In a roller motor (305) is a TPI and TBI distributor interchangeable? (1989)

 

Longs as years are '87-up (divorced coil)...

I/e the dizzy in my 91RS is the same as in my '89IROC

 

It was a major problem on my swapover. I have a1993 Caprice wagon that I'm swapping from TBI to TPI. The base circle at the top of the shaft was a different diameter. The old shaft from the 93 was a larger diameter base than the TPI manifold hole was. I had to hog out the hole larger.

It was not fun. The shaft would not engage the oil pump, and it took me a while to realize why, that the distributor was not dropping down all the way into the manifold hole. It had nothing to do with the Oil pump.

The alternative would have been getting a new Distribuotor.

 

I was told the newer caprice had a different size hole, I'm not sure that is a tbi/tpi difference, rather a difference between models and more specifically, years. I believe the diameter will be the same if it was before 1992, or so I've been told.

 

Basically what lakeeffect said and what u were told norcal.

Think it is 93-95 caprice TBI are different.

Long as u go from say small cap to small cap from 87-92 range u should be fine.

I am not quite sure if anything else used the larger small cap base or it was just common to the caprice or all later TBI setups.

U can easily see it if u walk thru a junkyard and look at them or have one of each to compare.

later
Jeremy

 

So the point is... Measure what you have, and make sure the sixes both match up. Then at least you'll be ok on that portion of things...

 

Yep, measure twice and cut.... well you know. My biggest concern was that the distributor was from a roller motor as I believe the gears are made differently..... one is more likely to do damage to the cam gear.

Thanks so much for your reply. You really can learn a bunch if you just read and listen. I'm hoping this distributor is the reason I'm not getting spark as I have replaced both the coil and the ICM.

Ken

 

GM cams (roller or flat tappet) all used the same cam gear and therefore the same distributor gear. It's aftermarket roller cams that might need a softer distributor gear to keep from chewing them up.

 

That puts my mind to rest. Thanks for the information.