Looking at two dizzy's side by side, both large cap hei, whats the best way to tell if they're compatible for the 87+ roller cams?

I can't tell by looking.

-- Joe

 

FACTORY roller cams? If so, they take the same distributor gear as an old flat tappet cam. It's AFTERMARKET roller cams (usually retro roller conversions- not ones that are designed as direct replacements for factory 87-up rolers) that often require a softer distributor gear to keep from chewing it to pieces.

 

Are you sure? I have always been told that factory distributor gears are different for flat tappet vs. roller applications.

 

Me too...

-- Joe

 

Factory dist gears since sometime around 1980 have been "melonized" (somebody's trade name for a surface hardening process....), which is all that's needed to run it with a cast-iron roller cam. So if your dist is from the 80s or later, or has a newer gear, then you've got all you need.

Billet cores WITHOUT the pressed-on cast-iron gear are a different matter. Those, you need the softer gear. If you've got a billet cam, then you already know how different it looks from a cast cam core; if the dist gear looks REAL DIFFERENT from the rest of the billet core, then you can use a factory dist gear.

Look in this thread, scroll down to post #41, for what a billet core with a cast gear looks like.

 

I've got a bunch of dizzy's on the shelf. the one that came out of the vette motor, the gear is like. The teeth are chewed. kinda weird, like they are wicked thin. I dunno why they look like that, but the dizzy is not going into the new motor.

I wanted to use one of my other dizzy's, I noticed the cap is NOT screw on like the vette dizzy, but instead uses those spring loaded L shapped locks.

Is it 'safe' to assume, any 4-wire plug HEI dizzy is gonna work with an 87+ (cc-07-306-8 lt1 cam to be exact) cam w/out problems?

-- Joe

 

Cool, that means I can run this TPI roller cam dist in my 86 tappet motor without any issues? That's good news, I don't have to upgrade my gear. I'm running small cap for electrical reasons.

 

Yes, you're going to have issues. How are you going to keep the lifters from rotating? How are you going to keep the cam from walking out the front of the block?

You're going to have to use lifters with link-bars (horizontal or vertical) and a cam button. Then you'll have to provide a spacer the same thickness as the retainer plate between the block and the cam sprocket.

If you're running a mechanical fuel pump you have to make sure the TPI cam has a lobe for that.

 

wtf are you talking about? he's asking if he can run a later small cap dizzy in a earlier block.

-- Joe

 

Is there really any need for the "wtf"?

Honest mistake. I missed the "dist" part of his post. I call it a distributor.

Forgive me for trying to help.

 

Sorry. The thread was about dizzy's. I looked at your post and said "what the heck is he talking about!??!"..

- Joe