water in oil after 15psi block pressure

[78 propduster]

78 Cole, new to me.
Fresh block
30 over 454
Merlin rectangle port heads (4 less intake bolts than stock )
Copper head gaskets
Dry stacks
671
MPD worked 12JG
Plumbing---- Pump to T (water dump) to valve ( I installed ) to block to dump.
Had a Dan Olson oil cooler which was taken out due to suspected of a leak.
The first run on the fresh motor showed water.
Replaced intake gaskets then discovered pressure most likely went over 40.
is it possible that I damaged a head gasket? Motor will hold 15psi air for 1 hr.
Last run no water until water pressue exceeded 15 or 20 psi.
Temp. holds at 160/170 at 3500 RPM. (@ 10 psi water)
Blower manifold has a cross over water hose at the rear, is this neccessary?
What about pressure regulators, do they also restrict flow volume?
Any replies will be greatly appreciated,
Thanks!

[obnoxious001]

What did you use on the copper head gaskets to seal the water passages? I suggest a real thin film of hi temp silicone. Also, you used a high quality sealer on the head bolts? Did you check the oil cooler after you pulled it for water flow? If it was plugged up, and inline after the block, it may have caused excess pressure in the block.

[78 propduster]

Heads were installed when I got it.
There was no sealant on the intake bolts so probably not on head bolts.
Oil cooler was not installed on fresh block.

[DMOORE]

If there is no sealent on the head bolts, your gonna have leaks.
Darrell.

[obnoxious001]

Heads were installed when I got it.
There was no sealant on the intake bolts so probably not on head bolts.
Oil cooler was not installed on fresh block.
Normally sealer is not applied to the intake bolts, but manditory on GM big blocks. Most of the aftermarket blocks have "blind" holes,, that don't enter the water jacket.
Also, the crossover on the rear of the blower intake is a good idea, I would leave it.
Have you tried retorquing heads? You might even pull one of the bolts to check for sealer.

[victorfb]

genV and genVI block have blind head bolt holes, but the mark 4 NEEDS sealer on the bolt threads. first place id look if your running a mark4.

[78 propduster]

Block #s say its a 1978 to 87. How do I determine the type?

[BrendellaJet]

if it could be a 78 its a mark iv, Might be worth while to change the head gaskets while you are at it. Not much more work than pulling the bolts one at a time...

[atxwrangler]

was the oil actually milky,or just some condensation in the valve cover?jjust a thought:)

[DMOORE]

Block #s say its a 1978 to 87. How do I determine the type?
That's a mark IV block. It has to have sealant on the headbolts into the water passages.
Darrell.

[78 propduster]

Mark lV, Thanks.
With this info. about bolts into water jackets, I wonder just how much pressure the sealant can handle.
The Merlin heads have bolts into water jackets, I did silicone those.
Water in oil is not condensation, I have tested this theory. No signs of water under 15psi block pressure, 1/2 mile run bumping 20 psi = cloudy. A high rpm 9 mile run, unknown high pressure = 1 qt of water in pan,
I hear that over 15psi is high, also hear that some crate motors are tested at 40psi.

[DMOORE]

A lot of the builders like to keep water pressure under 25psi. many new cars have 18 lb caps on the rads. So 15psi is fairly low. 20 psi should be no problem at all.
Darrell.

[78 propduster]

Thanks for the info.