No I agree with you!! Im just taking what I can get because most of its all warranty so far. Thanks Ill be back up & running soon im sure.

I had an issue sticking valves and hitting pistons when I changed over heads. I was getting steam pockets in the rear of my engine due to different water flow from one brand of head to the next. Also, I assume the MarkIV, Gen 5/Gen 6 heads stuff played a factor. I ended up drilling out the back of my intakes into the water channels to propagate better flow throughout the engine. I took out valves 3 times before I figured this out. It was in the first 5 minutes of running on plane. If I shot the engine with an infrared pyrometer I would see well over 100*F from the front to the rear of the heads. I no you have small blocks and not saying this is your issue just throwing out some ideas.

Thanks for the idea!

Sounds just like my issue, the water & oil temps are not consistent at all, Ive replaced both sea pumps, temp sensors, belts. cleaned out all 4 coolers found nothing. Its doing it within 2-3 minutes of being on plane or less. I also noticed how tiny the water holes are in the "marine" head gaskets. Ill take my infrared temp gun next time I go & see were it getting hottest.

Here is my experience.

http://forums.boatfreaks.org/showthread.php?t=14365

Good read! thanks, I have cross cooling on all my racecar motors makes perfect sense. Im going to do some research about different gaskets & ill probably drill a couple more holes in my thermostat restrictor plate. is has a 1/2 hole in it now I wonder if thats part of the issue. just plain not enough water.

I wonder if thats part of the issue. just plain not enough water.

Uhhhhh-.-.-. there's water all around your boat. could it possibly not be deep enough?
Sometimes I just out do myself! I have to go look at my smile in the mirror. BBL

You have 400 blocks right? I've heard mixed thoughts on drilling the steam holes in the heads, but maybe it's worth a shot?

haha im about to pull the plugs then it will have plenty of water lying on the bottom of the lake!!


Lil red yes, Dart Motown blocks they are .05 under a stk 400 bore. Thanks for the idea ill research it a bit.

FYI Guides have .027 clearance going to take them to .03 or should that be written .0027 & .003 I think, I have all the A.N. lines & fitting to do cross cooling but it was the front that failed. Going to lake test it with the infrared gun & see were the heat really is.

what drives do you have, or are you pulling water thru the bottom or transom pickups, I have a pair or lowers with nose cone welded on that would get hot, pulled the lower and the tube in the lower was pinched close, barely any water worked good at idle but once on plane it was not enough water, water gauge showed 12psi but it didn't matter cause there was no water flow. hope this helps

I just went through this entire thread again & you have done an incredible job! I hope you get your engine problems fixed soon, Randy