getitmann

I have a 1975 olsdmobile 455 motor, and I dont know much about heads but I think I have "J" heads or whatever one's are the worst. Should I look for heads from a older 455 to rebuild or try to save money up for aluminum heads?

P.S. I'm really just looking for good street performance.

67 Cutlass Freak

Yeah sorry to say but those "J" heads are pretty much junk. You should look for a set of large valve "C" castings. They are readily available as cores for roughly $200. Depending on what they will need you can ad at least $500 to that for new valves and a good 3 angle valve job. Hopefully they won't need guides or seats. You might want to call Cody here-
http://www.realoldspower.com/phpBB2/...ic.php?t=82138
He's a good guy with plenty of good cores, and the knowledge to help you. It's too bad the cast iron heads are so heavy, they cost a lot to ship. If you are ready to step up to aluminum you might want to check out the new Pro Comps. The price is reasonable-
http://www.realoldspower.com/phpBB2/...ic.php?t=79326
Lastly, if you really want to wake up your engine you should ditch the low compression pistons and get a hotter cam. You might want to talk to Mark (Culassefi) about that. He's helped a lot of us on here choose the right custom cam for our specific aplications.

BILL DEMMER

C, E, G, & GA heads are all good easy to find heads, of those, there are some specifics to be noted.
C & E heads have shallower spring pockets because they weren't designed for use with valve rotators, G and later had the valve rotators which helped extend valve life. i skipped the best heads because they're too expensive/hard to find for your needs.


bill

firefrost gold

I have a set of E heads need rebuilding would sell for 100 buck plus shipping.

oldsmobiledave

Add to this list the 1966 B heads from Toro (39 deg) & the Ka heads. Both are big valve versions with flow characteristics that meet or excede any other big valve olds head.

chadman

Big valve A heads are the best in untouched form.

AZ455

Here is a head flow comparison.

http://nichibei.tripod.com/headflow.htm

chadman

That link shows exactly what I would expect to see. The A,B, and C heads are identical on the intake and the A's are a little better on the exhaust.

joepenoso

Looking at the flow chart comparing all the heads there is little difference from the best(C) to the worst(J). Remember the later G ,Ga etc heads have hardened valve seats making them more compatible for no lead. For the small difference in price I would go with new aluminum heads. Your choice Pro Comp or Edelbrock. The flow figures given on the previous posts show little difference between Edel or Pro Comp
joepenoso.

AZ455

I'd think J heads wouldn't be that bad in a low revving street driven engine.

joepenoso

"J" heads flow stalls abpve .400 lift so a mild cam won't show much difference between them.
joepenoso

chadman

J is for junk

droptopron

That may be true but why bother when there are so many better alternatives readily available for not that much? You will still have to put money into the J's to freshen them up

AZ455

True. I wouldn't put any money into the J's either, just run 'em til I could replace them. Which is exactly what I am doing.

Run to Rund

Shipping ain't cheap either. If you are still looking, I will see what I have if you want to come to Vegas some time.

DeltaPace77

When I built my 455(.30 over) in the 90's, used Dave Smith S-S W30 heads. Not sure what factory cores he started with, but chambers are fully polished and cc'd. Lightly ported and gasket matched intake runners. Also upgraded to his adjustible valvetrain kit, so just like setting up a Chevy or Pontiac. Don't have any flow numbers, but with .560 lift cam and port matched intake, thing's making some power. Recall, when Dave shipped these, was one per box, so no problem UPS.

amesolds

getitman-
We took a stock '75 455 engine from a 442, added an Edelbock Performer intake and did a 3 angle valve job, filled the crossovers and did a mild port job on the heads. We added the larger 1970 442 exhaust manifolds and put it in my son's '75 Pontiac Grand Am (4400 lbs. with him in it) With 2.56 gears and a Turbo 400, this boat covered the quarter in 14.84 seconds, better than my friends '70 442 convertible with 3.08 gears who clicked off a 15.05. We did not have much invested either

Fastback71

is there really a noticable difference with the stock in take and performer?

joe_padavano

Back on the flow rate link data, I'm betting that these numbers are for ONE test each, right? I find it hard to believe that the D and F heads are that much worse than earlier heads - why bother using them if they are? The reality is that any mass-produced casting has a pretty wide manufacturing tolerance and you'd need to test a statistically viable sample size to draw any conclusion other than they are all equivalent. Any one little casting flash bump can cause the differences in the chart. Bottom line is that with a mild cleanup, ALL Olds heads (J included) will flow about the same. Keep the J heads, put the money into porting, and you've got a sleeper.

DeltaPace77

Agree with "joe" on certain things as production head tolerances were all over the place. Chamber volume variances from cylinder to cylinder could vary quite a bit, and why important to have the heads cc'd. Keep in mind, properly worked on factory heads may outflow Edelbrock Aluminum heads, but could end up costing several time more, and still be much heavier.

Octania

I have some J's getting refreshed right now.
Not sure what the final cost will be, depends on the work they need.

If they don't sell as J's in a couple weeks they will become F's or D's and see what happens.

spacecadetdave

I have a set. If I get the number off of them, can you identify what size they are? I belive they are 455 but not sure. My Father had them rebuilt but he past acouple months ago. I have been looking for any papers he left that mit tell me what they are. I do know they were out of his Olds 98 1975 or 76.

gcw13

What is a set of pressure tested Ka heads with Valves, rocker arms, and spriings worth?

gcw13

"J" heads are great for use on the 455 in the GMC Motor homes. Low rpm and high torque. It is what came on them and it is also most recommended. Cam change
was recommended by Mondello.

cdoering

Im interested, please call me

chris
314-495-1700

Oldmofogo

The A heads with the larger valves, I personally would run aluminum, much easier to produce flow

squirtacious

Interesting. I know I've seen an Olds ad that stated 1970 Toronado had valve rotators. Those all had E heads.

aqua67w30

Don't be afraid of small valve C heads. My car ran 12.60's with 455, stock small valve C heads, Sealed Power 10.5:1 forged pistons, Crane .496" lift 232 duration cam, iron intake with Q jet.

70W-32

All E heads came with Rotators

4+4+2=10

I have a good pair of core Ga heads You can have for $150. I'm about 2 hours south of you on I 35 near Wichita. Drive down and get them..no shipping.

matt69olds

The BEST heads are obviously aftermarket. As others pointed out, all the heads with the exception of the J casting flow about the same.

The question to ask is what’s the best bang for the buck? Machine work and parts get expensive fast, aftermarket heads are an easy 40hp bolt on. If the iron heads needs a bunch of machine work, things like guides, valves, new seats installed, plus some porting, it’s not hard to approach the cost of aftermarket.

Jj77firebird

Do you still have these? If so, I will take them. Willing to pay shipping. Thanks.

edzolz

And another thread revived from the DEAD FILEs.