433 Build 

I hope to now have the engine my car finally deserves. To make a long story short, I have had terrible luck with the current 455 based motor in the car. The first .035 over 455 sucked down a carb base plate bolt cracking one cylinder wall and scoring another. I put a sleeve in the one cylinder but the score in the other did not hone out so I went with new ICON .040 pistons which gave me a 9.6:1 compression and required a re-balance etc so the repair turned into a full on rebuild. The new 464's mains went out of alignment likely due to the sleeve installation and wiped out a main bearing. Out came the block again, the mains were aligned and a new shorter timing chain was installed.


The engine did well enough for me to replace my ported iron heads with a new set of KRE aluminum heads which were CNC ported by SD performance. The new heads also boosted the compression to 10.5:1 and the performance was phenomenal. So much so, I overspun the engine, hit 7,000 RPM and promptly spun #7 rod bearing. Out came the motor again. The crank was reground, the H-beam rods were re-sized and fitted with new ARP capscrews. The solid flat tappet cam was showing signs of going flat so it was replaced with a roller cam. To lower the RPM range a bit, a dual plane manifold was installed along with a rev limiter.

This 464 is truly a nasty street engine making every bit of 530-550hp. With the dual plane and current valve springs, it's done before 5800 RPM which does not match my gearing or the way I drive the car. It eventually developed a knock which I knew well by now and I pulled the oil filter and it looked like someone dropped a glitter bomb into my oil filter.

So, I have concluded the 455 is both cursed and more importantly, not well suited for my car due to the long 4.21" stroke. My car was designed around a 3.75" stroke 400 engine. I am not getting any younger and outside of the engine, I am really happy with the way the car works. Time to build a proper engine for the car.

I have had virgin 400 (988 casting) engine stored away for the last 15 years out of a Canadian Oldsmobile Delta (go figure). I took apart this motor and it was perfect and had absolutely no signs of any wear or that it had ever been opened up. The 400 is the best base to build a stock block Pontiac. Relative to displacement, I believe my needs would be best served with a 4" stroke combination which combined with a 4.150 bore will put this engine at 433ci. There is a reason why this combination is well suited to my intended use and if you want a good read, go here: http://wallaceracing.com/enginetheory.htm

Since I needed this engine to be virtually indestructible, I am going with a .030 overbore, Racetech custom flat top pistons, 6.8" long Eagle rods and a Scat 4" stroke, forged steel crank. Final compression ratio will be 10.6:1. All of it will be held together by Program engineering splayed 4 bolt main caps. I will mill the KRE's down to 77cc and retain the 464's roller cam. I will keep the dual plane but this motor may very well work better with a single plane manifold. We'll see. This engine should be capable of handling anything I can throw at it and have headroom for more. Goal will be to equal if not exceed the 464's HP but improve performance by making torque where I can use it and extending the RPM range out. Here is a link to a build that is 100hp more than my target but a virtually identical short block. http://www.hotrod.com/articles/ccrp-1012-pontiac-400-poncho-engine-build/

I will post updates as I go along but thanks for going along this far with me. This promises to be a long and expensive ride!!

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