I'm putting a 390 together for my 76 F250 4x4 it has a C6 trans, Np 205 transfer case and 4.10 gearing. The gvw of the truck is 7300 and i run 33x12.50x16.5 tires.

My 390 build is going to run
a set of edelbrock performer rpm heads
performer intake manifold
a 770 truck avenger carb
erson roller rockers
speed pro forged pistons with 9.5 to 1 compresson

now this vechicle is my everyday driver, it does towing in the summer and plowing in the winter. Crane recommended their
#134042 cam. is this compariable to the 901 that i here about on this forum alot, i'm looking to make a good amount of torque in the motor. What do you guys think?

Thanks
David

 

Tough call. For a 4x4 and towing, you typically don't get carried away with a big cam. But, you've already got good flowing heads, a healthy carb and a nice roller rocker setup. These parts compliment a bigger cam.

If you can spend the extra bucks. I think the cam I'm running would be good. But it's a hydraulic roller. It will cost a good bit more than the standard hydraulics. $400 lifters, $70 pushrods (custom), and the cam runs about $250 more. OK, maybe that's not such a good reccomendation :-) but it makes good low end grunt, with a decent idle and healthy vacuum, but it also breathes a little better when you open it up.

I like one of the bigger hydraulics (maybe 343941). You may lose a little low end, but I'd feel worse about not waking up those high-flowing top-end parts (heads, carb). And the roller rockers are a bit over-kill for a smaller cam.

Just my novice engine builder 2cent opinion.

Of course, it was this kind of thinking that resulted in a very expensive, way overkill motor for my project.

 

Greg is right. I would worry about detonation with a cam that small. Keep your LCA around 112 - 114 to keep the cylinder pressure down as much as possible. The aluminum heads should help out a little as far as detonation goes. I run the 801 cam and would not recommend anything close to that size for towing. The 941 might be the ticket.

 

a couple of Desk top dyno numbers for some people. What kind of numbers would my motor show with the 343941 cam and with the 343901? I'm running a set of Dyno max headers, they have 1 5/8 set of tubes on them. Also Gtex what kind of cam is that roller you have, also how well do you like those hydralic rollers?

And last but not least the intake i have is the performer Rpm not the performer.

Thanks

David

 

It's good that you have the RPM. I noticed that earlier, and thought the Performer to be a little mild for the Edelbrock heads and the bigger carb.

It's a Crane Cam, part 349521. I like the whole roller setup. It's expensive, but it just makes sense to me. Especially, since I planned to go with the Erson roller Rocker assembly.

 

So hows it run for you, any problems with Detonation ? Also what did you have to do to run the hydralic roller cam and lifters? Was it a straight bolt in or did you have to modify your block ?

David

 

The Crane Hydraulic lifter setup is a drop in. The ersons on the edel heads, took some mods. They now offer the Ersons made for edelbrock heads, make sure to get those.

The truck runs pretty good. No detonation isues on super unleaded, so long as the timing is adjust correctly. I'm also running 10.5:1 compression ratio.

It's doing what I designed it to do, Deliver gobs of torque thru a pretty big power band. It made about 400+lb-ft of torque from about 2600-4800 rpm. HP peaked at 5200 RPM at 360. these are rear wheel numbers through a C6 auto tranny and a Dana 60 rear axle. So, I was happy!

Cou can find more details about the project here. take the motor link for more info and links to the dyno graph.


http://www.thedreyerfamily.com/69f25.../67project.htm

 

David

 

Nope..had a deal workin' on a 6000lb boat/trailer and then pulled the plug.

So, no towing done yet. I still have some work to do. It's potent, but there is some intermittent power loss.