seabeach

Need some advice on whats causing popping in the exhaust, it happens when cruising at 3200 rpm. I have dominator 1050, stelling headers (dry exhaust), Crane 139651 with hydraulic rollers, 540 cui, standard mercruiser 990 heads. Thunderbolt ignotion. Please let me know if you need more info to help me.

Thanks in advance!
/Torbjorn

Vinny P

There are several things that can cause this. But, I would first look at the valve springs. Make sure they are not broken and have enough seat pressure to match your cams requirement. If that yields no results, try to run a leak down test to check that the valve angles are not worn out.

epeek

Sounds like a valve leaking to me. Spring, seat,valve
face, all possible, test compression & leak down.

Unchained

A buddy of mine had the same problem and after tons of trouble shooting it turned out to be incorrect push rod length. Just something to consider.

seabeach

I dont think the valves are worn out they only have 15 hours since rebuild (complete engine). In some way there must be fuel and oxygen in the header for this to happen.

I will do a compression test later today, would like to do a leak down but I dont have the means for it.

Why is this condition only at 3200 rpm?

Thanks!

seabeach

Sorry forgot, the pushrods (length checked) are the same in both engines and this only happens in one of them.

Thanks!

maverick1

Recheck the plug wires that you haven't crossed two, and check them for an Open circuit or bad insulation.

seabeach

The funny thing is that it only happens at 3200 rpm, I will check wires and plugs.

Thanks!

maverick1

If the motor (cam) is new I fear you may have had a lobe go down on your cam. I'd pop the valve covers and rotate the assembly and look for one valve with little lift.

Sorry....

John B

Maybe a valve sticking in the guide.

Maybe valves adjusted too tight.

Carb jetting may be too lean. Who set up the 1050? Does it have intermediate circuits?

Could be an ignition crossfire, or crossed wires. Check the firing order.

JB