422 dyno fail

512Stroker

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I’m open to some suggestions to help the combo. I know the number sucks. What opinions to change do you recommend?
It is apparent that one of the issues is that the engine is starving for air.
Port matching the intake to the heads along with the correct intake gasket will help it to breath. 850 cfm carb with a carb spacer will help also.
I run a roller 340 with ported X heads and matched AirGap intake, 800 cfm carb and it pulled 442 hp with a smaller cam than you have.
The guy who did my porting wont even touch your heads unless you give him the intake and the gaskets you are going to use.
 

ir3333

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2 camps here.In camp 1 everybody with a 408 makes 500hp.In camp 2 somewhat less.
Stock iron heads stall out at about .480 lift.I know of quite a few 408's with iron heads that made your numbers. But don't forget 440's made 375 hp.
 

rumblefish360

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Stock iron heads stall out at about .480 lift.I know of quite a few 408's with iron heads that made your numbers. But don't forget 440's made 375 hp.
His stock iron is ported so those numbers fly out the window for his build.
Your mention of the big block 440 doesn’t help much since it’s bore and stroke are different by a huge margin and it’s cylinder heads are not comparable.
 

cookietruck

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i think it's plenty of camshaft. I'd be curious of there is some valvetrain instability with a hydro roller with listed powerband of 2500-6500
the compression is kinda low but you gotta be safe with a non quench motor.
what is cranking PSI and what is the ICL of the camshaft?
 

PRH

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While the combo is far from optimum....... the numbers are ridiculously low.

I’d have to see a dyno sheet from this motor along side a sheet from a better performing streetable stroker, off the same dyno, before I’d condemn it.

I agree with the OP in that I’d have expected 500tq/400hp to be “easily attainable”.

I’ve never run a port-o-sonic on a SBM, but it would really have to suck to be “the problem” with this build.
 
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Jim Ward

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This was the sheet from yesterday.

895C3F03-C231-479E-8E15-F3F328237A42.jpeg
 

pittsburghracer

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This is why I don’t jump on the “you gotta build a stroker” bandwagon. Some combos that work perfectly at 360 cubic inches suck at 408. It’s like having the best worlds famous thick milkshake sitting in front of you a drinking it with an eye dropper.
 

4spdragtop

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Stupid question here, but what is the "purpose" of a stroker build?
This is why I don’t jump on the “you gotta build a stroker” bandwagon. Some combos that work perfectly at 360 cubic inches suck at 408. It’s like having the best worlds famous thick milkshake sitting in front of you a drinking it with an eye dropper.
 

PRH

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I don’t see anything that really stands out as a red flag on the dyno sheet, other than the ridiculously low numbers.

That said, I’m confident that the issue with the low numbers isn’t that the “combo” is that bad.

Cam is in wrong, carb isn’t getting full throttle, timing mark on the damper is off, timing light is off, carb sucks, etc, is where I’d be looking.
Or...... the dyno is just wrong.

Even very mild stock engines will make over 1 ft/lb per ci on the dyno with headers.
This motor barely does it?
Is it “possible”? Sure...... but.....Not likely.

I’d be more inclined to retest somewhere else........ that’s known for producing good power from Mopars before I spent a bunch of $$$ on engine parts.
 

'68cuda416

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This is why I don’t jump on the “you gotta build a stroker” bandwagon. Some combos that work perfectly at 360 cubic inches suck at 408. It’s like having the best worlds famous thick milkshake sitting in front of you a drinking it with an eye dropper.
A better response would have been a properly thought out engine and parts selection will and should yield very satisfying results with stroker engines providing the typical best bang for the buck.
 

PRH

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You can buy a set of heads that are significantly better than what he has for $600-800??

No one likes it when I mention this, because it often goes against things they “know”........ but......
My friends Pontiac Stocker makes way way more power than this motor does(or at least what this dyno sheet says.....and is more than 500tq/450hp) with a 412” build that has heads that flow 220cfm, a cam that’s .420” lift at the valve, and the stock intake and carb.
 
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pittsburghracer

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You can buy a set of heads that are significantly better than what he has for $600-800??

No one likes it when I mention this, because it often goes against things they “know”........ but......
My friends Pontiac Stocker makes way way more power than this motor does(or at least what this dyno sheet says.....and is more than 500tq/450hp) with a 412” build that has heads that flow 220cfm, a cam that’s .420” lift at the valve, and the stock intake and carb.


I’m guessing if you add in what he paid for the heads that are on that engine you could more than do it. Someone mentioned his intake as being questionable. Although maybe not the best choice I ran 11.82 with one on a 340 back in the 1970’s early 1980’s at 3200 plus pounds. It was pulled out of the box and installed on a set of J heads. But then again something that works great at 340-360 cubic inches my hurt you at 408. Not sure what horsepower I was putting out but I’m guessing it’s more than this engine is.
 

rumblefish360

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I made the mention that the intake was an old design and done around the 340/360 engine. I think it’s a good intake but on the wrong application here. I could be wrong since I’m just only reading things here and not holding parts.

I gave my worthless 2 cents. I’m just going to spectate from here and learn something.
 

pittsburghracer

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I made the mention that the intake was an old design and done around the 340/360 engine. I think it’s a good intake but on the wrong application here. I could be wrong since I’m just only reading things here and not holding parts.

I gave my worthless 2 cents. I’m just going to spectate from here and learn something.


I said basically the same thing. I honestly wouldn’t know either as that was way before I ever did any testing. I’m not sure why I even bought it other than I probably saw it in a magazine. Lol.
 

Jim Ward

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We swapped the distributor and added a 1” carb spacer and got 454 ft lbs and 380 horse. We will do more pills with the quick fuel 850 and Edelbrock air gap tomorrow. I will keep everyone posted.

For what it’s worth I chose to stay with iron heads. I paid pretty much what I could have bought a set of aluminum heads for to have the cast heads done and to work with the roller valve train but I knew that they would be limiting me for power. I’m pretty happy with the torque number and believe that will even go up with the dual plane air gap.

01740442-661B-497C-BE35-898845674363.jpeg
 

PRH

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I guess since iron heads can’t make any power on a stroker...... then if you combine them with the stock intake, TQ, air filter, and exhaust manifolds....... a combo like that doesn’t have a chance.

4FA2696E-54B7-4CAA-BCAD-EBF177154BBF.png


23587B1C-D540-4028-B8E7-4FCD94CB0243.png
 

autoxcuda

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I don’t see anything that really stands out as a red flag on the dyno sheet, other than the ridiculously low numbers.

That said, I’m confident that the issue with the low numbers isn’t that the “combo” is that bad.

Cam is in wrong, carb isn’t getting full throttle, timing mark on the damper is off, timing light is off, carb sucks, etc, is where I’d be looking.
Or...... the dyno is just wrong.

Even very mild stock engines will make over 1 ft/lb per ci on the dyno with headers.
This motor barely does it?
Is it “possible”? Sure...... but.....Not likely.

I’d be more inclined to retest somewhere else........ that’s known for producing good power from Mopars before I spent a bunch of $$$ on engine parts.

i agree.

This seams to be down like 50+ hp from where it should be.

there’s a bad part somewhere (a lot of that going around), something not working right, or a stingy dyno…

ported intakes, 1/8” more diameter headers, heads that support 500hp… are those keeping it 50 hp from reaching 1hp/cu in?
 

Jim Ward

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I believe we will get to 1hp per cube with the different intake and carb. I do know this dyno is very conservative which I want real numbers and not an inflated one so I can feel good but I was hoping for 1.2hp per cube. I’ll have to go to aluminum heads to get there it seems. All in time I guess.
 


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