Are these good heads, #462624 74 cc ? Also I'am having trouble with the casting date its f64. I think its f= june 6=day 4=74

Run of the mill smogger 1.72 or 1.94, prone to cracking from the exhaust seat into the chamber.

The chevy tech web site says in 74 they would be 202s heavy castings. Are you sure they smog heads?

The set I have cracked all 4 center exhausts. Dual exhaust crossover thin castings. Only good if thats all you have. Look at the edge of the heads on the outside row of head bolts below the exhaust manifold flange. If they are heavy castings they will be a stright edge along the bolts with a dimple for the dipstick. Light castings cut out the extra metal and are cut back between the bolts. All heads if after 69-70 are smogger heads.

Here is how http://www.mortec.com/castnum.htm has them listed. Any way you slice them, thick or thin, it's not a good performance casting.

462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves

Here is the argument ender. They are lightweight castings. Notice in the picture below that you can see parts of the workbench along the near edge.

Between these two heads, there are two cracked exhaust seats.

http://craig.backfire.ca/img_sized/500/vehicles/chevrolet-caprice-1982/engine/IMG_2036.jpg

If they have 2.02 valves, they will also have screw in studs and guideplates installed from the factory.

What am I going to do? Thats what I have on my engine. They are on ok for a street car, right?

I fixed the set I have they work pretty good with some porting on my k-10 daily driver. Like I said if thats what you have then use them. There are better heads but worse as well.

What hapens when the exaust seats crack?

What hapens when the exaust seats crack?

Improper valve seating, or better, crack propagation through the head. Either way, cracked valve seats need to be serviced.

Don't worry too much about the cracks, unless the heads are overheated, they tend not to leak. Generally, we've seen those heads with cracks coming off of well worked trucks and less common off of passenger cars.

FWIW, my first camaro was a 79 4 speed with the low HP 350. I had those exact heads, and by having them flat milled .030, an aftermarket intake, carb, headers and 4.10 gears I got my full weight car down to 13.7's at 101, and it was a blast to drive.

My heads came off my 81 camaro and it may have been hot before me but I never had it hot. If you have the heads off have them crack checked.

Is'nt 30 thousanths alot to take off. Did you have good valve clearence and what about the intake did that line up? That might be the way for me to go. What was the compretion when you were done? Could you still run 87 octane/

The intake bolted right up, .030" is no issue, and valve to piston was lots, but the cam lift was only .436". Always check, but .500 lift "shouldn't" be an issue with most pistons. I don't recall what I ran for fuel, but if your engine has dished pistons, there should be no problem running regular.