Trying a new carb

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May 1, 2005 | 08:22 PM

#16

Bear 45/70

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From: Union, Washington

Quote:

Originally Posted by Fordbronco69

Both carbs where setup the exact same as the other. Same spacer, fuel line, type of fuel, ect. The only difference where the 2 different carbs. And i didnt adjust the carbs right away...they came pre-adjusted from the factory. It the only way my dad will buy them. After 2 weeks of testing both carbs my dad tuned them to see what they can do, and the Edelbrock came out on top. When he tuned it to max hp it spun all 4's on my truck. Right now the Edelbrock is on my truck and he stuck the holley on his 3500 and is trying to find out what exactly is wrong with it. Its a dog at 2900 RPM on his truck.

I'm talking the carb itself. What vacuum secondary spring, jets, how were the mixture screws set, what power valve was in the carb. From your discripton sounds like the secondaries are either open way to fast (probably not) or not opening at all (most likely). A new carb, factory adjusted doesn't mean anything, they set thing for an average. Each engine is an individual and the factory is not perfect, bad thing get out to the public.

May 1, 2005 | 09:08 PM

#17

dffay

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Joined: Dec 2003

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From: New Mexico

Which model of Holley 600 cfm carb have you guys been using? There is a double pumper version (4150) and then there are the 1850 series square bores.

May 1, 2005 | 09:44 PM

#18

Bear 45/70

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From: Union, Washington

Quote:

Originally Posted by dffay

Which model of Holley 600 cfm carb have you guys been using? There is a double pumper version (4150) and then there are the 1850 series square bores.

Unless you are building a race setup, go with 1850 series carb. BTW, I have 4 of them on my bench right now, one is a parts carb and one is going on my 460 and one is for a buddies 396 chebby and the other is spare for anything the goes wrong.

May 1, 2005 | 11:39 PM

#19

Fordbronco69

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Joined: Aug 2003

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From: Elkhorn WI

1850 is the number i just pulled off of it. Dad says the secondarys would get stuck half way when they would try to open. It runs ok now..but somthing is still not right. Its 2 weeks old and already we are having problems with it!

May 2, 2005 | 02:03 PM

#20

dffay

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Joined: Dec 2003

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From: New Mexico

Glad to see you guys are having good luck with it. On the Holley website, 600 cfm is listed as too small for a 390 cid engine. It shows it would work better on 351.

May 2, 2005 | 06:43 PM

#21

Bear 45/70

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From: Union, Washington

Quote:

Originally Posted by dffay

Glad to see you guys are having good luck with it. On the Holley website, 600 cfm is listed as too small for a 390 cid engine. It shows it would work better on 351.

I don't see how anyone could say that a 390 street motor needs more than a 600 CFM carb. Fords HP 390 engines came with them except for the 3X2 setups. At 5000 RPMs a390 only needs a 600. A 600 CFM is good to damn near 6000 RPMs on a 351 and a street motor is wasting its time up there unless the own cares naught about the price of fuel. A 460 truck engine come with one too,

May 2, 2005 | 08:37 PM

#22

rusty70f100

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From: Iowa

FWIW, my 390 motor makes noticably more power with the 700cfm fuel injection than with the 600cfm Holley vacuum secondary carb. Too many variables to draw any definate conclusions though.

May 2, 2005 | 10:14 PM

#23

Bear 45/70

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From: Union, Washington

Quote:

Originally Posted by rusty70f100

FWIW, my 390 motor makes noticably more power with the 700cfm fuel injection than with the 600cfm Holley vacuum secondary carb. Too many variables to draw any definate conclusions though.

A carburator works very well at Idle and WOT. Everything else is compromise. The FI makes for correct fuel mixture and distribution at all engine speeds, there for overall better preformance and fuel economy. Carb to FI comparisionds are an apples an orange comparision and unfair to the carbs design limitations. FI also covers up overlarge throttle bores also and thats why most EFIs run on very large throttle bore areas compared to the amount of area carbs can run.