422 dyno fail

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Jim Ward

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I had a local shop build a 422 stroker. 340 .060 over with a 4” crank. I have 9.5:1 compression because I wanted to keep the stock 2.02/1.88 J heads. I had the heads ported and they flow 255@.600. I have a non ported offy port o sonic single plane intake and hydraulic roller valve train. I will upload a pic of the cam specs. The shop called today to tell me they made a pull with a 750 Edelbrock carb and it made 355 hp and 421 ft lbs. I think it should be at least 100 more on each spec. Any thoughts on what the issue on my set up is would be appreciated.

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Non ported intake on ported heads and an Edelbrock. none of "that" is the best case for optimum HP. That said, do you honestly think it should have made over 500 LBFT?
 
More head, more cam, more intake, more carb. Feed the cubes!
 
HP is low for sure, and the torque is shy of potential also. A stock 360 magnum long block with a mild street cam/air gap and 750 DP will make 340 hp pretty easy
 
I get all of that but that low of HP?? I think it should be darn close to 500lb ft. I asked the shop about porting the intake and they didn’t recommend it which also seemed odd to me. I know Edelbrock isn’t known for Optimim HP but again I think it should of at least made 1hp per cube…
 
i thought that 421 fpt was pretty good torq for 422 ci , its still fresh n tight too . loosen it up some it should get better .
 
I really wanted to stay with the iron cylinder head. I paid good money to have them ported so they would flow. I am open to any intake suggestion as well as carb suggestions. Cams are very hard to come by I felt lucky to be able to get this camshaft. Open to any and all technical suggestions.
 
Could be any number of things, need a lot more info. How was the cam installed? Where's the timing at? Out of the box carb? Did the shop do any tuning? Do you have the dyno session printout?
 
Not that small of a cam. Lots of lift.. .570"

Did that have a dyno carb they could have put on it? Not sure if the Edelbrock is a great match of HP dyno numbers.

Interesting to see what a Holley 750 DP and Edelbrock RPM or M1 would do.
 
Non optimal carburetor, not great intake, and heads that peak @ 255 @600 lift mean nothing when your cam is way undersized for the cubes, as in your case. Its definitely a under performing engine based on there numbers, but you cant exactly trust dyno numbers either.
 
Non optimal carburetor, not great intake, and heads that peak @ 255 @600 lift mean nothing when your cam is way undersized for the cubes, as in your case. Its definitely a under performing engine based on there numbers, but you cant exactly trust dyno numbers either.

Wouldn't you think that cam would produce 1 hp / cu inch ?
 
I’m open to some suggestions to help the combo. I know the number sucks. What opinions to change do you recommend?
 
Your combo is out of wack. Heads, intake, carb, out of wack. All of it to small.

The cylinder heads being factory iron oil to so far and to say it flow 255cfm is great for a ported stock head. But against a ported Edelbrock that will go 300cfm with a larger port window is worth that 100HP easy.

The intake is super old school and will not support much more than 370 cubes and that’s seriously borderline IMO. It was made with 340 cubes in mind.

At 750 cfm, it’s small never mind being an Edelbrock. The style of carb isn’t giving up a lot of HP at this level vs a Holley but there is more power in the Holley and a good bunch of you gave it some more cfm. The air entry into the Edelbrock is what I’d call compromised. It’s fine for a street engine but not a really a great choice for a nice bruiser of a 422 that’s under it.

I don’t see an issue with the cam. I’m figuring it’s the inability to breath. If that top end package was on a 340/360, I’d bet it would be pretty OK.
 
The way I understand it that manifold needs quite a bit of modification to work to its maximum potential see-direct connection race manual, that being said how was the Edelbrock jetted what was the air fuel ratio, I agree I would like to see it with an m1 and possibly an 850 Holly if you're going for numbers. Where did your maximum horsepower come in at RPM wise?
 
I will post them once I get them. I am going at 10am tomorrow morning. He just called this afternoon.
 
Something is definitely a miss.
Cam installed advanced, straight up or retarded.
I know cam is hydraulic, but is the preload good?
Compression is a little low,but should have better results.
There is room for improvement with the carb and manifold.
I think hp should be easily in the 425 to 450 range and torque around high 4's.
What are the air/fuel numbers?
 
I was going to run a Edelbrock 800 cfm but I will run a Holley 850 if needed. It’s going in a 71 duster with 727 trans and 3800 stall with a 4.30 gear. None of that matters to my original post as why the hp and torque numbers are low. I’m open to any suggestions to help from a technical build standpoint
 
Everyone is also taking for granted the dyno numbers are actually correct.
 
I will get the actual dyno sheets tomorrow I was hoping for better results for sure.
 
I’m open to some suggestions to help the combo. I know the number sucks. What opinions to change do you recommend?

Why not try to tune it first before you start throwing more money at it? The dyno is a good tool, if you have it at your disposal use it to it's full potential. It sounds like the shop may have broke it in (did they?) and did a cursory dyno pull and that's what they got. Probably has more in it, just have to find it.

You might want to ask the dyno shop some questions about their procedures. What was the air like when they ran it? What was the correction factor? Did they use a carb hat/fan? Is the dyno properly calibrated? There's so many things that could be in play, it's hard to know exactly what we are looking at.

As far as parts - is it going to be raced or street driven? If you're going to drag race it regularly, the combo is definitely off. Race engine would be a solid roller, bigger headers, Holley 850+, electric water pump, etc. Race engine stuff.

The Port-O-Sonic used to be a well-regarded intake but there's probably better pieces out there now. An RPM Air Gap might be a better choice, they perform well on milder combos like yours and will run with a single plane to the upper RPMS.

The pics show a Mallory Unilite distributor - is it electronic? How is it set up? Is that the coil they used? Seems kinda chintzy for a dyno cell. What ignition was used? Figure there would at least be an MSD box of some sort, preferably a digital one.

What size are the headers? They look like TTi 1 5/8"- 1 3/4" step headers. They're on the small side but they do work. Full exhaust in the car?

Do you have another carb to try? Most dyno shops have a proven unit they have on hand in case the customer's doesn't work.

Too many variables and unanswered questions to be able to help accurately.
 
Everyone is also taking for granted the dyno numbers are actually correct.

Indeed. It would help if the shop could share dyno results from some kind of known combo that might even have a time slip behind it. Something to ground the results.

Lots of "500 ft lb" builds are bogus, and make it seem like an easy task. It may not be hard, but ported iron with a questionable intake make it more of an uphill climb.

Lots of professional porters have shared that flow can be deceptive. Lots of ways to get "excellent" flow from iron while making bupkis for power. So there's that too. Flow at .600 isn't the whole story, and cfm isn't the whole story either..
 
I will get the actual dyno sheets tomorrow I was hoping for better results for sure.

Might ask about the weather too.
Humidity, temp, water grains, corrected altitude. Etc…
We’re not talking a lot of horsepower but it could be some
 
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