I have a chance to do a 94 LT1 conversion on my 79 L-82 it is a Iron head out of a B body with 260 HP I know the one from the F body is 300HP but this is what I have a shot at doing. Has any one done a LT swap was it worth it in your opinion. any comments, Hints tips or other wise.
Thanks.

 

There are some who have done it. I have a TPI conversion in mine. LT1 is similar except you have to use LT1 accessories. Also the MAF sensor is not easy to locate. B-body accessories put the a/c compressor low on the passenger side, I think you have to have C4 accessories to make it work best. Below is my TPI "primer", LT1 is similar. I would get my harness from Howell or Street & Performance.
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You have a unit
First you have to determine whether you want mass air flow or speed density. The C3 is more conducive to speed-density due to space issues. Mass-air flow is easier to make engine changes without PROM changes. If you are technically proficient enough to make a Camaro harness work they can be bought for $100 or less. I have been told that you can also use a 3.1 Corsica or Cavailier harness with a little work, it uses the same 7730 Speed-Density ECM. Aftermarket harnesses range from about $300 for Painless to $500 for Howell to $700 for Street and Performance. Howell makes a great harness, but for a Tuned Port they do not make one that will control the converter lockup on a 200R4/700R4/4L60 transmission. If you are running a manual or non-overdrive-automatic transmission I highly recommend them. I have heard great things about Street and Performance harness, but do not have first hand experience with them. I also have a Fuel Injection Specialties (FIS) harness and it is OK. The ECM can be had used for $10-50. A good external fuel pump will cost at least $100. I use an 88 Ford Truck external pump,$114 from CarQuest, made in Texas by Airtech. If you have a 78-82 you can use your fuel tank with an 82 sending unit and a TPI pump. An aftermarket PROM with VATS and Emissions codes removed will be $100-200 depending on source and complexity. You will have to add an oxygen sensor to your exhaust, $20 for the sensor, $5 for the weld-in bung, and say $25 for an exhaust shop to weld it in if you can’t. Some harnesses use VSS and some do not. An auxiliary VSS sensor is around $75. To install a TPI I say figure at least $800 plus the TPI unit and whatever repairs are necessary to bring it up to useable status. I have TPI/700R4 in my 69 Corvette (Howell harness) and an 83 Pickup (FIS harness) and I love it. Starts good, great torque, good fuel mileage, easy to swap onto stock engines (although both of mine are complete engines out of 90/91 ‘Vettes).

Differences in years
All Corvette TPI intake manifolds work with the older (through 86) iron heads and the factory aluminum heads through 91. F-body TPI intakes use the upright center bolts on 87-92 and thus fit all 87-95 iron heads (non LT1). Either can be swapped to fit the other with some drilling. F-body has the fuel lines come out on the drivers side and has a central port for EGR. Corvette has fuel lines that come out on the passenger side and has an external port for EGR. Corvette fuel rails fit F-body intakes and vise-versa. The runners are all the same through the years, but the LH runner has a hole for a 9th injector in the 85-88 runners. This can be plugged off if you get a nice LH runner and don’t want the 9th injector or decide to run speed-density. The plenums all physically interchange, but 90-92 have an extra vacuum port for the MAP sensor used with the speed-density computers and wiring. 89 is an odd year, it is mass-air flow but without the 9th injector. 89 up throttle bodies can be used on all years, but a 85-88 throttle body requires a ½” hole be drilled in the front of a 89-92 Plenum for idle air. 89-92 Throttle bodies have a bit more desirable cable attachment. The cable attaches around a circular linkage which has a smoother actuation than the straight linkage on the 85-88. The Corvettes have an aluminum plenum extension over the distributor, the F-body extensions are plastic. The Corvettes use an HEI coil-in-cap distributor for 85-91 (Delco 1103680). 85-86 F-body also used a big-cap distributor. 87-92 F-Body used a small cap distributor with an external coil (Delco 1103479). This same distributor is used in the 87-95 5.0/5.7/7.4 TBI injected trucks. The F-body intake gets it's exhaust for EGR from the center passages in the heads like most SB Chevys. A Corvette intake gets it's EGR exhaust from the RH exhaust manifold/header through a flex-tube to an opening near the distributor-no center passages in the intake. If you are required to keep EGR and you have a Corvette intake, I recommend getting the C4 exhaust manifolds. They are like mini-headers, and have a 2 1/2"
outlet. I have them on my 69 and like them. As far as a throttle cable to use, on my Vette, I used a TPI Corvette cable, 1990 I think (discontinued now from GM) but you have to cut the end off inside the car and use a hood-release-cable end (Corvette Central 342138 "cable stop") to get it the correct cable length (the housing is OK). You must use a cable from the type car your throttle body came from if you want to have a chance of not cutting it. Again, 85-88 use a straight pull, while 89-92 have a circular attachment for more smooth actuation and so the inner cable is longer. On my 83 truck I used a TPI F-Body cable and it was OK, but I had to coil it up into a loop in the engine compartment because the housing was so long. I also TPI'd a 72 Chevy truck and used a 90 350 TBI truck cable for it. It was 1/2" short outside if anything, but I was pretty pleased with it all told-I didn't have to shorten it. In a Vette it might be about right. In all vehicles I've done you need a die grinder to square the firewall hole off a bit. All vehicles I've done used the late throttle-body.

 

Thanks for all the good info.

 

I would be happy to answer any questions if you have any more. LT1 is a good engine. Change the water pump while you have it out, they leak and can damage the optispark. You will have to use electric fans, the b-body HD fan is in the wrong place for a C3, besides you will need C4 accessories anyway. Motor mounts will bolt up, if you use the 4L60E transmission, follow all instructions for mounting a 700R4 as they are the same length. If you use a manual trans, you can use a flywheel from a 1-piece seal motor. Anyway, good luck with your conversion. Fuel injection is very much worth the effort IMHO.

 

A couple of years ago I needed to change out my 79 350 L48 w/TH350. I was kicking myself because I had just a few months earlier passed on keeping my totalled 93 firebird LT1 for a couple hundred bucks (wife didn't want the wreck sitting on the side of the house). Ended up going LS1 but it cost an arm and leg more than if I would've kept my LT1 - would have had all the part needed to swap out engine, OD tranny, fuel pump, harness ....
If you have a great deal on LT1 - I'd say go for it - ensure you redo water pump as a wet opti costs a bit and is a pain to change. LS1 is even better IMHO but LT1 would be a great change from L48, and should cost less.

markdtn - great writeup!

 

I put a 94 LT1 with T56 in mine. Definitely worthwhile. The iron headed LT1 is a good motor, just needs more cam. The iron heads flow a little better than the early aluminum castings. I would have them upgraded to screw in studs and machined for larger springs if you are going to have them off, otherwise do it later. As mentioned by someone else, you will need Corvette accessories including the crankshaft hub and balancer. I used an F body radiator in mine with some custom upper mounts and clipped on the F body electric fans. Let me know if you need any other info.

 

Im planning the same thing on my 1980 l82, old engine is out and i have my 94 B body LT1 just sitting. Planning on total rebuild and a increase in cubes, but would love any info on wiring, speed density and other major components.

 

Unless the present engine is in lousey shape, I would not bother, no weight savings for iron heads, the opti is a terminal problem you can't get around easy....and you can do a plain simple TPI conversion for way cheeper and keep your HEI.....

having said all that, I had a TPI on my OEM '72 engine and it ran fine, but a few years later I went to a '89 truck all roller engine, had several heads on it, currently it's L98 aluminum vette heads and just Feb last year I did get a highly modified LT1 induction onto the L98 engine....IMO that cleaned up the engine compartment a LOT, and I retained the HEI....it was a LOT of work...

today, the LS engine is a FAR better bet, really...

 

Aluminum heads for LT1 are easy to come by, optispark is a good system if taken care of and kept out of water (I wont drive in rain) and the only reason im not doing an LS is because the huge cost difference and i like my hooker side exhaust