I have a stock 69 Vette with 350/350 and I'd like to replace the intake manifold so a 4 barrel square bore Holley will fit the question I have is what kind of modifications do I have to make? Will the hood hit the air cleaner? Will the stock accelerator linkage from the quadrajet fit? Anything else I should be aware of?
Thanks Joe

 

Hi jgrado69, I just installed an Eldebrock 2101 on my 69, which is a performer series manifold. No problems with the hood. It has the spreadbore design, I'm running a Holley spreadbore carb, but if you look at Eldebrocks website you'll find the manifold [squarebore] you're after and compare the measurements between the two. The performer RPM is taller, maybe another CF member can advise on that as far as hood clearance issues. Yes to linkage, just use the ballstud from Q-jet to Holley, also the calbe mounting bracket. When done have someone push the accel pedal down, then you look down the carb and you will see that the carb is not all the way open. Another tidbit of advice; mark distributor location with cylinder #1 at TDC, you'll mark the rotor location and the tachometer hook up location . Good luck with your upgrade. T

 

The Weiand Team G 7530 has a carburetor mounting pad that is very close to the stock Q-jet manifold and is the only intake worth switching to if you feel you must do the change. The reason for this is the Team G, a single plane intake developed in the '70s and still in production today, has more plenum volume than most of the dual plane intakes and has very good runner velocity. It gives up nearly nothing on the bottom and gains a useful amount on the top end when complimented by other changes, like cam and exhaust. It will fit under the stock hood of your car with the factory air cleaner.

To run a square bore Holley, you will have to switch to a 70-72 LT-1 cable bracket to use your original throttle cable. The reason for this is the Q-jet bracket will not bolt up to the Holley flange. Yes, you could make the Q-jet bracket work with some fabrication -and I'm sure some have done that- but you can just buy the correct bracket for the Holley mount and have no issues. The carburetor should include the proper ball stud for the throttle, so that's not really an issue.

Now, the question not asked, is will you gain anything significant from the swap? No, not really. The factory intake and correctly-functioning Quadrajet is a pretty good combination and it's hard to improve on it unless your engine's airflow needs exceed the capacity of the factory intake combination. With the right intake and carburetor, you can make gains, but they are not significant unto themselves -like 20 hp- and the gains would be in the upper rpms where, in a street car, you don't spend that much time.

 

Edelbrock makes a thin metal adapter plate for funning a square bore carb on a spread bore intake.It is designed to run a squarebore carb on their dual pattern intake.I don't see why you couldn't use it on a q-jet intake.
That being said I would stick with a well functioning q-jet unless it was a max performance build.