Topic: Blowing your motor?

[Don R]

 I can find gasket leaks on my big block race engine by blowing into the valve cover, and yes I check for phone cameras first. (Insert witty remark here)

 I was thinking it would be a piece of cake on a  K0 750 but not so much.
 I tried sealing the oil cap and blowing into the rocker cover vent, either I'm missing something or there's a big air leak somewhere. I have an 836 with an MLS gasket, oil from the top of the rocker cover down, on the fins and something behind the shifter cover area.  Maybe the dyno cover inside the shifter cover. This seems easy but like most of my projects, it isn't.  I do have a frame kit, that eases my pain somewhat.

 Ideas?

[PeWe]

The case sealer will withstand high pressure? Or it will blow out via the case ventilation to the oil tank?
I had a leak last year. from front fins under the valve cover  around cylinder 2. Most of it due to copper spray on a fiber gasket that must be installed dry, the gaskets graphite is the sealer.

I had thoughts about leaks via valve cover bolts, some of them has holes in the head going thru. I made the threads deeper and used longer bolts when the threads were damaged. I think it was the 2 holes with guides. Maybe leak here if valve cover gasket does not seal completely around the bolts.
These got time serts this year. So far no leaks from valve cover or around the head.
Valve cover has a std gasket only, no additional sealer.
Head has Cometic 68mm MLS. I hammered the MLS rivets flat AND drilled dimples for the rivets in both head and cylinder just for sure.

Have you checked in the ign plugs "caves" for oil?  In cave seeling hole for the cam holder studs. No plug and finger inside and feel if its oily were the stud holes are going tru. My 2-3 studs got bad thread despite thread insert (helicoil) and tough Loctite (green). Repaired with Big Sert glued with Loctite 272 and studs sealed with high temp thread sealer. Time serts is much better than helicoil in many of these threads. Leaking rubber nickels under the ham holders will leak direct into the 2-3, maybe possible to find its way out via 1-4 too.

All of these things "easy" to fix with the frame mod. Lifting head more job when carbs and exhaust must go...

[Don R]

 Not much pressure, I'm talking lung power. I've helped seal several race engines this way. It's hard to believe you can pressurize a big block chevy but it works.

[mystic_1]

In terms of sealing things up to try to pressurize the crankcase, I'd suggest removing the oil return line that plugs into the spigot on the back of the motor, and sealing that port.  Otherwise your pressure will leak up into the oil tank and escape via the air/oil seperator's breather , I'd think.

mystic_1