So youve done a few mods and now you want to put on an intake. Most carb intakes can be used with a tbi provided that you use an adapter. There are things to consider, though.

A few things to consider...

For most applications here, Id recommend using a dual plane intake. A single plane wouldnt be a good match to the powerbands of stock to mildly modified tbis and most good single plane intakes are too high to be used under a stock hood. Hence, a low rise intake is a better choice. The other problem is that the single planes larger plenum volume and different charicteristics would mean that tuning may be necessary to get the car to run properly.

The next thing to be considered is if the intake manifold accepts egr. Not using an egr will have two effects. First, youll get an intermittent code 32 and SES light since the egr is no longer present. Secondly, the ecm adds additional spark advance and reduces fueling since the exaust gasses cool the combustion and also are a fuel themselves. Without the exaust gasses present, the reduced fuel, higher temps, and more spark advance may cause detonation. The remedy for this is to either tune the egr out or run an intake that accepts an egr. Theres nothing wrong with the latter. The egr keeps you legal and doesnt effect performance in any way.

Lastly, 'airgap' type manifolds should be avoided on a stock type tbi setup. The cooler temperatures will effect how well the fuel evaporates. A tbi has a fully heated manifold and is set up to work with this. A cooler manifold like an airgap may cause fuel puddling and have an adverse effect on drivability.

Adapter plates

There are several adapters made. Id recommend the Turbo City ( http://www.turbocity.com ) adapter. It looks good and its thin so hood clearence issues will be minimal.





Holley also makes an adapter and I used it before I knew any better. There are some problems with it such as: its too thick, the tbi is off center, and it just generally sucks. The offset part of it is the part that makes it unacceptable. Not only do you have to carefully rebend the fuel lines and redo the cables, but the geometry of the tv cable is changed when you use a stock tbi. In short it ends up ruining the transmission because the line pressures are off.

Intakes

There are many intakes out there so doing some research isnt a bad idea. But, here are a few to get you started.

The first intake we'll look at is the edelbrock performer. It has more plenum volume then the stock intake so it can help reduce the pressure losses when an intake cycle occurs. The runners are similar to most stock intakes. The ones will look at are the pre-86 spread bore, 87+ spread bore, and the tbi.

A pre-86 intake is a good solution if your using an older style set of heads that doesnt have the angled center intake bolts. The performer is available in both non-egr and egr versions to suit your taste. Its similar to a stock Q-jet intake.



The later model intake will bolt directly to all non-vortec stock SBC cast iron heads made after '86 and is also available in both egr and non-egr versions



Both of these intakes also accept the stock brackets and some of the performers will accept all the sensors and fittings. However, the some of them only have two 1/2" NPT fittings and the stock waterneck prohibits using one of the fittings so the unused boss must be drilled and tapped for either 3/8" NPT for the CTS or 1/2" for the heater if your keeping the stock slanted waterneck.

The tbi performer intake should be a direct bolt on. It has a larger plenum so it should be a step up from the stock one so its not a bad choice as far as thats concerned. Its not the best flowing thing out there, however, so keep in mind that with a healthy 350+ ci motor itll be a restriction. Also, its only setup for the standard sized tbis so itll have to be bored out for a larger tbi



Holley also has several intakes that can be used.

The weiand action plus intake looks like it would work well. However, it may not have a mount for the stock brackets and it doesnt support egr. There is a square bore version that does have egr provisions but its a high rise design and with the adapter hood clearence will be greatly reduced.



Holley also has a tbi type intake available, however, some appear to have the tbi offset, which causes problems although provisions for egr seem to be available on them. The edelbrock tbi intake would be better for ease of installation. The holley does have one advantage. Its set up to accept a 2" tbi as its meant for use with thier projection setups. Dont take this as a final word, though. Holley seems to have variations of this intake floating around so some may be better then others.



Finally, there is the gm zz4 intake. This is a good intake and sometimes they can be found on ebay for not too much. They are somewhat expensive new, however.



As a final note to these, some intakes will need a choke blockoff plate. Also, after 1986, the center of the bolt angles changed, most likely to allow for more clearence between the bolts and the pushrods running behind that area. This can be remedied by grinding/machining the center four bolt holes to the proper angle.

Installation

Its best that you get a repair manual such as the chiltons f-body repair manual. The procedures are covered in there. In addion, id recommend not using the rubber china walls as they leak. If you see them in your gasket kit, toss them. You should just use a small bead of rtv to seal the front and rear of the intake. Also, make sure to clean all the surfaces thoroughly with miniral spirits prior to installation.

As always: , visit sites, and make your own judgment on what appears to be best for your setup.

Happy modding!