800 CFM carb on 69 400 stock manifold

Will the 72/4 800 CFM carb fit and seal on a stock 69 GS 400 intake? For some reason I thought the base was different and you would have a leak. Is there a special gasket that is needed. Thanks Bill.

 

You will need to use a spacer. I think the kit I used was made by Mr. Gasket. I may still have the package in the garage, I'll check tonight.

I just checked and I still had the package: Mr. Gasket #86B Carb. Heat Dissipator 1/2"

http://www.summitracing.com/parts/mrg-86b
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Check the application with Ken at Everyday Performance - I also did a thread with pictures on various combinations clearence, I dont remember when.. I dont think it makes a difference if it's a 71-74 4M 800 CFM carb, or a 75-79 M4M....

 

Actually, this isn't true. Part of the linkage on later carbs will hit the manifold on earlier cars and prevent the carb from bolting down flat and cause binding. I know because I put a later 800cfm Q-jet on my 68 GS400 and had to put a spacer on it. Mark Northcutt can confirm this.

Here is a previous thread about it:

~http://www.v8buick.com/showthread.php?297175-Mounting-800-CFM-Q-Jet-onto-1967-430-cid&p=2459942&highlight=#post2459942

 

The 67 has a complete different base and fast idle adjustment components. And there is an issue with later 800 cfm on 67 intake without a change.
The 68 baseplate is a little different design than the 72, but I believe they are same width and they use same fast idle adjustment items. I will verify this today with side by side comparison.
Larry's right too, that all of the quadrajets had same bolt pattern, but there were some different width baseplates used.

 

Here is the info Rhett put together on the subject....
http://www.v8buick.com/showthread.p...cations-and-modifications&highlight=bigpig455

 

Thanks everyone for the reply's and info. Yes I am aware of the 800 problems when mounting to a 66 Q jet maniflold for a nailhead. That project is for a later date. My current problem is mounting a 72/6 800 cfm q jet to a 69 400 stock manifold, and wondering if I need a special gasket to seal or a small spacer to clear some of linkage. The car I am working on is put away for winter, so I am going to look to see if I have a 68/9 400 manifold off a car and try to mound a later 800 cfm carb and see if it fits and seals before rebuilding an 800, other wise I will look for a 68/70 730 carb to rebuild. This will be the third attempt to get a good carb for this car, first one ended up with primary problems after I rebuilt, second one was nice carb but old time rebuilder service that did the re-mfg years ago, made it so is not re-buildable. Thanks Bill.

 

I have a 71 or 72 800 cfm q jet on my stock 400 manifold without an issue///

 

Ken, could this be my high idle problem?? I have the 72 800 cfm QJ on my original GS 400 intake.

 

I've fo gotten now, but I think the same issues that a nailhead manifold have also carry over to any wedge motor with a heat trough "smile" on the carb base...What is the last year they used those? 67?

I'd think you shouldn't have any issues on a 69 manifold....if I'm not mistaken it looks a lot like a 70.

There are different baseplate widths, but on 68 and up carbs I don't think it matters for sealing.....

 

'68 400 manifold has a clearance issue, 69 does not

 

doubtful. Check that the choke cam is disengaged. Alternately you could plug the idle bypass air to gain more control via the throttle screw.

 

I learned something here. I thought it was the 69 and earlier manifolds. I stand corrected.