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head gasket thickness how much is too much?

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crider:
Just fired the BBC in my dragster for the first time today, It acts like it had a giant vacuum leak. doesn't want to stay running I have closed the idle mixture screws completely and have the carb idle speed screws backed all the way out as well. I even tried taping the air bleeds off. It will stay running like that but is idling around 3,000 rpm with everything closed off? It's a 427 tall deck block. never decked. 1050 dominator on a victor tall deck intake, so no spacers between heads and intake.  I had to go with a .065 head gasket to compensate for a bit of positive deck height on the pistons. Is it possible that has raised the heads up enough that it could be sucking air around the intake manifold? or should I be looking at something else?

Frontenginedragsters:
Hello Crider:
 Sounds like a vacuum leak to me.
If its a tall deck block are you using spacers or do you have a tall deck intake?
Spacers work well but have an increase chance of vacuum leak.
Two types of vacuum leak are usually easy to find.
Use some type of spray can cleaner like brake clean. First spray it down the carb to see the reaction your looking for.
Some sprays will burn well and the engine will rev up. Some will try and kill the engine. Spray all around the intake to cylinder head area.
Also spray the base of the carburator to the manifold. Look for the same reaction as when you sprayed down the carb.
 The other type of vacuum leak is internal. Blank off the valve cover vents until you only have one open hole venting the engine.
You should have a small amount of blow-by or pulsing. If you have Vacuum there then the intake gasket is leaking from inside, in the lifter valley.
Most of the time when its internal its also sucking oil in from the lifter valley. Look at your spark plugs.

Hope you get her fixed, summer is winding down.

Matt

crider:
Yes, it's a tall deck manifold, so no spacers. I'm pretty sure it is a vacuum leak too. Hopefully I will get a chance to work on it some this week. I'm still a long way from being ready to make a pass down the track. But I have until early Dec. before the last of the semi-local tracks closes down for the winter. Hoping to get it to a point I can make a few passes so I know what needs changes so I can be ready next spring

crider:
Ok, still struggling with this thing. What can act like a vacuum leak that isn't a vacuum leak? I have checked for leaks everywhere I can think of to look. I've sprayed starting fluid around the carb base and intake flanges with it running. No changes while being sprayed. I puled the intake off and sealed off then pulled vacuum on each intake runner again no leak found. Put the intake back on and sealed the carb flange off and hooked up a smoke machine to it and couldn't find any leak that way either. I am stumped. Is there anything in the carb that could be causing this? 1150 2 circuit dominator. I pulled it completely apart and cleaned every passage. Didn't find anything that was blocked.  Or any other ideas as to what may be causing the problem? I'm out of ideas

BK:
Are your headers real short or real big? I watched an engine without headers, just open exhaust ports not idle. Put headers on ran normal.

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