new combo missing a bunch of power?

[pfordamx]

So after a major overhaul, our car starts and ideals and does everything well its just way down on power. and i was wondering if you guys could give some ideas on where to look. the car is 1969 amx with a 427inch amc stroker 13.1 compression .740 and .760 lift solid roller duration is 278 and 284 @ .050 108 lobe separation installed at 104.5. Hemi Adkins did the heads they flow 305 @ .700 on a stingy bench. it weighs 3264 with me in it its got 727 torque flight with a brake and a turbo action 8 inch converter that should stall at 5900 and 28 inch tires and 4.10 gears and spool. the rear suspension is all calvert stuff. i don't think the lack is in the chassis or transmission because the car is ok in the 60ft if it was down 300hp becuase it went 12.00 at 106 with 1.51 60ft lifting the wheels about 6 inches. i've thought it could be in the converter. it just does not pull like it should, the motor hasn't been dynoed but i would think it should make 600hp. when its right i wondered about valve springs but if that was the case it would hit a rpm wall right? i'm open to any and all ideas. The things i've considered that could be wrong are.

The plug wires are over 5 years old those will be changed soon.
I'm curious about our digital 6 thinking about having it tested
its 1000cfm e85 carb we have a gas dominator we intend to test in its place. the timing is locked at 38 and has been checked repeatedly. that setting might be a little soft alot of amc's like 40 but it shouldn't make 2 seconds worth of difference. the fuel system is overkill magnafuel 500 pump and regulator and -10 line holds 6.5psi with out flinching. i'm kinda at a loss any help is appreciated

Thank you
Patrick Ford

[bigfoot584]

My only question is what is different from before.
Be real you know it's not identical from before what
have you change, so we can get a handle it and
maybe of some help you with.

[Barnstorm]

what do the plugs look like?

[pfordamx]

whats different? the old motor was 9.5 to 1 stock stroke 390 with a 238@.050 hydraulic flat tappet with some iron heads that flowed about 260@.700 a torker and a 850 holley behind it was a 904 and 8inch 3800 stall converter and 4.10 gears car ran 11.50s at 115 at the time the car had all stock suspenion except caltracks and some 90/10's and almost wieghted the exact same took out a 6 point steel bar added 10 point molly cage. out side of that the car has been completely rewired and re plumbed fuel and brakes have been redone the whole front end has been gone through. its basicly a new car theres not much to compare from the old combo the heads flow 40 cfm better its got a much bigger solid roller, 3.5 points more compression and 30 cubes on the old combo but somehow it is slower. the only similarity is the 4.10 gear and 28 inch tires although we went from a bias ply to a probracket radial.

[pfordamx]

oh and the plugs look good for a gas motor but i'm not as schooled in reading e85 plugs i sent a few photos to the carb builder and he said they looked a little rich, but i don't think a little rich is causing this kind of power loss.

[Tom Goldman]

Having built many similar AMC engines ,I have to say , you could pour fuel thru the manifold out of a coffee can and it would run faster than that !
I would be very suspicious of the converter sprag .
That combo should run hi 9's lo10's with ease .

[CFMCNC]

Do 2 quick diagnostic checks,Cylinder leakage test and cranking compression test.If good go directly to a well instrumented engine dyno ,That will save you many dollars in track testing and parts changing.One obsveration if static compression ratio is as stated ,cam durations are to big.Bill C.

[CFMCNC]

305 CFMs will support over 730Hp.Were heads flowed with manifold attached?.Bill C.

[pfordamx]

no they were not, the intake is a modified edelbrock torker, we have a better manifold that will be going on but i don't think the the manifold is a 300hp problem will do a leak down and compression test and the converter is going back to tci which is funny because they had it and put a new hub in it about 3 weeks ago that actually might make it more suspect. its maddening to know you have a combo thats a solid 2 seconds slower than it should be without an obvious reason.

[ss3011]

What's the scoop with the e85 carb ? Are you running e85 fuel ? Certainly the jetting would be way off if you were running a carb jetted for e85 , but were running race gas .