un-sticking Chevy (OMC) 350 V8

[jimbunyard]

Forgot to ask. What did you do about the MMO you put in the cylinders? You may need to remove and clean the plugs, maybe several times, especially if you have a weak spark condition...

[travis_farmer]

Originally Posted by jimbunyard

Forgot to ask. What did you do about the MMO you put in the cylinders? You may need to remove and clean the plugs, maybe several times, especially if you have a weak spark condition...

forgot about the MMO...


~Travis

[jimbunyard]

One additional thing. This will solve most of the ignition related problems associated with a points-type ignition. The coil is in the cap. At 90.00, if it will fit (it's a bit taller than the original), it's a good investment.


https://www.amazon.com/dp/B078WHWJQ8...&pd_rd_w=T1Cjl

[travis_farmer]

it fires! not running, but it fires.
i shot a blast of carb cleaner in every plug hole, and the next time i cranked it, i got a back-fire. (distributor was 180 degrees). fixed the timing, and tried again. several fires in succession!
as for draining the carb float, it does not separate from the carb body, so i suspect i may have to pull the carb and clean it. in any case, it has started to rain. i have a tarp over the back of the boat, but with the gas fumes, i didn't want to work under a tarp. but i have paused the project with great progress! i am positively elated right now!


~Travis

[travis_farmer]

it runs! the problem is, apparently so does the water, right out the side of the exhaust header.


really wasn't expecting that, and i really can't afford new/used exhaust headers right now.


~Travis

[Cheechako]

Cool! They are pretty common, maybe you can find a used header.

[tschmidty]

I am guessing it is raw water cooled which means it isn’t pressurized. Is it an obvious crack or is it at the gasket? In any case you may have success patching it with jb weld or similar

[travis_farmer]

won't the JB weld burn off?


it has a section of side wall blown out. not missing, just sticking out, like it wasn't winterized, and possibly freeze fractured.


i hope the block is alright... i didn't notice any block cracks, or grey sludge in the oil.


if it wasn't for the heat part, i would try truck/car headers, but i think that would cause bad heat issues. maybe just run some exhaust stacks out the back with some flowmaster exhaust.


~Travis

[hellosailor]

If the exhaust header is just leaking water, there are ways to patch that. There are damage controls clamps, rubber padded half circles of pipe, that bolt up around pipes to seal leaks. And if it is at low pressure, you can usually clean off the metal, then apply some stainless steel (kitchen scrubber pad) loaded with JBWeld, to form a nice hard scab over the leaking around. Many ways to get by on that one.

[travis_farmer]

yeah, i will take a better look at it some time. right now i am avoiding the stares of the neighbors. that beast is pretty loud! but other than the water leak, i loved every second of it.


oh, what are the chances of brazing the leak? either way i have to remove the header, as it is on the inside face of the header, but not interfering with the head-manifold joint.

i may remove the other one too, if only to just inspect it better.


~Travis

[hellosailor]

I'm told that JBWeld is dark gray because there's a lot of steel dust in it, which helps spread the heat. And that's the other reason I suggest using it worked into stainless steel curly stuff, the metal dissipates the heat. JBWeld alone holds up on engine blocks, which are not manifold temperature but may exceed what the water-cooled portion of a manifold is running at. I've used plain silicone filled stainless mesh on exhaust pipes--and seen that last for years. (Hey, it wasn't elegant, but it worked.)

[a64pilot]

I think JB weld is epoxy with aluminum powder in it.
I know Metal set, a competing and I think pretty identical product is.

Cast iron can be welded with a nickel rod, with good success too. I have done a lot of it on the farm. Best to preheat and stop drill a crack though or you can chase it a long ways

[jimbunyard]

Usually a false economy to try and repair a cracked water cooled exhaust manifold, especially when a new one can be had for 205.54.


Is this what yours looks like, or is the exhaust outlet on the end?


914035 OMC EXHAUST MANIFOLD




Or if you're talking about this part, called the riser, for 147.00 from the same place.

[travis_farmer]

my exhaust manifold exits from the end. log style i think it is called.


~Travis

[tschmidty]

The exhaust manifold doesn’t get that hot, it’s basically an exhaust manifold surrounded by the heated water exiting. The water and exhaust gases mix and head out through the outdrive. I wouldn’t put too much effort into welding it to be honest.