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post #1 of 13 (permalink) Old 06-12-2015, 07:42 PM Thread Starter
 
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Head swap

I have a 400 with 114 cc combustion chamber. The compression is pretty low and I am looking at a set of heads with 98cc. is this worth the trouble and expense or will I even be able to tell the difference. Please advise, I would like to boost the power but this may not be the way to go.
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post #2 of 13 (permalink) Old 06-12-2015, 10:41 PM
 
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YES ! Swap the heads. 114 cc heads are for low compression 455 engines.

In the late '70's, they put 6x-8 heads on 400's. They made about 7.6 CR. The chambers were about 101cc.

The W-72 400's had 6x-4 heads with about 93-94cc. These were said to have a little over 8:1 CR. With CR this low, you need one of the steep ramp cams like a Lunati Voodoo 256 or 262.

You can also use thinner Cometic head gaskets to raise the CR slightly. And if you are rebuilding the shortblock, you can zero deck it, and use the SP forged flat top pistons, NOT the cast 8-eyebrow pistons. this will also raise CR slightly.

The 6x heads are real good heads. They have screw-in studs, hardened valve seats, and 2.11 intake valves. If you want a bit more CR with 6x heads, you can have 'em cut some on the chamber surface, and the same amount on the intake surface of the heads. This will insure that the intake will fit, after cutting the chamber surface. In fact, if you're gonna use thin head gaskets and zero deck the block, it may help to cut a bit extra from the intake surface of the head. If you cut the intake manifold itself, then it won't fit other engines, and if you decide to try another intake, it will need to be cut the same amount the old manifold was.

But there is not much help for 114cc heads on a 400 shortblock. Even if you cut the heads to the max safe cc, they are still gonna be low CR and may cause intake fitment problems.

Last edited by oldskool; 06-12-2015 at 10:58 PM.
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post #3 of 13 (permalink) Old 06-13-2015, 09:17 AM
 
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I had 6x-4s on a stock bottom end 400 and it ran pretty good. They ran much better on the 455 though. Dont go nuts with them dollar wise. By the time you buy valves and guides, springs and machine work for porting etc etc you might as well start hunting some Eddys or KREs. If you have access to relatively complete ready to go 6x-4s on the cheap go for it itll run much better than the big chambers you have now.

I woudnt get 6x cores and throw more than $500 at them. Keep saving and do some 87cc aluminum heads. I had about $800 in my 6x-4s and now that I have a set of KREs I wonder why did that at all. $1,900 is alot of money for heads I know, but we are Pontiac guys we knew everything would be more costly. Buy them once and you're done. My KRE headed 455 pushes my 3650lb '66 to 113mph in 1320' so imo they are 100% worth the money.

You outta see her on a road course, or a quarter mile
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post #4 of 13 (permalink) Old 06-13-2015, 02:41 PM
 
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$1900 ?

Don't think you can get by with only $1900 nowadays for even out of the box stock alum heads, with bolts. So unless you have the 6x heads ported, they will be around $1500 or so cheaper than the cheapest alum heads.

If somebody knows of a source for KRE or Edelbrock D-port alum heads with bolts, for less than $2000 shipped, please post a link to the info.

Then there are lots of guys who say the stock valves and springs are poor quality, out of the box, and that you should upgrade to better parts when you buy. I cannot verify any of that.

The KRE 74cc D-ports are $1037.50 each + $75 for bolts, + shipping. So you're up to $2150 + shipping, quick. Then, most guys wouldn't want to use stock rocker arms with new alum heads, so there's another $150 + or more for roller tip rockers and polylocks. Hey, it'll scare $2500 to go with new alum heads.

Kauffman Racing Equipment

And what about the Edelbrock D-ports ? Well, they are only a few bucks cheaper--higher from some vendors.

Edelbrock 61599 Performer Pontiac 389-455 72cc (With CNC Ported Combustion Chambers) Assembled Single 1962-79 Pontiac 389/400/421/428/455 V8

So, to me, for a decent street motor, a thousand bucks for some good 6x heads, with new Stainless valves, bronze guides, good seals, 7/16 studs, done by somebody who will do 'em correctly, is a better buy than paying $2500 + for alum heads. But hey, if you got the coins, drop 'em. I'd buy everything I wanted, that I could afford. Why not ?

Butler Performance - Edelbrock Aluminum D Port Pontiac Cylinder Heads

SD Performance- Pontiac Performance Specialists
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post #5 of 13 (permalink) Old 06-13-2015, 03:15 PM
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I was in the same boat.....had 114cc #66 heads on my 400. 7.25CR, terrible gas mileage. I installed a set of 1970 #15 heads, which are 87cc. Had screw in studs installed, but kept the small valves. Now at about 9.3 CR. HUGE difference in power and fuel economy. You can get a set of 87-90cc iron heads if you look around and do the research. Mine were so rough it cost about $1400 to re-do them......not a good deal. But, It's been about 8 years now, and I'm happy with the result. 98cc heads IMO are too big for a 400. You want closer to 90cc....you can mill the 98cc heads, but this leads to other fab work, like milling the intake and using special pushrods. In any case, lose the 114cc heads!!
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post #6 of 13 (permalink) Old 06-13-2015, 09:35 PM
 
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As already stated, the 114cc chambers are way too big for any decent compression. Keep in mind, we don't know the condition of your engine or how many miles. Raising your compression will mean increasing cylinder pressure and if your engine's cylinders/rings are worn, you may experience blow-by, oil consumption, oil smoke out your exhaust pipes.....or all three.

What will it cost to prep a set of heads??? I recently did my 1972 96cc chambered 7K3 heads for my 455 that ended up with a final chamber size of 98cc's. These parts reflect a build aimed at a .550" maximum cam lift (possibly more, but I don't plan on hitting .550" so I'm safe). You could possibly save a few bucks by cutting some corners, but it will only be a few bucks.

You don't really need to do any head work as I did if you are using a factory type cam profile. Not included is the price of a set of heads. Any head you select, have them disassembled, cleaned, inspected, and magnafluxed for cracks BEFORE you do any other work or buy any parts. If they have ANY cracks or are damaged in any way, don't use them -find another set.

Here is a good general cost expectation based on the prices I paid for parts and services - which will vary depending on your machine shop. I don't think I forgot anything.

Disassemble,Clean, Magnaflux Heads..................$40
Surface Heads............................................. .$100
16 Bronze Valve Guides....................................$52
Bore & Install Valve Guides...............................$200
8 Ferrea RAIV Stainless Steel Intake Valves.........$88
8 Ferrea RAIV Stainless Steel Exhaust Valves.......$88
16 Valve Springs........................................... .$92
16 Valve Spring Retainers.................................$48
3 Angle Valve Job,Set Valve Spring,Install Valves..$300
and Install Viton Valve Seals.
7/16" ARP Big Block Rocker Studs.......................$118
Heater Hose Nipple/Passenger Side.....................$25
Freeze Plugs (6)..............................................$ 16
OWNER Supplied Heads.....................................$0
OWNER Port/Polish/Open Valve Throats and .........$0
Chamber Work
TOTAL less heads & any head work.....................$1,167
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post #7 of 13 (permalink) Old 06-15-2015, 08:40 AM
 
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Yah I guess I forgot about new rocker arms.. I did put the Harland Sharps on mine which were damn pricey. $2,075 for the pair complete from Kaufman so I was $125 off + shipping. They used to be $1950 assembled but if you have your credit card ready you can get free shipping if youre persistant enough. Dave at SD shipped me ported heads plus a roller cam and lifter set for free. That bill was HUGE though so maybe thats why. Plus rockers and bolts, yes. For the cost of ARPs I wouldn't re-use the stock head bolts anyway even doing the 6x's. All said and done the aluminum is about double the cost of non ported rebuilt iron heads and yes thats some real coin to drop no doubt!

For what its worth my 10.5:1 468 with 295cfm kre heads gets 15+mpg on the freeway behind a 5 speed and runs 112mph 1/4s on 93 pump gas while maintaining 170-180 degrees everywhere it goes. I cant say enough good things about the KREs if you feel like getting crazy with the VISA card!

You outta see her on a road course, or a quarter mile

Last edited by Bensjammin66; 06-15-2015 at 08:52 AM.
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post #8 of 13 (permalink) Old 06-15-2015, 08:51 AM
 
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$1,167 + $200-$300 for good cores and thats with no porting?! Thats not worth it in my own personal opinion but thats just an opinion. Maybe if you got the cores for free then ok.. $1700 from SD for 250cfm ported iron with his cores or $2100 for KREs ready to bolt on and yes, PLUS $75 BOLTS

This is right off SD's website, Mark Kaufman will tell you his work is some of the finest in the nation. $1700 ported iron or $2100 box stock aluminum. If you got free cores then by all means $1200 for a rebuild seems like a good move.

CNC Street port D-port heads (available for 670, 16, 62, 46, 47, 48, 11, 12, 13, 17, 18, 96, 7K3, 4X, 5C, 6X and other castings). Includes everything above, plus fully CNC ported 250 cfm @ .550” lift @ 28” intake ports, fully CNC ported exhaust ports, Comp Cams 995-16 valve springs, spring cups or locators are installed for increased spring stability and longevity, ARP 7/16” rocker studs, pushrod holes notched for 1.65 rockers, flow chart included. Complete package using customers cores from $1395.00 or complete package including SD supplied cores starting from $1695.00 (core charges vary with casting numbers - please call for availability and pricing)
Most mild street applications will experience an easy 50+hp gain over stock heads and even more with more aggressive combo's!!!

Additonal Options for above heads

Fill exhaust crossovers with aluminum add $75.00

You outta see her on a road course, or a quarter mile

Last edited by Bensjammin66; 06-15-2015 at 09:10 AM.
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post #9 of 13 (permalink) Old 06-15-2015, 09:51 AM
 
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Originally Posted by PontiacJim View Post
As already stated, the 114cc chambers are way too big for any decent compression. Keep in mind, we don't know the condition of your engine or how many miles. Raising your compression will mean increasing cylinder pressure and if your engine's cylinders/rings are worn, you may experience blow-by, oil consumption, oil smoke out your exhaust pipes.....or all three.

What will it cost to prep a set of heads??? I recently did my 1972 96cc chambered 7K3 heads for my 455 that ended up with a final chamber size of 98cc's...Here is a good general cost expectation based on the prices I paid for parts and services - which will vary depending on your machine shop. I don't think I forgot anything.

Disassemble,Clean, Magnaflux Heads..................$40
Surface Heads............................................. .$100
16 Bronze Valve Guides....................................$52
Bore & Install Valve Guides...............................$200
8 Ferrea RAIV Stainless Steel Intake Valves.........$88
8 Ferrea RAIV Stainless Steel Exhaust Valves.......$88
16 Valve Springs........................................... .$92
16 Valve Spring Retainers.................................$48
3 Angle Valve Job,Set Valve Spring,Install Valves..$300
and Install Viton Valve Seals.
7/16" ARP Big Block Rocker Studs.......................$118
Heater Hose Nipple/Passenger Side.....................$25
Freeze Plugs (6)..............................................$ 16
OWNER Supplied Heads.....................................$0
OWNER Port/Polish/Open Valve Throats and .........$0
Chamber Work
TOTAL less heads & any head work.....................$1,167
Just viewing those prices, some are on the money and some are quite high. Jmho, have had MANY pair of Pontiac cyl heads prepared through 3 different shops, one being a very well known Pontiac engine builder, and have never paid anywhere near $200 for guide replacement, or $300 for a competition VJ...speaking top notch work, just saying, total price, could be quite a bit less.
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post #10 of 13 (permalink) Old 06-15-2015, 03:42 PM
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I think it depends on where you are. In CA, labor is super expensive. Had I known that it would cost me $1400 to acquire and rebuild the #15 heads for my '67, I would have been better off to kick in another $800 and buy some KRE aluminum heads. It all depends on the condition of the cores you are using and the labor costs in your area. My heads needed all new seats, guides, rocker arms, the whole enchilada. $$$$!
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