I'm switching out an old Quadrajet carb for a new Holley. I have a question about the throttle linkage. How do you link up the new throttle linkage to the Holley. It doesn't look like the old bracket that was used to hold the Mercathode and the throttle linkage will work. Is there a kit you can get to make the conversion?
The motor is a 502 and the carb was from a 454.
Thx,
Eric

Marine aftermarket suppliers offer brackets that will adapt the merc linkage to a Holley carb. One style bolts between the carb and manifold and another bolts onto the top of the base plate. Give Fred a call at Trick Marine.

Why? You could rebuild the Q jet. The Holley wont make any difference in performance.
Also The Q jet is a spreadbore, the Holley is a probably squarebore, are you planning on changing intake manifolds or using an adapter plate?
Gary

I agree, if you have a spread bore manifold, have the Q-jet rebuillt, and get it set up correctly for your engine. The q-jet will idle well and milage is great. Just to change to a Holley for the sake of changing will get you nothing. You can purchase the bracket for your throttle through Summitt or Jegs or any race shop.

Thanks for the responses. The reason I'm changing is the carb I had on there was too small (came off a 454). I think it's a 600cfm AFB built by Weber. It was running my motor lean. I was looking at changing it out for a 750 qjet, but figured I'd give Holley a try. I'm putting on an 850 holley worked over by Nickerson.
I do have a spreadbore manifold, with a one inch squarebore spacer. All cylinders seem to get equal mixtures with that setup.

Cast iron intake ? With squarebore adapter ?


Get rid of it.

That was going to be my next upgrade, along with removing the Mercathode unit. What's a good replacement for the manifold and the Mercathode?

You will need both the Merc/Holley Linkage Adapter 710-717-7 and a Holley 4150 Throttle Bracket

I don't want to keep sounding negative, but an 850 CFM is a little large for your engine. You may not like throttle response. A 750 or 800 at the largest would work a lot better.

I'm pretty sure all the Q jets were 750's. Just different metering rods.