[Zenith]

My 73 Ventura has some serious valve issues with it's 350. I just today found a pair of matching 4C heads that are in much better order. Supposedly, they came out of a 350 in a 1973 Firebird. The chambers have a fairly low amount of carbon buildup or other signs of wear, so I have high hopes.

Heads are 4C, stamped 2H.

My question is: Should I take this to a head worker/machinist to have the heads checked out? What questions should I ask?

[Zenith]

A little advice, please? :

[Donovan]

probably 46 not 4C

They are a good low compression 350 head. Do you just want to keep your engine on the road or do you have performance goals?

If the heads are rough, do you know the shortblock is worth putting a rebuilt set of heads on it?

just for starters.

[Zenith]

Well, unless I missed something, they're 4C heads. Says right on it.

The engine is street only, with no intention greater than stock at the moment. Money is tight and I found a good deal on these heads.

They look in good shape, but I wanted to know what about them I should be checking. Like did the 4C heads really come in multiple chamber sizes? Should I have them hot tanked, or media blasted? Would it be ok to reuse my old rocker arms?

I don't know what the bottom end of the motor is like, but I intend to find out what I can without removing the block from the car.

[steve25]

Unless you heads have been overheated or have very high milage, it is usally not valve issues with a pontiac, its cam and lifter.
you will find that fully rebuilt heads on a 60k or higher milage bottom end to be a waste of time, if your current heads are truly that dead, than I would have the #46 taken apart to just install new intake seals and all 16 o-rings and jst use them as they are.

[PONTIAC DUDE]

Any head should be cleaned and checked for cracks before being installed. Period. Cheap insurance on a redo if bad. Most cracks occur in the exh seat area and can be magged without pulling the valves. Also have them checked with a straight edge for warp. Also have the exh flange checked for straight and errosion. Between the center two won't be a problem.

You can fill the head with gas to check the condition of the seats and valves yourself. I recommend filling the ports and check for leakage into the chamber. Seapage isn't a problem, but a steady fast rate of seapage can be.

I would never recommend installing a head without first having it checked.

[Rocky Rotella]

Pontiac Dude has you covered on the quality checks, but just to clarify, 4C is a valid head casting code. It was used as a replacement for #46 on 73-74 350 applications destined for high altitude or California emissions. It should have an AIR rail cast into the ends and ventilation holes in the exhaust port roof.

[Zenith]

Thanks for the advice, PONTIAC DUDE. Would you recommend they be magnafluxed as well?

Well steve25, that's the rub. A leakdown test showed my valve issues, one exhaust one intake, on separate heads. The exhaust valve is pretty much shot, 90% leakage reported.