jetting a carb - 460 Ford Forum
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post #1 of 10 (permalink) Old 09-21-2008, 09:37 PM Thread Starter
 
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jetting a carb

What jet should i run in my carb?
combo: 1970 460 4v 360 horse 480 tq 11:1 compression
small comp hydraulic cam 268 / .494
stealth intake, 1" spacer (nos plate)
2" supercomps
MSD ignition
C4 3500 stall T brake 389 gears
850 mighty demon ...stock jetting... 85 pri, 93sec
This is the only carb I could get a hold of (borrowed). I know a lot of members here do not care for them. but its what I have till I get the 521 back together.
Problem is, its loading up really bad at idle. I think to much jet. should i jet it down to 82/90? thanks for the help Jason
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post #2 of 10 (permalink) Old 09-22-2008, 07:33 AM
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Seems like a lot of jet but i dont know anything about those carbs im using a holly 950 hp and the jets are 75-84 and its runs great the motor is a 70 472" with 68 heads ported with 219-173 valves the cam is a comp 292 hyd magnum [email protected] -560 lift ,stealth intake,2" supercomps.
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post #3 of 10 (permalink) Old 09-22-2008, 03:06 PM
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A couple of questions before we offer jetting advice

Hi there,

that sounds like a fun project!

Couple of questions?
1-what fuel pressure?
2-what pump is feeding this carb?
3-how many fuel pumps?
4-How many and what size lines feeding it?
5-Is there a fuel log inline?
6-Float level-Most modern carbs have a fuel window to check float level.
7- have you had the needle and seats out to clean them?
8-Is there a fuel filter inline?

That should get it started, help out all I can but this is the info needed to start. Yes, you can start guessing and throwing all sorts fo combinations at it. But this approach above will eliminate things one at at time and get you a result that fixes the 'loading issue'.

One last question Did this engine load up before you put this carb on it? or only since puttting this carb?

11 YEAR BUILD OF CHAMPIONSHIP WINNING FORD 460 WITH CJ HEADS AT 16:1 COMP SINGLE CARB 1550 CFM, MAX CUBICH INCH 476, 900+ DYNO'D HP
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post #4 of 10 (permalink) Old 09-22-2008, 04:32 PM Thread Starter
 
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It sounds like a fun project, but its not! The 65 still has shock towers in it, with the Crites kit. SN 95 Mustang front struts, etc....
15 lbs @ pump
8 lbs @ carb
BG 400
1 pump
-12cell to pump,-10 to 4port regulator, -6 x 2 to carb
no fuel log
fuel level fine
new carb was on a 400 chevy for 3 days deamed to big for his car,his jets 80/93, stock new 83/95
neddle & seats never out...Aeromotive -12 inline filter before pump
this engine had a 600 edelbrock on it when it was in my buddy dump truck. So the answer to your question . no!
thanks Blue Thunder for the help
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post #5 of 10 (permalink) Old 09-22-2008, 04:45 PM
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When you say it's loading up really bad at idle, do you mean just idle, or part throttle too? If it's just idle the main jets have nothing to do with the mixture at that point - look to the idle adjustment screws.

Luke
Aircraft Engine Mech
'88 Mustang Notch inheriting a 466, SCJ setup for fun
'85 Mustang GT Hatch, 429, retired
'02 F-350 7.3L struggling to survive NE winters..
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post #6 of 10 (permalink) Old 09-22-2008, 04:59 PM Thread Starter
 
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Luke, when you try to rev it it just will not take the gas. Im going out to jet it down. I will report back with what i find. Jason
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post #7 of 10 (permalink) Old 09-22-2008, 05:30 PM
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Quote:
Originally Posted by '65 T-BOLT
Luke, when you try to rev it it just will not take the gas. Im going out to jet it down. I will report back with what i find. Jason
Ahh, ok. For such a small cam, it just may be too much carb. I had a similar experience with a friend who decided he 'needed' a new 750 on his stock-ish 302. You may find you get the tune right at one or two points in the range, but the rest will not fall in.

For reference, I ran my D0VE-C 429 with Comp's 275DEH (275/285, .515/541), and I think I was riding the edge of too much carb (Holley 800 - found it on a sweet deal - free!)

I'm thinking that 850 on a smaller cam, even in a 460, is a bit much.

Luke
Aircraft Engine Mech
'88 Mustang Notch inheriting a 466, SCJ setup for fun
'85 Mustang GT Hatch, 429, retired
'02 F-350 7.3L struggling to survive NE winters..
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post #8 of 10 (permalink) Old 09-22-2008, 06:02 PM
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Does the carb have any power valves?

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post #9 of 10 (permalink) Old 09-22-2008, 07:12 PM Thread Starter
 
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yes hot rod it has a power valve primary.
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post #10 of 10 (permalink) Old 09-22-2008, 07:18 PM Thread Starter
 
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I posted the combo awhile back. the few that responded thought an 850 cfm would work.....well it works, jetted it down to 81p/89 sec.
has a bog & stumble like its not taking fuel.
after i get in on it and come to a stop... it doesn't want to idle down without reving the piss out of it. any ideas?
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