1966 L36 Holley 3370 Carburetor Questions

[Joseph S.]

Having some issues with my '66 L36 Holley model 3370 Carb.

Primary fuel bowl is leaking through into the intake manifold, have changed metering block gasket but still drips through. The carb continues to drip from a port adjacent to the passenger side primary venturi. The port originates on the metering block but seems to go nowhere - everything else seems flat and true. I have read another forum where the advice was to plug the port. Maybe someone has experienced similar issues.

In addition, can't seem to find (from suppliers or Holley) a base gasket that totally fits the contour of the heat riser cavity. Am concerned with an exhaust leak and considering plugging up heat riser holes in the manifold under the carb. Does anyone know of a good supplier for the base gasket or know of any issues plugging the exhaust ports.

Thx Joe

[Joe L.]

Re: 1966 L36 Holley 3370 Carburetor Questions

Having some issues with my '66 L36 Holley model 3370 Carb.

Primary fuel bowl is leaking through into the intake manifold, have changed metering block gasket but still drips through. The carb continues to drip from a port adjacent to the passenger side primary venturi. The port originates on the metering block but seems to go nowhere - everything else seems flat and true. I have read another forum where the advice was to plug the port. Maybe someone has experienced similar issues.

In addition, can't seem to find (from suppliers or Holley) a base gasket that totally fits the contour of the heat riser cavity. Am concerned with an exhaust leak and considering plugging up heat riser holes in the manifold under the carb. Does anyone know of a good supplier for the base gasket or know of any issues plugging the exhaust ports.

Thx Joe

Joe------

I HIGHLY RECOMMEND plugging the holes at the ends of the heat slot under the carb. No significant problems will be created. That heat slot has destroyed more carburetors than anything else I know of short of "klutz" rebuilders. In addition, if the stainless steel shield between the carb base and the gasket is omitted, the carburetor will be destroyed in short order.

GM abandoned the heat slot manifolds completely after 1969 for all applications.

[Timothy B.]

Re: 1966 L36 Holley 3370 Carburetor Questions

Can you post a picture of the leaking port you refer to. My guess is irregular surfaces at the gasket area or a mismatched gasket.

[Joseph S.]

Re: 1966 L36 Holley 3370 Carburetor Questions

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Appreciate the advice to block the ports on the exhaust slots. Have done it on small blocks in theist with good results.
Attached is a the picture of the dripping port on the base plate of 3370 carburetor. (top under pen point)

Joe

[Joseph S.]

Re: 1966 L36 Holley 3370 Carburetor Questions

Authored this post some time ago, about an issue with my '66 L36 Holley 4160 list 3370 carb. It may be of value to give an update as I have seen subsequent posts of members with Holley 4150 or 4160 carbs that have similar internal leakage and flooding issues.

After a few attempts at resealing the metering block to main carb body surface with different gaskets and insuring the main body and metering block (more later) surfaces were flat, the carb was sent off to one of the reputable carb rebuilders for testing. Best we could do was double gasket the metering block to main body surface interface, which only fixed the issue for a short period of time. However it confirmed what I thought the issue was, internal leakage between the metering block and carb body.

Carb body was flat, and I thought the metering block was also flat as I had put a strait edge across the entire length, however on further examination with a small straight edge there was a 1/32" warpage around the idle air passage troughs in the metering block. These troughs are adjacent to the power valve. I assume this was where my fuel leakage was occurring.

To my surprise I was also able to acquire a new service replacement metering block from Chicago Corvette. It would seem they have access to information and product I could not even get from Holley on replacement metering blocks, although they would prefer you send them the carb for complete rebuild.

Thought this would be of information to members who may be looking for new replacement parts and information on vintage Holley carbs. All is well with the replacement metering block - now just need to possibly get the original 4796 block resurfaced and the STV in the AC system straightened out. Joe