Edelbrock 4 Barrell

[37fatfender]

If anyone is using a Edelbrock 4 bbl on the flathead I would be interested if you have rejetted the carb or what other tuning you have done. I have mine on a 255 ci motor with a Schnieder cam. The plugs are always black, so I went to smaller jets per Edelbrocks tuning chart...still rich. I live at 2000 ft above sea level and frequently go over 5000. How does altitude affect jetting? Higher the altitude smaller jets ?

[52merc]

what size edelbrock you running a 500 or 650

[52merc]

richard in fl runs a 500 on a 276ci engine he has not changed the jets but has played around with ignition timing he gets great milage,i have however have a500 on my 271ci ive gone down 2 jets sizes also took out the main jets and put them into the vac secondary hope this helps

[37fatfender]

I have the 500 cfm carb, gone done one size. Ignition is the MSD ready to run dizzy.

[Chuck Sea/Tac]

The altitude does make a difference . I'm sure an engineer type will chime in with the figures.

[Richard in Florida]

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Originally Posted by 52merc

richard in fl runs a 500 on a 276ci engine he has not changed the jets but has played around with ignition timing he gets great mileage.

As Trev said, I'm running a Performer 500 on my 276 with stock valves, an L100 cam, Red's headers, and various other touches.

Back when I was running a simple HEI module driven by a Chevy distributor converted to a magnetic trigger I was getting about 8.5 mpg with the stock Edelbrock setup.

After a lot of experimenting I ended up using Setup #11. I now run high 14 to high 15 A/Fs with occasional 16s in cruise. My mileage went up to 21.3 in my 3300 lb '53 Victoria with a 4.10 rear and .72 overdrive.

[36rgtop]

Originally Posted by Richard in Florida

My mileage went up to 21.3 in my 3300 lb '53 Victoria with a 4.10 rear and .72 overdrive.

Is that 21.3 MPG best highway MPG or best combined MPG (highway+city)?

[Richard in Florida]

Originally Posted by 36rgtop

Is that 21.3 MPG best highway MPG or best combined MPG (highway+city)?

That was 2/3 city (town) and 1/3 highway. You have to drive the 2/3 to get to the 1/3.

[37fatfender]

Richard, What jets did you put in the secondary, if any change? Did you do any secondary tuning ? what plugs do you use? and their gap?

[36rgtop]

Originally Posted by Richard in Florida

That was 2/3 city (town) and 1/3 highway. You have to drive the 2/3 to get to the 1/3.

Thanks, then I can assume that's a little less around town and a little better on the highway.

[dude]

Good base line would be to call Edelbrock tech. They are very helpfull. Might just save you some time and money.

[Ol' Ron]

We've been tuning with a wide band AF meter. This also includes a vacuum advance curve as well as the Mechanical. Different engines require different settings to get this kind of economy. Also piston to head clearance is critical.

[Richard in Florida]

Originally Posted by 37fatfender

Richard, What jets did you put in the secondary, if any change? Did you do any secondary tuning ? what plugs do you use? and their gap?

Setup #11 uses the stock .065 x .052 metering rod; the main jets are changed from .086 to .083.

I didn't do any secondary tuning. When I floor it and the secondaries open, the A/F goes to 12s and 13s, which is good.

I run NGK F4 plugs gapped at .025 which is right for the flathead even though I'm running electronic ignition.

[Richard in Florida]

Originally Posted by 36rgtop

Thanks, then I can assume that's a little less around town and a little better on the highway.

Probably, but I didn't try to separate them.

That 21.3 mpg run was made with a 4.10 rear end. The next run should be interesting with the 3.54 I recently installed.

Setup #11 has proven to be the best blend of economy and performance for my car.