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Michael Dalke's 1967 Firebird

2020 March
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steveeoaktree

Planned engine overhaul with minimal changes from stock

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   Hey fellas, I've been enjoying reading through your forums! I am going to pull the '76 400 2bbl and just do a basic re ring, and machine (where necessary). Have all checked including lifter bores, mains, rods, cylinders etc... and the cross hatch put into them...  I'm looking for a mild, fun to drive cam to stick in there, and from what I have learned, these ol ponchos love a wide lsa? what about the summit k2801? Since I'm just going to do a valve job, take the die grinder to match the ports to the exhaust man gaskets, and of course change the bearings, oil pump and timing set wouldn't this work well? No plans to mill the heads or increase compression with the exception of maybe a thinner head gasket. I don't want this thing loping around just something to throw new duals on and drive her.


 


Any advice is appreciated!


 


Thanks, Stevee


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Hi Steve


 


Your Summit cam choice is a fairly decent one and it should work rather well. I do have some questions for you though.


 


What are your goals with this motor besides freshing it up a bit?


 


Are you going to replace the stock 2bbl with a 4bbl? If so, what manifold are you going to run? Port matching always is a good thing to improve air flow in and out. Are you going to improve the exhaust system (headers/factory high flow exhaust manifolds)? Cat back exhaust? High flow cat? High volume, high pressure or stock replacement oil pump? 


 


I ask since all these things can have an impact on your choice of camshaft profiles.


 


Also have you considered a hydraulic roller cam over the flat tappet design? A hydraulic roller can give you a little more aggressive profile but its a little more expensive. 


 


All this comes down to choices and your wallet. 


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True that.


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No plans to do anything more than just cruise the car. If it was a 30,000 mile car, I wouldn't touch it except for routine maintenance. I will install dual exhaust, but not huge with a crossover. Stock manifolds and the stock 2bbl Rochester as it functions very smoothly. Mileage is important of course, and I don't really stick my foot in it enough to warrant a 4bbl anyway. I'd just rather spend the money on the paint and interior truthfully. Growing up, dad called this type of engine work an engine "service" lol but I personally haven't worked on anything old since 1991 when I got rid of my '71 Olds. The BOP main seal is something I will surely purchase as well. I will purchase a good quality oil pump, just not a "race" type. Even though these motors had little horsepower, I was thinking that with that mild cam, the torque would be more than adequate . I do realize though, that planning correctly is very important. Thanks fellas for the thoughts!


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Hp is over rated. Torque is what you want, and those old motors came with that in abundance.  If you want to embarrass some Fart-Canners, look at the rear end ratio. A little work there will leave them farting in your wake.


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Hp is over rated. Torque is what you want, and those old motors came with that in abundance.  If you want to embarrass some Fart-Canners, look at the rear end ratio. A little work there will leave them farting in your wake.

 Ha Ha that is true... Honestly, in my humble opinion, this car was built for driving comfort and style which is what I plan to do with her. This winter, I'll work on a poncho build with a 389 block that I bought from Franks (maybe clone the 421 SD?) to put in something else. Maybe a 60's GP? I'm fine with the ratio, especially if that mild cam gets the torque number above 300 and reliability and longevity is good. One thing that I have been considering is that "hidden" oil gallery plug: Some say to drill her out a tad to help with distributor to cam gear lubrication but I surely don't want to disrupt the oil pressure. I will surely tap the gallery plugs and use threaded plugs to eliminate the chance of them popping out. Another is the porting. I will stick with a 2bbl but I will help the airflow out by smoothing them out. I have also seen threads on blocking the exhaust crossover and machining the intake to remove the heat from underneath the carb, but surely there must be a reason that the Pontiac engineers designed them that way right?

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 Ha Ha that is true... Honestly, in my humble opinion, this car was built for driving comfort and style which is what I plan to do with her.

You're preaching to the choir on that point. I drive B-bodys. '85 Parisienne and an '81 Olds full sized wagon. I've said many times ... I don't want go any faster ... I want to just keep driving. Fools with their form fitting bucket seats ... I drive to work on a flammin' sofa every morning.

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 Ha Ha that is true... Honestly, in my humble opinion, this car was built for driving comfort and style which is what I plan to do with her. This winter, I'll work on a poncho build with a 389 block that I bought from Franks (maybe clone the 421 SD?) to put in something else. Maybe a 60's GP? I'm fine with the ratio, especially if that mild cam gets the torque number above 300 and reliability and longevity is good. One thing that I have been considering is that "hidden" oil gallery plug: Some say to drill her out a tad to help with distributor to cam gear lubrication but I surely don't want to disrupt the oil pressure. I will surely tap the gallery plugs and use threaded plugs to eliminate the chance of them popping out. Another is the porting. I will stick with a 2bbl but I will help the airflow out by smoothing them out. I have also seen threads on blocking the exhaust crossover and machining the intake to remove the heat from underneath the carb, but surely there must be a reason that the Pontiac engineers designed them that way right?

 

The idea of the heat cross over is to help quickly atomize the fuel better in cold weather climates as it helps warm up the fuel in the carburetor quickly. Guys typically remove or seal up the exhaust heat crossover in order to keep the fuel cooler - mainly for racing purposes since you don't want to boil the fuel in hot/racing applications. Since you plan to drive this car on the street, I would leave it alone.

 

Caution when tapping and installing the oil gallery plugs. You don't want to run them in too far because then you will restrict oil flow.

 

You said something that has me a little worried about your goals. You want to make over 300 lb-ft of torque with this motor. I hope you mean at the flywheel and not at the rear wheels since this car was rated at only 170 HP from the factory to begin with (a 400 with a 2 bbl). Yes, Pontiac engines are torque monsters and its relatively easy to achieve this goal (both at the flywheel and the rear tires), but as Pro said, an engine is an air pump. So it has to be able to breath in and out well in order to produce better HP and torque numbers. So port matching will be great but it won't be that noticeable of a difference if it is still breathing through a proverbial straw, like the stock 2bbl and factory exhaust system.

 

I am suggesting that you do some more homework and when you tear down your engine that you examine:

 

1. the catalytic converter - most like it is the old pellet style - it may restrict flow - consider replacing it with a more free flowing cat - assuming that there is money in the budget

2. the stock carb - there are more performance oriented / higher cfm rated 2 and 4 bbl carbs on the market - research the pros and cons over the stock Rochester

3. more performance oriented muffler (still use a relatively quiet one but a little more aggressive sounding and free flowing)

4. flush and fill the transmission and replace the transmission filter - consider using a quality synthetic transmission oil to help reduce friction

5. flush and fill the rear diff - again consider using synthetic gear lube to help reduce friction.

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For what it's worth, the 2bbl and the quad are essentially the same carb until you lean on the loud pedal a little harder.  Put a puppy under the pedal and keep your foot light and the quad keeps those two big back throats shut. 


 


 


Of course, that takes a level of self control. All it takes is one annoying Prius at the stop light and suddenly that puppy and your wallet are gonna get thinner in a hurry ... as will your back tires .... and the Prius's owners self esteem.


 


 


Don't kill the puppy. Priuses just aren't worth it.


 


 


 


 


 


High flow cats are something like $40 a piece, and worth a couple of horses all by their lonesome. Cheap power no matter what else you're considering.


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For what it's worth, the 2bbl and the quad are essentially the same carb until you lean on the loud pedal a little harder.  Put a puppy under the pedal and keep your foot light and the quad keeps those two big back throats shut. 

 

 

Of course, that takes a level of self control. All it takes is one annoying Prius at the stop light and suddenly that puppy and your wallet are gonna get thinner in a hurry ... as will your back tires .... and the Prius's owners self esteem.

 

Don't kill the puppy. Priuses just aren't worth it.

 

 

High flow cats are something like $40 a piece, and worth a couple of horses all by their lonesome. Cheap power no matter what else you're considering.

 

I agree with Pro. The conversion to a 4bbl will require a new intake manifold. Again since you are keeping things relatively stock, a used stock manifold are relatively cheap on eBay and Craigslist. Obviously if you live in a state with emissions compliance testing, then you will need a manifold that maintain your working EGR valve.

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Thanks for all the great tips! Nose to tail service including all lube points is the first goal to complete. Most people don't remember, or think to have the tranny serviced, but it's something that is necessary. Regarding the torque goal, it's not imperative, especially compared to longevity, mileage, and keeping the engine parts working together as well as possible. I do realize that the 2bbl is not many peoples choice, but I figured it to be similar (as century has stated) to the roch. 4bbl without the secondaries, so it didn't concern me much. Dual exhaust is a must, possibly with lower restrictive cats and mufflers, but nothing too exotic as like you stated there is no point with the 2bbl. The same amount of air goes in and out. The torque converter is a great point as well, I'd surely never thought that it would be that much of a difference, that's for sure. I just don't really want to mess with changing the carb and intake as it works very well and truthfully has plenty of torque for cruising right now. Will feel much better though after seeing inside the engine to assess any issues that may have gone unnoticed... oil starvation, sludge, etc... That will make some decisions for me right there in some areas. Thank y'all again for all of the great tips. First on the agenda during our plant shutdown next week is the nose to tail lube and fluid changes and constructing a temporary red plexi sunroof cover to seal out the moisture!


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Well, after an exhaustive period of research, (and reading Jim Hand's book) I have learned a lot about the Pontiac engine. The blocks and internals are mostly very sturdy for up to 400 HP/450 TQ with minimal changes. As long as there is not any abnormal wear inside, I can just hone, crosshatch, and re ring her along with a polishing of the crank and new Clevite bearings. I was going to modify the intake to remove the exhaust crossover, but decided not to as I would pay for it this winter... haha (Indiana sometimes has pretty rough winters) The number 068 cam equivalent is going to now be my choice, as it was either that or the comp XE262 instead of the mild summit cam. The wide LSA will keep the power band consistent from idle to 3000+ and that is what I need. Replacing the valve springs, exhaust valves, and going to ARP studs is all I really need to change from stock. shaving .020 off the heads, (and having the intake ports matched to this) and a good valve job along with getting the timing correct will put me in the 8:1 dynamic compression range which is fine for torque. I just wanted to let y'all know what I found out, and thanks again for the advice!


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I think those are wise decisions Steve. The only other suggestions I would make is:


 


A. Port match / blend your intake runners, heads, and gaskets as a set for better airflow


B. Triple angle valve job for better transition air flow into the cylinders.


C. Replace your valve guides and perhaps your valves (based on wear). 


D. Install hardened valve seats for use with unleaded fuel since Pontiac didn't build them that way originally unless your heads were buitl in the mid-to-late 70s or have been rebuilt since


E. Consider upgrading to a stamped steel roller rocker arm for longevity.


F. Buy a set of Ram Air Restoration reproduction factory Ram Air/HO exhaust manifolds or a set of headers for better exhaust flow.


G. Inspect your oil pump and pick-up / replace if necessary.


H. Replace the points & condenser in your distributor with a Petronix breakless set-up.

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All great advice once again Frosty. The engine in the car now is the stock '76 400 which is going to remain that way, and is fine for unleaded fuel, although I did have to just rebuild the carb and change the fuel pump... (of course due to the dang methanol and 40 years old.. ha ha) The old oil smelled like 100 octane ethyl... No knocks or ticks after that and t5he tune up/oil change (knock on wood). With 66,000 on her that engine should last until next spring when the build will be ready (I hope). I'll be working on the body and interior this weekend, so I'll be sure to upload some progress, and hopefully the weather seal kit'll arrive too!


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For what it's worth, the 2bbl and the quad are essentially the same carb until you lean on the loud pedal a little harder.  Put a puppy under the pedal and keep your foot light and the quad keeps those two big back throats shut. 

 

 

Of course, that takes a level of self control. All it takes is one annoying Prius at the stop light and suddenly that puppy and your wallet are gonna get thinner in a hurry ... as will your back tires .... and the Prius's owners self esteem.

 

 

Don't kill the puppy. Priuses just aren't worth it.

 

 

 

 

 

High flow cats are something like $40 a piece, and worth a couple of horses all by their lonesome. Cheap power no matter what else you're considering.

I have researched several brands of cats, and the prices vary considerably. Which would you consider to have the best price to performance ratio? Living in Indiana, I don't really have to worry about any sort of emissions testing but then again, am not wanting to create a pollution machine either... (If it was the late 80's I may just weld up the exhaust having forgotten to install cats... ha ha) Already have the x-pipe and am planning to order the ram-air resto manifolds when the budget allows.

 

Thanks

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I stuck a plain jane Walker on the parisienne and didn't notice any difference from the straight pipe the previous owner had .. but the bowtie 305 isn't exactly suffering from tight pipe syndrome.


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