ProjectBird85

Just got word from the shop that they can't install my MSD because the engine has a misfire. When I got my car all the spark plugs were loose and the wires off (previous owner did a compression test) I was able to get them tight with the exception of a couple that I could only hand tight. I replaced the cap/rotor that has the HEI. I thought the car ran great. Anyone know what might cause the misfire in only 1 cylinder?

ploegi

Plug still loose. Wire loose. Corrosion. Fouled plug. Failing injector. Loose connection on injector. Low fuel pressure... maybe.

In any event, none of this should matter as far as the MSD box is concerned. They should be able to install it anyway. Not sure where that reasoning came from. (unless, they want the miss fixed first, so if it runs funny when they are done, they know they started with a good running car.)

ProjectBird85

Doesnt have Fuel injection it's carbed. They didnt want to install the MSD because they want to get it dyno tuned. Thats what Im leading to, either that or the firing order is off. Not sure, I hope it's nothing internal. Also before I got the car it sat for about 4 years so Im not sure if the plugs and wires are bad.

ploegi

Erm, what does the MSD have to do with being dyno tuned? I would think they would WANT it on there for that exercise???? No??

If the firing order was off, you would have misfire on two cylinders. In your first post, you stated that at least one of the plugs was only hand tight, start the engine, and run it, and the plug WILL back out. That might be the whole problem right there....

A vacuum leak where the intake manifold hits the head, if is leaks into a runner, would also cause a misfire on one cylinder.

ProjectBird85

Im not sure why they didnt install the ignition first. Yeah they told me only 1 cyl was misfiring. They are going to check it Im hoping tomorrow. The shop has had it for 2 day's and this is as far as they've gotten. Very frustrating.