carb. help

[penceracing]

got a 302 with ported and polished e7 heads with e cam bbk shorties elderbrock performer intake and all pro comp ignition kit. it has a 600 holley carb. now and its back firing.

need some help or maybe someone might have better idea on a bigger carb.

[85_SS_302_Coupe]

You don't need a bigger carb that's for sure...not enough head/cam/etc. I'd first check to make sure your firing order is right. Then make sure the base timing is right. Could be a tooth off...but definitely sounds like an ignition problem and not a carb problem.

[Squale iii]

I remember changing heads on my 302...all those distributor wires get kinda confusing! Coil packs FTW!!! (that's about the only convenient part about working on my car lol)

[penceracing]

u dont think the cam and heads arn't big enough. the heads are ported and polished with the gt 40 valves and the cam is a e-cam.

[draggin50]

I think what he was saying is you dont have big enough heads, cam, and intake to support a bigger carb. This was my motor and it was fuel injected and ran fine. It did run real rich but no misfiring. Id check the timing also. And fix the exhaust leak also. Ill stop over tomorrow or saturday and take a look.

[85_SS_302_Coupe]

Even ported with GT40 valves, they're not flowing a whole lot or at least not as much as the lower end aluminum heads out there with 1.90 valves. That plus the E303 being a really mild cam and you having a really mild duel plane intake all add up to a 600cfm carb being right about spot on. You *might* pick up something on the very very top end with a 650 but i doubt it, and you'll have better throttle response with the 600.

[penceracing]

i did find out that i was a tooth out its running alittle bit better. i think the carb. is still to small. am getting a set of bbk long tube headers from draggin50 on saturday cause of a exhaust leak. i did a compression test yesterday and each cyl. had 90 psi. the motor is fresh once it losens up the compression will come up. i think i put the 355 gear in it and work out the bugs it will run some 12's

[draggin50]

Yeah this motor probably only has 1000 to 1500 miles on it. Id have to look at the odometer to see for sure but it was just gone through.

[outlaw85]

In my past anything with the name PROCOMP = PROBLEMS.

There's various things that could be wrong with ur engine:
Carb
Ignition
Timing
valve adjustment
plug wires switched up

[draggin50]

In my past anything with the name PROCOMP = PROBLEMS.

There's various things that could be wrong with ur engine:
Carb
Ignition
Timing
valve adjustment
plug wires switched up

The valve adjustment is good. Its just the old bolt down stock rockers. I think its in the carb or ignition myself since it ran perfect for me when it was in my car and that is the only things he swapped since he got it.

[outlaw85]

DRAGGIN50: PM SENT BACK:

Sounds to me like your on the right track then

[draggin50]

Thanks Josh! Ill get a hold of you and Jason sometime in the future to get some work done. Mini Tub the blue car!

[outlaw85]

Thanks Josh! Ill get a hold of you and Jason sometime in the future to get some work done. Mini Tub the blue car!

No problem just let me know!

[85_SS_302_Coupe]

Well if you wanna get mathematical with this...read this whole page http://www.thecarburetorshop.com/Carburetorsizeselection.htm

Then do some math:

CFM = (RPM times CID) / 3456, or:

(6000rpm*302) / 3456 = 525cfm rounded up. There's no chance in hell a stockish 302 is running at 100% volumetric efficiency, so even 525 is a stretch. Now...all that aside, remember that Ford equipped the '85 Mustang with a 575cfm carb (most people believe it's a 600cfm, but no it's a 575cfm). So...just slightly warmed over, i think a properly jetting 600cfm will do you good. I'm sure you can make a 650 work well too (i did for years) but i wouldn't go throwing a bunch of money away because i doubt you'll see any gains over a 600.

[draggin50]

He has changed the jets a few times and I rode in it last night and it feels fine. It has some popping while under a load around 2500 rpms and up. It dont do it all the time though. The fuel system isnt properly set up but it does seem like a fuel problem. I think the 600 is fine and yes he could make a 650 work well too.

[85_SS_302_Coupe]

What's funny is, i just bought a Pro Systems carb, and it seems like everything i knew about carb sizing is wrong cause they sold me a 780 "REAL" cfm carb for my 347 which seems way bigger than i need but Patrick says this is the ticket. So..i dunno. My experience is some what limited...i ran a 650 on my 302 for 6 years, and i always felt that it was a little too big. If you have good heads and a healthy cam...it's probably about right but i did try a buddy's 600 and it was night and day with the throttle response....the 600 cracked open so fast compared to the 650 and no matter what jetting i ran in the 650 it was never as responsive as the 600.

I haven't put the Pro Systems carb on yet cause SOMEBODY has my car in painter jail (lol JFWY Chris).

[draggin50]

Yeah I think the 600 is about perfect for that combo. Its not an all out race car and is just driven around alot on good days. I think if he gets his fuel system set up better and a good 600 Holley it would be a good running car.

[penceracing]

yeah i have been thinking of my fuel system i have it might be lacking fuel pressure in between 2000 and 3500 it just kind of fall on its face alittle bit but at 5000 it comes alive. am running a jegs 90 with the stock fuel line on the car it might be my problem

[87stangbbb]

i thought you had this pile fixed

[penceracing]

nope not yet. but i think i know what the problem is though