The Stovebolt Site Forums The Shop Area Engine Shop 235 Vacumm + Tune-up Questions

Hi Everyone,
I got a few questions.
When does the vacumm advance work on the distributor, and how do you check to see if it's not working?
If the VA is fine, what would cause pour vacumm?
Also how do you use the dwell on the 235?

vacuum advance, you can watch it move when the engine is revved. And you can check the module by gently sucking or blowing in it. Don't do either very hard, you will crack the diaphragm.

Dwell should be about 32, I usually set with a feeler gauge then check with the meter. V8s were easier, they had a window in the cap to set the dwell. Usually takes a couple of times to get reasonably close.

Do you have a vacuum gauge? It is a big help in tuning these non-computer engines. If your vacuum is low overall, check for leaks, either hoses or intake manifold.

Hi Fred T,
The vacumm advance on the distributor isn't working. I think i'm gonna have to replace it. I checked the vacumm line. I do have vacumm, but it isn't alot. Should there be alot of vacumm on a 1962 235?
I located a small exhaust leak on the #1 cylinder exhaust manifold. Would that cause low vacumm?
Also how much is a new manifold gasket, a exhaust doughnut gasket, and new manifold bolts?

You should have low vacuum at idle at the vacuum advance but it should shoot up to about 15-17 lbs when you rev the engine up to about 1200 rpm.

The easy was to set the dwell is : remove the plugs then adjut it whilst spinning that starter . more accurate and way faster that way .

if the dwell varies by more than 3 degrees when you rev. the engine , the dist. bushings are shot - time for another one , Pomona is March 2nd.

I recall you're in the SGV , go to NAPA on Truman in SF and ask Dave or Sue for NAPA Gasket # MS12185X tell 'em Nate sentcha for a discount .

When re-tighening the manifold to the head , start in the center and work your way out , this will prevent future leaks .

Should be _no_ vacuum at the dizzy @ idle , 18" ~ 21" at the manifold . retarded timing can cause low vacuum readings .

I " recall " you also Volkswagen Nate. Is your truck running HOT !!! I though you moved over to the " Old chevy Truck " section ??????????

Hi MT , no it never runs hot , even in Death Valley it keeps it's cool :-) . I had a custom oversize core installed in an original '49 radiator , I gotta find the time to install it though - it pukes excess water out the tiny header tank I have in there now .

I get hasseled for being here (work) so I can sneak on the other list more easily - hope you all are doing well .