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Re: 318/392 Stroker Motors

Posted: Thu Sep 05, 2019 2:38 pm
by EWRice
It sounds to me like you have a warped head/block or are developing a hot spot in the head or block between those two cylinders. I have read that the later 318 blocks had substantially thinner cylinder walls compared to the early blocks. Can I assume you have a .040" over bore to get to 392ci? It is possible too that over torquing the head bolts has distorted the block in that area. A picture of the failed gaskets would be helpful. Also, do you have any pictures of the combustion chambers in the head that failed the gasket?

Re: 318/392 Stroker Motors

Posted: Thu Sep 05, 2019 3:08 pm
by jralbert
I know you are not looking at overheating as an issue but the post above referring to a "hot spot" raises the question again - is it possible coolant isn't getting to that part of the engine? I recall that with engines on a slant, the fwd end doesn't get all the coolant it needs at times.

Re: 318/392 Stroker Motors

Posted: Fri Sep 06, 2019 1:22 pm
by EWRice
About the only way coolant won't flow to a certain part of the block is if you develop steam pockets under the deck. The old 400 chevys had special steam holes drilled between block and head to minimize this. Coolant only enters the block through one spot on each bank, but flows around the cylinders and up through the deck into the head. Then out the front to the intake, t stat, etc. It is odd that a hot spot would develop between 1 and 3 as they get coolant first. Unless there is an issue with gasket or head port matching (which i have seen on chryslers using heads and blocks across different years). I would take a really close look at the deck and head surfaces with a VERY high quality straight edge and feeler gauges. Then triple check ALL ports, block and head, with a new gasket.

This is more interesting than an Olds 403 that had the cam installed 30 degrees off. Tore my hair out on that one for quite a while.

Good luck

Re: 318/392 Stroker Motors

Posted: Sat Sep 07, 2019 7:19 am
by Fastjeff
That 9.8:1 seems a bit high for 89 octane gas. I assume that's what you're running on (since only millionaires can afford the 92 stuff).

Also, look for light under the straight edge using a mini flashlight.

Good luck! Yours are my all time favorite Marinette repowers.

Jeff

Re: 318/392 Stroker Motors

Posted: Sun Sep 08, 2019 10:10 pm
by Trowerpower
Most of the marinas on Norris Lake have 93 octane fuel made by Phillips 66. I believe they call it valvetech. It has no ethynol. Thanks for all the comments! Starboard engine is still running great.

Re: 318/392 Stroker Motors

Posted: Sun Sep 08, 2019 10:20 pm
by Trowerpower
The blocks were bored .030 over and there is a rotating assembly from Scat Enterprises including, pistons, rods and a forged crank. Custom ground cams and Scorpion roller rockers.
The valves were enlarged slightly to help it breath better. 750 edlebrock carbs stock intake.
My e mail address is gregstarks57@gmail.com i will share photos of the last time it was apart.

Re: 318/392 Stroker Motors

Posted: Wed Feb 26, 2020 9:31 pm
by Trowerpower
Happy New Year! Spring is just around the corner. In Tennessee. Our marina was building new docks, no place to park the boat in the yard until now. Hope to pull her out of the water to repair the port motor blown head gasket in the next few weeks. We believe something is not flat, head or block. While she is out of the water we will clean and paint the bottom as needed. Also will install the 4 blade props I bought a few years ago. I will update this post as we move forward.

Re: 318/392 Stroker Motors

Posted: Thu Feb 27, 2020 6:53 am
by Fastjeff
Use a straight edge and a thin feeler gage across the block surfaces. If you see any gap you'll have to resurface it.

Good luck! (One of my favorite big M projects.)

Jeff

Re: 318/392 Stroker Motors

Posted: Thu Feb 27, 2020 9:57 pm
by Trowerpower
Hey Jeff! Thanks! Will post an update soon!

Re: 318/392 Stroker Motors

Posted: Thu Feb 27, 2020 11:03 pm
by legendlc
Just about finished with a head job myself on a 440. Good luck. I purchased a project boat that had a apparently blown head gasket. Or at least the empty heat exchanger milky oil and a couple of cylinders full of antifreeze led me to that conclusion. I have everything back on except the exhaust bellow's. Getting the manifold on by myself was a chore. But as Jeff said a nice metal straightedge and feeler gauges are your friend. My deck and head both checked okay but I had some valves that needed reseating and one exhaust valve replaced. So I had the head machined while there. Good luck and I hope spring hits Kentucky soon as well.