I'm using a painless harness that calls for the small cap computer controlled distributor, so it has the two seperate connections, i have heard that the large cap or coil in cap designs last longer and are more desirable, i have a buddy who works at a junkyard, i have a small cap in my hand, no coil though, but i asked him to keep looking for a large cap, is the harness adaptable, i think they are the same wires just different connectors correct ?? Which should i go for ?? Thanks.

 

Never really had more or less of a problem with either unless they were in the way.

 

You need to post your motor specs and year of car etc. If you have an HSR system then you will need a small cap. Otherwise a large will do fine. If you have a 93-97 you will need small cap and seperate coil. On my 85Z28 i had large cap HEI. If the painless calls for small then you may have to have a special connector to hook to large cap.

 

Stick with the small cap so the computer connections are all correct and your ECM can control it. I don't believe the large caps are computer controllable.....

 

Nope, you're wrong. Computer controlled large caps were available through '86 on TPI cars as well as computer controlled carb and TBI cars. In '87 TPI cars and most trucks went to small cap with computer control. There were some engine combos that will overlap those years a bit, but for the most part it holds true.

Connector change is all that is needed from one to the other. Find a Chiltons that covers both kinds and you can label and splice in the other type of connector. People that are doing the Stealth Ram or the LT1 swap on pre '87 cars are going from large cap computer controlled to small cap design all of the time.

 

Okey-Dokey, I stand corrected. Thanks for educating me!

Still, seems like staying with a small cap since that's what his harness is built for would be a lot easier. Using a small cap would also remove the possibility of him getting the wrong kind of large cap from the neighborhood pick-and-pull......

 

It's pretty easy to tell though. No vacuum advance on CC'ed ones, and a few extra electrical connectors on the CC'ed ones, but not the old mechanical ones. Just pop the cap and see the electronic ignition module to be double sure it's the right one.

 

I agree with vern. If painless says go small cap then stay with the small cap. I dont think the large lasts longer than the small. I have had both and neither one has ever gone bad. Only the coils crap out.

 

Painless provides an adaptor if you want to use the large cap distributor instead of the small one. It's really all about space between your motor and the firewall. I have run both on my car after installing a painless harness. I have not been able to notice any difference between the 2 of them. They both are equal unless one of the distributor's have modified parts such as a high performance coil or module. I use a small cap MSD HEI at present and have a MSD 6AL and a MSD Blaster coil and yes it all out performs the big cap by far. I also have a Excell High Voltage in cap coil for the large cap distributor with a aftermarket module replacing the small cap setup I have in it nowwith the large cap would not show or run any better. If the small cap dist was stock then yes the large cap would perform better. Vise-a versa.

It's all a matter of what you like or have room for. Stock Small vs. Stock Large= same performance from either one stock distributors.

 

You get less spark scatter with the large cap distributor. All TPI Corvettes used the large cap even after the f-body switched to small in '87.

 

This is true, and you're likely to run into the problem somewhere around 8000 RPMs.