427 BB Chevy problem

[DieselPower]

I agree with the othes that a check of the machining surfaces needs to be done to see if the intake was machined to match. However, the first thing's I would do are a leak down test to verify cylinder integrity. Next I would fill the crankcase full of smoke from my smoke machine and see if and where it comes out of. If smoke starts to come out of the carb, you found the problem, intake to block sealing surface.

I had a similar problem in a brand new W4500 Chevrolet cab over truck with a 350 Chevrolet small block. Nasty oily plugs, bad oil consumption at around 1 quart every 200-300 miles and poor performance. What I found was that the rings had been installed upside down at the factory. That's right, rings were installed upside down from the GM factory. Long story short, since it was a commercial truck owned by a commercial client GM payed to have a new motor installed. I ended up getting the old engine that had less than 2,500 miles on it. Pulled it apart and stuck a new set of rings in it right side up and sold it to a friend of mine. Has been powering a friends P/U truck for a couple of years now and works great. Got to love factory screw up's.

 

[sandman2234]

I have a 66 with a 69 motor in it. (smallblock)
The original aluminum 66 valve covers didn't have a place for a pcv to be installed, but the 69 did. The 66 used the downdraft tube to rid pressure from the crankcase.
Is there a chance your sucking oil from your lifters and sending them right to the carbs?
My brother told me about a '53 sitting behind a friends barn out in Arkansas. Seems everyone knows where there is an original '53 sitting. He mentioned it again six months later, so I went and got my picture book and made him pick out the right body style. He did, then mentioned it was a V-8, which put it at '55. I tried to call the guy, but no luck finding his number. About a year later I went out there, found out he moved to town, and located his number. Finally got ahold of him, only to find out that yes, his Dad's old '55 sat out back of the barn, with the top and interior in terrible shape, but it did turn over when they stuck a hot battery to it. Since interiors were done by my inlaws for a living, I was sick. Then he told me a guy from Dallas bought it for $500, about six months ago, I really was sick.
Point is, he also had a 67 motor, 427 with the tri-carbs on it, for a grand.
It is probably sold by now, but if I had the money, insight, I could probably have made some change off that deal.
Guess I will go out to the garage and sit in my toy and forget about missing deals.
David from jax

 

[cp1969]

Is there a chance your sucking oil from your lifters and sending them right to the carbs?

This isn't the tri-power engine; it has a single Holley. But, yes, that is the area in which I'm concentrating--a leaking intake.

We've devised a test that may or may not prove this. The plan is to remove all the intake pushrods, remove the carb and block it off with a plate, block the power brake vacuum line and then use either vacuum or a leak-down pressure test on the manifold to see if it has gross leaks. Of course, leakage by the valve guides might blow this test out of the water but I think we're looking for much worse leak(s) than can get by the valve guides.

 

[Hooked_on_HP]

Use vacuum if you can. Air pressure will try to open the valve and vacuum will try to close them. One more thing I thought about. Since it has a PVC valve it should have a breather on the other valve cover. Another thing, does it have the stock dipstick. If it has a chrome aftermarket one it may be way off(over full).Do you know how much oil is in it. It should hold 5qts with filter.

 

[Hooked_on_HP]

Did your friend put the intake on or did the machine shop. 427's used 2 different port designs. oval and rectangle. You can run an intake with an oval port on heads with rectangle ports but not rectangle intake on oval heads. And both take different gaskets.

 

[cp1969]

It's the stock dipstick and rectangular port heads with rectangular port intake.

I'm thinking like you are, that vacuum might work better than pressure.

Thanks for the help.

 

[johnk]

Spray some starting fluid arounf the intake at idle and see if the RPM's go up. If so bad seal between the 2.

 

[TractorLegend]

Spray some starting fluid arounf the intake at idle and see if the RPM's go up. If so bad seal between the 2.

Thats an ok, yet not really fire safety conscious approach...If you are going to squirt flamables around- carb cleaner is a bit more precise with the nozzle straw and consistent acting than ether. A propane torch used for the gas only with the flame off of course and a hose for extension is even better. But these approaches wont tell you if the gasket is sucked in toward the intake valley under the intake, only if there is a sealing defect above.