Who would you let rebuild your Holley carb?

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Sedanman

Sedanman

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I have 750 Vac secondaries that I need to get rebuilt. I put a kit,pump and valve in it and I can't get it work right. I took it apart again and blew it out and still have the same issue. I picked it up used so no telling if it had issues before.
 

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What are the issues? Did you true up the surfaces on the main body to ensure proper gasket seal? Did you get a manifold vacuum reading at idle and in gear to help you select the proper power valve? The sight ports for float level are only approximate and often require a level higher than the bottom of the hole to get good transition. Lots of things to play with like pump cams, arm settings and squirter nozzels too. To get initial set up down always turn the choke stat to full open then once the engine and choke stat are warmed up and you have set idle mixture and base idle turn the choke stat so you know where the end of travel is. In other words turn it back to where the choke plate starts to move and back it up just enough so that it is open fully. Mark that as a reference and you will know what position you should never go past. Also check the footprint of the base gasket. There are a few different designs and some will cause a vacuum leak on different brand carbs. Whenever possible always use the thicker insulator type base gasket and never over torque the bolts or you will break an ear on Holleys.
 
It gets fuel if I pump it but not if I don't. This is a fresh engine I am trying to get fired up to break in the cam and set timing. I have to pump it 3 times and hold the throttle 1/4 way open and with a screwdriver in the butterflies before in order for it to fire. It wants to run but the carb is holding it back. If I hold the throttle at 1/2 or more it backfires. It acts like it's starving for fuel the few times it actually ran for a few minutes.
 
I would look at what size jets are in it, usually 72 is what those are born with. There may be some deposits in the idle circuits of the metering block which may be able to be removed by taking out the idle screws and putting the block in a jar with acetone for an hour or two and then blow it out. Also take a look at the holes in your metering block gasket. The kits usually come with a couple of different types and one will not have all the holes needed for the idle circuit of your carb. Also look at the fitment of your base gasket to the carb and manifold for a possible leak.
 
Is DemonSizzler still around? It would be nice if the rebuilder had a test engine to test it out on. I had a feeling this was going to be an issue buying an unknown condition carb but I crossed my fingers.
 
They are 72 jets. I used brake cleaner with the nozzle to get in the passages and then blew it all out with air. I did go through the gaskets and installed the right one but I will tripple check it. Thanks
 
To get it to idle for break in you may also have to bump up the timing a bit more as well. Best of luck and keep us posted. If you need to file the main body a bit or true up any aluminum surface a ferrier's file for hoof work is excellent for this.
 
There is also the possibility of a mismatched metering block. Are you running a mechanical or electric fuel pump?
 
When I rebuilt it I didn't change the main body gaskets since gas didn't flow through these area's. Should I have?
 
alsosounds like you might be 180 out on the distrib make sure that is right that wil lcause all you are saying. If you want an awsome carb go to e- bay look up holley double pumper then look for the seller name toyot111 his name is mike tallman tell him jon in wisc sent you he will give you a better than new carb bolt on and run tell him your engine build , he will set it real close for you , then tune it after the brake in .just write him under the sale deal where it says contact seller Mike is very good with holley"s at a very good price ,you cant beat his work
 
Ok I was curious if the carb was full and if the fuel levels were visible from the sight plug holes. Several of the newer pump manufactures lack quality control and often pump more air than fuel. Have you filled the carb by hand?
 
Sedanman said:
It gets fuel if I pump it but not if I don't. This is a fresh engine I am trying to get fired up to break in the cam and set timing. I have to pump it 3 times and hold the throttle 1/4 way open and with a screwdriver in the butterflies before in order for it to fire. It wants to run but the carb is holding it back. If I hold the throttle at 1/2 or more it backfires. It acts like it's starving for fuel the few times it actually ran for a few minutes.
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This is classic retarded timing.
And if the cam is not broken in, this is not the time to be fussing with timing. By now the cam has thrown most of the break-in lube off. If you have big seat pressure, I would be worried.

Go back and get the timing sorted. She will want as much as possible without starter kickback, perhaps 20 to 25 degrees advance. If you do not know how to do this with the engine not running;just ask.
Then fill the carb with gas. Let it sit for at least 4 hours from the last start attempt, to give the gas that's inside the engine, time to flash and evaporate.

Holleys are very simple to rebuild. If the parts are all OEM for that carb, they are about as simple as it gets. That's one of the reasons they are so popular.
 
Sedanman said:
When I rebuilt it I didn't change the main body gaskets since gas didn't flow through these area's. Should I have?
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The gasket between the base plate and the main body is probably ok. I have seen them become brittle and leak. This is what seals the idle circuits to the delivery point so it is always a good idea to replace it.
 
harms auto rebuilds carbs,he did my 1961 carter,and did a fine job.they are a bit pricey.
 
you need a carb to get your engine started for break in? come by my house i have a 1406 you can use
 
From you symptoms, it is hard to say if it is lean or rich... It looks like the choke butterfly is snapping closed when cold and not running; is this correct? Is the choke butterfly popping open a bit when the engine fires? It should open up a bit as airflow gets established; this is the choke pull off function. If not, try turning the choke adjustment (the round black thing on the passenger side) 1/8 to 1/4 turn CW to lighten up the choke action a bit.

With cold weather, it may be a bit hard to get the choke and fist idle set right, especially with a strong cam, so it may be easier to just keep lightly pumping the throttle and holding yourself at a fast idle setting to get it warmed up, and then set the throttle higher for break-in. For anyone not used not used to carbs (and you may indeed be), this is a learned technique.

Also, look down the secondary throat and see if the back edge of the secondary throttle plates have just a tiny crack between the rear edge and the throat.
 
KrazyKuda brought over a new 600 and it started and we ran it for the full break in,so it was the carb. I'll post the video shortly. Do you think a 600 Vac sec will be good for a 9.1 340. The one I have is a 750. We shut it down after break in to let it cool off and to let the smoke air out and now it's not getting spark and only 4v at coil. I installed a new mp kit I had laying around.
 
Kinda depends on the cam for the displacement..... I ran a 600 cfm vac sec for years just fine on a 351C but it was a torque cam with limited duration, not a drag cam. What cam do you have and what is the intended use for the car?
 
UREMCO rebuilt my thermoquad. Total including shipping both ways approx $300. I believe they are rebuild suppliers for Summit.
 
How about Rob/Rusty Rat Rod? He's pretty awesome,in this department...
 
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