[rustycarr]

Ok guys, my 67 Camaro, currently has a 68 327 from a chevelle in it, with a stock 4-barrell intake with a 4-barrel carb, the heads are the 210 hp , single hump heads (3917290) they have 1.72/1.5 valves. I will be running this motor with stocker exhaust manifolds with dual exhaust, hei, with the stock 4barrel. The machine shop is putting a cam just above stock, My question is : I have the opportunity to change out the heads with some camel hump (3927186) 1.94/1.5, Will I see a huge difference in performance by changing out heads, with they way i have my motor setup or no? I just dropped off the Camaro at the machine shop, ive got a while before i have to decide.. thanks in advance. (O'yea I Don't want Vortecs..)

[DT]

I don't think a HUGH increase but an increase none the less. Going with 2.02/1.60 valves is the way to go. Just MHO.

[Z15CAM]

1.72/1.5 valves "Vs" 1.94/1.5's

The 3917290 would be a 2BBL 307/327 Cylinder Head but the 64cc Chambered 3927186 is a 69-70 302/350 Turbo Flow Casting and still provide about the best flow for small Displacement SBC's like the 302 and 327. They where used on the infamous 360 Hp 70Z 350 LT1 Engine. With them small valves they are excellent candidates, with lots of meat, to install 2.02's/1.6's at OEM Specs - Install Screw in Studs with Guide Plates and open the spring pockets up to 1.439 for Dual Springs - Do some bowl porting and Port matching - that 327 will want to rev over 7000 rpm with say a 10:1 Static and a 274H-10 Cam. You will not get much more then 6800 rpm with HFT and a Cast Crank anyway - Top them Flat Top Pistons with a 650 Holley/Elelbrock rpm - Easy 350 Hp.

If you happen to have the Rare 68 Medium Journal Forged Crank with Forged Pistons the Sky's the limit with them 3927186 heads and 8000 rpm, 425 Hp, 11:1 SFT 327 is within reach in which case you would use the L2166NF Piston ;o)

The 327 has aways made 5 to 10 Hp more then the 350 Set up similar because it rev's as high as the 302. Big plus is that you will have the Alternator Accessory Hole to use the tight Belt system.

Depending on todays machining costs it may be just as cheap to buy something similar in after market Alu-Heads, like EdelBrock, but then it's not Original GM ;o)

I love the 327 SBC and 454 BBC cubic inch Chevy Mills.

[ace's68]

My motor went from around 250-270 hp to 420hp with an after market head, and cam change, 2.02's aluminum, 190cc runners, comp cam etc...
Those heads are the worst thing to be casted by GM ever, they are that bad.
My 1.72's even had 1.94's, milled a tad, and had a 4 or so angle done, and they were still horrible. Any head besides those and you should see at least 25-50hp.

[rustycarr]

Originally Posted by ace's68

My motor went from around 250-270 hp to 420hp with an after market head, and cam change, 2.02's aluminum, 190cc runners, comp cam etc...
Those heads are the worst thing to be casted by GM ever, they are that bad.
My 1.72's even had 1.94's, milled a tad, and had a 4 or so angle done, and they were still horrible. Any head besides those and you should see at least 25-50hp.

Thanks

[Z15CAM]

John: Were not the 3927186 Turbo Castings used on the 69 and 70Z 302 & 350 Mills or am I Wrong? I never owned ether engine but MORTEC Lists them for the 69/70 302 and 350. My Guess would be the 1.97/1.5 version would be for the HFT 4BBL 70 350 SS Engine - What was that the L48 - Approx 275 to 300 Hp?

My SFT 68 Forged Assembly 327 with Grumpy Spec'd 3917291 Turbo Flows will hit 8000 rpm nicely - Never dyno'd but has to be putting out 425Hp. There should not be much difference between the 3927186 and 3917291 and suspect the 3927186 more likely forerunner to the 3947041 casting. The 391292's where probably the BEST. None of them Flowed very well with lifts over .510" Lifts unless they where worked on and the 292's must have responded best because Grumpy liked them - LOL - One thing about meeting Grumpy's specifications - The Casting had better be about flawless without core shift. I running a Sigerson F-296-1 SFT 296/302, 258/264 @ .050” - .563”/.563” 108 LSA under 11:1 Static Compression. I ran a Crane HFT CCH-290 290/290, 242/242 @ .050" - .482"/.482" 110 LSA before I went SFT and Shaft Rockers on the 291's in search of 8G's. NOT Exactly a Friendly Grocery Getter but doesn't mean it can't ;o)

I admit I put months of work into my 291's to meet Grumpy's specifications, which I would never do again or recommend considering Machining Costs today and Lost Art; but can't see why them 3927186 with 2.02's/1.6's should not take a HFT 327 to at least 6500 rpm and 340 Hp providing they are Port Matched, Bowls worked a touch and intake runner widened to 1 1/8", or closet you can get, between the Inside wall and Push Rod. I suppose you could un-shroud the Back wall behind the Larger 2.02 Intake Valve but if your not planning revving over 7G's with a 327 forget it.

Granted the Old Turbo Flows can't compete with the newer after market Alu-Heads if used on 350 and larger CI SBC's but for a 302 or 327 they work just fine without much work to get into the mid 300 Hp Range with Stock Components including a Cast Crank.

I would not give 2 cents for the 3917290 castings or spend BIG Bucks for after Market Alu-Heads for either a 302 or 327 if I had a Set of Turbo Flows that didn't require much work. I use the .015" Felpro Z1094 Rubber Coated Shim Head Gasket and the block has never been Decked.

[rustycarr]

Thanks for all the information,I just dropped
the 186's off at the machine shop, one
last question do they share the same valve cover
bolt pattern?..I didn't look...

[67 Plum]

Originally Posted by rustycarr

do they share the same valve cover
bolt pattern?..I didn't look...

Yes.The 186s will work very good on your 327.

[Nashville Beth]

[QUOTE=rustycarr;1475782]I will be running this motor with stocker exhaust manifolds with dual exhaust, hei, with the stock 4barrel. QUOTE]

If you keep the stock exhaust manifolds, the heads won't help you at all.

You can install a set of 1 1/2" or 1 5/8" shorty headers with minimal exhaust work.

[ace's68]

Ron, no idea man, I've been deprived of what went on what ever since mortec went down.
I do know the single humps and the camel humps that had the square tops (not really camel humps, just used the camel part for sake of visual) sucked bad, and were used on low power 327's and 307's. 76cc chambers, 1.72" intakes.

The Camel humps will support as much power as you want basically, especially how exotic you make them, and how exotic the rest of your motor is.
you need a dual pattern cam to support those heads with exhaust lift and duration being favored.

Ron, you basically described my 327" motor with good heads and cam, revs easily and puts out potent hp with the right compression, little motors really do need all the compression you can give them IMHO.

[rustycarr]

[quote=Nashville Beth;1476305]

Originally Posted by rustycarr

I will be running this motor with stocker exhaust manifolds with dual exhaust, hei, with the stock 4barrel. QUOTE]

If you keep the stock exhaust manifolds, the heads won't help you at all.

You can install a set of 1 1/2" or 1 5/8" shorty headers with minimal exhaust work.

so did camel hump applications run a higher flowing
exhaust manifold than other heads?

[67 Plum]

Originally Posted by Nashville Beth

If you keep the stock exhaust manifolds, the heads won't help you at all.

Not true.The difference between a 210hp and a 275hp 327 was heads , intake and carb. Both ran the same exhaust manifolds.Yes headers will add more HP but exhaust manifolds wont kill it.On a mild 327 you would gain 15 to 20 Hp with headers.Not worth it IMO.