Will it run on Pump Gas?

[Johnny Blaze]

Getting ready to finish up my 355 build. Here is the info,


355 SBC
Hyperutectic pistons flat top with 4 valve releif

Heads areCast Iron 083 castings 64 cc chambers. Chambers polished.

Quench is .035" if I run a thin head gasket.

Static compression with thin gasket comes out to 10.23:1 Custom Tuned ECM

Engine will be fed by a TPI Mass Air Flow system.

Cam is a Comp Hyd. Roller part number 08-501-8

212 intake 218 exhaust @.050"


Will this combo be happy with 92 octane?

If I put a thicker head gasket on it will drop my compression to about 9.73:1 but quench will jump to .059"

Thoughts?

[72BBSwinger]

If the cam has a lsa of 112 or so that would help and along with that so would more duration at .050 like in the 240 range. With the right cam specs you can leave the quench alone. Try to emulate like an ls7 cam with less lift. Look at the cams in the newer engines and you will see how they're living on pump gas with their 11.1 + comp. Aluminum heads would put you in the safe zone too.

[Johnny Blaze]

I don't think the TPI would be too happy with 240 @ .050"

LSA on cam is 112.

[Steve Chryssos]

It sure will. Especially with EFI and the extra duration on the exhaust side to help "get the heat out". So can a good valve job and bowl blending. The polished chambers will help eliminate hot spots. You'll fiddle with timing to find the sweet spot, but other than that, go for it.

[Johnny Blaze]

Just an update.

I finished this engine and ended up
installing it in a 1988 c1500 swb truck.
The truck was a 4.3 5 speed. I swapped in the 355, added 65lb injectors and a v8 chip. Bolted up to the 5 speed. Used a set of shorty eBay headers that worked great.

So far I have put 700 miles on the engine. I broke it in with Brad Penn Break in oil. After 500 miles I swapped to Pennzoil Platinum 10w30. I've read great things about it and fell for the hype. Seems like good oil.

I also switched to Wix oil filters, after hearing bad things about others.

I swapped in a v8 radiator and an electric fan.

The engine runs great! I am suprised at the power. It really takes off at 3000 and pulls hard on up. I've only gone up to about 5500, which is about as high at it needs to go.
Thing is it doesn't fall flat before then, and that's with a stock tbi intake and tb! Not too mention stock size single exhaust!

I plan to swap a 3" single exhaust and y pipe soon, along with the dynomax ultra flow sitting on my shelf.

I'm not sure about the intake, I have a 454 tb, but I also have a ported tpi with slp runners that were planed for this engine. Just not sure I want to deal with the swap. I'll gain low end, which this truck doesn't lack.

Anyway, as for running on pump gas, it does just fine! In fact, it's been running on 87!