This is topic carb tuning in forum Tech Talk at Northern California Ford Owners  .


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Posted by sac 5.0 (Member # 2980) on 2004-04-23 06:49 AM :
 
does anybody know of somebody who can show and teach me how to tune my carb a little better here in sac it is a holley 750 4 barell on a 331 stroker it seems to be running rich then lean rich then lean i think the secondary are messing me up
 

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Posted by stoauto (Member # 2803) on 2004-04-23 07:38 AM :
 
thats a big carb on a little motor,i'd run a 650dp. unless your running nitrous or something, but then again, how often are you gonna squeeze.
 

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Posted by big matt (Member # 1124) on 2004-04-23 02:10 PM :
 
im runnin a 850 on my 331 and it works great
 

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Posted by stoauto (Member # 2803) on 2004-04-23 02:17 PM :
 
theres just no need for that big of a carb on that motor. but shit, if it works great, more power to ya!

[ April 23, 2004, 02:28 PM: Message edited by: stoauto ]
 

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Posted by 2stangs69-91 (Member # 1951) on 2004-04-24 08:32 AM :
 
is it a vac secondary or mechanical.
 

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Posted by mtbaughs (Member # 4052) on 2004-04-24 08:35 AM :
 
If you want the best tune for your carb contact the carb shop. I don't recall their contact info but if you run a search under The carb shop on yahoo they pop up. You can't get anything closer than they provide as every carb they tune is custom tailored to your combo and dynoed in house before it leaves back to you. I've seen many of their carbs pull perfect AFR levels when taken out of their shipping box and placed right onto the car. I've never had to re-tune one following their tune. Just a thought if you want to go that route

[ April 24, 2004, 08:36 AM: Message edited by: mtbaughs ]
 

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Posted by sac 5.0 (Member # 2980) on 2004-04-24 08:39 AM :
 

quote:

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Originally posted by 2stangs69-91:
is it a vac secondary or mechanical.

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quote:

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Originally posted by Fostang:
mechanical 750 on a 331

If it were a vacuum I think you'd be happier wouldn't run as rich.


But since you have it you can always de tune it.

What are your spark plugs gapped at? Electronic or points distributor?

Timing? Full?

What size jets and what are your floats at?

Whats your fuel pressure?

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msd elec dist
10 and total is 32
fuel pressure is 6 1/2 lbs
jets primary 72 sec 80
floats in glass sight barely showing any fuel
 

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Posted by Wolfie351 (Member # 651) on 2004-04-24 11:03 AM :
 
Just for a reference...the Carb Shop reccommended and modded my Holley 4180 to run 633cfm, and this is for my 351W. Over carburation may in fact give you higher peak hp numbers, but your overall power curve will suffer for it.
 

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Posted by 2stangs69-91 (Member # 1951) on 2004-04-24 11:11 AM :
 
I belive most 750 DP carbs came with 72/76 jets. I would try running 70/74 for starters. Does your car bog off the line at all? do you run power vales? Some 750 had 2 power valves most did not. What number power valve are you running? 6 1/2 is good fuel pressure but you need that at wide open throttle around 4000 rpm or so at least.
 

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Posted by sac 5.0 (Member # 2980) on 2004-04-24 12:36 PM :
 
i have about 6 lbs at wot and i frogget what size power valve i have i have like 6 pounds(not pounds i froget what it is called) of vacum
 

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Posted by 2stangs69-91 (Member # 1951) on 2004-04-24 01:12 PM :
 
you need to take a vacuum reading at idle to see what it is. If you have a auto trans drop it in gear see what it is at. Make sure your power valve is rated around 2lbs less than your lowest vacuum at idle
 

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Posted by slidewayz94 (Member # 3101) on 2004-04-24 08:02 PM :
 
Joe- I can't think of the place but I know where it is at, my boss just took his 68 camaro to it. Awesome place they will dial it perfect. It will be well worth the money to have it done right hit me up you know the #
 

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