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Discussion Starter #1
I finally got the 70 running however she will not idle at alll. I have to keep reving to keep the car going otherwise it sputters and dies. The carb is a Holley 4160 DP, 800 cfm. I picked up a Holley tuning book from Haynes at the auto parts store and I look at some of the solutions to what my problem is and most of them have already been done (two holes drilled in the back two barrels, butterflly taken off, etc). The two screws on either side near the front two barrels which are supposed to let you adjust the flow dont work and I think thats because the car has to idle at above 1000rpm to stay running, thusly bypassing the idle circuit. Is it something with my floats or something else internally? The guy I purchased the car from said he had purchased a rebuild kit and had his father rebuild it for him however I have read that you should not use the generic over the counter rebuild kits for Holley carbs, and to get a direct one that Holley makes. Could this "rebuild" be whats causing my problem? Any help is appreciated!
 

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Before everyone chimes in and tells you the carb is grossly oversized for your engine, I'll ask what intake?
 

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A "rebuild" done improperly or with inferior parts can sometimes be a problem. Since you didn't do it there's no way to tell if it was done correctly.

The first thing I would do is pull the carb and set the throttle blades in the correct position. That is, exposing approx .020 to .040 of the transition slot.

After reinstalling I would double check timing and adjust the float bowls before doing anything else.

Once those things are done you can proceed to the mixture/idle adjustments.

Here are some links with good info:

http://www.bob2000.com/carb.htm

http://www.mortec.com/carbtip1.htm

Don't know your exact application, but it could be too much
for a standard 289/302 mill.

Good luck. ;)
 

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I believe I had the same problem when I got my rebuilt 650DP from a friend. Once I readjusted the floats, I haven't had any problems since.
 

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Discussion Starter #5
Sorry about the lack of information there. Its for my 70 428 SCJ thats been pretty well built up. It is an offenhauser intake (not sure what type). Could timing really affect the idle that much? I will have to take the carb apart and check it out, just wanted some .02 worth to see what I should go for first (only played with the stock ford 2v and the stock ford 4v so a Holley is a new beast to me). Thanks guys!
 

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I hate to tell you, but you'll have to turn over one of your Mustangs because you have too many ;) Since that '70 is really not working....I'll take that one :)


-KoolKat
 

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Discussion Starter #7
Haha...you know my mom tells me I have too many mustangs all the time! I think you and her would get along great!
 

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Try the good suggestions already posted first. I had a Holley dbl pumper on my pickup once, that got a little silicone in it (don't ask). I was cruising home after a weekend campout, and suddenly it wouldn't run on the front 2 bbls at all. The only way I could keep it running was to engage the mechanical secondaries, then it would scream. Now that was fun going through town with the automatic transmission. Was also a bugger to get into the garage without taking the back wall out. :: Anyway, you may need to disassemble the carb and blow out all passages and jets. It could have collected some trash during the "rebuild". That carb is the reason I still have a bad taste in my mouth when it comes to Holleys!
 

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Discussion Starter #10
Is it possible that the floats are bad? As in the floats have soaked up fuel over the years and are now being bogged down? I think I will actually end up breaking down and rebuilding this carb as well unless I can figure something out because adjusting the floats didnt help at all, she still wont idle right.
 

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So you did the things I suggested and it still won't idle?

What effect does turning the idle mixture screws have?

BTW, floats can go bad, but it's not all that likely.
 

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Make sure the air bleeds are clear. Your Haynes book should show you where those are.

Make sure you don't have a vaccum leak.

If the carb sat for a long time, rebuild it.

And what the others have said. . .

Robert
 

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Discussion Starter #13
Well we finally got her running right, it turns out that the nut that is screwed onto the adjustment for the float had been tightened so much that is was no longer connected to the screw. Once we fixed this the front bowls were able to be adjusted for the float and we had her idling for 20 mins, solid as a rock. Thanks for all the help guys, it was very much appreciated!
 
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