SBC vortec distributor cap issues

[BILL-C]

I have an old beater 1998 chevy K1500 with 5.7 vortec engine that kills distributor caps like crazy .Engine starts with random missfire and pinging then one morning won't start. Replace cap and all good again. NAPA caps go for 6 months, genuine GM 1 year at most. Iv'e heard that there is a marine version that has brass terminals and works much longer. Anyone have any input? maybe a source for a marine cap? This truck is "dirty work" truck for plowing, fire wood, hay, etc and sits more than it runs.

[BillK]

Bill,
There is probably something else causing the problem. How are the plugs and wires ? Are you using GM rotors ?

I just changed all of the original parts on my 99 Tahoe last spring with 245K miles on it all. I have not heard of anyone having any problems as long as they use GM parts.

[rfoll]

I brought this up a while ago. Same problem, and caps from Napa. The consensus was moisture in the cap with nowhere to go. I believe MSD makes a cap for this application now.

[mag2555]

I would look into how much play you have in the timing chain and or what the Distributor gear looks like.

[Schurkey]

I'm on some truck forums, and there's no end of bitching about distributor cap life on the Vortecs. I don't know if that's realistic or not. I'm a recent owner, so far...so good. They do claim that the GM/Delco/Delphi caps last the longest.

Excess voltage due to excess plug gap or dead plug wires, or excess blow-by leading to vapor 'n' moisture in the distributor seems likely to me. That and the crappy plastic distributors tend to crack at the mounting holes for the caps. Dorman even makes a hold-down repair kit for them. But given their tendency to wipe out the bushings--most folks seem to chuck the distributor in favor of an aluminum aftermarket replacement.

Since timing isn't controlled by distributor rotation, I wonder if rotor-to-cap alignment problems lead to high firing voltage, lots of ozone in the cap, and misfire. Have you checked the "Distributor Offset" using a scan tool? When I got my '97, the offset was 29 degrees, when it's supposed to be + or - 2 degrees.

The last MSD distributor cap I bought (for an earlier TBI application) the stupid thing was a cheap Chinese unit in an MSD blister pack. I need that like I need to put a power drill to my temple.

[ProPower engines]

There is 2 things that will make a cap last a very long time.
1 is the use of brass contacts and the brass tipped rotor like the marine cap+rotor. Also a decent vent system to
remove the ionized air in the cap when running.
Most marine dist.'s have a vented cap and a vented dist. body. They also use a small vacuum port on the dist. that connects to the flame arrestor to draw the burned air from the cap on the older Mercrusier and Volvo-Penta engines.
I personally use a MSD marine drop in dist. on all new builds running a carb and update the newer ignition systems to use a purge vent connected to the flame arrestor.

The frustration level of having a no start issue when you done fishing on the kicker and the main engine won't light to get
home is not only life threatening but the whining from customers is unlimited when it happens and they think you
did something wrong or used cheap shit when you did a tune up and they need yet another dist. cap after 1/2 a season.

[BILL-C]

The NAPA marine distributor cap is on national backorder and costs $ 90.00. Wires and plugs new with new GM cap and rotor 9 months ago. We rebuilt engine 10 K miles ago, so it should be good inside. I don't see a MSD version of this distributor in catalog, or a replacement cap.

[superpursuit]

Are the contacts inside the cap brass or aluminium? I used to have a car that used to have the brass contacts but then they stopped making that and the replacement cap had alloy contacts that did exactly as you describe. After replacing the cap several times I got tired of that and started bead blasting the contacts inside the cap to get rid of the oxidation. Worked perfectly after that until they oxidised again a few months later so after a quick bead blast it was good to go again. I did this for years on the same cap. This was never an issue with the brass contacts, only the alloy ones.

[midnightbluS10]

The NAPA marine distributor cap is on national backorder and costs $ 90.00. Wires and plugs new with new GM cap and rotor 9 months ago. We rebuilt engine 10 K miles ago, so it should be good inside. I don't see a MSD version of this distributor in catalog, or a replacement cap.

PN 8017 is the MSD Vortec flat distributor cap.

https://www.summitracing.com/parts/msd- ... PIQAvD_BwE

And they sell it with this distributor

https://www.jegs.com/i/MSD/121/5592/100 ... mIQAvD_BwE

[BILL-C]

The NAPA marine distributor cap is on national backorder and costs $ 90.00. Wires and plugs new with new GM cap and rotor 9 months ago. We rebuilt engine 10 K miles ago, so it should be good inside. I don't see a MSD version of this distributor in catalog, or a replacement cap.

PN 8017 is the MSD Vortec flat distributor cap.

https://www.summitracing.com/parts/msd- ... PIQAvD_BwE

And they sell it with this distributor

https://www.jegs.com/i/MSD/121/5592/100 ... mIQAvD_BwE

Thanks for the info! I just ordered one. I gave up too quick when i didn't see anything with the race distributors in catalog. Never noticed the "street" section at end of catalog.

[af2]

The NAPA marine distributor cap is on national backorder and costs $ 90.00. Wires and plugs new with new GM cap and rotor 9 months ago. We rebuilt engine 10 K miles ago, so it should be good inside. I don't see a MSD version of this distributor in catalog, or a replacement cap.

PN 8017 is the MSD Vortec flat distributor cap.

https://www.summitracing.com/parts/msd- ... PIQAvD_BwE

And they sell it with this distributor

https://www.jegs.com/i/MSD/121/5592/100 ... mIQAvD_BwE

Excellent info!! I fight the service van every couple years going through 2 a couple months when it rains then fine in the summers.

[woody b]

The V-6's with a cap that looked like that had a recall to make sure the vent holes were open in the bottom of the distributor, replace the cap, and put a piece of insulation on the A/C line that ran right above the cap. I don't think there was such a recall on the V8's. I'd check and make sure there's open holes in the bottom of the distributor. IIRC the V6's has screens in the holes and we removed the screens when doing the recall. I don't think the A/C line runs over the cap on the V8's. If it does put a piece of pipe insulation on it to keep it from sweating, and dripping moisture on the distributor.

[midnightbluS10]

I'm not even sure if my aftermarket distributor had screens. I finally got away from the plastic housing with the ears that crack and break off I was replacing them every time I did a cap. The last one I got had an aluminum? housing.

[Racer71]

Gm recommends opening the holes in the bottom and or knocking the screen out to allow better cooling. Being a plastic housing they flex and wear the thrust washer and the teeth of the gear badly as well. I know I can buy a complete new distributor with the cam sensor and cap and rotor for 79 locally at at zone or Oreilly, which is not much more than the cap and rotor kit. We go through these frequently, another great generous motors design.