I have been fighting an air/fuel problem since I got my 383 going, swapping carbs, changing jets, timing, nothing seems to work
Then I thought to pop the cap on my MSD Pro-Billiet distributor(has the small cap, tach drive, part# 8572, and I'm using the MS6 box also) and check how things were going in there. Now, isn't there supposed to be a spring-loaded carbon nub in the center that makes contact with the rotor(like on an HEI)? If so, it's worn down to about nothing!
This particular cap can't have more than 500 miles on it. Anyone have any suggestions as to what might be going on here, or of maybe a replacement cap that won't wear out so fast?
Thanks in advance

 

yep, should be there.....check end play of dist shaft....should be no more than about .010 inch but at least .002

 

Took the cap off again before going to work this morning for a closer look, the carbon piece almost looks like it sheared off! I don't think it wore down, as there is no residue in the cap or on the distributor.
I'll pick up another cap and rotor from the local speed merchant and try it again tonight.

 

Keep us posted, I am curious about this

 

certainly will

 

Check the end play and shim it to what David said. If you have to much it could tear the nub up on the cap.

 

Ordered up a new cap and rotor, they won't be here till tomorrow afternoon. I'll post results as they happen

 

Put the new cap and rotor on, and the car does run better, but it was not the problem. I'll keep looking!

 

Hi Randall, exactly what is your engine doing....Running rich or lean? Is the engine new or if not , whats parts are older, like the cam, dist., timing stuff up front, etc.

 

Dave-the engine is new, here are the specs:

1991 roller 350 block junkyard special, magged and bored
Scat 9000 3.75 stroke crank and rods
KB-100 pistons
Comp Cams .560 lift 286 duration roller cam
Brodix IK200 heads
Summit aluminum full roller rockers
Hooker headers
Edelbrock RPM Air-gap(fits under the stock hood with about 1/4 clearance)
Holley 750 vacuum secondary carb w/ #70 jets
MSD pro-billet distributor w/ tach drive and MS6 box
BTO 200 R-4 w/ 2200 stall converter
3:73 posi rear
Dewitts radiator

Right now the timing is set at 8 degrees, using the heavier silver springs in the distributor to bring all the advance in by 3000 rpm. The engine idles as though it has a vacuum leak someplace, the idle seems to pick up with both mixture screws turned about 1/2 to 1 turn out. Checked for leaks by capping all the ports and hooking up a vacuum gage, seems to be steady at 11 inches with no change in idle.
With a road test, it pings when I step on it
By moving the timing back 4 degrees it doesn't ping, but there is a noticable drop in acceleration
Next chance I get this afternoon I was going to try jetting up and see if that stops the pinging, but it probably won't do anything for the idle.
I should also point out I have a TV made EZ plate by BTO between the carb and intake, and wonder if the extra sealing area could have a small leak someplace that I haven't found yet.
So there you have it, I tried to include as many details as possible, if theres something I missed, let me know, Thanx!

 

Looks like a really great setup to me. You gonna love that 200r and 3.73 gears.
You might find that vac leak by spot spraying a bit of starting fluid around the intake to head or intake to carb. with engine running. If you hit the spot the idle will increase .
Have you looked at the plugs?

 

Been watching the little one today, so Dad can't go out to the garage to play wife will be home in a half hour, then I'll be free

Checked the plugs a couple days ago, they still looked fairly clean.

Boss is home, I'm off to the garage! I'll report back when I find something out