48 Heads or Edelbrock Aluminum
 

Dealing with a head gasket leak on the driver's side.
Head is out and obvious leak near cylinder #1 where after checking EVERYTHING else and pressure consistent at 75psi, it is the head gasket.

So I have the head off and it's a 48.... and thought should I change now to aluminum?
It's a 1970 WT bored .040 over with comp camshaft and rollers.

Comments welcomed...

If the wallet can afford it, he!! yes.
KREs

That motor should when tuned right and even thru exh manifolds make a solid 360 hp or a tad more.

If that’s not enough and you do not want to run more Cam and port those 48 castings somewhat then go with the a aftermarket D port head.

Just note that to get what you pay for out of those heads you should be running headers.

Whatever heads you plop back on be sure all the head bolt holes are cleaned out and that bolts thread into there hole with just finger effort and your not using too long of a bolt such that it bottoms out before clamping down on the head as needed.

If you put the iron heads back on then be sure to torque the center two head bolts to 100, not the stock 95.

I’ve yet to meet anyone who regretted going to aluminum heads. That said, what are your performance goals and how is the car used?

Thanks Gents; when I removed the head the only bolts with any real resistance were the two center. And the gasket was a felPro 8518; not a 1016 as it should have been.
I am running headers now; street brawler 650CFM, and edelbrock intake.
Engine is bored .040 over with comp cams cam, rockers, lifters
No idea what the cam is.....
HEI distributor

Short trips and occasional long hauls....
Bought the car unseen in Seattle in July. Drove her cross country to Florida.
It was very cool and very hot.

Whichever way you go would be a good idea to cc the 48s - typically come in at 72cc so you have a good idea what your compression ratio is. Any idea what the cam specs are and were you happy with the performance before the blown head gasket? Based on your intended use the 48s should be more than enough…

I priced a set of Kauffman aluminum heads from them 2 yrs ago. I thought reasonable what I was getting,New heads ready to bolt on.

Looks like the Kaufmann are priced near everyone else now :(

Concerned about fuel octane and always finding 93+, concerned about the heat in traffic and Florida, concerned about current valves and whether worth spending money on the 48s or just mortgaging the Aluminum....

No idea what the current cam is but she hops when I step on it....

FYI my 4 speed Muncie is also toast; gears popping and clutch slipping...
So upgrading to Tremec 5 speed which also $$$ sucks

Well, no doubt some 74cc KRE heads and a TKX will make it an awesome ride. Are you doing a cam change to compliment the heads?

It's obviously a new cam; any suggestions how to determine what it is?

If it is Comp Cams you can pull it and get the numbers off the back to identify it. Otherwise, you can use a degree wheel on an intake and an exhaust lobe to get an idea of general specs but that won't help identify the actual grind. If you decide to pull it, make sure you keep track of/return lifters to their original lifter bore.

20mpg plus as well

If you still one head on, then do a cranking compression test on that bank.

Stan

All cylinders tested at 150psi except #1 which was 75....

Was that a hot test?

Idled for 5 min prior

Would that also be applicable to the aluminum heads

Also, for me I’d ditch that carb, 650 is not big enough for a Pontiac. You’d probably gain more performance, real and seat of the pants with just a carb swap once you take care of the head gasket without spending the money on new heads or even porting your current ones IMO.

Wow; what size? Discovered the engine is bored .040 over

Still battling this.
Reinstalled head with new bolts to 100ft lbs and Felpro1016 gasket.
Surfaces cleaned for operating room....

I must be too stupid to get exact TDC because can not stop air sound coming from valley from leak down test. Tried the same on Cylinder 3 that pressure tested at 150psi and same air sound.

just rocking the crank between TDC I can not stop the sound of air - pretty loud whoosh at 60psi
Clylinder bore is super clean

Thinking now I have to pull that piston on Cylinder #1?
Someone once said hit those valve springs on #1 to make the valves seat from potential carbon buildup?

Engine will kick with air applied to cylinder 3 and not right on TDC but cylinder 1 will not

did you look at the valves while head was off? any pictures? lash too tight or bent valve/bad seat?

Pack number one intake port with paper towels, does cranking the motor with the starter then move / blow the towel out?

Attachment 664441

Attachment 664442

I've got the valley pan off. Can i crank with just the head and rockers back on?

Yes just be careful fuel pump doesn't spray all
Over

What does the valves sealing have to do with the air leaking from the valley?

Stan

I just read your entire thread. Based on the information I was able to gather, you most likely have a broken ring land, stuck piston ring (s) in cylinder #1. A blown head gasket rarely effects just 1 cylinder, almost always 2 are effected, side by side. But the loose head bolts you found, anything is possible. Cast pistons are particularly prone to detonation damage. I mention this because you mentioned 93+ octane gasoline was hard to find in your area. That leads me to believe some detonation was happening and it doesn't take much to kill those pistons. To me, it looks like a disassembly is in your future. Once disassembled, you can figure out what cam is actually in there and the condition of the pistons and ring lands. All I can say concerning aluminum vs iron heads is aluminum is more tolerant of lower octane fuel. Good luck with it.

As far as heads iron vs aluminum take one of each and pick them up and put them up on a flow bench. The one that does not hurt your back also probably flows better too-and it is not the iron one!

I can remember pulling and swapping cast heads in my younger days. Now with my funky back ..no way bending over a fender and lifting a cast head! I would probably use my picker!

I can tell you’ve never had the joyfully experience of setting up an international 392 head or a 671 Diesel head in a milling machine! :-)

I can tell you’ve never had the joyfully experience of setting up an international 392 head or a 671 Diesel head in a milling machine! :-)

Wow didn't anyone notice the burnt exuast valve in the picture.
Think that might have something to do with it?

GT

the cylinder did hold fluid for 24hrs with a 50/50 acetone/ATF soak.
So I still have 70 psi and this is driving me crazy.
Someone mentioned a burnt valve?

Adjusted the rockers, replaced the head gasket.
175psi on 7 cylinders..... 70psi on Cylinder 1

Pressure test this morning now 40psi on cylinder 1 when I let the rockers go loose.
Idk

Lightly tapped on top of valve with the rockers loose and out of the way...
Now 25psi........