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Hi All,
KC asked me to post the results for his pump gas 496 with the AFR 265cc CNC chamber heads, Chris Straub hybrid solid roller, Victor Jr & Pro Systems SV1
Not too shabby for a set of poor little 265cc oval heads RIGHT OUT OF THE BOX, ABSOLUTELY NO EXTRA WORK

I did not dyno this it was independently dynoed in Las Vegas by HBR Engines

A couple of comments after looking this over
It appears there is a valve control issue or an ignition issue
Torque curve shows this as does the air flow
Also BSFC goes rich on the top which could well be valve control or the carb might need an air bleed change
If I had to guess from the numbers I would look at the valve springs first.








 

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Wow its making good tq! That would be a fun street motor fosho!
 

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Nice 4 sure!!
Makes me wonder where my hp peak is.......more head, 20* more intake duration. However I have .010" more valve lash.
THis thing peaks hp at 6400 and tq at 4600 with a 265 head, and a 248 cam........

Oops I guess it peaked at 6100.......
 

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Thanks for putting up my numbers Mike. I was very pleased with the results, as this was my very first performance piece. Rick at HBR prior to the run said that he couldn't fathom my 496 making more than 575hp/575tq. BOY WAS HE SURPRISED!!! I had faith in the build and all that I have learned from the very knowledgeable members of this site.
Cstraub told me where it should make power and how much to expect, we exceeded that by quite a few. Whatever the valvetrain issues are, I'm sure we can iron them out and I plan on it. Once again, thank you to everyone directly and indirectly involved with the build, it paid off and should be fun. 10.999 here I come(hopefully)!!!! Next stop..... Suspension.
 

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I'll say not too shabby .......wow flat torque curve 600 at 3900 and still 600 at 5800!! ... once sorted out should be nice
x2 :thumbsup:
 

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Very nice numbers! But nothing "poor" about dem heads.
 

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HBR= Heads By Rick... was a mainstay here in S FL seemingly forever till he moved out west.

Any idea what valve springs came on those heads and with how much pressure ?

600 Lbs is pretty nice !

The only thing I don`t understand is the duration on the cam. I would have thought the 255 @ .050 lobe to be on the intake side.

Great numbers no matter :thumbsup:
 

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I see you used a Vic Jr. manifold. Was it a square port with epoxy added to match the AFR runners or an oval port Vic Jr. with the runner exits opened up?


Randy
 

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Great #'s...man, it doesnt even take "alot" of cam anymore to do this. That thing is gonna be killer!

I see the #'s are sorta jagged even at the bottom of the pull - doesnt that kinda rule out valvetrain???
 

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It holds a torque band of 2700 rpm within 10% of peak. It holds a 2000 rpm torque band to within 7% of peak. Should rpm like a rocket.

I noticed the upper rpm "set". Could be some pushrod flex also.

KC wanted something to move his 4000# war wagon...well this should do real well.
 

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Very nice build. Lots of good ol' experience in this build. That torque curve should work great with that big Impala.
 

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It holds a torque band of 2700 rpm within 10% of peak. It holds a 2000 rpm torque band to within 7% of peak. Should rpm like a rocket.

I noticed the upper rpm "set". Could be some pushrod flex also.

KC wanted something to move his 4000# war wagon...well this should do real well.
Think you are right with pushrod flex factored in. We've ran my hybrid with hot lash all the way from .004" to .010". To get .004", set them hot to .004", which pretty much meant the valves were negative or "0" if there was any pushrod flex. Motor was noticeably smoother ( and quieter) when ran tight. At .010 on a hybrid, you get near the practical limits of the ramps. I've found that the best compromise for lashing a hybrid is set them to "0" stone cold, just to the point where the slackmis taken up, but no preload at all on the pushrod. Window for setting these is very small.
 

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Nice Job! :thumbsup:

Also BSFC goes rich on the top which could well be valve control or the carb might need an air bleed change
If I had to guess from the numbers I would look at the valve springs first.

QUOTE]

Mike, seems like it would stop pulling fuel if it was out of spring????
 

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now thats sweet! enough HP there for a race car, and enough torque down low to put the same motor in the tow rig and be happy:beers:
 

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Discussion Starter #20
nice....I think that cam may be part of the "non-secret" to that motors success. not to mention the "wolf" build...great job....
I did not build this, credit goes to KC ;)
I just got a "few" phone calls :D :D

Mike, seems like it would stop pulling fuel if it was out of spring????
John

Look at the air & fuel flow numbers from about 5800 & up
They shouldn't go backwards or be bouncing around unless something is not happy
I do not think it has enough spring & I would look at the intake side first.
BTW, they are the AFR hyd roller springs
About 170/480 in, 460 ex which you would think should work depending on the lobe but that intake valve is not exacty light & I don't have a clue what the lobe is doing on closing with 8 to 10 thou of lash

The first thing I would have done being a hyd lobe is to tighten the lash a few thou to be sure it wasn't bouncing the valve closed
This can be a issue with a hyd lobe & solid lifters sometimes because some have no clearance or closing ramps to soften the seating

It could also be there is no smoothing in the software in which case you are not going to get a nice smooth curve most of the time but the BSFC going way rich, the air & fuel numbers backing up & the torque curve would make me look at the valvetrain

It could be a number of things not even related to the valvetrain but this is where I would go first because it is what could do the most damage if there were an issue.
 
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