416 Dyno

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bigjeepmudder

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I'm off to the dyno for the day, I built a 68 340 to a 416, ported O heads with 2.02 1.6s. Flat tops, not sure on the compression but guessing around 11:1, .571 lift old Mopar oval track cam, ported Mopar single plane intake. The stock heads are the down fall for power but I'm guessing around 480. I'll post on here tonight what it made if it survives the beating. Any guesses? :coffee2:
 
Without much to go off of on the heads and a "guess" of 11:1 CR will make this even more of a guess but I'll take a shot at:

514 hp
487 tq
 
Is this in a car or motor only?
Flywheel HP , I think your right on the money with the 480.
 
The motor ended up making 479hp @ 5800 and 489tq @ 4600. It was on 91 octane, with a 1" open carb spacer. With a 2" spacer it made 493TQ but lost 4hp. I accidentally put the wrong timing cover on, so I had to guess and make a timing pointer. It made its best power at 38 degrees but had some pre-ignition towards 6000 rpm so we backed it down to 34 degrees, give or take if my pointer was right.
 
sounds pretty good for a stock iron head motor!
what kind of specs on that cam?
 
It was a used cam that I had out of a 340 that made 430hp. I thought it was an older mopar performance cam and the lobes are .571... These are specs I found from a forum for a mopar performance oval track cam

40418
Cam Style Mechanical flat tappet
Basic Operating RPM Range 4,200-7,500
Intake Duration at 050 inch Lift 256
Exhaust Duration at 050 inch Lift 268
Duration at 050 inch Lift 256 int./268 exh.
Advertised Intake Duration 292
Advertised Exhaust Duration 302
Advertised Duration 292 int./302 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.550 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.571 in.
Valve Lift with Factory Rocker Arm Ratio 0.550 int./0.571 exh. lift
Lobe Separation (degrees) 106
Intake Valve Lash 0.024 in.
Exhaust Valve Lash 0.026 in.
Computer-Controlled Compatible No
Grind Number SPI2-292-302
 
Makes me wonder .. do we really need aluminum heads if we can get roughly 500 tq/hp out of cast iron heads ...
What would a port job cost to get near 500 hp/tq out of iron heads ?
 
Almost nailed the torque number! I bet that cam sounds nice too.
 
You could get 500 tq from factory heads. It's the cam that's hurting that one. With lash and pushrod angle taken out they're only opening about .500".
But - the cost vs benefits make iron less desirable when there is a choice.
 
Its hard to tell on the dyno how it will act on the street but yes it idles very rough. but it's a 4 speed and I use to drive that 340 with that cam a lot on the street, just keep it reved up. You've just gota get use to and drive it like your mad at it.
:burnout:
 
bigjeepmudder said:
Its hard to tell on the dyno how it will act on the street but yes it idles very rough. but it's a 4 speed and I use to drive that 340 with that cam a lot on the street, just keep it reved up. You've just gota get use to and drive it like your mad at it.
:burnout:
Click to expand...

My old cam was almost identical to yours and I had no issues driving around town. I kept the idle about 1100 rpm.
 
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