blackozvet

I ordered a MSD dizzy cap (picture below) from Summitracing, I made sure i checked application, yes it says, '85 Corvette,
when it turned up i noticed it had long quarter turn clips, my distributor has 4 short screws so i cant use it,
So what does the long quarter turn cap fit ?? I looked at some on ebay and it would appear the long clips are C3 ?
I sent Summit an email saying their application list is wrong, but the response is "you better check with MSD, it should fit"
so before i send Summit a more strongly worded email, I thought I better check with the CF guru's

AGENT 86

Looking at Summit, I see you had 3 MSD choices. The first 2 list clamp down, while the third lists bolt down. They all say they fit 85, but it seems only one does.

http://www.summitracing.com/search/y...?Ns=Rank%7cAsc



Summit does need to correct this, and you need to read more of the info.

Can you replace the clamps for screws and make it work ? Long wet drive to get replacement.

c4cruiser

I ran into the same problem when I ordered a MSD Cap from Summit for my 87. It also uses a screw-down style cap. Not only is their catalog part number/description wrong, so is the MSD Catalog part number/description.

The MSD Website catalog is wrong. Maybe somebody from Summit should be working with MSD.

I wound up exchanging it for a Taylor cap and rotor (TAY-918131) and it was $4 cheaper. It's a good heavy cap with brass terminals just like the MSD cap.

JackDidley

Vettes and Caddies used the screw down cap. Most other GMs, the clamp style.

blackozvet

thanks for the info guys,
and yes agent86 I shouldnt be so naive as to think Summit and MSD would actually get their fitment details correct !
As far as modifying it, i would have to cut the angled clamps off and buy 4 screws the right length, or sell it to another c4 owner who doesnt know the difference !

c4cruiser

You can certainly sell it to anyone who has a GM car that uses a HEI distributor. The later C3's used them as did Firebirds and Camaros, and all sorts of other GM cars with V8's from the mid 70's thru the early 90's.

DA1984VETTE

My 84 doesn't use the screw down cap, it has the clamp style...

bwiencek

Not to bail out Summit but they simply receive fitment information from their suppliers (in this case MSD) so any "wrong" information in the application listing is coming from MSD. I believe the MSD "replacement" distributor for the C4 used the more traditional clamp style so that may be what they're referring to as it "fits". Also - I think some of the generic (read real cheap) parts store replacements may have the clamps and not the screws so that they fit a lot more applications and thus can be mass produced cheaper... Just sucks since you're apparently overseas...

I looked at the summit link - they even have the filter to select "bolt down" or "clamp down" under the 'Cap Attachment Style' heading so they must know it's important to be able to select the style.

HlhnEast

I just put a new red Taylor screw down cap on my 85. Who designed the firewall where the cowl drip edge(18 torx screws) hasta come off to get to the back dizzy screw??? Sheesh. Your on the right track buying a quality cap. I always buy one that has brass terminals and you certainly dont wanna change it often with the PITA location.

JackDidley

Maybe I should have said L98s. My 86 and 87 had screw down caps.

blackozvet

thanks for the feedback guys, you live and learn !
HlhnEast, I know what your saying about the tight fit, I thought i would do it while the TPI was off, I had to take the old cap off to put on the new rotor, used a 1/4" drive with a knuckle joint, did the trick on those back screws !
I am tempted to take the clamps off and buy longer screws, might be the easiest option ?

c4cruiser

Never had to remove that drip rail when I swapped caps. Was pretty easy to access and I just used a Torx screwdriver.