far as intake manifolds would recommend using dual plane rather than open plenum Edelbrock performer would be an excellent choice as far as carbs go wouldn't go any smaller than 650 CFM. Also completely 100% agree with Frosty on changing out all the rubber hoses cannot go wrong by doing that . Like I said don't have a lot of time right now. Will elaborate on all these issues. And valve grinding angles. Thanks for the good compliments.

Edited by TWO LANE BLACK TOP

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Was looking at your post about your 307 block 283 head combo find that interesting. I have never done a 307 build before. May do one in the future though with the bore and the stroke being close to the same dimension would lend itself to an engine that is designed to run a steady RPM all the time and be most efficient cruising on the interstate cruising steady speed all the time. The small bore would hurt it in a high performance application. as it would shroud the valves and severely limit the amount of air you can put into it. Could be why in ran out of everything @4500 RPMs. Anyway have been doing a little research and can not find anything on the #0 camshaft profile or on any factory cam profile used in Pontiac in 1963. Can find all the specs for 1962 and 1964 Don't know why that is. If I had to guess I would say it is somewhere around 260 to 270 duration with the lift somewhere 450s to 460s lobe separation 110 that is just a guess could be way off. Please don't take that as fact. Being that you are doing a basically stock rebuild as far as the heads go besides dulling the sharp edges and installing hardend valve seats would do a three angle 30 degrees 45 degrees 60 degrees valve job that will improve the velocity and cut down the turbulence of the air as it passes the valve when it enters and exits the combustion chamber. Your cylinder head guy would probably recommend that too and would have no problem executing that on both intake and exhaust. Other than that  would leave them alone. If you are going to stick with the original 2 barrel set up a thorough rebuild of the carb making sure the airhorn isn't warped along with the base and doesn't have vacuum leak where the rod that holds the throttle plates goes thru it. Realistically would get at least 15 mpg in the city if it is properly tuned. and you don't have a heavy foot in stop and go traffic. 19 to 20 MPG on open road would be realistic too .with that set up. If you want run a 4 bbl would recommend using a edelbrock performer intake manifold it is a dual plane. open plenum intakes like the torquer are more geared to high RPMs and not low end torque. I like Q jet carbs myself on GM cars they can intimidating to someone unfamiliar with them but in reality they are no harder to tune than an AFB. 600 to 650 cfm  would be the size you would want to use. Start with #68 jets. if tuned right would deliver same MPG as the 2 bbl. that is just my opinion there are alot really good carbs out there. Frosty is also correct in swapping out the points in the distributor to the petronix set up have used them a lot and have 0 issues with them. with a stock engine the MSD is just overkill you would not notice any difference in the way the car runs or drives if you used one. Hopefully COMP cams will help with right grind for your application I am sure they will give you exactly what you want and well suited to your car. And you will be happy with the results.They will need to know the gear ratio in the rear end and what kind of fuel system 2bbl or 4bbl you when you forward that code to me will tell what the ratio is without a doubt. Hopefully the information and rambling I have done in the last few days has helped you in your quest. One other thing the line bore and squaring the decks would be money that is well spent....

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Posted (edited)

I appreciate the input on the intake manifold, I was debating single plane vs. dual plane. On chevy mileage builds we had really good luck with the edelbrock streetmaster which was a single plane but had really small runners. I personally prefer the AFB style carburetor because I can change the step up rods by loosening the small plates on the top and removing the rods and pistons. I was doing this professionally when the Quadrajunk was in its prime. Don't know how many cars I saw with under hood fire damage from a leaking Q jet. the biggest problem we had on them was the brass cup style plugs in the float bowl leaking, or falling out. It may have been a So Cal problem with the considerable summer temperatures. They may have solved the problem by now but it was epidemic when I was working on them on a regular basis. Agreeably with the tiny primaries you need more throttle opening to get anything done and therefore spent less time running on the idle circuit as you do with a bigger primary in heavy LA traffic. The biggest offender of this phenomenon is the end bowl holley. Have spent many hours restricting the huge idle passages in the primary metering block on them to get the light throttle mixture leaned out. But I digress.

Oh by the way my cylinder head guy is Larry Ofria at Valley Head service.

I e mailed Comp cams and did not get a response, but I have seen more than one e mail get lost in cyberspace. When I have the time I will call and spend the time waiting on hold to have a conversation with one of their tech people. Someone out there must grind a short camshaft for the 389. Right now I am trying to put in an A/C and replace all the rotten 54 year old front end bushings while the engine is out so right now I have 389 scattered all over the garage. 

About ignition, I was looking on line and there are several of the coil in cap HEI's out there for reasonable prices. Seems like a little wider plug gap and hotter spark couldn't hurt.

The front end is on jack stands , I need to jack the rear end up long enough to read the tag.

Edited by Old guy44

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Two Lane,

Up jumped the devil. Apparently no one makes an intake manifold for the '63, everything starts at '65 or do you know of anything? If not I will be going with the two barrel as it apparently is my only option. I can only hope that the carb it is repairable because it was running so fat it was almost running raw fuel out the exhaust. 

Also I spoke to comp cams and they don't grind anything specifically for economy. 

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Apparently Pontiac pre 1965 Pontiac 389 cylinder head cooling passages are located differently and the intake manifold flanges are different they have 6 bolts on each side instead of 5 bolts. Guess 1964 was the changeover year real late 1964 could have 1965 revisions ? I didn't know that. I learned something today! Only company that has aluminum intakes for that  I have found 1964 and earlier is Offenhauser and they only make dual quad and three deuce intakes no single 4bbl. As far as Comp cams We had a catalog of all their lobe numbers each number indicated a specific individual lobe profile. Would give them the lobe numbers and the separation we wanted then they ground the cam for us. Have a special computer program where put in specific engine combos and run simulated dyno runs and could mix and match different cam grinds (lobe numbers) cylinder heads port volumes carbs etc until came up with results we were looking for. The actual dyno runs on the finished engines was usually within 3 or 4 horsepower of that figure. Torque curves,horsepower,and RPMs where the torque curve is. It is possible to move your torque curves as little 100 RPMS one way or the other or flatten it for a few hundred RPMs in the center of the power band with different profiles. to help keep the from spinning tires off the corner with an aggressive driver at the track. Sure could do the same thing with mileage and economy.  Larry at Valley head service might know of someone out there who has that same program and access to the lobe #s. As far as the carb goes a thorough rebuild and adjustment will work wonders for it. Don't remember what the exact name of that software but can find out.      Q jets do have their issues for sure.Still love them anyway .

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