Omicron

There's a ton of different heads out there for Olds 455s, and even more info on them. Can anyone help me with rank-ordering the Olds heads from best to worse (eg, D is best, then C, then F, then E, then J, then L, etc), and tell me if the best are really that much better than later heads, like say the "J" if a good port/polish is done on them? How much of a net horsepower difference will there be between the best and the worst? Also what about a set of aftermarket heads, like Dart or Edelbrock?

Rallye469

Buy a new set of edelbrocks and be done with it.



I'll take a crack at it.

Large valves. Get heads with the large 2.07 valves -OR- be prepared to put
them in.
Heads with large valves...
Some B,C,E,G,Ga,K & Ka
All D,F,H (good luck nabbing these!)

With enough work...they CAN all flow the same.
But I'd start with(in this order)
C's,E's,Ga's,G's,K/Ka's and then..............................J's.

(B's are good too but you get into the whole wrong angle headache)

Please correct me somebody if I goofed.

Omicron

Yeah the Edelbrocks are a thought, and yet, their quality has gone downhill of late and even they need port work nowadays. If I'm going to do portwork, I'd rather stay original Olds, unless the Edelbrocks are that much better.

So what's the HP diff between the J's (at the bottom) versus the D, F, or H (at the top)?

J-(Chicago)

How FAST do you want to go??
You can run 10s with these.
http://www.rocketracingperformance.c...eads/index.htm

Rallye469

That's what's on my engine right now.
There's a few guys in the 9's with these heads now.
And I guarantee someone will crack low 8's with them this season.

http://homepage.mac.com/ph12/.Pictur...ts/fender1.jpg

Omicron

Those are pretty sweet. Any idea how much they are?

But again, I come back to my original question: how much better is a "Best" Olds head versus a "Worst" ?

Rallye469

They're about $2500 and come with a designated manifold.

As to stock heads...what do you want to do?
I can't tell you about J heads because I've never run them.
I can tell you with the exhaust ports ground down, large valves
and port work, they're as good as anything probably.
I've seen J heads go 10's.

I can tell you about stock C's though...
'67 425
2.07 valves(stock large valves)
226/230 Duration .496/.512 lift cam
performer w/ 750 Vac. Holley
1 5/8 headers, 2.5" flowmaster system to the rear bumber
3.42 gears in a 3895 lb. '70 Post coupe.

13.05@102.6

That's not bad for stock heads and a small cam and mild gears.
It pulled 1.72 60fts on radials.
(and I swear, the car leaned out at the tall end...with a better
tune, it would've been 12.8 no sweat)

So how fast do you wanna go?

Omicron

Not bad at all! It's sounding like a set of C's might be the way to go... with a little porting work.

As far as how fast I wanta go, I'd say mid 11s, which should make for a fairly streetable combo. I'm not far off that now, but as I want to take it to the next step, heads are going to have to be it.

Still wish I could quantify this a bit better. I have J heads now but they've been P&P so they flow fairly well. Don't know exactly HOW well as I didn't build the engine myself, or spec it out... I bought it pre-built. If I slap a set of C's on there I was hoping to see a dramatic improvement.

Anyway, thanks!

Rallye469

I don't think you will, IF your J's have been done right.

Mid 11's is a stout goal...IMHO.
What are you running now?

J-(Chicago)

Especially a streetable mid 11 car. It'd be annoying to run power anything.

Omicron

Dunno... have not yet had it to the strip. Soon as I can I plan to use my GTech Pro to at least get an idea of how it's running now. I'd guess mid-high 12s, but then my butt-dyno's been wrong before.

Rallye469

You got that right!
You can usually kiss power brakes goodbye unless you run
a hyroboost system off your PS pump.

Omicron

So the problem is low manifold vacuum then?

Rallye469

Yeah...
The problem with big cams is big duration = low vacuum.
To run 11's you'll have to be right around 380hp to the wheels.
That's about 460-480 at the fly wheel.
You'll need lift, duration and heads that will use all of it.
They'll probably need to flow 270cfm @ .500 , 290 @ .600

These are really general #'s. But I bet they're close.
If anyone has flow #'s with timeslips PLEASE chime in...

(I switched to manual brakes...and I really don't mind as
much as I thought I would...you can stop just as quick,
you just get bigger calf muscles!)

Omicron

Now that is some AWESOME info! SO lets see here, some questions... you're figuring roughly 20% driveline loss? Also what's the weight of the vehicle you're using for this calculation?

And yeah, I'd love to have flow numbers with timeslips, or was hoping I'd find someone who had run X time with one type of manifold, but then had switched manifolds and run Y time, thereby allowing a rough comparison.

Warhead

You will also need a 3.73 gear, 3500 converter, and I did not catch your compression & cam.

The J heads will do it.

A/B/C heads have a shorter floor, and bowl on the longside. The later heads have a taller bowl, and shortturn radius (and actually will flow a little bit less). You have to get them side by side, and measure with a micrometer, to tell the diference.
There is only about a 10hp (max) difference though. Lowering the floor gains a little bit more, but that is best left to a professional.

Fill in the heat risers with aluminum for an easy 20hp.

And better yet, get some larger intake valves. 2.07's are good, but 2.125 inatkes are better. This is where the bigger gains come in. Have your machinist cut 4 angles (30/45seat/60/75). A 30 degree seat will give you more low lift flow, at the expense of high lift (.500-up) flow. Works great on the street.

Keep the 1.625 exhausts.

Dart does not manufacture heads for Oldsmobile's.

If you think your car run's 12's, it will be lucky to chase down a 13 sec e/t. Butt dyno is the worst. Followed by that computer thing. No comparison to a Chrondek.

JME
Jim in Phx.

Rallye469

At least...

Ha! Nope...they're close guesses.
Based on my builds that have spanned the 11-15 second range.
Weight would be about 3700 with driver.


But what IS totally 100% accurate is this...

Omicron

Rear end is a 3.73 and stall is a 2400-2800, so I'm close there. Compression is supposedly 10.5:1 but not sure, nor am I of the cam duration/lift, as I bought the motor pre-built. Motor's moderately lumpy at idle. This summer I plan to dyno it and probably take it to the strip to see what it'll do. Based on what you've said, it sounds like I'm at about 300HP at the wheels, but we shall see.

Warhead

BTW, get some REEL sticky rubber for it, keep the spare tire in it (maybe even keep one that is full of water or concrete), ice down the intake, plastic carb spacer, 36 degrees total advance, and due to the unknown cam and headwork, check your et with shift points from 4400 rpm-5000 rpm.

It's funny how some people can sneak up on their number.

Omicron

Very cool, will do. Thanks.

Omicron

Ok so to continue this thread, I managed to pick up a set of well done C heads for the proverbial "song" - complete with larger valves, plugged heat riser, ported/polished, etc.

Now the next question is, what cam should I be looking at? Again, I have no idea what's in there now, and won't till I pull it out. But were I to replace it, does the peanut gallery here have any recommendations, keeping in mind I need to keep it streetable?

Rallye469 above talked about a fairly mild cam with 226/230 Duration and .496/.512 lift. How much less mild could I go? I'm not opposed to using a vaccum booster if that's all that's lost, but in my experience, too hot a motor is like driving with an on/off switch: you're either going ***** to the wall or you're sitting still. Can't abide that, but still want to run mid 11's to mid 12's at the highest.

gearheads78

Quit guessing and take it to the track. I wore out a guy whos g-tech computer thingy said mid 10's. My track proven 7.1's 1/8 mile (guess 11.0 1/4 but never verified) street car beat him by bus lenths.
See where you are then start making changes. No matter how much power you make its worthless if you can't get it to the ground. Work in tires chassis and suspension. Once you get it as fast as the current motor will go then start making upgrades to the power.

Omicron

Yes thanks track time is pretty much a given.

Reason I'm going down this path now is that with the current engine and tires, on a good dry clean road, the car hooks pretty well (I spin maybe 25 feet but not badly) and launches well. That tells me the engine is down on power from where I want it to be, hence my discussion on the cam. Between now and when I can get to the track, I'm wanting to narrow down on cams - this is the research phase, especially since I now know I've gotta pull the engine partially apart eventually anyway to put those heads on. Might as well do the cam while I'm in there to best match the heads and where I want to be, ya know?

gearheads78

Thats understandable but I would still see if you can dial in what you have. If you don't care about originality just buy bare Edelbrocks and invest in a good valve job. Buy the time you spend the money on building and professonally porting OEM castings you will have just as much tied up in them. You also get the weight savings as a bonus.

As you are thinking out your new combo think it all out. The entire comination working together will make a big difference.

The last quick car I built was for a buddy. I spent I lot of time thinking out the combo and its more than supprised a few people in race cars at the track. On a shoe string budget 4200 lbs street truck 461 BBC oval port heads solid flat tappet cam with a ysi Vortech blower with 8lbs of non intercooled boost. As of a few months ago that truck has been 6.58 @108 in the 1/8 and its driven on the street all the time.

Its all about the combo. Good luck

Omicron

Excellent - I appreciate the advice. A blower is likely in my future too. But in the mean time, I've already got the new heads...... so now I'm studying cams, and looking to see what other people have used with success.

jonstringer

http://www.442.com/oldsfaq/ofhed.htm

Everything you need to know about Oldsmobile Cylinder Heads. Combustion chambers, valve sizes, intake runners, etc... The rare and valuable are highlighted.

gearheads78

Sorry I overlooked that part. I would be them flowed to see where they are. The low lift numbers are going to be more important for your application. Once you know the numbers call around to some of the speciallty cam manufactures. I have never built an Olds before but I have had great luck with Cam Motion for other makes. I may cheat on my Olds motor for the 66 do to time constraints. I already have a set of mild ported E-brocks but I may have Bill @ BTR build my short block.

Omicron

Awesome! Thanks to this info, I now know I have these now:
ID/Code: C
Year(s): '67 - '69
Use CID: 425, 455
CC's: 80
Casting Number: 394548
Notes: A/C '68 H/O's. Toro's and 442's got big valves. Rumored to flow the best of all BB heads. Can still be found.

Even better than the above, I found this about cams. Time to do some studyin!

Omicron

No worries, and thanks for your input - I really appreciate it.

Rallye469

You're going to need a LOT bigger cam then that to go mid 11's. A LOT BIGGER. Your looking at a cam around 250+ duration and .550+ for lift.

And...before you put too much weight into that cam theory write up...
This quote was lifted from that faq...
This dyno sheet is from an engine with a 108 degree LCA.
I don't think 473ft lbs at 3000 rpm is 'poor'.

Warhead

JM 25-28 worked for me.
Compression is key.

65Delta88

Where to A heads fit into the mix? are they that bad that they don't even rank??........lol

Rallye469

No, not at all!
I just left them out of the list because of the earlier lifter bank angle.
Figured he wouldn't want to worry about .921 lifters and a custom cam.

Omicron

Ok cool, thats helpful. What's that the manifold vacuum etc(streetability) going to be like with that big of a cam? And if that's too big, and 226-230 Duration/.496-.512 lift is too small, then is ~240 duration and ~525 lift (somewhere in the middle) going to be about right - as in streetable but still allowing me to get into say low 12s?

Sorry, what is "LCA" mean? Can you give me the lift/duration on what you were using here, 'cause yes I'd agree that 473ft lbs at 3000 rpm isn't "poor" at all.

Omicron

What is "JM 25-28" please?

Rallye469

That's not a bad cam at all, nice lift and the duration isn't too wild.
You got down into the mid 11's with it?
What heads were you running? Weight? Gears?

Rallye469

Lobe Center Angle.
It's a 254/260 duration .575/.580 lift cam
It's not what you're looking for.
As Warhead pointed out...what is your compression ratio anyway?

Omicron

10.5:1 compression, currently J heads but soon to have well done C heads with oversize valves. Edelbrock performer intake, Holley 750. Rearend is a 3.73, tranny is a built TH350. Not sure on the weight of the car as I haven't made it to the scales, but it's a convertible so it should be in the neighborhood of 3700+ pounds.

Again, what is "JM 25-28" please? is that a brand/model or what?

Rallye469

It's a cam made by engle, sold by mondello's

Warhead

Get the Engle version, deal with nicer people, better price, and it will have a hair more lift with the same duration.
11.80's...425, 3500 converter, t-350, 4.56 gears (too much gear-would have run just as well with 4.10's, ran same et with 28 inch & 29.5 M/T) Torquer, 850 Holley with a blue pump. Custom 2 1/8 inch headers (this was before Hooker made an A body 78 up, header). 3200, not including my fat 225# ***.

Sold the car last year. Still have the engine.