*NEW UPDATED* W72 Build Plans, Getting Stroked
Good Evening everyone, as many of you are aware of from my other W72 build thread, we are getting ready to build yet another Pontiac 400, this time a 1979 PWH W72 400 out of a Trans Am. The original plan in my other thread was to upgrade the 400 as much as possible while retaining the numbers matching parts on the outside, but after calculating the cost of good pistons, better 5140 rods, and having the crank turned and everything balanced, it comes within a few hundred dollars of just buying the Butler Performance Balanced Stoker rotating assembly ready to install, after I get the block decked and bored, and the end result is much better parts for the money, a bigger 467 c.i. engine, while retaining the numbers matching look to the eye. At this time there will be no head porting in the budget, just a nice rebuild and valve job on the 6x4 heads, upgraded with Ferrea stainless valves, Crower 68404 springs set up at 1.570" Installed Height, and 7/16" studs and poly locks. This engine should come out somewhere between 9.6 to 9.8- 1 compression. We are now thinking we will use the Lunati VooDoo 704 camshaft in this. Here is how the build plan looks now
1979 PWH 400 XX block Bore- 4.181" Zero Decked Butler Performance Rotating Assembly Eagle 4.250" crank Eagle 6.800" H-Beam rod Ross/Butler 8cc Flat Top 2VR piston Total Seal Plasma Moly rings Melling M54DS pump Stock (non ported) 6X4 heads, 7/16" Studs and Polylocks, Ferrea Valves Felpro 1016 .039" head gasket Quench .039" Compression- 9.6 to 9.8-1 Lunati VooDoo 704 Camshaft 276/281 Advertised Duration 233/241@.050 .504"/.527" lift 110° Lobe Seperation Thinking of Installing it at 104° I.C. according to the advice of Harold Brookshire and Paul Carter Crower Camsaver lifters Crower 68404 Valve Spring installed at 1.570" Cloyes 3512X9 billet timing set Stock 1.5 rockers Stock Cast Iron intake Qjet Recalibrated with Cliff Ruggles parts Recurved HEI distributor 1 3/4" headers, dual 2.5" exhaust Super T10 4-Speed Manual transmission 3.23 rear gears This is 100% street car on pump gas in an original 1979 Trans Am. What do you'll think about the new stroker plans? I know head porting would be even better for the bigger engine, but it is not in the budget at this time. Sound like a good plan? Thanks |
To help that late production block live with that .060” overbore you going to want to do a half fill on that block!
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Build looks good, hopefully it's a later 4 speed block. I'd opt for the forged crank option. I've seen just enough of the Eagle cast cranks break to avoid them, if nothing else you'll sleep better at night. Never tried one of those cams but I have had Lunati grind several custom cams for us on wider LSA's with excellent results. Most recently they did a cam for us for a 425 Olds build, then another for an Olds 455. Both were in the 230-240 @ .050" range moved out on a 113LSA. Good idle, throttle response, street manners and no issues whatsoever on pump gas with mid 10's for compression........Cliff
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That's our recommended build for the 78 and 79 400's. We build a lot of them. You can save money by using a cast crank, cheaper forged rods and put that money towards some head work and pick up extra power.
You will need to swap out the flywheel because the aftermarket cranks use the 2.75 hub |
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The extra stroke will get the CR better also. If you are going Ferrera valves I'd still go longer so you have a better IH.
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That is what the "For Sale" section is for:)
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Interesting build, what horsepower are you shooting for/expecting? How come you're not keeping manifolds vs headers while retaining numbers matching parts throughout?
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Evaulate what the pressure will be with the Crower 68404 valve springs at your VERIFIED installed height. With that in mind take notice that based upon his dyno testing and extensive use of Voodoo cams Paul Carter recommends 130-135 lbs seat pressure with 30 degree seats and 330-340 lbs open pressure with the Voodoo hyd flat tappet lobes. Less pressure ok with 45 degree seats, still shoot for 110-115 at least for the Voodoo 702 & 703.
Also he suggests to keep the distance from coil bind around or under 0.100". Also keep in mind valvesprings will lose pressure after run in. . |
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I love PY, So much knowledge in these pages.
GT. |
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That's a pretty choppy cam if ground on a 110 LSA. Not saying it won't work, at all, but be prepared for a pretty rough idle.
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