Thread: Chevy 350, zero compression. engine not starting

Tweet

Originally Posted by JbRat

oh.... why is that?

Because:
1. You cannot intelligently choose a camshaft for a motor until you know the exact static compression ratio, which requires knowing 5 different volumes: cylinder volume, combustion chamber volume, piston deck height volume, piston crown volume and gasket volume.
2. Looking for a lope without the supporting static compression ratio and other speed parts tags you as a poser, a person who wants to pretend he has a hot motor in an otherwise stock street cruiser. Not sure why, but that really whizzes me off. I very much dislike pretentiousness in any form. I got into trouble on another forum for calling one of the posters a poser, but it is what it is. If I get bounced from this forum, I suppose I'll live through it.
3. According to Iskenderian, extending the intake closing point past where it should be for a low compression motor will allow the ascending piston to push air/fuel mixture back out the "closing, but still open" intake valve and up the intake tract to disrupt the metering of the carb. The venturi adds fuel to the air slug on its first trip down into the motor and then adds more fuel when the slug goes backwards past the venturi again, then even more fuel when the slug reverses and is sucked back down into the motor for a final trip. This is why motors with lumpy cams load up and have to have the throttle blipped every few seconds just to keep idling.

I wrote this tutorial. It may help you to understand what cam to use with what static compression ratio to make a solid performer, not a poser motor.
http://www.crankshaftcoalition.com/w..._compatibility

Glenn, there may be some validity to the overlap period causing a lumpy idle, but Isky says that there is insufficient pressure in the cylinder during overlap to cause reversion of the intake slug back up the intake tract. I know nothing, I only write what others tell me if it sounds right according to common sense and my experiences.

.