Hello,
Thanks for all the great info so far; I just picked up a 76 f-250 and started a rebuild of the motor. So far I have ordered a scat 4.25 crank with rods and diamond pistons that will have a 9.8 to 1 compression ratio with the new edelbrock 72cc heads for the 428 cobra jet. I also ordered a 800 cfm holley double pumper with edelbrock rpm manifold and hedman ceramic coated headers. The engine will be 445ci with the .030 overbore. I was wondering what you thought would be a good cam for this truck. I just changed the gears front and rear last week to 4.56 with a detroit locker in the rear. It will be used for highway, some pulling and offroad. The tires are 38" tall. I have noticed you like the crane 343941; will this work for this motor. Any advice on ignition, coil etc will be appreciated. If you would not mind a desk top dyno would be great. Thanks again. O- the block is D4TE casting which I think is the heavy duty if I am not mistaken.

 

I love my 45 ACP, so does my wife. I would recommend putting the larger 1.65 CJ exhaust valves in your cylinder heads, also hardened seats while your at it. I have heard lots of forum folks like Crane cams 343901. I would check your piston installed height and set your quench to 0.035-0.040. I wouldn't be surprised if your pistons are down in the bores. At your estimated compression rato you won't run well on regular gas. My 416 as quench set to 0.038 (9.5:1 compression) and runs great on regular gas at 5000 ft elevation. I have read many times that vacuum secondaries are better for the street than mechanical w/ dbl pumper. My edel RPM intake works well, though has sealing problems at the water passages to the heads. Need to use that new expensive silicone I'm told. My truck has the 4.56 gears with tires shorter than yours. I have great low end torque. I would think your tire/gear combo should work fine. YOur D4 block should have the reverse 105 casting at the front left of the block just below the cylinder head surface if its the better block. The crank saddles in the block will have 3 webs rather than only 2 for the better blocks, plus they weigh about 20 pounds more with the extra beef. I"m running DUI ignition, kinda spendy, but it really puts out the volts. Engine starts easier than with Ford's duraspark ignition, and no messy wire harness to deal with. Ignition timing is rock solid at all rpms.

 

Thanks for the reply; the heads have 1.66 and 2.09 valves. I am 300 ft above sea level, what quench would you go for on this motor? What kind of cam would you suggest? Thanks again

 

I have Comp cam 260H camshaft. It works ok, idle is a little rough, and the mid to higher rpm torque is not really there. I tried comps 268H in a 390 I built for a local rancher. It had not much low speed torque, but mid to upper rpm worked great. That 268H cam is a copy of Ford's OEM 291 truck cam, just advanced 4 degrees. I want to try crane's 343901 cam next. By the way. I would NOT recommend comp cam valve springs. I bought a set, only 4 or 5 met comps specs, the rest were weak on pressure and 2 had coils missing from the damper springs. I returned them. I bought Crane's springs, they all met their spec, which also met the 390 GT/428 CJ factory specs.
I just looked up your cam on Crane's web site. Check your dynamic compression ratio. With your 941 cam's late intake closing event, your compression ratio may be fine, but you'll have to check it. I'm running 8.0:1 dynamic compression which is good for street use and pump gas. Sorry about the valve sizes, I realized your edel heads probably came with good sizes already. What I've read about quench is set it 0.035-0.045. There have been experiments done with as little as 0.025, but the pistons were touching the cylinder heads at high rpm due to rod stretch, etc. Two sources of info I really like are Smokey Yunick's book "Power Secrets", and David Vizard's books "How to build horsepower" volume 1, and "Modifying chevy small block cylinder heads". Barnes and Noble shoud have them both or this forum, or abebooks website. Silvolite piston has a dynamic compression ratio calculator (its free to use). Smokey recommended building your engine twice. First time to fit everything, second time for real and ready to run. This really made sense to me. I had my crankshaft and one piston/rod in and out of the block several times while measuring to get the block decked so I knew exactly what quench clearance I had between piston and head. I've been really impressed with the torque my 416 has (390 with 428 crank), your combo should be that much better - should be a blast to drive. I can drive up a mountain pass in our area with a 1 ton load, and the truck doesn't even care, just touch the gas a little more and off you go.

 

that cam will be a great runner in that truck.. compression with the aluminum heads will be a non issue for you... I run that cam with ported out iron heads and big valves in a 390 and it flat gets it... i have 38.5x15 boggers with 4.10's and there is no lack of power. kurt and russ will be on here in a bit as well as greg, those guys got a wealth of info.. you may be able to run a bit bigger cam if thats your thing, but the your money's best spent for torque on the 941.. i like vacuum secondaries in my 4x4 just because when you get it bogged down deep you won't drown it with fuel like you can with a DP carb..JMO if you're gonna run it of road hard the put in the fuel jet extensions, they're a hardcore drag race item but when you're at weird off road angles they keep fuel to the jets at all times.. spend the money and get a MSD 6AL ignition box, cheap insurance against overrev's and they really shine at low rpm's with their multiple sparks.. i like the mallory unilite distributor, they work great even under water!! been there, done that! LOL

 

With your 72 cc combustion chambers, you may not have a choice except use the 941 cam you have picked out. Checking the dynamic compression ratio is the best answer. You can run higher compression (up to 1 point higher) with aluminum heads vs. cast iron so your kinda on the dividing line between the two cams. Most people pick a cam thats too big. For good street manners, pick the 901 cam IF your dynamic compression ratio (dcr) stays below 8:1 for regular pump gas. If you don't mind running premium, then you can go higher on DCR. For low elevation like you are at you may have to run less initial ignition advance, maybe 8-10 degrees rather than 10-12.

 

i run 14 initial and 36 total in by 2800 with that cam on the street, i'm at 600ft.. that many cubes are gonna eat up alot of duration for you... you'll get a good idle with a bit of lope at 750-800. is it a auto or a manual tranny?

 

if the budget permits, look at the Crane Hydraulic Roller 521. That's what I run in my 428 Stroker. It makes a lot of torque at a low RPM, but still lets it breathe up top. I'm also running Edelbrock heads and teh RPM intake with a BG Demon 850 carb. So, our setups would be similar. Mine is in a 4600lb 3/4 ton truck taht can still work like a truck, but it runs under 14 seconds at the track.

 

whats the over and above cost for the roller versus hydraulic greg? have parts come down any? i haven't looked roller for a few years now...

 

I personally would go with the comp 274ex cam, kinda funny that i like smaller cams and I pick the biggest. That 941 would be kinda small but have loads of power.

As for the 901, its too small but i love it in my 390.

 

Converting to the hydraulic roller setup is not cheap. the Hyd. roller Lifters are about $450, then you'll need about $150 in custom pushrods (including measuring rods), you should probably look at the uprade stands/shafts/rockers as well (Ersons or Crane assemblies, $650, $500).


but, if you're bulding a SCAT crank based stroker with custom pistons, then money is not an issue, right? :-) Seriously, there Hyd. roller offers a nice combination of small duration and big lift that make for a nice torque curve and still makes some nice HP at the higher RPMs. And, you still get the benefits of a hydraulic lifter.

 

i'd love a roller FE.. maybe i need to be content with the mild 390 and start accumulating roller parts for a bad mother dog FE down the road....

 

45ACP, I dont know that I would change much on your build, maybe other than have the heads cleaned up from casting flash and some bowl work done to clean them up.. I would also go with the Davis Unified Ignition..1 wire hook up, and you can always get an aftermarket Rev limiter...As far as the Cam Goes..as Greg Mentioned a Hyd. Roller is very nice if the wallet will allow for it....

I just went from the CompCams XE284 on My build to a Solid Roller By Comp...But I wouldnt recommend it on a daily driver, unless every few thousand miles you dont mind pulling the rocker covers and checking lash... I was originally going with the CompCams XE274 which is a nice cam and makes good Tq down to about 2300-2400rpm's....

And with My Cam and Heads at .032" quench My Dynamic CR is still under 8.0 as to run on Pump gas..I think its 7.56....with a 10.16 to 1 CR...

Maybe one of the Guys can run the Cams for you and give you some Approx. Numbers on HP and Tq....to see where you'll set at with different combo's on the Cams..I would but I have 2 more in front of you.. This Is JMO!!

Happy Building...Enjoy!!

Russ

 

heres some stuff

343901,343941,343801,comp 274ex, crane 521

901
1000 rpm 72 377
2500rpm 248 522
peak hp 435 at 5000
peak tq 527 at 3500

941
1000 rpm 65 341
2500rpm 235 493
peak hp 452 at 5000
peak tq 510 at 3500

801
1000rpm 64 335
2500 229 482
peak hp 456 at 5500
peak tq 507 at 4000

521(roller)
1000rpm 60 317
2500rpm 224 470
peak hp 452 at 5000-5500
peak tq 496 at 4000

comp 274x
1000rpm 64 334
2500rpm 233 489
peak hp 473 at 5500
peak tq 513 at 4000

 

Well Matt thanks for posting those #s... there are to many Guys on this forum that think one Cam maker is the anwer for many builds...

Are you using the DD2 ?? If not I may have some #'s for you to run if you would for Verification of what I'am getting on my EA3...Mine seem way to high..I'am having the Roller Cam custom ground on a 112*LSA instead of the Normal 108* or 110* it will work for a little better Vacuum....and I had to step up too 2 750 Holley Vac. Secs..to keep the Intake restricted Vaccum a far below 1.ohg as possible..So it at .06 at 6100rpm now..

Russ