67 400 HP conversion to aftermarket intake & carb

[Stephen G.]

My 67 400 HP, side pipe, factory air car has been thru the system. I like to drive the car. But after a brief interval of working carbs I'm back to leaky Holly's and I'm just tired of it.

Has anyone installed an aftermarket (i.e. Edlebrock) intake and carb on a car like mine? The plan would be to remove the factory equipment and put aside for the next owner while I enjoy driving my car without the fear of going up in flames!

[Gene M.]

Re: 67 400 HP conversion to aftermarket intake & carb

Steve
If going aftermarket just be sure to get low profile manifold to clear the hood. Assume you are looking at Edlebrock single 4 barrel?

[Stephen G.]

Re: 67 400 HP conversion to aftermarket intake & carb

Hi Gene

Yes a single 4 barrel. I'm going to start calling around some of the local speed shops and see if there might be a "kit". Then I'll have to find an air cleaner too. Obviously it all has to be low profile.

Thanks for your input. I'll miss you this year in FL at the tech seminar. The date change messed me up.


Steve

[Keith B.]

Re: 67 400 HP conversion to aftermarket intake & carb

you can make it easy and find the correct 390 intake with a service dated carb

[Joe L.]

Re: 67 400 HP conversion to aftermarket intake & carb

you can make it easy and find the correct 390 intake with a service dated carb

Keith------


Yes, but that will still be a Holley carb which I expect he wants to stay clear of.

The best option for a street car would be to use one of the Q-Jet 1968-69 L-36 aluminum manifolds (expensive) or the 1970-72 L-36 cast iron manifolds. I think the 1966-69 passenger car manifolds, GM casting # 3883948 or 3931067 should work OK. These should be relatively cheap.

For the street, there is no better carburetor than a Q-Jet. None. Period. They're also a great performing carburetor with air valve secondaries and a flow rate up to 850 CFM.

As far as aftermarket manifolds go, the only one that I KNOW will fit is the Edelbrock Torker II. However, this is a single plane manifold and I do not recommend it for street operation. There MAY be others that will fit under the hood of a C2 but, if so, I'm not aware of them.

[Stephen G.]

Re: 67 400 HP conversion to aftermarket intake & carb

Thanks Joe. I think I do want to stay away from Holley. The 4 BBL can also leak. Any problems with intake fit since its an air car?

Also are you talking about the 3947801 or 3937793 intake?

[Joe L.]

Re: 67 400 HP conversion to aftermarket intake & carb

Thanks Joe. I think I do want to stay away from Holley. The 4 BBL can also leak. Any problems with intake fit since its an air car?

Also are you talking about the 3947801 intake?

Stephen------

I anticipate no problem with intake fit for an A/C-equipped car. All of the GM manifolds I mentioned were originally used on some cars equipped with A/C.

The 1968-69 L-36 manifolds were GM #3919849, 3937793, and 3947801. All are virtually identical and 100% interchangeable for your purposes. However, these are expensive manifolds and often need reconditioning.

[Keith B.]

Re: 67 400 HP conversion to aftermarket intake & carb

In the interest of keeping the car original and fixing the fuel leaks where are they leaking and how have you attempted to correct the problem.

[Stephen G.]

Re: 67 400 HP conversion to aftermarket intake & carb

I rebuilt them, had them rebuild, tried many types of gaskets. They leak at the fuel bowls after they sit for a while (and dry out & shrink). Also at base gaskets on secondary's and even the accelerator pump.

Many 400 HP cars were lost to engine fires from these carbs.

[Joe L.]

Re: 67 400 HP conversion to aftermarket intake & carb

I rebuilt them, had them rebuild, tried many types of gaskets. They leak at the fuel bowls after they sit for a while (and dry out & shrink). Also at base gaskets on secondary's and even the accelerator pump.

Many 400 HP cars were lost to engine fires from these carbs.

Stephen------

Plus, this is an easily reversed mod if you ever wish to return it to the original set-up. As long as you're driving it, you won't want to. But, if you ever plan to relegate it to "show only" or to sell it, you might want to re-install the original manifold and carbs.

Personally, if I ever had a 3X2 car, the very first thing I'd do is to remove the manifold and carbs and replace with a Q-Jet manifold and carb. It's much more of a problem doing this with an L-71, though. There is no rectangular port, Q-Jet manifold I know of available, either GM or aftermarket.

[Peter M.]

Re: 67 400 HP conversion to aftermarket intake & carb

Joe,
Do you know who makes the Chevrolet Bow Tie performance intakes listed in the performance catalog?
Thanks.

[Joe L.]

Re: 67 400 HP conversion to aftermarket intake & carb

Joe,
Do you know who makes the Chevrolet Bow Tie performance intakes listed in the performance catalog?
Thanks.

Peter------


I do not know. The aluminum manifolds may be made by Edelbrock as Edelbrock does manufacture the current big block aluminum heads.

GMPP also has available a cast iron manifold for Q-Jet, oval port applications. This manifold is very similar in configuration to the 1968-69 Corvette aluminum manifolds. I have no idea who manufactures it. This manifold is GM #14097092. It's been around for quite a few years and might be old stock from the days GM was actually casting and machining big block engine parts in-house.

[Patrick B.]

Re: 67 400 HP conversion to aftermarket intake & carb

The best driving Corvette I ever had was a 67 427 390 that had the born-with engine but with a cast iron 948 intake and Q-jet. I bought it in west Texas and drove it home to Maryland without a problem. The 948 manifolds should be easy to get since the 396 Chevelles and Impalas had them. A stock air cleaner would work without any hassle.

[Timothy B.]

Re: 67 400 HP conversion to aftermarket intake & carb

I rebuilt them, had them rebuild, tried many types of gaskets. They leak at the fuel bowls after they sit for a while (and dry out & shrink). Also at base gaskets on secondary's and even the accelerator pump.

Many 400 HP cars were lost to engine fires from these carbs.

Steve,

I feel your pain but if it were mine I would not give up on the Holley's. In the end though you will be a Holley expert. :-)

[Patrick B.]

Re: 67 400 HP conversion to aftermarket intake & carb

Part of the difficulty of getting the 3X2 to run well and return to the proper idle is that you don't know which carb is leaking or hanging up. A simple solution is to make aluminum block off plates to replace the end carbs and just run it on the center carb until you get it to run well. After you master the simple center carb you can replace the end carbs one at a time to trouble shoot them. However, it may run so well on just the center carb that you don't want to bother with the end carbs.