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MASSIVE Vacuum Leak

Whose kit did you use? Was it from Holley or the local parts store? A word of advice. Don't use parts store kits for a Holley. Use only Holley or one from one of the carb specialty companies like Quik Fuel etc. The main bodies on the carbs can warp over time which will cause lots of grief like what you have now. If its warped its a simple fix. Also using the List number from the carb, which is on the airhorn and says "LIST" then a number like 1850/6619/4575/4781 etc with maybe a -1/2/3 etc after it. That is the Holley number you need to have to get replacement items for it. With that number, you can find through the company tech info/line what jets it came with when new. I'm guessing anywhere from a 61 to maybe a 66. That will give you a baseline to start with if you put it back to what it came with. From there once its running and you've eliminated the vacuum leaks, you can change jetting etc till its right for your car.
 
It was an Edelbrock kit for a Holley 4160 from O'Reilly. My list is 9210, which I can't find hardly anything on. Like Holley had it on a huge spreadsheet with very little information. It had clearly never been apart before, but when I pulled it apart, I think it had 62s in it. They were way too rich and I gradually stepped down to where I am now which are 58s. It might be the hose going to the PCV valve, I used a different one on the Carter, that'd be a big vacuum leak.
 
So I messed around a bit before the snow really started coming down. It’s not the PCV hose. I also can’t seem to find any vacuum leaks so my full attention is now the carb itself. I don’t know if it’s internally messed up or if the fast idle cam won’t let it drop or what, but something is broken.
 
Do you have access to another Holley to slap on from a friend etc? Can you get a picture of the carb flange on the manifold with the carb off? Did you check your hoses for cracks etc? Years ago when I worked at a speed shop, when the Edelbrock Performers came out, they made the manifold so it could take standard flange carbs, Holley/Carter, or spread bore, Holley/Q-Jet/T-Quad. We found that when using a standard flange carb, we needed to sell a plate that Ede made to go between the manifold and carb as you could have an area that was exposed and not sealed giving you a vacuum leak at the base.
 
I did take some pictures before going inside. I don't have any with the carb off, but I did notice the spacer leaves some of the manifold exposed at the front. The intake is a Holley Street Dominator though, so I can't imagine they'd make an adapter for Holley to Holley.
 
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I was afraid of this-Please re-engineer your throttle bracket and kickdown linkage. For the Holley, you need the 20-7 Holley-Chrysler bracket and some work to get it all lined up and adjusted correctly! Or you will be putting the big block in sooner that you think when your transmission fails.
 
The spacer concerns me. One thing about Holley to Holley. Sometimes design/engineering departments don't share critical info with each other. You "shouldn't" have an issue, but you may want to investigate it anyway.
 
I was afraid of this-Please re-engineer your throttle bracket and kickdown linkage. For the Holley, you need the 20-7 Holley-Chrysler bracket and some work to get it all lined up and adjusted correctly! Or you will be putting the big block in sooner that you think when your transmission fails.
I didn't know there was an adapter, I'll order one tomorrow.

If you go Holley put the proper one on with the fuel line on the passenger side.
Recommend you put flat washers under those carb nuts and relocate the return spring to where it belongs, on the throttle cable connection on the carb.

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https://www.manciniracing.com/search-results.html?query=throttle springs
I didn't know that's where the return spring went, I don't remember where it was on the two barrel, but it was someones homemade set up.
 
Alright, so I found another Holley locally that came off a running car, probably gonna pick that up to have another Holley carb kicking around. I'm also gonna start looking for the right AVS for the big block just in case there is one local. It's a 383 HP block so that's a 4616 I think. I found a 4615 local, but don't know if that's right. Right now I think I'm gonna pull my current Holley off and see how that gasket is playing with it and see if it's possible my secondaries are open enough to ruin my day.
 
maybe not related; but check the port size dia on the intake with the throttle plates (dia) clearance - in one case found the plates were unable to open fully hitting the intake ports. A spacer took care of this.
 
Alright, so I found another Holley locally that came off a running car, probably gonna pick that up to have another Holley carb kicking around. I'm also gonna start looking for the right AVS for the big block just in case there is one local. It's a 383 HP block so that's a 4616 I think. I found a 4615 local, but don't know if that's right. Right now I think I'm gonna pull my current Holley off and see how that gasket is playing with it and see if it's possible my secondaries are open enough to ruin my day.
4616 is for a 1969 383 automatic transmission car, 4615 is for 1969 383 manual transmission car, a 4401 would be for a '68 383 automatic transmission car.
 
Right-o, pulled the carb off after work today. Secondaries appear to be closed, and you can see the impression left by the intake on my gasket. Doesn’t appear anything would be interfering. I did read, however, that a blown power valve could be an issue and if I can turn my idle screws in all the way and have it run then it was bad. I happen to be able to do that so I’m putting in the power valve from my rebuild kit later.
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So this is weird, it doesn’t look like there are the holes I’ve seen in a lot of videos above the transfer slots on my carb.
 
What does the carb side of the gasket look like with its impressions? The manifold side looks a little narrow in back at the secondaries by the fuel bowl.
 
Just me but I don't like how the impressions look on that gasket. With that type of unit the plastic inserts act as a positive stop so you can't get too carried away on tightening the nuts down plus the thicker units seem to be more vacuum leak prevalent. I'm thinking you may be better off with the plate Edelbrock makes still that we sold for the AFB to Performer manifolds. Number is 2732 and shows up on Summit. With less stack up of material it makes it less prone for vacuum leaks.
 
I think I got it! I replaced the power valve and all seems well except it's pouring gas from the transfer tube because those things suck. It runs so well, it idles LOWER than what I'd want cold. It's around 700 instead of the 1200 I'd want but that's by ear. I was reading the manifold instructions again and it says I need a phenolic spacer so I guess I'll get one of those too.
 
You have to be gentle with the transfer tube putting it back into the bowls otherwise you tear the o-rings. They need to be lubed some. When you are pushing the bowl on GENTLY, twist the tube back and forth to facilitate assembly. Don't just mash them together. Holley has those available in a service pack. I would highly recommend you get some plus bowl screw gaskets, bowl gaskets, metering block to main body gaskets, mounting flange gaskets, a couple of spare needle and seat units, power valves, gaskets for the needle adjusting nut and screw. Put them in a plastic divided box so they are ready when needed. You can't find that stuff at a regular parts store when you need it right then. Speed shop maybe.
 
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