Carb jetting

[elwood]

Hey guys, I was wondering what would be a good starting point for jetting a couple 8ba carbs ?
Merc crank in a french block, factory relief, Potvin cam from Pete, Edelbrock heads and 2pot intake ..
Thanks ...

[Mart]

94s or 97s?

I use 2100s which are 94s with a 1" venturi. I have jets which are the equivalent of a 54. I use stock power valves but shorten the springs so they close easier. I often hear people say to use leaner jets than stock. 51s are stock. I believe if leaner jets work, the carb is running rich doe to another problem. There are many reasons it will run rich, including bad power valve, bad power valve gasket, warped housings, bad float setting etc etc.

I'd just chuck em on there with stock jetting and see what happens. But if rich, make sure it is not due to one of the other reasons. You should be able to tune the idle mixture on the idle mixture screws. If it runs with them all the way in, It is too rich for one of the other reasons.

Mart.

[weemark]

if you have 97s, I would go with a 67 powervalve and a 43 jet to start with.

[1952henry]

He stated 8BA carbs, which would be 94s.

[Curt in AZ]

What change to sea level jetting for an engine living at 4,000 ft? Is there a rule of thumb?

[elwood]

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Thanks guys,
Mart, that helps a lot, gives me a good start

[FlatheadTed]

A lot of the carb kits now have the jets drilled incorrectly ,Don't ask me how I know ? (Ford Escort ) Ted

[ford38v8]

Originally Posted by elwood

Hey guys, I was wondering what would be a good starting point for jetting a couple 8ba carbs ?
Merc crank in a french block, factory relief, Potvin cam from Pete, Edelbrock heads and 2pot intake ..
Thanks ...

Elwood, I didn't answer initially because I thought you had dual carbs. Mart is correct for a single carb, at .051", but dual carbs would be smaller, I don't know how much because I never ran duals.

[ford38v8]

Originally Posted by Curt in AZ

What change to sea level jetting for an engine living at 4,000 ft? Is there a rule of thumb?

Curt, Sea level to 4000' can use the same jets. If you have 51's in there now and drop to 50's, that should work for both elevations. Bottom line, of course, is how it runs, and what the plugs tell you.

[Mart]

Originally Posted by ford38v8

Elwood, I didn't answer initially because I thought you had dual carbs. Mart is correct for a single carb, at .051", but dual carbs would be smaller, I don't know how much because I never ran duals.

That was the point I was trying to make. Try it with stock jets in both carbs first. Only try smaller jets if you are sure it is too rich purely due to the jet size and for none of the other reasons given above.

Automatically assuming smaller jets are needed may be a mistake. My personal experience was that my car ran bad with anything smaller than 51s. (With twin carbs).

Mart.

[Curt in AZ]

Thanks ford38v8. I'll check the plugs, but it's good to know a starting point.

[scicala]

Originally Posted by FlatheadTed

A lot of the carb kits now have the jets drilled incorrectly ,Don't ask me how I know ? (Ford Escort ) Ted

FlatheadTed,

Where did you find a carb kit with main jets ? In all of the carb work I've done in my life, the only ones I can think of are the old old Holley Master Kits, or some of the Stromberg 97 kits I've seen online.

Sal