http://stewartcomponents.com/index.p...ormation_id=11

http://www.stewartcomponents.com/ind...&product_id=58

http://www.cpperformance.com/p-14342...hermostat.aspx

Your basic "merc" "sierra" "quicksilver" thermostat, is more like a car thermostat. They are and were designed to run with a bypass style water pump, like most stock GM cars. Dont confuse the bypass term. What I mean, is the water on stock merc engines, and car engines, gets recirculated, coming out of the intake, back into the "CIRCULATING" pump, and then back thru the engine, while the thermostat is CLOSED.

However, with an aftermarket crossover, that water that is entering the engine, NEEDS air relief pockets in the thermostat. Using a car or "merc" style stat, with no holes, the water is being "trapped" and forming "steam" pockets, and uneven thermostat operation is gonna happen.

Tim, I think I'd give those thermostats I posted in the links a try. I know I've posted them before. Theres a reason I posted them, and not the link to a stock merc or sierra thermostat. You arent running a stock setup. :frog:

sturgismac - Good info above on holes. I ended up with 4 x 3/16" (that's just what I picked for a drill bit) and worked okay....but still needed to add a psi regulator.....and then when lake is cold (1/2 our boating season) I had horrible time with getting oil temp good until I could go WFO.

=======================

Anyway - crossover systems are pain in the azz.

Installed recirculating system and never looked back.

BTW: Part of my dyno testing mentioned above, was different intakes, wet vs dry exhaust, and yeh, you got it....with, without each accessory....other than PS pump as I left that off.

Recirculating pump vs crossover was nothing (less than 3hp which is within dyno error) up to the tested 5600-5800rpm.

I wish I never wasted the time....but I did learn something. LOL.

I was looking back when you posted those before and did not see a 140 I wasn't sure so I got the merc 142's and made holes just to play with since they were cheap and local..

I will be running the boat this weekend either with restrictors plates or nothing and play with this later the cold water temps won't kill it and it's not 50 degree water and 65 outside anymore...

I honestly think with lifter bores and valve guides opened up more this is not even an issue and I am creating
More grief then good.... I know
Many agree with this...

I've used the Hardin crossovers with their thermostat housings with the divider in it with good success. I still find myself having to drill a few holes in the thermostats to A) lessen the water pressure a bit and B) send a little more water to the exhaust when the thermostat is closed. I also like to have a way to expel any and all air that can get trapped beyond the thermostat when it's closed.
They will all generally have water pressure issues without some holes drilled in the thermo. A bunch of the setups out there only use a 1/2" or 5/8" hose for the bypass. You have (2) 1" hoses feeding the exhaust. The crossover is being fed by 1 1/4" hose. How in the hell can you possibly remove all of that water through a 1/2" hose. You can't. So, the water pressure spikes. The new Hardin setup uses a 1" bypass hose so it doesn't cause nearly as bad of a water pressure spike. Combine that with a few holes in the thermo and you have a really nice crossover setup.
Eddie

Tim, here is an idea and I've tested it. It works. If your intake has a bypass hole in it under the thermostat you can run a small hose from under the thermostat to the top of the thermostat housing (I used -6 or -8 can remember) I had a bunch of 1/16" holes drilled in a 140 "car thermostat" and my temp pretty much stayed at 135. If you don't have the bypass hole in the intake it wouldn't take much to drill and tap it to 1/2" pipe. Just an idea it works. At least this way you are heating the bypass water through the motor. Just block off your bypass on the crossover and don't use it. At this point it would be a cost effective way to get a little bit of temperature in the motor.

Hmmm that could work

All it's doing is basically restricting the flow until the thermostat opens when idling. A little extra block pressure at idle isn't a bad thing cause it's gonna help move the steam from the heads. It doesn't take long with this setup for it to get some temperature in it. Thermostat opens and you have full flow. Actually might flow a little more when it opens. I'm sure with this setup the thermostat is going to open and close a lot.

Could kill two birds with one stone.

Run water lines from rear ports of intake manifold to a water block like Brodix's MSWT-4WT with thermostat between block and intake.
http://www.summitracing.com/search/p...ibution-blocks

http://ecx.images-amazon.com/images/I/41y7Das5JYL.jpg

^^^^^^^^^^^^That's gonna be me. Thanks SB

You know, I wish more aftermarket manifolds came with the rear water passages drilled and tapped. My Dart intake did not have provisions for this, or I would have added some hoses here to promote better flow to the rear of the heads. I don't think I want to take a chance on trying to drill and tap these with the intake on the engine. Of course, I am running a circ pump, so it may not be an issue.