327 carb jet size - Team Camaro Tech
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post #1 of 25 (permalink) Old Apr 7th, 10, 06:57 PM Thread Starter
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Logan
 
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327 carb jet size

I have a 327, .60 over, with a lunati cam with 290/297 duration .490 lift, 1.5 roller rockers, KB flat tops and holley 68cc 2.02/1.60 valve heads. Weind dual plane intake, and i have a double pumper with no choke tower and the main body has the numbers 6R2762 and i dont kno for sure what size it is. I put it on their and it had a horrible bog, so i took it apart and cleaned it up and seen it had 70 jets in the front, and 75 in the back. Does anyone know for sure what size this carb is, ive looked it up on the internet and some say its a 750, some say its a 780, and some say its an 850. I was just wondering what size jets i should use and if the jets in it right now are too small or too big. Any help is appreciated and i thank you all in advance!
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post #2 of 25 (permalink) Old Apr 9th, 10, 09:53 PM Thread Starter
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Re: 327 carb jet size

Does anyone have a carb like this and kno what size it is for sure?
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post #3 of 25 (permalink) Old Apr 10th, 10, 01:44 AM
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AJ
 
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Re: 327 carb jet size

I can't tell you the size, but we have about the same set up and I can tell you 750 is huge on a 327" motor.
If you can find out near the stock specs for the mystery carb or similar I would go back to the factory jets from what others have said to do.
I do know that those jet sizes are huge. If you cant find factory specs try going to 65 up front, and get the correct power valve.
The choke tower missing usually has a pretty important part number and could be associated with the bog, more air coming in and the fuel mixture needs to be adjusted.
Also, if your timing isn't set right, I'd suggest at least 18*-22* initial advance.

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post #4 of 25 (permalink) Old Apr 10th, 10, 08:25 AM Thread Starter
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Re: 327 carb jet size

Ok thanks, i will probally try 65s in the front and 70s in the back. Thank you for your help
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post #5 of 25 (permalink) Old Apr 10th, 10, 08:29 AM
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Re: 327 carb jet size

I wouldn't say a 750 is too large at all. I have a simular build and mine loves a 750. I've put a 670 on it for some type of fuel savings, but had to go to a larger squirter to match that of the 750 to match peddal response and get rid of the bog. I believe it's a 37 now. Jets are 74 in front and 78 in the rear.

750 would be too large for a stock build though.

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post #6 of 25 (permalink) Old Apr 10th, 10, 10:12 AM
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Re: 327 carb jet size

X2

I have a Holley 750 on my 327, but it's pretty stout little motor and runs just fine!
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post #7 of 25 (permalink) Old Apr 11th, 10, 01:12 AM
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Re: 327 carb jet size

FWIW I do have a 750 eddy on a hot .040" 327.
The problem is at idle the little motors aren't as efficient at idle and low end, and the big cams make the scenario even worse. At idle the 750 is way too big if set up incorrectly for our motors, but in the upper rpm bands where these motors like to be, the fuel mixture goes dangerously lean, which is my problem.

The only Mustang I'd ever own is a Fender.

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post #8 of 25 (permalink) Old Apr 11th, 10, 06:18 AM
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Re: 327 carb jet size

Quote:
Originally Posted by ace's68 View Post
FWIW I do have a 750 eddy on a hot .040" 327.
The problem is at idle the little motors aren't as efficient at idle and low end, and the big cams make the scenario even worse. At idle the 750 is way too big if set up incorrectly for our motors, but in the upper rpm bands where these motors like to be, the fuel mixture goes dangerously lean, which is my problem.
The problem is the operation of your carb, not the size of it.

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post #9 of 25 (permalink) Old Apr 11th, 10, 07:11 PM Thread Starter
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Re: 327 carb jet size

Well, i put the 750 on, and it actually idled better for some reason, and but bogged really bad when i opened it up, and when i took it apart it had some trash, so im thinking bout trying it agian with the same jets and seeing what happens now that its cleaned out
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post #10 of 25 (permalink) Old Apr 12th, 10, 01:16 AM
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Re: 327 carb jet size

Test wide open throttle from different rpm's. Start low around 2,000rpm floor it and see if the bog decreases with rpm. This will tell you a lot about what is going on, if you need more of accelerator pump shot or not and so on.

The only Mustang I'd ever own is a Fender.

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'14 5.0 Mustang
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post #11 of 25 (permalink) Old Apr 12th, 10, 09:11 PM Thread Starter
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Re: 327 carb jet size

Well I didn't get the time to try it out today but tomarow I'm gonna put it on their and see what it does
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post #12 of 25 (permalink) Old Apr 14th, 10, 06:26 PM Thread Starter
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Re: 327 carb jet size

Ok i changed the jets, 68s in front and 73s in back, and when i get the rpms up around ay 2500 or 3000 and punch it, it stumbles, but not so bad, but from a dead stop its pretty bad, so im wondering should i just go down a few more sizes in the primarys or should i go down in both?
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post #13 of 25 (permalink) Old Apr 14th, 10, 09:07 PM
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Re: 327 carb jet size

double check the fuel levels/float setting... just in case

as for jet sizes... sounds like you need to keep messing w/ it. I would go up and see if that makes it worse....
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post #14 of 25 (permalink) Old Apr 15th, 10, 08:46 PM Thread Starter
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Re: 327 carb jet size

I checked the floats, they where good, so i dont kno if its still to much or not enough, carbs are killing me!
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post #15 of 25 (permalink) Old Apr 15th, 10, 10:49 PM
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Re: 327 carb jet size

What are your timing specs, intital, total, and what rpm is it all in?
That cam needs alot of initial, and may not run well with vacuum advance, but give it a shot.

The only Mustang I'd ever own is a Fender.

'68 333" Camaro
'14 5.0 Mustang
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