What is the best adaptor for an Edelbrock Performer Spreadbore?

[alsalp]

I am adapting a stock rebuilt Pontiac 350 in a 68 Pontiac Tempest wagon to stock 350 TBI.

I am running an Edelbrock Performer dual plane for a Q-jet.

What would be the best adapter for my manifold?

Anyone WITH experience with these?

I'm looking at these:

INJECT-IT (looks like it is center pattern)

http://www.ebay.com/itm/46mm-1-13-16...dTOZXX&vxp=mtr

HOLLEY (looks like it can be above either the primary or secondary side, does it matter?)

http://www.ebay.com/itm/Holley-17-41...VVit90&vxp=mtr

TRANS-DAPT (read that some don't like the 1/4" thickness do to limited number of threads)

http://www.ebay.com/itm/Trans-Dapt-T...FVAS~M&vxp=mtr

Thanks, Al

[Nasty-Z]

As a user of all three at one point in time , the Inject-It is by far the most refined unit of them all.

That being said , any of the three will work just fine for a conversion , I also use the factory GM BBC "Water donut" adapter used on 87-90 GM BBC trucks , it is an economical alternative if looks are not your primary concern. http://www.ebay.com/itm/CHEVROLET-CH...JXy0rc&vxp=mtr This is a crazy price for one , but you know what I'm referring to.

TOM

[alsalp]

Tom,
Any mods needed to the divider in the manifold?
Also does it matter if the TBI is centered or favoring the primarys or secondaries or anything?

[Nasty-Z]

Tom,
Any mods needed to the divider in the manifold?
Also does it matter if the TBI is centered or favoring the primarys or secondaries or anything?

I usually cut the center devider down in a dual plane manifold , but on a relatively stock engine I don't see it as a requirement . TBI likes a single plane intake , so anything you do to open the plenum will be a net gain.

Maybe a tad bit to the rear , but it has never been tooo much of a concern to me .

TOM

[Fast355]

The best adapter I have ever used came Mercruiser engines. It had a 2" bore for the TBI and mated to a square pattern intake. Most of the Edelbrock intakes accept both types of carbs. Just need the Edelbrock metal plate to cover the spreadbore on the carbs but this adapter covered the opening just fine on my SBC Spreadbore Performer RPM. Ran even better with the single plane in the picture.

[Loyd]

match the adapter bore size with the tbi as there can be a vacuum leak. We had a 2" adapter with a (
I believe ) 1 7/8 tbi and the gasket had a very small area for sealing, changed to smaller adapter no more vacuum leak

[geewhiz]

What do you think of just machining the bottom on the 7.4L adapter off flat, to aid in gasket sealing.?

[dave w]

Interesting DIY adapter thread: http://www.gearhead-efi.com/Fuel-Inj...Mount-Adapter&

dave w

[dave w]

Interesting plan for a "NO VACUUM LEAK" Factory 454 TBI adapter.

dave w