412 Carburation

[Pogel]

My daughter's 412 has a Progressive carb. It does lousy gas mileage It was doing only 12 mpg, but after some tuning it's up to 16. What would be the best jet set up? We are at sea level. Some of the literature shows putting the larger jets as primary while others say smaller as primary.

I have read that center Progressives are no good on Type 4s. It runs nicely, just does poor mpg.

[sharkskinman]

dual solex 40s is what the type 4s ended up with After the F.I.

altho the F.I. is great
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74 Mexi Swamp Thing. 70 square volksrod (Swamp Rat)..65 C10

[raygreenwood]

With low milage ...it means that it is also running a short dirty life inside of the engine. I am not a fan of the progressive carb on these engines. It requires not only proper jetting but manifold heat. That carb was never built for runners that long.

That being said....send a PM to Wildthings. I understand he is an expert at getting progs to run much better than average on these engines. Ray

[Pogel]

Sharkskinman do you have a photo of your set up? Do the carbs fit beneath the engine cover? I also have some dual Dellorto carbs which I might be able to fit on.

Ray thanks for the info. I'll see if Wildthing can help.

[sharkskinman]

sorry mine is F.I. and i have a 411 so no engine lid
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74 Mexi Swamp Thing. 70 square volksrod (Swamp Rat)..65 C10

[rjhucka]

New to posting so excuse me if I am improperly posting this. I have a 71 411 I have purchased for my son. the 411 came with an old Rochester carb. I have it running fine, with the exception that the idle of the engine surghes up and down, and the power is not so great. I have rebuilt the old Rochester and no real change. Any ideas?

Thanks!

rjhucka

[Mike Fisher]

Change it back to it's original fuel injection or dual Solex/Weber carburetors? Does the single Rochester stick up through the engine lid?
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https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[rjhucka]

No, the Rochester fits fine as it is a fastback with plenty of room. I have most of the FI parts and can probably find needed items, but as I am recently unemployed and working on a shoe-string, trying to make the Rochester work.

I suspect the problem might be one of the following:

1. The two leads out of the fuel tank, one is being used with an electronic fuel pump to push to the carb. The lead is other is capped off altogether. Would this lead to a pressure surge up and down? Like a "gurgle" in a gas can without the air release cap opened?
2. When I bought the vehicle there was a pressure regulator (after market - not a regular FI pressure regulator) with a dial on it that was leaking so I toook it off. Maybe fixing the regulator and setting properly might help? I have seen such aftermarket regulators on other bugs etc.

Thanks for any help and for your reply

[Mike Fisher]

You better buy a buy a new Holley etc fuel pressure regulator and PRAY you can dial your electric fuel pump down to about 3 lbs pressure for carburetors.
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[rjhucka]

Thanks! I give this a try and will let you know.