the only difference is the resonator refered to as a "Home Plate" to quiet down the intake noise on the family sedans, and as i said before, the heads are different. Just remove that big resonator and put a hockey puck in its place (literally) and youll gain a couple HP and it will look identical.

As I said, I wasn't sure about the Caprice. I have never had the displeasure of working on one. As to the 289cid, my intention was to let you know that that variant exists, should you run into one by accident on your project. Sorry if I got the application wrong, the only LT1'* I've encountered are F-Body versions.

BTW, on the resonator plate, did GM machine a pocket into the top of the manifold or is it a different casting?

Last, going back to your original post. Why the heck do you want to run the LT1 that you have as a TPI? Yeah, it does produce more torque with the longer intake runners, and some people think those tubes look cool, but what is your rationale for trying to go to a TPI or TBI manifold?

[quote="clm2112"]the intake itself is the same, the rubber elbow is different tho.. in this pic you can kindof see where the resonator connects to the intake elbow. as i said before, put a hockey puck in its place, or use an f-body intake elbow and it will look the same

(my friends 94 roadmaster)

The other posts about covered most things, but that optispark is such a POS and thats why LT1 cars, at least with the fbody people are now shunned. For what you might spend to convert your lt you could get a LS1 off the shelf used and have more pwr and less issues. MSD does finally make a replacement but it'* $$$.

Ok, now I see where the puck goes. I was thinking they connected the resonator to the manifold instead of the rubber elbow of the inlet duct. The LT1 out in the garage has an aluminum elbow, so the whole "puck" thing didn't register.


The Optispark gets a bad rap due to the early ones that died if they got wet. The later ones with the vents work pretty well (provided the vent plumbing is kept in good shape). Only advantage the MSD one offers is a timing adjust, which is a mixed blessing since you can code out the PCM with it if you get too agressive with the advance.

Now, if GM made the Hall effect triggered HEI distributor in the OptiSpark form, that would be an improvement. HEI'* are an old design, but they are reliable and last a heck of a long time.

I wouldn't convert an LT1 to a TPI, just sell the LT1 and buy a TPI motor. As for the intake differences, all you have to do is change the intake elbows to an F-Body one or an aluminum Trick Flow or Vortech unit (which I have). The Opti Spark is a good distributer as long as it doesn't get wet. I converted mine over to the vented kind when my water pump went out. Since then my radiator blew a hole in the side and soaked my engine bay and the opti spark was fine (gotta love chevys, gotta carry tools )