I have driven a Summit 600 more than a year now. After buying a new one I noticed it leaking from the throttle shaft while working on the return spring, trying the throttle several times with engine not running. I called Summit while it was still under warranty. Because I was in and out of the country, it was nearly a year before I could remove it and ship it back. Summit was good enough to warranty it with full refund.

The tech told me they were made by Holley, and that some of the first ones had a problem with the seal being installed correctly in the factory. Okay, I thought. After a short time elapsed I bought another one, new. I drove it about a month and was pleased. Today I was tinkering, as before, with the spring, and fuel dripped from the throttle shaft.

Yes, I was working the throttle by hand. Yes, the acc. pump was shooting fuel into the bore. Yes it was flooded. But it leaked. It is my reasoning that if tolerances are such to allow fuel out, it will allow vacuum in.

I have tried two now and both, brand new, leaked as described. It is time to change brands.

 

I had the same problem on the first one I installed. The issue I had was it wouldn't return to idle. It would hang around 1100 rpm. While on the phone with their tech support, I was working the throttle with the engine off and saw fuel leak from the pass throttle shaft. They sent a new one out that day.

The new one works great. It ran great out the box but I rejected it along with new secondary springs so it would get better mileage. Mines been installed for 5 months with around 5000 miles and I haven't had any other issues.

 

thanks for the feedback guys - I think i will stay with Holley quality instead of a lower-cost alternative.

 

Quick Fuel Technologies Slayer series available in 600CFM vacuam secondary. I have bought 2 in the last year for my vehicles. I can't say enough good things about them. And only $310-$330 on Amazon.

 

Why not the Edelbrock 1406?

 

I have talked to a lot of very knowledgable mechanics who say the Edelbrock carbs are not great. Granted I have nothing to back it up but I know from my experience of buying 2 QFT carbs that I have no reason to ever buy anything else. I have a friend who has built hundreds of race and high performance engines and he said he ALWAYS used to buy only Holley's and a few years ago he switched to QFT and has never bought any other brand since then. They have some advanced features that similar price competitors don't have. Both of the ones I bought I took out of the box and bolted on with virtually NO ADJUSTMENTS necessary. The last one I put on my Ford F250 CC all I had to do was adjust the electric choke to lean it out some. I have NO AFFILIATION with QFT I am just sharing my positive experience. If you do a search you will find a comparison test done by an independent party that rates the QFT very highly.

 

I had an eddy 600 electric choke and vacuum secondary. It ran pretty good and always started. Well until it had a problem and some drag racing friends convinced me to sell it.


After selling the used and needing rebuilt eddy for $120, I paid $160 for a 650cfm Double pumper that had been rebuilt. The difference driving was night and day. Its a whole different animal when you put it to the floor. I'm completely sold on Holley double pumpers. I tried a vacuum secondary and it had too much hesitation for my liking. An added bonus is that nearly every part is made and there are loads of information available on them.


I just won an auction for another 650 double pumper to play around with and rebuild while keeping the current one on for daily driving.


I say you're on the right track with going for Holley rather than house brand. Sucks to hear about the poor quality.

 

Thanks for the feedback. I have heard of the QF carbs and am waiting for them to produce one in the 400-500 cfm range. I run a inline 300 with 270 hp and enjoy the off-the-line response of a carb in that range. "You can't jet down cfm."

So, for right now I'm using an 800 cfm Quadrajet, ha ha. Let me explain: The QJ has a very small primary side. It flows about the same as a 390 Holley. And, I can buy them everywhere for $10. I buy the later 76-79 model because it allows me to fine tune the cruise circuit to max mpg. Another nice thing is that the toilet flusher size secondaries only give as much as the engine will take, never more.

Of course I'm buying a 465 cfm Holley too.