Aluminum head + XFlow?

[No_6]

Okay, first off, no stuck/bent valve on the motor. Turns out I'm getting some blow-by and it's fouling my plugs. I feel like an idiot. Should have checked that first--but I've had so much work done to the motor, that I didn't expect this (but then again, that's what I get for choosing the wrong shop to work on the car--live and learn).

 

So anyhow, I was wondering if anyone has switched to an aluminum head for their Crossflow and if there are any advantages to doing so. I'm mainly interested in improving reliability. My head does have the hardened valve seats, but I still add Marvell Mystery oil to my fuel (on the advice of my previous mechanic) to keep things slippery. I was hoping an aluminum head would run unleaded without the need for such improvisations.

[Kitcat]

Well, it's 20 lbs lighter, but that's a lotta $ for 20 lbs. I havent heard of any particular Crossflow head reliabilty issues. Valve guides and other internals wear out. I put 17K on my X-flow before selling it and it had 32K total miles and the head was fine, with never a drop of mystery oil. Also ran on Mobile 1 full synthetic 95% of the time, as did prior owner, in spite of popular wisdom that the low-tech motor needed pure mineral oil.

Edited May 14, 2013 by Kitcat

[xflow7]

I'm not very knowledgeable about it, but from what I've picked up:

 

a) builders like the aluminum head because the softer material makes porting a lot easier.

 

b) I believe setting valve clearances becomes more finicky to what temperature the engine is at when it's done because of the differential expansion of the aluminum head and the steel block/pushrods.

[bsimon]

I really don't think an alloy head is going to help blow-by. Severe blow-by is usually the product of the rings not sealing the bore. If the valve guides are clapped out there might be some blow-by, but usually not enough to fowl plugs.

 

I'd get the engine leak-down tested to find out where you stand.

 

Do you get oil smoke when getting back on the throttle after down shifts or throttle closed periods? That would be a sign of bad guides. Smoke on constant acceleration is a sign of bad rings/pistons/bores.

[danilo]

X flows were 'fine' engines in '69. Shortish stroke, good power, light weight.

But they Also timed out v quickly, needing rebuilds far more often than anything else, except perhaps a BMC product.

Marvel Mystery oil? is your mechanic in his eighties by chance?

That swill faded from popular lore decades ago.. 'Mechanix Illustrated' era goop.

Plug fouling blowby is either from a direct feed/circuit from the crankcase vent setup into the intake manifold OR Several ! broken rings., possibly even both issues.

Regardless, it needs immediate attention.