Author Topic: Help tuning my holley....  (Read 13695 times)

Offline 85MudMonster

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Help tuning my holley....
« on: January 17, 2009, 06:05:51 pm »
Okay, I got my holley carb put on today, I set the mixture screws all the way in then backed them out a full turn each one. Then set the idle to about what I thought was good. But the idle is all over the place and very choppy, I tried everything I could think of but nothing seems to get it to idle right. I went to the holley website and this is what they said to do:

QUESTION How do I adjust the mixture screws on my carburetor?
ANSWER To set idle mixture screws: 1.Get the engine up to temp 2.Shut the engine off 3.Install a vacuum gauge to a full manifold vacuum port 4.Turn the screws all the way in until lightly seated 5.Next, back them out 1 full turn and restart the engine making sure the choke is completely off 6.While at idle, back them out 1/8 turn at a time, alternating between the 2 or 4, until highest vacuum is achieved. Be sure you keep all 2 or 4 screws even. You can also do this adjustment without a vacuum gauge, the adjustment are the same except you will adjust to highest engine RPM at idle.

I did that and still nothing. I've given up for tonight, but if anyone knows the secret to the holley please let me know.
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline TexasRed

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Re: Help tuning my holley....
« Reply #1 on: January 17, 2009, 07:57:16 pm »
My holley preferred 1.5 turns out. No vacuum leaks and what RPM are you setting the idle mixture at? I'd try to do it at the lowest rpm you can run the engine at. What kind of cam do you have?

Offline joesgarage71

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Re: Help tuning my holley....
« Reply #2 on: January 17, 2009, 10:16:21 pm »
No vacuum leaks
I have learned long ago when bolting a holley to any intake I use one of those steel plates(there about a 1/32 thick) under the carb. And don't overtighten the nuts either.
 You can check for leaks with a shot of WD-40 around the base of the carb while running, if the idle(or fast idle) rases when sprayed you found it.
 Did you set the float level yet? Might affect your idle.
« Last Edit: January 17, 2009, 10:19:15 pm by joesgarage71 »
78' K-20 355/SM465/twin stick 205 6" on 36's
14 bolt FF/big bearing Dana 44 4.56 gears

92' GMC C-1500 454/4L80E/14 bolt

Offline HAULIN IT

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Re: Help tuning my holley....
« Reply #3 on: January 18, 2009, 07:26:21 am »
Joe is very likely on the right track. What intake do you have? Sounds like you have a vacuum (air) leak, we just need to find out where. Lorne   

Offline TexasRed

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Re: Help tuning my holley....
« Reply #4 on: January 18, 2009, 09:41:50 am »
Also, do you have idle mixture screws on the secondaries?

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #5 on: January 18, 2009, 05:55:28 pm »
okay, I'm not a carb expert, but here we go....
there are only 2 mixture screws on the front of the carb, also, I know for a fact that all the vacuum lines are either hooked up or capped off. also, I have the factory cam, and the factory intake.

It is hard to set the mixture screws because the idle is all over the place. with where I have the idle screw set at right now it fluctuates between about 550-750 rpm, no matter how i adjust it it's the same amount of flutuation, then at some point in attempting to adjust the mixture screws it jumps to about 1400rpm, and at that speed it is pretty steady. then I've got to back the idle screw back down and we end up back where we started.

And finally, to answer this: Did you set the float level yet?

A: the floats have to be set???
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline joesgarage71

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Re: Help tuning my holley....
« Reply #6 on: January 18, 2009, 06:26:10 pm »
 You have a square bore carb on a stock spreadbore intake?
here is the holley site.
http://www.holley.com/TechService/Library.asp
78' K-20 355/SM465/twin stick 205 6" on 36's
14 bolt FF/big bearing Dana 44 4.56 gears

92' GMC C-1500 454/4L80E/14 bolt

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #7 on: January 18, 2009, 08:21:03 pm »
yes, but I bought an adapter. I'm not that dumb.... ;)
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #8 on: January 18, 2009, 08:29:12 pm »
Also for further reference the exact hooley I have is a model 4160 Part #: 6619
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #9 on: January 18, 2009, 09:22:49 pm »
one other thing, how do I know what type of floats I have, the brass ones, the nitrophyl ones, or the plastic ones....
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #10 on: January 19, 2009, 03:51:54 pm »
No vacuum leaks
I have learned long ago when bolting a holley to any intake I use one of those steel plates(there about a 1/32 thick) under the carb. And don't overtighten the nuts either.
 You can check for leaks with a shot of WD-40 around the base of the carb while running, if the idle(or fast idle) rases when sprayed you found it.
 Did you set the float level yet? Might affect your idle.

couldn't find anything like that plate thing you were talking about, but I found a bit thicker one that I figured if used in conjunction with some silicon sealant would make a great reusable gasket. plus the silicone will make sure it's not leaking around the bottom.
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline HAULIN IT

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Re: Help tuning my holley....
« Reply #11 on: January 19, 2009, 04:20:04 pm »
Dan, Do you have the 3/4" or so adapter with the Holley bolts that go up through from the bottom? Do you have a Q-jet pattern gasket on the bottom? Do you have a Holley pattern gasket on the top? Typical silicone sealer is not gas resistant & should not be used in this application. Lorne

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #12 on: January 19, 2009, 04:35:57 pm »
yes to all those questions. I've already assembled it with all the silicon and stuff. Is it going to hurt anything to have that there or what???
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T

Offline joesgarage71

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Re: Help tuning my holley....
« Reply #13 on: January 19, 2009, 11:21:07 pm »
yes, but I bought an adapter. I'm not that dumb.... ;)

I didn't think you were dumb.
 Here a sealing plate like I use.
http://store.summitracing.com/partdetail.asp?autofilter=1&part=EDL%2D2732&N=700+115&autoview=sku
 
78' K-20 355/SM465/twin stick 205 6" on 36's
14 bolt FF/big bearing Dana 44 4.56 gears

92' GMC C-1500 454/4L80E/14 bolt

Offline 85MudMonster

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Re: Help tuning my holley....
« Reply #14 on: January 22, 2009, 07:38:48 pm »
okay here's an update, I need to know a place where I can buy a carburator that need no tuning other than adjusting the idle on it?

I know that there are no vac. leaks on this thing cause I bought those thick gaskets for the spreadbore and squarebore sides and then tightened down the area that was leaking more than the rest of the bolts and so if it is leaking then I'm just going to set the dang truck on fire cause it's pissing me off, and I just want to buy a carb put it on and set the idle and go.
Dan

85 Chevy K10 - 408 BBC from a 71 Chevelle SS, TH350, NP208, 33" Mastercraft Courser M/T