OE Cylinder Head Opinions

[Diogenes]

Hello All, I'm looking for some opinions and thoughts regarding the following:

I have a 66 Galaxie with a 390 C-6, the heads are C6AE-U with adjustable OE rockers and GT manifolds. She is a good runner but is a bit smoky. It's a cruiser, not a racer. I am planning on either having guides/inserts done on them or perhaps looking to purchase heads that are already good to go to. At present, I'd like to keep the exhaust I have in place, keeping costs in check. I'm looking for thoughts on how much it may cost to install guides/inserts, and if I may do just as well to locate a set of heads to purchase instead of having the machine work done (with cylinder head recommendations). I realize exhaust manifold bolt pattern may limit the heads I can purchase, but....

Any and all thoughts are welcome and appreciated.

[410bruce]

Hello All, I'm looking for some opinions and thoughts regarding the following:

I have a 66 Galaxie with a 390 C-6, the heads are C6AE-U with adjustable OE rockers and GT manifolds. She is a good runner but is a bit smoky. It's a cruiser, not a racer. I am planning on either having guides/inserts done on them or perhaps looking to purchase heads that are already good to go to. At present, I'd like to keep the exhaust I have in place, keeping costs in check. I'm looking for thoughts on how much it may cost to install guides/inserts, and if I may do just as well to locate a set of heads to purchase instead of having the machine work done (with cylinder head recommendations). I realize exhaust manifold bolt pattern may limit the heads I can purchase, but....

Any and all thoughts are welcome and appreciated.

I have been thinking of going Edelbrock for my build and have a set of C6AE-Rs that are ready to bolt on and go.
I bought them from a forum member who had put about $1100 into them. Cobra Jet stainless valves, dual springs for hydraulic flat tappet cam, hardened exhaust seats and whatever guide work that was needed. About 350 miles on them.
When I received them, I took them to the machine shop and had them checked out. Vacuum checked, magna fluxed and skim cut the deck surface. Checked out 100%. $850 shipped if you're interested.
They do have the 16 bolt exhaust.

[GerryP]

If you want to keep your GT manifolds, the easiest solution is to just re-do your existing heads.  There is proof beyond any doubt that your manifolds fit those heads.  Here's the detail:  "GT" heads or more correctly; unibody heads, are drilled with a 14-bolt exhaust flange.  The top two bolt holes on the ends of the heads are a bit lower than the traditional FE vertical bolt location.  So, there are three bolt configurations for FE heads:  Your 14-bolt unibody pattern, the 16-bolt Cobra Jet pattern, and the traditional vertical 8-bolt pattern.  Your manifold will fit only the unibody heads without modification.  Any other head either requires modification or can't be used at all since there is no flange material for the horizontal bolt holes.

Could you use your GT manifolds on something like an Edelbrock alloy head?  Only if you drill those two end bolt holes into the head.  There could be port mismatch issues, but I can't say that for certain.

What would it cost to freshen up your heads?  It depends on what work the heads need and what work you're willing to pay for.  If the seats and valves, and springs check out and you need only guide inserts, maybe a couple hundred bucks.  More work means more items on the bill.  You would need to take the heads to a machinist for a thorough examination.

[410bruce]

GerryP- I had forgotten that the top bolt holes on the end ports were different. Thanks for pointing that out.


Diogenes- My heads won't work for you if you keep your current exhaust manifold.

Thanks.

[GerryP]

Maybe not, Bruce.  C6AE heads would be factory drilled with either the vertical 8-bolt pattern, or the 14-bolt unibody pattern.  You'd have to count the bolt holes to know for sure.  Yeah, it's possible someone took some C6AE 8-bolt heads and drilled them to a 16-bolt pattern.  It's also possible to re-drill 14-bolt heads to the 16-bolt pattern.  Whether they would work for the OP would depend upon the location of those two upper bolt holes.

[Joe-JDC]

For the cost of bronze guide liners, cut bosses for PC seals, valve job, mill heads and gasket set, maybe fresh springs, retainers, keepers, around here that would be lot less than aluminum heads.  Joe-JDC

[Diogenes]

@GerryP: Thank you for all the info. I would like to think my heads will only need inserts, but that would likely not be the case. Machine work has gotten pricey and I don't know if it is a good investment to put the money in these heads. From what I've read here, the GT manifolds flow worse than the std. manifold, so I may do better to change heads and exhaust manifolds/headers. I'm just weighing my options and trying to gather information to make the best selection and correct purchases.

@410bruce: Thank you for the offer. I am going to check into machine work on the heads I currently have, but will keep your offer in mind. At this point I suspect I could have my heads gone through for less money and retain my manifolds, though this is not certain. I will contact you one way or the other. I am in NW Ohio.

[GerryP]

There's one thing I'm wondering and don't have any direct knowledge of:  You have a '66 Galaxie.  You say you're using GT manifolds.  The only "GT" manifolds are for the unibody cars...Fairlane and Mustang.  While everyone says GT manifolds, they were used on any FE installed in the unibody cars, so even a 2bbl low compression 390 H-code engine in a Mustang got the same manifolds.

The thing is, I don't know if unibody "GT" manifolds fit a '66 Galaxie chassis.  So, with that, I'm wondering what manifolds you do have?  There were long and short "header" manifolds which flow really good.  And then you have the box manifolds used on just about everything.  I call the flat manifolds box manifolds.  I don't know what their proper name is.  They're not even close in appearance to GT manifolds.

So, what options are easily available to you depend upon what manifolds you have.

[Diogenes]

They appear to be the GT manifolds--I wished they were cast iron headers . The GT manifolds are aesthetically better than the flat manifold, as you call them, but I recall reading here that they flow better than the GT's. At this point, I just want to make the process simple, it is a matter of time and convenience as much as funds. My schedule will make a new exhaust a challenging affair.

[1964Fastback]

You might consider the cheap FE block hugger headers on eBay, especially if you will have the heads off for a valve job.  They fit fine on my '64 with C4AE-G heads (low riser, 8 bolts of course), clutch and power steering.  The reason I mention them is that with the heads off it was pretty painless to drop them in place, put the heads on and then bolt them up.  Of course with any headers some of the bolts are a pain to reach but it didn't take me that long, and I would think they have to be better than log manifolds.  Of course the '64 is quite a bit different than the '65 and later so no guarantees on fit to the frame, let alone the port and bolt considerations - just throwing it out there.

Pat