Long time lurker but never posted much on here! I have a 1975 F250 that I rescued from an ill fated destiny to the scrap yard I've been rebuilding and have started doing some research for the engine build as the rebuilt motor was pulled when I bought it.

I plan on using the truck to tow my jeep around (4,000lbs) on a 16 foot bumper pull trailer and possibly put a camper in the bed down the road. But still want plenty of usable power also.

I have a fresh 1969 block I bought from the machine shop that is line bored and bored .060 over with fresh cam bearings ready to assemble, a set of factory rods and a polished standard crank so far. The heads are 67 models as the original 69 head had a hole in the combustion chamber. They are getting a 3 angle valve job and new springs,retainers.

There are a set of .060 over cast flat top pistons out of my block that we are going to check ring lands and skirt size to determine if they are usable but I am leaning towards just replacing them.

As soon as I get pistons the entire rotating assembly will be balanced, the rod and main fasteners already have arp replacements.

One option I have been looking at is https://www.mabbcomotors.com/catalog..._1964-1976/734

With this kit I was leaning towards this cam http://www.summitracing.com/parts/cc...view/make/ford

Lastly an edelbrock streetmaster intake with a 650 Holley and good set of headers to finish up the build. I'm on a fairly tight budget and trying to make a decent performance motor that will be able to tow decently and cruise comfortably. I do have a 4 speed transmission and 3.55 rear gear. Sorry for the long winded post but I want to get others input before I'm dissapointed in the power.

 

In my opinion, that cam is way too much for a 3.55 geared truck that's going to pull that much, including the camper.

"With a very aggressive profile, these camshafts provide maximum top-end performance for your high performance car."

You might be better off getting a less radical cam if you're looking for torque.

Of course, that's only MY opinion. I ran a cam with even higher lift (and duration) than the one you linked to, and high 10:1 compression, and the cam was degreed in for lower-end torque, and it pulled 2 tons of scrap iron in the bed without issue, and that was with 33" tires with 4.10 gears. But I didn't build it to do that a lot, I built it for mud and other off-road fun. And it WAS a lot of fun

I think you're going to have a problem with that cam getting that load moving from a dead stop without better gearing. Of course, you probably have the 435NP tranny with the granny 1st gear, but that only gets you crawling before you gotta get into 2nd and the RPMs will drop too far to let that cam run ...

Again, only MY opinion, let others chime in. Many here have way more experience than I do in terms of low-end-torque builds.

 

This is the cam I'm running COMP Cams CL33-238-4 - COMP Cams Xtreme Energy Cam and Lifter Kits even though the recommend cam (by comp & others) was COMP Cams CL33-234-4 - COMP Cams Xtreme Energy Cam and Lifter Kits .

It performs great, but I've only towed with it a couple times (7,000lbs) and even though I haven't had any issues taking off, it does feel like a little to much cam (barely) but it does make awesome power @ 2,500 - 3,500 RPM's.

I'm running a F250 4X4 with a 4speed, 35"tires and 4.10's

 

I was wondering about the duration being a little to much for towing the camper will be a seldom deal if it happens down the road.

With the 3.55 gears and 4 speed on 235/85 16's I should be around 2500 rpm at 65, I'm mainly looking for a cam that will deliver the power when you put your foot down at that rpm to pass or pull hills decently.

The truck isn't going to be constantly dragging the trailer though in reality 3-4 times a year about 200 mile distance is all it will see pulling otherwise it will be just a toy to drive on nice days.

I also have a msd 6al setup with a 5500 rpm pill in it, I think that should be plenty conservative to keep the 390 happy with stock crank and rods?

 

Zach, your cam choice is very close to the cam I'm running.. I think your in the ballpark, from the research I've done FE's seem to like split duration cam shafts..All I can say is if my engine was in a 2wd truck like yours, it would absolutely rip (tire melting). I'm sure some others will chime in so please do some research and don't get in a hurry.

 

Well, why didn't you say so in the first place?

Go for the cam you had picked out. It'll be just about right.

BUT - take what stromburg said to heart - the "split duration" comment.

The cam you picked is a like-for-like intake/exhaust duration and lift. Stromburg's is not.

On an FE with the stock size exhaust valve (1.560") a split duration is good. When you go to the CJ size exhaust valve (1.650"), you can lower the exhaust duration/lift a little which backs off the overlap a little.

But since you didn't say you're going with bigger exhaust valves, a split-duration like Stromburg has might be your best bet.

Hang on a little while longer for some of the other old-timers to chime in, though.

 

Thanks for the input guys, I'm not going to jump in and order one quite yet, the motor is still getting machine work done while I have the extra time ( I used to work at the shop but didn't do many performance builds). I just wanna get all the specs so I can set the valve guide clearance etc.

The heads are just a basically stock rebuild otherwise no oversize valves because I am wanting to upgrade to aluminum heads in the future when I build the other block I have sitting in storage!

 

You know about the pistons and not to use the pickup spec down the hole piston, right?

 

Yes I did know that, the pistons in the kit I am looking at are the high compression flat tops. They claim 10.5:1, I'm not afraid to run 91 octane fuel to gain performance.

 

I've done some more digging and that kit has a good price but several things included with it are of no use to me.
- Has anyone used the Keith Black Hypertuectic Pistons? That would put me at 10.2:1 compression.

Wrap them in a set of Moly rings since I have a fresh bore and then go ahead and use my factory crank and rods with ARP fasteners.

Are main studs worth the extra money with a 5,500 rev limiter?

I'm going to stick with the 270/270 cam I may give up a little by not running a split duration but not a huge amount.

Intakes I have to buy one still, I have a source with streetmaster, perfpormer and performer rpm available to me. I know the streetmaster is a single plane but I like the throttle response it offers, is their a better option in those three?

I'm trying to build this motor to last reliably but deliver the power I'm looking for.

 

I know this is an old thread but do you have an update on your build and how it tows?

 

I don't have much input to be useful unfortunately, my block was bored .060 over and needed bored again which we both decided wasn't worth trying to do. The crank and rods were also junk and so were the heads..the only usable pieces of the motor ended up being the oil pan, exhaust and intake manifolds.

I have a 1966 352 that's a fresh rebuild I picked up for $300 in the truck, it's basically stock except for headers and a mild cam. The truck absolutely loves to tow, I enjoy driving it much more with the trailer on it but I haven't driven it far enough to give you accurate mpg feedback or anything of the sort.

 

I'm glad you got the truck going. Are you using a stock 2v intake and Motorcraft 2100 carb?

 

I had that 270H in a 76 F250, it was OK for towing but a bit soft down low.