Holley rebuild questions

[HSSS427]

Found another thread from last April where a guy had similar challenge when he installed a new Proform body so hoping he'll chime in. Got it running but it won't idle - it will run at about 2000 rpm, so I'm assuming I've just got to get the adjustments right. I'm assuming the main jets wouldn't impact it not idleing since it's not pulling fuel from the main circuit. Trying to get a vacum reading as well. I'm looking for more tips or suggestions!
Thanks!

[HSSS427]

at about 2500 rpm is was showing 14 hg and would go up to 19 when i upped the rpms. I tried to hold the rpms steady and the needle was bouncing back and forth over a 3 hg range.

[HSSS427]

In short - in carburetor helllll!!!!!

So, let me summarize from the begining and see if someone has a magic answer.

Setup: 427 side oiler, medium rise aluminum intake, Isky cam 250 duration, .525 lift, Holley 750 double pumper part # 4150-9379 w mechanical secondaries, no choke. Base timing is at 20 degrees (I think as I can't get the thing to idle now to verify) have 18 degree mechanical advance for total of 38

What I did: Rebuilt the carb and replaced stock main body and throttle plate with ProForm main body and throttle plate. Set primary jets at #70 and secondaries at #73. Idle air bleeds are #75, and main bleeds are #36. Capped the PCV port for now, but will have PCV on it when I get it straightened out.

Symptoms: Won't idle consistently. I've had it idleing at higher rpms and just held it steady and sometimes if will just die - like fuel is not flowing. Vacum reading was 14 hg at 2500rpm, and it was really low when I did have it ideling for a bit - like 4-5 Hg. Fumes coming off the thing that are burning my eyes - rich fuel mix?

Please help or recommend where I might go for help.
Thanks again!
Scott

[Rick Parker]

How did you decide on #36 for the main air bleeds? That sounds like it could be part of the problem?? What were the bleed sizes in the original Main Body? Did the original Main Body have 4 corner idle?

Rick

[392cobra]

You need to rejet the secondaries back to 80 -81. 73's would be with a PV.

PV's are equal to about 7 jet sizes.

Have you put the spacers and turkey pan on ??

You should check for vacuum leaks.

[HSSS427]

Well took everything off, checked it out, went to #79 jets on secondaries, kept #70 on primaries, installed new gaskets between throttle plate and turkey pan, and turkey pan and intake. Have managed to get it to idle at 1100rpm with 18 degrees initial timing advance. Had a fuel line leak, so had to shut all the adjusting down while I fixed that.

Going to take it to a local long time carb guy who has a Sun diagnostic machine and shell out the $50 to get him to adjust it for me. Hate to give in when I feel I'm close, but figure I'm never going to get it tuned as close as he can with the machine and lots of experience.

BTW, Rick Parker, the air bleeds are at the sizes that came on the ProForm body. Haven't bought any different sizes yet, so will see what the guy tomorrow says. I'm wondering if the idle bleeds are too small and I'm getting a rich mixture that requires more air through the throttle plates?

Will let you know!
Thanks!
Scott

[HSSS427]

The local carb doctor worked his magic and it now seems to be running great. Here's the run down as I recall of what we did:
- Found the Power Valve was bad, so replaced that
- Changed jets to 73 on mains, 80 on secondaries
- Adjusted the floats - I had them way too low
- Spent a lot of time adjusting the idle mix screws. Tried to basically screw the secondaries all the way in and just use the primaries, but that didn't work. Do ended up adjusting all four. He said she was very finicky, so don't know exactly where we ended up on settings as he was working from a vacum gauge and RPMs. He said don't try to screw them in to measure and then return to the same spot as he'd tried that and it didn't seem to work ie when you returned everything back to where you thought you started, it ended up with a different result!
- Set the floats correctly with fuel just sloshing out of the sight windows if you rocked the car
- Changed the accelerator pump shooters to #40s - I only had 37s, so he drilled them out to 40
- He has it idleing at around 880 - 900 rpm - lower than I've ever been able to run it.
- Got initial timing at 14 degrees, and 18 mechanical with the 2 light silver springs in the MSD for quickest advance. All in by around 2500.

Things he said I should do, that we didn't have the stuff for:
- Install the 1/2" spacer I've got
- Install 50cc accelerator pumps on both primary and secondary
- Install a 4.5 power valve vs the 6.5 I've got
- Install a fuel pressure regulator to get the pressure to 5 to 6 vs the 7 1/2 it's showing now straight from the pump

After driving it he said it may still need more fuel & air, but he said before re jetting that we could install his 850 cfm and see what the result was. He said he thought the engine would probably use a bigger carb. But that's for later.

Thanks for all the help and advice, and if I find out anything else earth shattering I will post it here!
Thanks!
Scott

[cuda66273]

?????????

You guy's have got me confused????

1st off the power valve stays in the front, no PV in the back.

It needs to be 1.5 to 2" lower than idle vacuum, in gear on an automatic and 2" below on a stick car.

The jets split front to rear should be 8 points.

The Proform main body is a Chinese plagerized copy of an old BG design, that was abandoned.

You'll need the Ricer metering blocks to make it work right.

You can remove the puple anodizing with oven cleaner so it doesn't look like it came from the Honda performance center.

"I should have bought a Demon"...you said that not me.

You could call the tech department at Proform to get a baseline set-up...oh, sorry....they don't have one?

Maybe Holley Techs could help you.....Oh, I forgot they won't offer advice on Proform parts.

Have you tried the Carb tech line at Summit?....sorry.....I'm just trying to make a point. Don't thow your money away on this Magical stuff, you won't see any improvement over the original design and unless your an expert you'll have tuning nightmare.

Get a carb that has good tech support, parts available and a warranty.

[John A. Simpson]

Why don't you talk to these guys, they advertise here. I've talked to a couple of people who've had good success with them.

Pro-Systems