??? SBC Distributor Cap Dimensions stock and aftermarket???

[bjhines]

I have the worst time finding stuff like this on the interweb.

What are some of the choices I have to get the clearance I want?

 

I want a 4.5" dia. cap. I figure this will give me .75" clearance to the firewall's closest point(the "X" embossed in the middle).

 

I realize that there are several different HEI cap diameters. There are various aftermarket distributors that use cap designs from other cars(Crane uses a Chrysler cap). The older points style caps were much smaller than any HEI.

 

Why does no one put this info out there??? Is it some kind of mystery?? Even the guys at the MSD tech forum asked that a poster call or Email for a response on cap dimensions. WTF was that?

 

 

 

I have found some dimensions that are not at all confirmed.

 

Old style points cap= 3.5" dia.

Early HEI?= 7" dia

Newer HEI(>1984)= 5"

[SpeedRacer]

Funny, I use this http://www.msdignition.com/product.aspx?id=5709 distributor because of my Tri-Power intake and MSD says it is "CNC machined billet aluminum housing is 3/8” smaller in diameter and 7/8” shorter than conventional Chevy V-8 distributors with the “points” type cap" but they never state the actual size.

 

I just went out in the garage and measured my MSD 8570 and its about 6 1/4" high off the manifold and the cap is about 3 1/4" in diameter. Sorry, its hard to get it exact.

[bjhines]

That is great info, THANK you!

 

I just don't understand the reluctance to print dimensions for SBC distributors. I figured MSD and others had some drawings or basic dimensions for these devices.

I called Crane about one of their distributor's dimensions and all they would tell me is that "it is a Chrysler style cap". I asked which years and I was told "early V8 cars and trucks". Jeeeze!!!

 

It appears that Speed racer is one of the first humans to ever type a dimension for a distributor to fit the SBC... in the last 60 years.

 

I was considering the 8570 because of it's advertized small size. I had no idea it was only 3.25" dia. Holy crap.. How can you get spark to the right places with a cap so small.

If we are to believe MSD's claims in reference to the standard points style distributor, "CNC machined billet aluminum housing is 3/8” smaller in diameter and 7/8” shorter than conventional Chevy V-8 distributors with the “points” type cap" then we can assume that the standard SBC points style distributor is 3.625" dia. and 7.125" tall.

 

That leaves me with:

 

Old points style cap= 3.625" dia. and 7.125" tall.

MSD 8570= 3.25" dia. and 6.25" tall.

Older HEI= 7" dia. and ???" tall.

Newer HEI= 5" dia. and ???" tall.

[jt1]

I have an older GM HEI that the cap is 6" in diameter if you include the lugs where the locking screws are, and 7 3/8" tall from the manifold.

 

A MSD 85551 is 7 1/4" tall and 5" dia with the screws, 4 1/8" without.

 

jt

[fastzcars]

I have that MSD small cap dist. I'll check out the diam and post later on tonight.

[lovemstr]

why not use old style GM points type dist.(cheap as dirt) with electronic conversion by Pertronics or Crane ( between $75 - $100) works great. it allowed me to set my engine back about another 3/4 in.

[hpltree]

well here is the same thing at a different angle.... do any of those distributors fit under the stock hood latch with the jtr mounts, looking at some of the small cap MSD or Mallory stuff, thanks

[hpltree]

well here is the same thing at a different angle.... do any of those distributors fit under the stock hood latch with the jtr mounts, looking at some of the small cap MSD or Mallory stuff, thanks

[hpltree]

why not use old style GM points type dist.(cheap as dirt) with electronic conversion by Pertronics or Crane ( between $75 - $100) works great. it allowed me to set my engine back about another 3/4 in.

[hpltree]

sorry guys im still learning how to do this

[BAINATSEABOARD]

John, I used the msd billet dist and had no issues with the clearance. I used the JTR kit and have about an inch to the firewall. I have had no issues with this combo.

[GLSHLE]

I have a Mallory Unilite. It's 4 7/8 wide, 2 5/8 tall. JTR mount, 5/8 to the firewall.

[kamikaZeS30]

I used the Pro-Comp billet distributor (I got the whole PC kit on Ebay for like $170 brand-new, comes with coil, distributor and CDI multi-spark box), I am using the Scarab mounts and a Camaro bellhousing T-5 transmission. I am also using professional products' Typhoon intake manifold (don't think that makes much of a difference).

 

The problem for me was: I slammed the engine as far back to the firewall as I could before I started getting clearance issues with the transmission lubricant fill-tube, and clutch slave cylinder/fork, the distributor still has quite a bit of clearance. I'll have to actually measure it, but the distributor looks like it can't be more than 4" or 4 1/4" in diameter, and the vacuum advance thing sticks out a little, but with no issues. And I'd say the back of the block is no more than maybe (at the most) 2" from the firewall, if that (like I said, it's slammed, the water-pump does not protrude beyond the plane of the "K-bar" or front susp. cross-member).

 

You should be "golden" if you go with any of the non-HEI distributors. I, personally, don't like HEI, but that's me.

Edited August 26, 2010 by kamikaZeS30