Thread: Chevy 350, zero compression. engine not starting

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Originally Posted by JbRat

old guys...hmmm I'm probably older..lol... how about the permatex copper spray, have you ever used that?

I have - but prefer a brush on as it's easier to control where it goes!!

Before copper coat, we used aluminum spray paint.. LOL!

wow.... when I was young we were so poor and so old we used pine tar mixed with wood ash.

I'm going to pine tar my engine...hang it up as decoration so i remember what a fool I was...

Originally Posted by JbRat

wow.... when I was young we were so poor and so old we used pine tar mixed with wood ash.

We were so poor we used both sides of the toilet paper.


(Sorry - couldn't help myself...)

at this point in time I need a bit of humor thanks....

Originally Posted by johnboy

We were so poor we used both sides of the toilet paper.


(Sorry - couldn't help myself...)

At least it wasn't corncobs.

Just a minute there-------I've used corn cobs and mostly Sears & Roebuck cataloques-some Wards and Pennys also-oak tree leaves aren't too bad but corn stalk leaves------UGGGGGGG

Update: I gave up... pulled the engine last night and taking it to a local shop that has full machining capabilities... we will see what is wrong with it and document everything. It will be interesting...

Getting pretty good at removing engines.. less than two hours from car to back of truck..lol..

well.... its been almost two weeks... as shared I pulled the engine and brought it to another local, recommended, that has a pretty extensive shop and does all his own machining. we started the tear down... here's an engine that was supposed to have the lower end done, new pistons, bored 30 over, heads machined and rebuilt... etc etc.... so far we have found 1972 bearings on the crank so definitely not touched, no bent rods so that was good but cam pretty beat up. Major ridges in the cylinders so definitely not bored...probally ball honed to take most of the ridge off. two different heads which i mentioned before.

What we are doing is grinding the crank...
new bearings
new pistons
bored least as possible to clean up the cylinders
swap the one head so I have two of the truck vortec heads with the hardened seats, magna fluxing them also
modified cam so it has a bit of a lope..i forget the specs off hand.
and the basics which goes with it all...

hoping to have it back wed or thursday and we'll try it again

Originally Posted by JbRat

also modified cam so it has a bit of a lope..i forget the specs off hand and the basics which goes with it all...

Mistake......

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oh.... why is that?

The whole “lopey cam” sound is really over rated. Its one thing to hear a lope at idle at the strip where the engine needs a lot of lift, lots of duration and a narrow lobe separation to maximize the air flow through the engine. It will scream to 6,500 RPM and beyond and run for a few seconds but idles like crap – which is okay at the strip. We all love that experience and somehow think it can be had with our street engines that rarely see over 5,000. The lope you hear is the overlap when the intake and exhaust valves are open at the same time and the intake charge is going out the exhaust port. Might sound “cool” but to an educated ear it indicates a bad choice of cam and money being wasted.

I’m really not trying to bust your chops, but extreme duration and narrow lobe separation on the street is a recipe for disappointment. 220-230 at 0.050 and 110-112 degrees separation are good numbers to work from for almost all street applications. I tend to take a somewhat conservative approach to cam selection for street drivers. My choice may not be the most powerful – especially above 5,000RPM, but it will offer an engine that will generate decent power and perform well for a long time between idle and 6,000RPM. To the untrained ear that lumpy cam may sound bad ass, but they just don't work well in street drivers.

My two cents,
Glenn

Definitely uneducated in this aspect so appreciate the responses... any and all work for me... going to call the builder and discuss in the am. Thanks...

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.

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