This is gonna be a LONG ass post.
The advertisement is a lie, assuming Coast High Performance's website
is accurate. In the eBay ad, it is stated:
PRO COMP 3037 SMALL BLOCK FORD BARE ALUMINUM ALLOY HEADS 60CC/190CC. GREAT STREET/ STRIP HEAD DESIGNED FOR USE WITH STOCK OR STROKED SMALL BLOCK SIZES LIKE:302/331/347/351W/393/408/418/427
HEADS ARE SUPER AFFORDABLE AND ARE DESIGNED WITH MUCH BETTER FLOW FOR LOW END TORQUE. NEW MUCH IMPROVED HEADS FROM EARLIER MODELS SOLD CHEAPER ON E-BAY. HAS A LOT THICKER DECK FOR IMPROVED SEALING. USED BY COAST HIGH PERFORMANCE (CHP), FOR THE BUDGET MINDED ENTHUSIASTS ON THEIR "STREET FIGHTER GT" 306/347/393 SERIES CRATE ENGINES.
According to CHP's website, even their 'budget' GT and Street Fighter series use AFR and Edelbrock heads, respectively. The ad makes yet another mistake; he can't even get the names of CHP's crate engines right! They don't even have
a "street fighter GT." It's either a GT or
a Street Fighter, not both
. He's trying to confuse people into believing this horse shit. If you don't believe me, check out CHP's site for yourself. I even downloaded their catalog and searched for these heads. They're nowhere to be found.
But wait, it gets better:
NOTES:* WHEN USING POP UP PISTONS, CHAMBER TO DOME CLEARANCE MUST BE CHECKED.
* WHEN USING HIGH LIFT CAMS, VALVE TO PISTON CLEARANCE MUST BE CHECKED.
* MAY NEED TO PORT ALIGN INTAKE MANIFOLD TO HEAD, VERY HIGH HEAD INTAKE RUNNER.
* BEST USED WITH FPP 1262-R INTAKE GASKET AND FELPRO 1487 HEADER GASKET.
* USES FLAT SEAT NOT TAPERED SPARK PLUGS.
If it was a quality casting, the intake runners would be dead-on or very close to it. I understand the need to gasket-match, but they're probably high so the Chinese company that cast them could screw up the deck bad enough, mill them down, enlarge the combustion chamber, and there wouldn't be a problem with the intake ports being too low. Just an assumption, but probably accurate.
Which leads me to my next itch to scratch about these: where the F*CK are these things made? Canada? Chile? No, wait...let's take a look at the casting numbers:
Here's a link to a LARGE picture, to let you get a closer look at the horror.
Just to clarify, look immediately to the right of the exhaust port. Are they serious? They let crap like that out their doors? I would be too embarrassed to sell anything
that looked like a 6-year-old Chinese kid stamped it with random numbers. In the same picture, look at the scribe and machining marks. These are NOT of any decent quality whatsoever, IMHO.
Bottom line: would they work? Sure. Maybe for a little while, but I sure wouldn't depend on them for anything. They are most likely Chinese castings
, because any quality aluminum heads, even used, are about $1000. According to the ad, they're bare heads. It'd be another $80 for the valves and springs, but who knows what the specs are on those
My recommendation: keep those GT40 heads, shop around the local engine rebuilders and machine shops in your area for prices on seat cutting, valve job, how much they'd want for valves and springs, etc. You might be able to keep your valves and retainer sleeves if the valves can be machined and the seats recut to match. This is where the touch of an experienced head builder can really help you. You'll be paying more for labor than parts, probably, but that's better IMO because if you have questions or anything bad happens, you can come back and ask or get service.
With those eBay heads, if something goes wrong, you're screwed. No warranty, no service place, nothing. Welcome to Boned Creek, Population: you!
If you need head parts, look up a 1993-1995 Lightning for them, since the GT40s came stock on those. I'm having a helluva time getting into Federal Mogul's website right now to list the factory valve specs for you, but just going off of RockAuto's prices for 1994 Lightning parts:
Springs: #VS718 & VS733 are $1.20 and $1.37 each, respectively.
Keepers: #VK115 are $0.15 each.
Exhaust Rotators (roto caps): #RC140 are $3.67 each, and you might not even need them.
Valve stem seals: Get anywhere, about $15-20 a box for Viton, and a box is good for one head.
I won't list valves for you since Federal Mogul's site isn't working now, but for comparison, I ordered valve numbers V1961 and V3926, and they're $4.78 and $4.67 each, respectively. That's a grand total of $75.60 for all new valves. I think you can do the math for new springs and keepers.
See what I meant about this being cheaper than it seems? Getting the seats cut will be the rest of the cost. It's going to be a toss-up as to whether getting your valves machined or getting new ones will be cheaper.