Speaking of the Holley HP 750

[mikepmcs]

 
I recently purchased a Holley 750 HP  and it seems to run fine right out of the box,(don't worry I'll tune it eventually) but I noticed after a while when i'm idling it idles real high(like 1500-1700) and won't come down.  When I go under the hood and bring the throttle lever adapter(lack of better words) arm down.  I can actually feel a detente like it got stuck in that position.  It almost feels like it is actually binding on something and once I clear it under the hood it's good (meaning I can rack the throttle and it won't do it)until i go driving again and it happens again.  It does it every time I run the car so it isn't an intermittent problem.  I'm just wondering if anyone else has experienced this or is there some kind of mechanical issue I need to worry about or maybe some kind of adjustment I need to make to keep it from sticking at what appears to be a fast idle condition after the car is warmed up.
Hope I've explained this well enough.
Thanks
v/r
Mike

[dodge freak]

I though you had a vacuum Holley hp ? If you got a regular 750 dp that has a choke, it might be the fast idle cam on the right side. Why when hot I don't know. Was it used ? If so maybe some how the base plate warps when hot and is hanging up the throttle blades. Thats a big problem you have, be care you don't rear end somebody.

[mikepmcs]

I knew you would be the first to answer...LOL
No, I have the VS just like you said to get.  Brand new from summit.  Any other thoughts now that you know it's vs or do I still have a problem???
Thanks DF
v/r
Mike

[dodge freak]

No I have no idea now that I know its a new Holley with no choke, sorry. I never had a vacuum secondary carb-I have 3.91 gears. Just guessing I say its a vacuum leak-but why only when hot ? Or the secondaries are opening up a little bit. Hopefully somebody here will know. If not call Holley tech tomorrow-I know I allways say that.

[dodge freak]

Oh do you have the vacuum advance on the dist. hook up ? Thats the only thing else I can think of, maybe somehow the timing is advancing when hot. Or the weights are sticking open a little when hot.

[dodge freak]

I look at your post again, its at the carb, maybe its in the throttle cable somehow. The cable could be holding it open and thats why you don't see it under the hood. Next time it acts up and you free it, try opening it up a few times with the gas pedal inside the car.

[mikepmcs]

Oh do you have the vacuum advance on the dist. hook up ? Thats the only thing else I can think of, maybe somehow the timing is advancing when hot. Or the weights are sticking open a little when hot.

No vac advance(disconnected), thanks RON...

It doesn't make a difference when I fix it under the hood and then hit the gas in the car.  When I fix it it's fixed until I ride it again for a while. I think it's a mechanical problem.  But it doesn't make sense to me. 

[dodge freak]

This sounds dumb and it is but did you try making the return springs tighter, like bending the bracket back a little ? I use 2 springs to close the throttle, one in front and another on the bottom to pull it back towards the fire wall. I like a soft throttle but if its too soft yeah it closes sometimes and sometimes not, so I have it the springs a little tighter than I like but the throttle always closes.

[mikepmcs]

No my springs are super tight and I have 3 of them controlling the throttle(and they are heavy).  One controls the tranny.      I have a heavy foot, this is not a spring problem.
v/r
Mike

[dodge freak]

Not being able to see it first hand I don't know. Get a strong light in there and take a good look around. Its in the carb,  or cable or the kickdown linkage for the trans. If you still can not find it , well drive it till it happens again and don't force it close, just shine a light in there and look until you see whats holding it open.

[mikepmcs]

I love you man, but I'm thinking it's mechanical at this point.  Makes no sense to me that it only does it when it's hot.  I'm looking for swelled pri's/  or some kind of mech issue.
Am I wacked, tell me so...

[dodge freak]

Its one of 2 things I think. 1-the throttle is not closing sometimes or 2-  its the weights inside the dist. are sometimes not going back all the way when the rpm's go down and the motor has more timing sometimes when hot. Those weights need a bit of oil now and then. Sometimes 1 spring breaks and maybe when its hot the other spring can not move the weights all the way back. But first make sure its not the in the throttle.

[Chryco Psycho]

check the carb gasket & or the intake for interference with the throttle plates sometimes just loosening the 4 mont bolts & moving things around si enough

[mikepmcs]

DF
Remember, I'm talking about a physical motion about racking the throttle once it is revving up to 1500-1700.  I go outside the car and physically pull the throttle back under the hood to 850. from 15-17 plus.  It makes no sense except that the throttle plate's are sticking to me.  I'm just looking for someone to verify.  I'm pretty sure it's a carb unfortunate issue.  Really wish it wasn't and hoping someone would give me an easy fix or heard or experienced something like ths before.  I guess it ain't gona happen
v/r
Mike

[dodge freak]

What Chryco said makes alot of sense, make sure those four nuts holding the carb down are tight but don't over thighten them and crack the throttle plate-I did that once-maybe look down the carb with the throttle all the way open, perhaps its a gasket holding it open. Just look when its jamming up and you should see it.

[TylerCharger69]

HMMMMMMMMM....lessee.....You have no vac. advance....that kills that theory.  You have good springs....that's killed too.   You have no choke,  which raises an eyebrow for me  (can ya smell  what the Rock is cookin'?)    I want to say that maybe that nylon cam may be holding you up when the car gets hot because it does not know what to do because your choke isn't hooked up.   Basically..."floating"  and it catches every once and again.   I had that happen randomly  on an old Holley I used to have.   The gasket matter holding the linkage up is a good theory,  but it isn't a rebuild, but out of the box, so I want to lean toward scrapping that theory.  Only other possibilities that I can think of is:   Maybe  your throttle cable is frayed  and catching.....Kickdown linkage is snagging somewhere,  or the linkage at the pedal is sticking.    Look at the two carbs side by side,  determine the differences, even the slight ones,  and see if there are any  that would cause it  all of a sudden after a new bolt-on.     About all I can say without being there to diagnose.     I still think it may be a choke issue...but I can be wrong

[mikepmcs]

You know what.. I've been thinking gasket all along cause I have the adaptor plate in there.  Dang, I'm gonna be  PO'd if it is that.  I'll do the right research and post the results.
Just gotta say this though, why does it happen only when it warms up???
OK stay tuned cause we're going for a hell ride tomorrow

[dodge freak]

The Holley HP carbs. have no choke what so ever, the front is just like the rear. Oh yeah you have that eddy "performer" intake that has that gold looking plate that goes between the carb and manifold. As for hot only, well most of the time the motor is hot. How long can you drive it and it stays cold ? Might just not happen when cold yet. My cable was frayed once also, went to the hardward store and found plain airplane cable and thread it in the old factory line, work great and cost me under $5.

[mikepmcs]

ok, you lost me on that one DF

[Chryco Psycho]

Make sure the adapter under the carb is not twisting the carb base as well

[mikepmcs]

Rode it for a while yesterday and the son of a gun never did it to me.  Idled at rest properly the whole time.  You all gave some pretty good ideas and I appreciate your knowledge and help.  If it happens again, I will definitely fool with the gasket and plate, and I also like that choke theory as well.  As always, thanks for all the responses and ideas. 
v/r
Mike

[mikepmcs]

Oh, not to revive this old post, but it was the gasket that was causing it to hang up.  New gasket and never had the problem again.

thanks
v/r
Mike

[Chryco Psycho]

Figured 

[mikepmcs]

Yeah, Sorry Chryco, I forgot to give you your props in my last post, but thanks again for that and to everyone else for their suggestions.

v/r
Mike