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265 afr headed 496

8K views 29 replies 20 participants last post by  Supernova72 
#1 ·
A while back I machined and built this 496:

4.310 X 4.250
Worked AFR 265 head
Performer RPM air gap intake
1000 CFM AED 4150 carb 1 inch open spacer
Mahle piston 10.5 compression
248/258/608/630/110 HYD roller
Scat 4340 crank
Scat 6.385 IRC rods
Modified Moroso 20401 oil pan
M77 oil pump
10/40 Maxima conventional oil, Wix 51061 filter
MSD 85551 dist
Tested on 91 octane 7-11 gas
 

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#2 ·
Very nice. Are you surprised it didn’t peak much higher than your 238/248 cammed engine?
 
#9 ·
My bad, Allan's original was 669 @ 5800. For some reason I was thinking it was over 6000K as well.

Where did this build taper off, doesn't look like it's shown in the readout?
 
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#4 ·
Good number, and a nice pan.
 
#10 ·
Mark how much work did the heads receive? And again, what would a single plane intake offer here, if anything? Thanks
 
#11 ·
Com'on Mark, where that's 700 ft lbs!? Don't be slackin' on us buddy! ;)

For sure Mike & Mike, the oil psi is dead steady at rpm, and HP is still climbing at 6300! That's a BIG HR cam ! ( to me we're at the place where I'd prefer a lighter solid lifter to get to those fat .200" duration numbers asap, says the ol' horsepower junkie and non-pro customer engine builder)

perfect rod/piston combo for this app. Mahle's make good power.

Hitting 685 ft lbs on the clutch drop is a dream!

OUTSTANDING! :thumbsup:

PS: for the record, when Mark asked me what my "goals" were with his new bullet, the first one on my mind was " 600 ft lbs please!" So, I'm all about the lbs ft Old Red sees anymore ( well with his old OEM bones - 600 @ a 4" arm is perfect!!)
 
#18 ·
Jeez. Thats a very stout build. Are those numbers with the mufflers attached? Didn't seem to hold anything back did they?
 
#25 ·
As much as I believe that AFR heads are nice pieces, I cannot help but think that Mark Jones' expert porting work has a lot more to do with why these 265 heads produced such great power. That makes me wonder about what the intake port volumes ended up as after Mark's porting work was completed. I'm in no way implying that port volume is everything when it comes to power potential. I'm well aware of the actual contour and the shape of the ports being at least as much, (if not more) of a factor in power production as the actual port volumes are.

I just think that the specific increase in port volume at the conclusion of the porting job might be an indication of how much the ports had to be massaged by the craftsman in order to yield the results spoken of here. Of course Markmay not be in the habit of CCing the ports after his port work is done since this whole porting this is probably second nature to him by now. So he might not even need to know what the port volumes end up being in order for him to know what will work
 
#30 ·
My out of the afr265s with a team g and .612 lift cam at low 250s @ .050 made 590/590. The ports on the I take were a poor match. The intake needed more work than the heads. That is one drawback to the roval shaped ports. The intake need a bunch of work and that's where I felt mine had trouble. Peak hp rpm was 5900 on a 489 with ~9.9 compression.
I would suspect Mark did short turn work and helped the I take vs opening up the intake runners. My afr265s had the runners opened up a bit. I might cc the while they are off the car.
I have pics in a different post to give an idea against a gasket.
 
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