Holley 4150 wet carb base gasket

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billytuffnuts

billytuffnuts

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I rebuilt my holley 650cfm double pumper carburetor (List 4777-5) and after reinstalling it, the engine had a high idle and unresponsive idle adjustment and idle mixture screws. I pulled the carb to verify the transfer slots on the primaries and secondaries were not over exposed and I noticed that the base gasket was wet. I did torque the carb to I think 75 or 80 in lbs per holley's website. The transfer slots looked ok so I am hoping this might be related.

The image shows what the gasket looked like after about 15 minutes of run time. There were no external fuel leaks. What would normally cause this? Warped baseplate?

holley.jpg
 
Never seen anything like that before.
Maybe check your base on a flat piece of glass with feeler gauges.
I tighten diagonal in stages by feel.
80 in.lbs. divided by 12=6.6666666666
there`s your problem, you introduced the number of the beast in your work:eek:
 
You should be using a thick insulator style gasket. They seal much and they can seal uneven surfaces. They also insulate the carburetor against fuel percolation. I'll never run a thin gasket again now.
 
RustyRatRod said:
You should be using a thick insulator style gasket. They seal much and they can seal uneven surfaces. They also insulate the carburetor against fuel percolation. I'll never run a thin gasket again now.
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Do you have any examples of the kind you use or where to get them?
 
billytuffnuts said:
Do you have any examples of the kind you use or where to get them?
Click to expand...
Yes sir. You should match up the gasket to the type of manifold you have. Since you're running an unmodified dual plane with the center divider intact, you should use the same type gasket, so I recommend this one. With the type gasket you have now, you really don't have a 100% dual plane intake manifold anymore. Even though it's a small amount, both sides of the intake are connected without that center divider on the gasket. That can do some funky stuff sometimes. You will likely need to retune the carburetor and I would also recheck the timing after you install that new gasket.
Caburetor Base Gasket
 
Just wanted to post an update: I pulled the primary metering block and noticed that somehow I managed to double gasket the power valve. Hoping that’s the cause
 
billytuffnuts said:
Just wanted to post an update: I pulled the primary metering block and noticed that somehow I managed to double gasket the power valve. Hoping that’s the cause
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Not likely. Just use a similar gasket to what Rusty showed and be done with it.
 
OldmanRick said:
Not likely. Just use a similar gasket to what Rusty showed and be done with it.
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News flash, it's quite likely gonna fix it.... I was about to post in this thread last weekend to double check the power valve, cause a leak at the power valve will cause the base gasket to get wet.... Unfortunately my computer froze & by the time I got it working again I forgot all about this thread...
 
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