I'm trying to get info on building my 455 into a "torque monster" stroker motor. I'm currently running a 461 (30 over 455) with a stock crank, perfromance ported "C" heads, Comp XE268H Cam with hydrolic lifters, 700R4 performance transmission, 2500 stall, 3:91.1 posi, O4B Aluminum intake with a 750 Holley double pumper. It's in a 70 442 convertible (heavy car) and I'm still not happy with performance.

I don't need 600 hp but would like 580 pf Torque if possible. I thought I might accomplish this with a "storker" crank and get the cubic inches closer to 500.

Anyone have any thoughts on how and if this can be accomplished on carburation without going to Mondello and shelling our $6,000 for a 485 short block? What can I do? Please help. Thank you.

442 Jack

 

Strokers are pricey...
off set grinds or custom 4.5" cranks, custom pistons, 7" rods...

I hope I'm not killin' your dreams but look at what you've got.
You've got good heads from what it sounds like, and then
you're running a ridiculously small cam.
Here's your specs from Comp:
Grind Number OL XE268H-10
Intake Exhaust
Gross Valve Lift 0.485 0.49
Duration At 0.05 224 230
Lobe Lift 0.303 0.306
Lobe Separation 110

Here's what I'd do. Put on a set of comp adjustable roller tip
rocker arms and look for a cam with (you've got power brakes right?)
Duration...230-246
Lift..........520-.540
LSA.........112-ish or higher(to keep vac. for your brakes)

You've got great gears...get a cam to match!
I guarantee it will be night and day over what you have.

 

Hi Rallye469:

Thanks for the quick reply and the info. Yes I have Power Brakes and I would like to keep them if possible. I just don't have enough guts on the bottom end. I don't race it but I do take it to the track once per year with my car club. Last year it ran 13.5 with street tires and closed exhaust (I'm running Hooker super comp headers 1 3/4 inch tubes matched to the heads into a 3 inch collector with 2 1/2 in. Flowmaster American Thunder crossover exhaust system with 40 series mufflers).

Any idea who makes a cam like you suggested? Are yoou saying a "hydrolic roller cam? Will I be able to run the low rise valve covers with the roller tip rockers (I have the original A/C and alternator brackets which require the low covers)? Please let me know. Thanks.

442 Jack

 

dude, don't you know that 455 is already a torque monster stock! I have a built 455 in my 69 442 and it is crazy fast. you have good heads and the cam is too small. My 455 is 30 over, .030 off deck, .030 off heads, c heads with large stainless steel racing valve, bronze guides, comp cam 292/518 magnum cam with hydrolic roller rockers, custom push rods, complete engine is arp studed, bottom end polished down, stock rods, windage tray, rotating mass is balanced and blueprinted, 11.5 alum speed pro pistons, much custom work done on block for high rpm oiling, milidon gear drive, 3500 stall, torquer 455 intake, holley 750 dp with hei msd and 3:90's and this car will throw you into the back seat. Not a drag car just much show and much go. set the motor up correctly and it will perform great! don't need a stroker.

 

442 jack,
I have roller rockers installed on 3/8 rocker studs with guide plates and still run stock elelbrock valve covers, i don't have air but stock ps,alt and brkts. i will help you with this motor as much as you want me to.
Robert
69 442 go onto www.69442.com, gallary page #6. yellow car in louisville, ky. that is mine.

 

Robert:
Sounds like it my cam that's causing the problem. You've got a bit more compression than I do but everthing elase is about the same. I'll look into the Comp 292. Thanks!
Also, My 442 is a very rare (one of 179 made) Sebring Yellow convertible, black stripes. Love those old yellow Oldsmobiles!
Thanks for the offer to help. I'll take you up on it as I go along. I'll keep watching this forum for details.
442 Jack

 

Jack,
I don't think you need a roller cam...they're nice, but it's not necessary.
If you go with the comp adjustable roller tip rockers, they'll fit under
any stock covers.
If you go with the harland sharp full rollers...I've heard you need a
spacer or use 2 gaskets per side...(don't quote me)

As far as cam manufacturers...
I'd try www.bulletcams.com
I've heard plenty of good things about these guys.
They specialize in custom grinds and they know Olds.
I've also heard a custom grind isn't as expensive as you'd think.
PLUS...it's made to be exactly what you want...keep your brakes
AND get as much cam as you need.

As far as comp goes...I'll hold my tongue.

You're most of the way there...13.5 with a cam that size, in a car that heavy is very respectable. A better cam and Drag Radials and your in the 12's.
-Pete

 

BTW...I'm really not trying to discourage anything you want to do.
With that said-
I'm running a stroked 469
I'm running a roller cam
I'm using full roller HS rockers
I'm running a 108 LSA

It just seems like going this route will tear up what sounds like a sweet car.

 

Pete:
Thanks for the info. I called Bullet today and got an education on cam shafts. He recommended a 226/235, 533/533, LSA 111 or 112. Said this would be the best for my application. You were pretty close! Thanks. With all the snow we're getting I think I still have time to finish this project before car season.
Jack

 

Not too shabby!
I should go bet the lottery tonight!
I'll never have that many numbers right again.

But good to hear they were cool and took some time with you.
I've heard nothing but praise about them.

 

Pete:
I'm not sure this will get me into the 11's?? I think I'll need more than a just a cam upgrade. I still have the idea to stroke the 461 but I don't know if this will help.
Jack

 

Oh, it will help.
It just costs a bunch to make an Olds-that quick, still drivable and live long.

There's a bunch of guys that do it, but 11's isn't as easy as Car Craft, or
popular Hotrodding would have you believe.

Start out with your cam & heads and then run it this year.
Springs here, enjoy it. Plan your attack for the fall and see
what upgrades you want to make next winter.

I bet you'll be happy once you get to the track.

 

Pete:
Now you sound like my Dad. You're both right.
Jack

 

If you got the $$ Then I say go for the stroker, but they are not cheap. Here is the details of my build;
http://www.realoldspower.com/phpBB2/...ic.php?t=37221
I'm running low 11's and I drive my car to the track. Its got good street manners until you mash the gas then all bets are off? JKaz

 

Why not just pull the crank and have it offset ground to get a longer stroke?

 

This is a good strong setup for the street and occasional race. It is too heavy for an all race car. - Stock 455 block and crank. Standard bore Speed Pro L2359 forged pistons for a 455 PONTIAC. Stock 425 connecting rods. You will have to do a little notching on the inside of the block to clear the rods. No fancy offset grinding or anything. You will need to run race gas or at least mix it. You will definately need a bigger cam and probably a better fuel pump. I`de get rid of the Holley and have a Q-Jet professionally done.

 

If your using the stock 425 rods and a stock 455 crank your not really making a stroker motor. The only way to make a stroker motor is to increase the stroke at the crank, if you use this setup all your doing is moving the piston closer to the head and increasing compression ratio.

 

Huh?
Stock 455 rods are 6.735", stock 425 rods are 7.0"

If you think that the extra .265" of rod length are
there for compression reasons...your wrong.

Compression ratio MAY be a bi-product of all of
this depending on piston choice and it's compression height.

What your doing is increasing the rod ratio.
So, yes overall 'stroke' is mantained but changes in the rod
ratio have an effect upon piston movement at both TDC & BDC,
which in turn creates changes in the effect of camshaft timing
events and the timing of the intake and exhaust charges.

 

this made me think of a thread from another site I read last week. It took a while for me to find it but here it is. They end up talking about dynamic compression, static compression, valve timing, stroke, etc. My head was swimming after reading the whole thread. And these guys are "Old Skool" people. It just goes to show that most of us (me included here) don't even begin to scratch the surface of understanding the dynamics involved in what makes our engines run much less getting a handle on what it REALLY takes to improve upon what has already been designed into any particular engine beyond slapping a 4bl carb, intake and headers onto it.

anyway...http://www.jalopyjournal.com/forum/s...3904&showall=1

 

Wow, great thread. I'm about half way through and need a break.
I was wondering when they're get to VE(volumetric Efficiency) and
then bang! There it is. Static compression, it's all there. I think I'll print
some of this.

You're right, there's more to it then most think. There's ways to make
smaller cammed engines run with bigger ones. Ways to bring down compression, bump compression, quench plays a huge part in detonation...
phew!!!
Great thread!!!

 

[quote=Rallye469;30934]Huh?
Stock 455 rods are 6.735", stock 425 rods are 7.0"

If you think that the extra .265" of rod length are
there for compression reasons...your wrong.

Compression ratio MAY be a bi-product of all of
this depending on piston choice and it's compression height.


I don't quite understand, correct me if I'm wrong but if your going from a 6.735 rod to a 7.0 rod wouldn't you be moving the piston closer to the head reducing the cc's of the combustion chamber therefore the compression ratio would be higher? I also understand if you use a piston with a different compression height you can accomplish the same thing, either way your not getting a stroker motor by switching rods.

 

In theory, yes. But if you keep the stock pistons, this combo would
send that piston through the head.
The combo above(and your correct, it's not a really a stroker)
is used to raise the rod ratio. Get some piston speed back.

 

I still don't quite understand. The formula to figure piston speed is

stroke in inches * rpm = mean piston speed.
6

So even if you go to the longer rod your really not gaining any piston speed or loosing any piston speed. The only way to gain or loose piston speed is to turn more rpm or change the stroke at the crank. I do agree that with that combo you would send the piston through the head, but that's where compression height and pin location come into affect.

 

Stroke = Distance between BDC and TDC, when you put in longer rods, you move BDC AND TDC tword the head, therefore gaining no lengh in your stroke, but increasing your compression ratio since the entire assembly moved toward the surface of the head. Am I right on this ? im not quite that good with engines LOL. but good topic

 

Well.....yes and no.
Over all -the piston has to move from TDC to BDC in 1 -360degree rotation of the crank right? No matter what the rod length or stroke length is.
1 crank revolution = 1 stroke cycle.

BUT...it's the length of that rod that determines how quick it's going at what part of that revolution/cycle/stroke.

A Short Rod is slower moving to and past BDC and faster at the TDC range.
A Long Rod is faster at BDC range and slower moving at TDC range.

Look at the 2 files attached.
The first shows 2 rod/piston combos. Both should have the exact same compression due to a piston with a different compression height making up the difference of the short & long rod choice.
They're identical overall right?

The second picture shows the exact same piston/rod combos -90 degrees past BDC.
They are at identical locations of the crank revolution/ cycle/stroke.
But...the long rod combo has moved the piston up further in the cylinder.
Why?

They will both reach TDC at the exact same time. But the long rod combo has moved the piston up further...faster...in the stroke cycle.
That...is a part of piston speed that the formula you shared doesn't take into account....The speed of the piston at different parts of the cycle.

So- overall average speed is the same for both. But the longer rod accelerates faster where you need it.
It's believed to increase cylinder pressure, reduce exhaust escaping back into the valve area during
the power stroke...it generally does more of what you want when your valves are opened...and when they are closed.

(a side note: Look at that rod angle!!! The short rod combo has a lot more force being exerted on the cylinder side walls...more force, more friction, more pin wear, more rod fatigue etc.)

-now I'm dizzy

 

Your totally correct...it won't give you anymore stroke. And could possibly give you extra compression, but you usually use different pistons which will soak up the added rod length. The pistons will give you desired compression.

I tell ya...it's a good topic because it makes you think a little differently.
I know some of this stuff in theory, but until I drew it out in those 2 illustrations I really didn't 'see' it quite as clearly.

This is old, old stuff developed by the super stock guys. They were measure by cubic inch, and they all had to account for the same total displacment...how they made power rested in the combinations they used

 

BUT...it's the length of that rod that determines how quick it's going at what part of that revolution/cycle/stroke.

A Short Rod is slower moving to and past BDC and faster at the TDC range.
A Long Rod is faster at BDC range and slower moving at TDC range.




I will agree with you to a certain point. As the crank pushes the piston toward the head on a long rod the piston will stop for a very brief moment, then the crank has to bring the rod back around to take the piston back down the cylinder. On the long long rod the piston will be at tdc longer and bdc longer than the short rod simply because it takes the crank longer to swing the long rod vs. the short rod. I believe the physical speed of either one is still the same though. It's not the speed of the piston it's the speed of the cycle. The long rod does push the piston higher therefore speeding up the cylcle.

 

This is a question of RPM now...totally different.
Were talking about 2 motors.
Same stroke, different rod length, same rpm...
The crank still takes the same time to turn 90 degrees- regardless of rod length.The cycle is the same.
It's the fact that the long rod has pushed the piston further in a given amount of time vs. the short rod.

Think of it this way.
2 cams, same lift, different duration.
They both open the valve the same height.
But one with more duration has the valve open wider/for a longer period.
The one with less duration has the valve moving faster/for a shorter period.

It's simple physics, a fulcrum and a lever.

 

From post #2

Looks like something is missing.

TDC to BDC = 180°

360° would be TDC to TDC or BDC to BDC.

1 revolution = 360° = 2 strokes.
2 revolutions = 720° = 1 four stroke cycle.

Which, unless the intake valve was closed earlier, would result in less cylinder pressure.

Norm

 

Good point. 360 is bdc to bdc or tdc to tdc.

 

If the stroke is the same and the piston is moving from bdc to tdc (180)how does rod length effect piston speed? The piston will be higher in the bore because of the rod length which will effect other things, but either way the actual piston speed will still be the same.

 

Oh my god...I'm smacking my head right now...
Sorry! It was late...trying to wrap my head around one thing
and not paying attention to another. My bad.

 

At 3000 RPM, the piston speed will be 2125 feet per second and at the end of each stroke, the piston comes to a complete stop, then reverses direction, regardless of rod length.

However, at 90° and 270°, the piston will be traveling faster with the 7" rod.

Norm

 

How did you figure that out? All the calculations that I could come up with say there the same.

 

Absolutely.
So...this would also be a good case for a higher lift cam with a smaller duration, right?
Opening the valve further but for less time to coincide with the piston
staying at TDC or BDC longer, right? Trying to keep the lifters on the cams
base line longer...

I gotta finish reading that thread you reposted...

 

Norm's absolutely right. Look at illustration #2 again.
How could the piston top be further up the bore with the same amount of
crank rotation?
Speed = distance over time.
The illustration shows the same time frame...different distance.
It's moving faster.

Your thinking of the average speed through out an entire stroke.
Break it down further into different parts of the stroke.

 

Ok, maybe I am thinking of average speed here but the reason the piston top is further up the bore with the same stroke is because it has a longer rod. How do you break it down to figure out piston speed at different parts of the stroke

 

math.


(that's not arrogance, it's ignorance! )

There's got to be a formula used to figure out the change in ratio
in distance traveled (or degrees) when comparing 2 levers of different length...
but I sure don't have it, and probably wouldn't know what to do with
it if I did.

 

I've seen longer rods and shorter rods effect piston loads and skirt clearances in different ways but I have not seen how to calculate piston speeds at different degrees of crank rotation.

 

Easier to advance the cam and spend the cash on beer.

Among other things, you need to make the cylinder pressure match the intended fuel use for that unique application.

That "among other things" thing, is why I don't make cam suggestions in forums.

All I know, is what I posted.

As far as I know, there is no reason to.


Using the numbers from my 468:

Static (mechanical) compression ratio = 11.94:1.
Dynamic CR with 6.735" rods = 8.540:1
Dynamic CR with 7.000" rods = 8.507:1

Norm