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holsey82979@hotmail.com

Need help wit this 428 build..Where the Pontiac gurus??

Question

Hello to whoever reads this..I am building a 428 .30 over flat top piston with 6x-4 heads.I had 16's but the cr was too high causing detonation.I am using these heads and 1.52 roller tip rockers,rpm intake,headers 2 1/2 exhaust,pertronix hei,and a jet street master 750 quadrajet. need info on a good camshaft(heard you cant beat the 068),stock converter or stall,headers or RA manifold,gearing,timing recommendations,spark plugs,best oil to use,and whatever else your wisdom can offer from experience.If I can get anywhere near 400 horsepower im good.I need too get this thing right this time.Its all in a 71 lemans.
Thanks

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It has some camshaft in it that is supposed to bleed off some compression.The motor was built and had detonation and tore back down to install it..This is my first Pontiac build.It doesn't ping at low rpm or when the timing is way low just under heavy stress.I found out that 9.5 to 1 is max cr on 93 octane in a Pontiac. Car will be a daily driver sometimes so i need everything to be very streetable. I bought a pair of 6x-4 heads to lower cr and need to set up the rest to make up for the loss of compression.I was told to try a cometic head gasket to lower the cr from Butler and they do have one to get around 9.5 to 1.I am open to any suggestions (other than aluminum heads) as the 6x heads can easily be sold and I just diddnt want to pass them by. Dont know anything about re curving a distributor as i hear this may stop it with the high compression #16 heads.Hoping i get good info on what to buy for a budget build.

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A Pontiac motor built like that with 400 hp will probably be around 500 ft lbs of torque.  That would be one hell of a stop light warrior. 

 

I am partial to comp cams so

http://www.summitracing.com/int/parts/cca-cl51-224-4/overview/make/pontiac

That would be my choice for the cam.  If budget is an issue chances are Summit has their in house brand that would be close to this.

 

Make sure you have either the 8.5 10 bolt rear axle or the 12 bolt.  The 8.2 would depend on you behaving yourself.  Frosty/Justa6 and Indyman may chime in on this as they have more knowledge than I do.

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IndymanJoe had some hair loss after bumpstick/valvetrain issues.  He would be the go to guy on that one.  Everyone I know that has gone to the Petronix???? electronic conversion for your dist, has been very happy.  Bolts right in.  What trans are you using?  This might make a difference in what rearend.  Mainly depends on how your gonna drive it, as Notallthere said.  Frosty and Indy are the Lemans guru's.

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I learned from my mistakes,Not an expert at all.ME i love my Headers by Doug.I have had zero issues and they hang tight to the frame.Ram air manifolds are easier to install for sure.ME i love the sound of headers.converter stall,i have a continental 2500 stall in a th400.works great for ME.Rear gears i have 3:55.I can cruise the highways around here at 60-70 and it isnt wound out.great tire frying gears.I would call Paul Knippen and see what he recommends  for a cam.I had the shitty comp cams roller lifters,noisey and 2 collapsed within 400 miles.went to cranes,which are just prechecked better.No issues yet.I wanted crowers but they kept going on Back order.Not alot of guys doing Pontiacs so i kept getting pushed back.Make sure you have a "Pontiac Builder" help you,i had a great chevy guy do my machine work but it all went to hell which i can only blame on myself for not overseeing his work.Distributer..couple guys that have a sun machine can recurve it for you.I have a guy that did 2 for me and im happy.I didnt want to mess around with detonation so it was worth the 175.00 to have it done.I also rebuilt my Quadrajet but sent it to Cliff Ruggles for the final security check.he rebushed the throttle plates made it look pretty and it works Damn well.As Justa Said ask away any questions.

 

Oh...as far as pertronix.The skip white 50.00 ebay distributor will get you in the ballpark.They have to be disassembled and properly cleaned and lubed but i used one for 2 yrs with no issues.And if you break down on road trip any parts store will have the module etc in stock.

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Thanks for all the responses its good to know people who will try to help you are still out there..I had the 428 built to stock spec with a .30 over bore..the result was detonation run on and just wasn't running right..we be backed the timing down and it helped but not enough.so we picked out a camshaft with longer duration and overlap and run it on 93 and it helped at low rpm but under heavy load it pings and rattles like hell and it's is a sob to start when it's hot..don't remember the cam specs..some say you can run 10.5 to 1 cr iron heads on 93 with a damn good tune but I'm not that good of a tuner to get it dialed in perfectly..so gonna try 6x 4 heads headers dui distributor and everything that thumpin455 has said..trying to make 400 horses and ass load of torque for a daily driver.probably not gonna see the track just light to light.having said all this the e85 idea is intriguing..then I could sell the 6x 4 heads keep my high compression and run a stout camshaft..what u guys think??

O forgot I running a 400 tranny

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Crane cam 20188 is an awsome grind.

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stock heads, stock turbo 400 converter then I would stay with a "near stock" cam.

Stock 6X-4 heads they don't flow air nowhere near the stock # 16 heads.

I have a 1968 Firebird coupe with a 428 +30 over - wide ratio Muncie and a 12 bolt 3.5 posi rear.

The heads I use are 1971 # 96 milled for a compression ratio of 9:1 with Magnum 1.52 roller tip rockers.

Stock heads only flow to about 4000 rpm. Check Out the Wallace Racing Calculators and shift points - very informative.

I have too much rear gearing in my 1968 Firebird. My latest Firebird project is a 1967 with a Mutt 455 again # 96 heads un-ported.

The 67 has a 3.07 rear and Big Injuns seem to love either a 3.07 or 2.73 rear gearing for a street car.

Good luck - Mutt 455

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On 3/26/2016 at 5:43 PM, holsey82979@hotmail.com said:

Hello to whoever reads this..I am building a 428 .30 over flat top piston with 6x-4 heads.I had 16's but the cr was too high causing detonation.I am using these heads and 1.52 roller tip rockers,rpm intake,headers 2 1/2 exhaust,pertronix hei,and a jet street master 750 quadrajet. need info on a good camshaft(heard you cant beat the 068),stock converter or stall,headers or RA manifold,gearing,timing recommendations,spark plugs,best oil to use,and whatever else your wisdom can offer from experience.If I can get anywhere near 400 horsepower im good.I need too get this thing right this time.Its all in a 71 lemans.
Thanks

you do know that some of your problem is 50 year old iron heads but i think you said your against aluminum for some reason. i dont know what cam your running but you have to watch your  overlap . if your going to buy another cam , buy something w/more lobe seperation. if your going to just cruise the streets you dont want to ruin your engine w/ detonation. get a spring kit for your dist and follow the directions you will be surprised. you can miss match different colored springs to rid yourself of detonation. the head gaskets mentioned are a quality product but as you probably know are expensive. summit has a cam for pontiac that has a part # SUM2800. if you want to really get down to it talk to comp and order a hyd roller you wont be sorry. good luck HTHOM

Edited by HTHOM
WRG #

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