very perplexing problem

[don werner]

I need some massive help from a smart motor guy...
I have a high compression, 9.8 to 1, 3 liter with RSR cylinders and pistons, it is new with a 1000 miles on it. Webbers, MSD 6a, Pertronix pointless module.
Runs like a r%ped ape, usually.
Driving home from work, it sputters and stalls at highway speed. coast to the side.

It tries to start, but dies. Then it starts, very rough. I drive away to get off the highway sputtering and dieing. Runs fine, then rough, sputtering, loses power, and dies again.

Starts like a champ and drives away 100% normal. Fixed. Get back on the highway and after 3-4 minutes, and it starts all over again. I let it rest 5 minutes. Speak to an officer of the law for a while. I finally get it home.

Clear K&N gas filter is fine with gas in it.

???????. Being it seems to have an intermittent nature, sometimes it runs great, others it runs like poop, I am really not sure what it is.

[RWebb]

if the gas is fine, then it has to be electrical...

[pixxi]

Ignition coil - fails once it gets hot from running? (had this issue with 454 chev in boat, new coil fixed it)...

[don werner]

Forgot one thing, possibly very important. If the car idles for any length of time it will cough once in a while just once, like a miss. Never thought too much of it.

[wwest]

CDI ignition..?

Turn on all the electrical loads and see if it runs better.

[Flieger]

How is the in-tank fuel filter screen? Rust can flake off the inside of the tank and get stuck in the screen and choke the engine after a while.

[wwest]

Oh, ICE formation in the carburator...

[don werner]

tank was drained and cleaned out about 3 tank-fulls ago. Most mileage was put on the motor by the builder. I only have a hundred or so miles on it in this car.
Ignition is MSD, I believe it is CDI.

[don werner]

it was about 62 degrees this afternoon, now this morning, it was 32, and it ran great.

[1QuickS]

Same thing happened to me, fuel tank strainer filled with tank debris starved the engine. Let it rest awhile and AOK.

Disconnect fuel supply at one of your carbs and let the fuel pump run and check fuel delivery. This could be a dynamic issue in that the debris may fall away when at rest but while driving it is drawn into the filter and plugs it. The tank filter is a fine wire mesh or strainer so this "dynamic" could occur which would make your problem seem to be intermittant.

[vwpartsman]

Just a shot in the dark........but venting on your fuel cap? Take your cap off and see if it helps or if it dies again take it off and see how much pressure is built up. Probably not the problem but a cheap and easy check.

[warner53]

Pretty engine, she runs just like a woman. LOL

[don werner]

yeah, reminds me of both x wives.
I will give these a try. Any thoughts of the occasional miss at idle prior to this?

[fastfredracing]

You would not be the first guy in history to get a faulty msd box. Do you have another one you could borrow, and try out ? Looks like a pretty clean install, but could not hurt to check the power and ground connections for the MSD as well.

[ghamilton]

My first guess was electrical also.

[Dan J]

Next time it happens remove the fuel bowl drain plugs (catch the fuel don't burn down your car)
If there's no fuel you've found your problem if there's plenty of fuel it's probably ign

[don werner]

nice.
great move.

[don werner]

Thankx folks.
Pulled the gas tank out today cuz I found lots of black ***** in there. Looks like a PO had coated the tank with something and it is all flaking off and clogging the tank filter. I am going to find a radiator shop and let them do what they do best....I cannot believe this was not the root of the problem.

[don werner]

Sorry i had forgotten the gratuitous picture of the offending tank

[Flieger]

Nice brace. Did you make it yourself?