New Member Introduction

[Kaboom]

Hello, I came across this forum while researching info on 7730/7727 GM ECM's. I have an LT1 in an offroad Jeep that i've modified the intake to use a rear distributor. In the process now of getting the harness and ECM together. Looks like alot of information here and good people willing to help.

[1project2many]

Hello, I came across this forum while researching info on 7730/7727 GM ECM's. I have an LT1 in an offroad Jeep that i've modified the intake to use a rear distributor. In the process now of getting the harness and ECM together. Looks like alot of information here and good people willing to help.

Welcome to the forum. Neat project! I didn't realize folks are still converting LT1 to use distributors. Good job.

[Aroberson77]

Welcome. I also have an LT1 swap but still using the optispark. I put mine in a 1985 RX7 and am about ready to tune it. Please let me know if you need any info on wiring or what stuff I am using to tune.

[Kaboom]

Welcome to the forum. Neat project! I didn't realize folks are still converting LT1 to use distributors. Good job.

I dont think there are very many people doing the LT1 rear distributor conversion these days. Most of the guys I wheel with have moved on to LS engines.

[Kaboom]

Welcome. I also have an LT1 swap but still using the optispark. I put mine in a 1985 RX7 and am about ready to tune it. Please let me know if you need any info on wiring or what stuff I am using to tune.

Thank you for the offer. It will probably be awhile before I get to tuning. I just work on it in my "spare time", and that's in short supply these days.

I ran the Jeep for about 10 years with the optispark (I paid to have the ECM programed). Then got married, had a couple kids, ect. so its been sitting for about 7 years. Just recently decided to drag it back out and try to get it running again.

The reason i'm doing the rear distributor conversion is because the optispark gave up the ghost in the middle of nowhere on me once and I just don't trust trust it (they don't seem to like water or high rpm's). I think the remote coil HEI will be more reliable and easier to work on.

[Aroberson77]

Thank you for the offer. It will probably be awhile before I get to tuning. I just work on it in my "spare time", and that's in short supply these days.

I ran the Jeep for about 10 years with the optispark (I paid to have the ECM programed). Then got married, had a couple kids, ect. so its been sitting for about 7 years. Just recently decided to drag it back out and try to get it running again.

The reason i'm doing the rear distributor conversion is because the optispark gave up the ghost in the middle of nowhere on me once and I just don't trust trust it (they don't seem to like water or high rpm's). I think the remote coil HEI will be more reliable and easier to work on.

Cool, mine has been a long project as well. I would love to see more on the distributor swap, I wonder if I should have done that when I had the engine apart this winter.

[Kaboom]

The rear distributor conversion amounts to drilling a hole in the rear of the intake, having an angled spacer machined to go under the distributor so it sets at the correct angle, and also making something to bolt the hold down clamp to. Then use a TPI type harness and ECM for fuel and spark control. I think it was fairly common back when the LT1 was more popular. There was at least one guy you could send your intake to be modified, I dont think he's doing it anymore, but the site is still up if you want look at it for more info i think its lt1intake.com.

The vented optispark is really pretty reliable. I only had a problem with mine once in ten years, but it was not fun to have to drain the coolant and remove the water pump on a trail in the woods. The main reason i'm doing it is so the distributor easier to access if something goes wrong.

The attached picture is one i found on the internet to give you an idea what the intake modification looks like.

[1project2many]

I worked in a Corvette shop for a few years. Back then we changed many Optisparks. Not fun. The cause was usually failure to replace a leaking water pump, or the owner pressure washing the engine. There were some tricks to making them more reliable but most of the support is probably long gone now.

I almost converted an LT1 intake to distributor. I needed a manifold for a set of Vortec heads before there were many aftermarket options. Luckily I found a marine intake.

[Kaboom]

After more research, think i'm going to go a little different route on my LT1. Planning now to use a crank sensor / 4x reluctor from a 96-97 LT1 and a vortec 1x distributor. Then use a 411 ECM with a 2002 express van tune.