I posted this in the 385 series forum, but they arent too friendly there. Having this information is pretty vital for me so i can order the correct gearing and slick size and carb siz the first time... If anyone can help it would be awesome.......


I have been racing my 79 f-250 4x4 with a 400 the last few years. My goal has to figure out "the top end" of the track as well as the light, and get in the habit of winning more than loosing. Now that i have been able to do that, its time to build something more race oriented... and instead of sticking with a 400 for my power, i found a 460 that a friend had built, and decided not to use the 400 because i think i have already proven to alot of people around here what a 400 can do.

The engine is fresh, and i think it will work pretty well in the truck i am building, a 73 f-100 2wd shortbox, but i wont have it together until next spring, and ofcourse wont be able to make a pass until next spring.

I am wanting to get an "approx" hp and tq for the engine, aswell as torque and HP curves, to help me figure out what gearing and tire diameter i should go with to put me in my peak HP at the traps.

The engine is a 460, .040 over.
The compression ratio right now is around an 11.6:1, but this is with extremly thick head gaskets.
The cam is a comp cams 34-250-4 ( COMP Cams - Cam Details )

I have 2 intake manifolds, one is an edelbrock RPM air gap, the other i think is just an edelbrock performer intake.

I dont know whether i should order a 750, 800, or 850 cfm carb for it.

I will be using headers, 1.75 primaries, and 3" collector.

Can anyone give me the "simulated" power for this combo?

Thanks. I have a feeling i will enjoy this truck just as much as i have enjoyed racing my 79, i just hope it will run faster right off the trailer.

 

I can help you but, What heads are you running on it?

 

I am not sure of what heads they are, let me go and take a look and see if i can find a casting number...

Thanks for your help...

 

The heads are c8ve-e heads, the exhaust ports felt like they had never been cleaned up at all, so im guessing that the intake ports have not been touched either. Found out it has a nice set of comp cams roller rockers and pushrod guides, and the valves look like manley valves, but i am un-sure if they are stock size or not.

Wish there was a way to find valve size without tearing a head off. I am guessing they are over sized valves with a multi angle grind on them (our engine guy likes bigger valves and multi angle grinds) but who knows.

 

A 750 cfm carb will do, an 800 shows almost no improvement over the 750, anyways, here`s your results with stock c8ve - e heads.

Big valves (2.200", 1.760"):

Torque:
497@2000
531@3000
535@3500

hp:
453@5000

Stock valves (2.080", 1.650"):

Torque:
501@2000
530@3000
528@3500

hp:
418@4500

nice engine...in my opinion a single plne would help alot along with the big valves...

 

Thanks for running the sim for me. Its nice knowing whether im dealing with a 300 HP or a 450HP engine before i start building the truck. Not too bad of a build, it should be enough to have some fun with next year, thats for sure...

 

Do you remember how much the HP dropped off between 5000 and 6000 rpm?

 

Sure:
436@5500
404@6000

 

Thanks!!!!

Knowing its making over 400 at 6000 rpm helps me out with gearing and tire size.. for awhile i was thinking i was going to have to use a 3.73 ratio to be where i wanted to be at the traps, but looks like i can use a 4.10 and a 29" slick and still be pretty well into the safe zone assuming the truck will run low-mid 12's at this elevation. Nitrous will have to be on a window switch to shut off about 2/3rd track, but ohhwell, the nitrous will do most of its work in the first 330'.


I cant wait until i have this truck together, because after i build this truck i get to build another 400 for my 79. One of the classes i am going to run in the 73 has a 14.000 et cutoff , and another has an et cutoff of 13.80. I am hoping that the next 400 i build for my 79 (the 4x4) will make enough power so that i could sub it in to race if something happened to the 73 and i wasnt able to run it, that way i could still earn points in my class.... RIght now the 4x4 would still be a tenth away from being able to pull off that 14.10 and 3 tenths away from pulling off that 13.80.