Opening the combustion chambers on a set of c8ae-h heads

[manofmerc]

I have a pretty nice set of c8s that I would like to use for a future truck build . It looks to me a machine shop installed new exhaust seats as well as intake seats .The valves sit proud not recessed at all and the stem lengths are all the same .I poured the chambers and come up with 64ccs .Can I use a head gasket and open my chambers to 70-74 ccs? I have cast flattop pistons I could have a dish milled into them but it would be a big dish .My compression calculator shows I need a 35 cc dish to get 9.66 compression ratio .That's with a .014 piston to deck height .042 gasket 3.780 stroke 4.50 bore .If I can enlarge my combustion chambers I wont need to mill my pistons so much. A set of d2s is probably what I need but I have these c8s they have new guides and valves a little rusty but nothing that cant be fixed. Just curious what your thoughts are .Doug

[JamesonRacing]

The C8 and D2 heads should have the same approximate chamber shape and size, so changing wouldn't help.  The heads you have are very small for a FE...specs have them ranging from 68-72cc.  Have your heads been milled some already? 

I have a set of D2 heads on the 445 in my truck and was able to increase the chamber size to about 78cc by sinking the valves a bit and opening up all the surfaces in the chamber.  There's a lot of material to work with, but also takes a lot of time and effort to get it right and have all the chambers the same.

[manofmerc]

I am sure these have been milled how much is the question .I know it would take time to get them all close just curious if it is possible .My valves not being recessed isn't helping either but sinking the valves seems to be going in the wrong direction .Thanks for your thoughts . Didn't you go to the moonshiners festival in Ga. last year ?Doug

[JamesonRacing]

Didn't you go to the moonshiners festival in Ga. last year ?Doug

Wasn't me, but sounds like a fun event to go to

[BigBlueIron]

I poured the chambers and come up with 64ccs .Can I use a head gasket and open my chambers to 70-74 ccs? I have cast flattop pistons I could have a dish milled into them but it would be a big dish .My compression calculator shows I need a 35 cc dish to get 9.66 compression ratio .That's with a .014 piston to deck height .042 gasket 3.780 stroke 4.50 bore .

4.5 Bore?? are you sure? Im guessing you mean 4.05 which would put you right at 10.2 with the 64cc heads, guessing a few of the other variables.

[rockhouse66]

I understand using what you have because I am working on my second engine using "scraps" but the H heads are so common I am puzzled why you would build around them.  Seems like the tail is wagging the dog here IMO.

[manofmerc]

That's right 4.050 typing error .Well these heads have new intake and exhaust seats all ready installed new guides and valves .To do that to another set of heads is kinda expensive .I might have to go with some d2s it would make things easier I am just curious if it is possible to enlarge the  combustion chambers on what I have .

[My427stang]

Time is money but if you have time and access to tools, why not?

So, if you want to save the heads, lots of options.  If you could find a shop willing to spend a couple hours per head, you could make a 3-4 cc cut on one chamber on a mill and then just copy from chamber to chamber.  You could even do a set of Singh grooves (nobody thinks the grooves really do anything, but you could play and eat up a cc or so more)



I'd likely not do this, but you could even sink the valves a little bit depending on how proud they are right now.

In the end, if you want to play, the heads aren't valuable, but could certainly be usable, depends what you want to spend in time or money

One thing to remember though.  Take the cost of a set of custom pistons minus a set of cheaper pistons.  If you spend more than that, you could just buy a set of modern pistons for the exact compression ratio and quench you want and never have to take the heads apart

[FElony]

...You could even do a set of Singh grooves (nobody thinks the grooves really do anything, ...)

Oh, I do. I've been following the Singh saga for at least a decade, and there are far too many positive results to dismiss the procedure as a flight of fancy. Matter of fact, this would be an ideal situation to run them.

In the end, if you want to play, the heads aren't valuable, but could certainly be usable, depends what you want to spend in time or money.

Early in the 2000's, I talked to a guy on the phone that was racing a lightened 67/68 Mustang fastback with a 428 and ported H heads. He was competing in the 10.90 Super Street bracket and could run 10.70 off the stop. No such thing as "bad" FE heads. Singh those H's!!

[manofmerc]

My situation is that I have an assembled short block with these cast flat top pistons .I could have a dish milled into my pistons I wanted to avoid doing so .But it really seems that is a better option .Thanks Ross for your thoughts and Felony is right no bad FE heads just some are better than others .Carry On ! Doug

[TomP]

What about the C6AE-J heads... they seem to be big chambers.

[FERoadster]

I've got a set of C4AE H 427 heads that were opened up by Mondello in 1971.
They have HR valves. I wonder what the Mondello company was thinking when they did this.

I got the heads for free but it cost $1K to fix the burn thru.

Richard >>> FERoadster