does anyone run a one inch spacer under carb. or know if there is room under the hood for it. i have a 68' 400 with the 400 hood,quadrajet carb. my engine is out and i can't recall how much room is under there. all my parts are finally getting to the builder. so it want be long know.

There are some generalities, spacers add more plenum volume so the intake “looks” bigger to the engine which, usually favors the upper rpm range but… that being said, every combo is different and it’s just a try it and see deal.

I have a 326 with a Edelbrock Performer Intake and a Carter AFB Comp series, it's the same as a edelbrock performer carb. I have a spacer it's a 1/4" and there is a little more space, I'll try to measure tomorrow.
You know they do make drop base Air Cleaners? I just found out about them. if it's not stock and a show car you can use this if space is a problem.

I have a 68 400 with a 1" spacer and holley carb and Edelbrock manifold with standard 400 air cleaner on my 1969 bird. Had no problem with clearance.

That is how it was when I bought the car. I am going back to original manifold and quadrajet carb. Not sure if the height of the std vs. Edelbrock is different or if the carbs are the same so I cannot speak to that. But as it was it was fine.

4dabird, just out of curiosity, why are you going back to the original intake and quadrajet?

Two reasons.

1. Originality
2. If you compare an Edelbrock manifold to a standard cast manifold side by side you will see the intake ports are smaller than the original manifold. I would say the OE manifold is 10-15% larger port size.

More airflow = more power assuming you can exhaust it fast also.

The originals are heavier by far, but the added flow should be better for my 400 than the Edelbrock, in my opinion.

Advice given to me was that the Edelbrock manifolds are fine for a 350 with standard HP.

As far as the Quadrajet - So many people have told me that they are great carbs for our birds and well capable. I picked up a 68 GTO auto carb for $5 and will have it rebuilt. If set up properly based on the engine set up, it should be better than my 600 cfm Holley. They also have very large secondaries and I know in my case will pull more air than the Holley. The Q-Jet is a 750 CFM vs. my Holley at 600 CFM.

Again this is only my opinion. My 400 with a low compression rebuild back in the 80's with maybe 275HP ran out of air at the higher RPM's. My new rebuild is bringing back the compression and needs to breathe with the cam I chose.

4dabird, I agree with you on the choice of wanting to go back to originality. Im a firm believer, and a big fan of quadrajets. I am curently running a performer manifold with a tweaked quadrajet on my mildly modified 1967 326. With the cam I am useing 260-272 duration and a 9.5 to 1 compression ratio this combo works great for street use

Plmcrzy which Qjet u using? I'm just wondering, I looking into testing out a qjet for my 326 with a 256-268 duration. I have a few in mind.

I have a 1" spacer under a Holley 950 using a drop base. No issues under the 400 hood.

Ragu, sorry for the late post, I didn't see your question until now. The one Im running now is 7044502 IE 1974 California, made for a chevy with auto trans.