Hey guys, I'm doing up a set of c9ve heads and am considering putting in a Comp cam #34-231-4. I live in the mountains of Oregon and use the truck primarily to tow a horse trailer. 1985 F250, 4 speed, 3.55 gears, 0 timing and tri-y headers currently and it does okay. Cam specs are 210/218 at .050 With .514"/.514" , 111 lobe separation. I'm concerned i'll lose my low end grunt which is where i spend most of the time. 60 MPH is 2500 RPM. Anyway, if anyone has used one, or has an opinion one way or the other I'd be glad to hear it. Thanks in advance.

Lance

1985 F250 460 4spd tow rig
1963 F100 292 4spd daily driver

 

Im not sure you have lift specs correct. But if you do i think you may want a different one in the 4x4 series with split duration and split lift as the exhaust on bbf heads needs a little more flow. I dont have my 460 in yet but on the desk top dyno it has 501 ftlbs of torque at 2000 rpm. Thats using a 4x4 extreme with 262/270 and 514/524. It seems to make great torque down low which i think would help your application. Plus you have alot better heads than me. Just my thoughts im sure you will get alot of great info here i know i have.

Good Luck Andy

 

The 210/218 cam will work fine for your combo. It will not give up any low end torque. You could even step up to a 218/218 and will still make plenty of bottom end torque. I agree that you should favor the exhaust side a little more. These big engines need to breath. I say buy the 210/218. It will work fine for your towing.

 

If the C9 is out of a '69 which I think it is, you'll bump up compression, but you'll probably have to run 91 octane when pulling. I am at 9.0 and have '89 in one tank and '87 in another with the '89 octane used for towing. I'm double checking the egr valve vacuum routing though, but just thought I'd throw this out to you.
I have 3.55 years too with 235/85/16's. What tires are you running on your truck? If you have the same tires as I do, either your tach or your speedo is off. You can do the calculation at http://www.race-cars.net/calculators/rpm_calculator.html 235/85/16's are 31.7" in diameter. If you have the 235's you should be taching about 2260 at 60. Your speedo might also be 10% off like mine is?..
Tony

 

Further info and food for thought. I have the 5 speed with the overdrive, so all info isn't quite applicable to your 4 speed. However, check out the RPM's you'll be turning at 65 with your 4 speed in 3rd and 4th gear. Then check out the powerband of the cam your thinking about. I just put a Comp Cams 260 high energy in the truck and I have some second thoughts about not going with the RV cam. With our 3.55's you'll want to keep as much power in the 1500 to 3500 powerband as possible and peak right about where you mentioned at 2500. But the xtreme 4X4 cam might have similar torque as the RV cams.
Tony

 

Yeah, the tach is off a little. Never worked the same since I put in the MSD box. I have the stock tires so 60 MPH is about 2250 RPM. The new heads should put the compression at about 9.3, and Iv'e been running 89 octane anyway because it pulls better off idle to 1800 RPM or so. Purely a seat of the pants thing. I looked at Comp Cams online catalog and ran some specs through my desktop dyno and had selected their RV cam 34-228-4-- 252/260 .467/.484 110 separation.
I called Comps cam help line 2 times and got 2 different guys. Both of them told me the 4x4 extreme cam 34-231-4 was what I wanted. I don't think they really understand the country I live in. I can't drive more than 20 miles on flat ground in any one direction before I am going up a hill. And what we call hills would be a mountain in most parts of the country. And then I get into the real Mountains. Any way I figured I had a choice of swapping axle ratios( this is a 4x4) or getting more go out of the motor for about the same price. I am just leery of putting too big of a cam in and not getting a significant gain for thr time and money invested. By the way, the desktop dyno starts at 2000 Rpm so it leaves a big hole right where I'd like the info. The 34-231 torque curve is flat and peaks at about 2500 RPM with 495 FT/LBS and the 34-228 RV shows peak at 2000 of 521 FT/LBS but the graph line is still going up back toward idle.

 

On the RV cam, how is the graph line after 2000 RPM's? There are going to be some times when your going to stick it in 3rd gear and ride it out up to 2500 to 3000 or so....like when coming on an entrance ramp to an interstate. If the torque curve stay's flat after 2000 on the RV cam, you can just drop it into 4th at 55-60 at 2000-2500 and keep pulling and increasing speed. If the torque on the rv cam falls off very sharply after 2000, you won't be able to wind out 3rd gear or to keep pulling in 4th going up any significant incline when you drop it in 4th at 55. This is maybe where the 4x4 cam has an advantage??... With the 5 speed overdrive, my highway cruising rpms at 65mph drop down to 1850 +/-. Here is where the RV cam would show it's grunt for me. I know I'm not supposed to tow in overdrive, but we all do some things where not supposed to do. I guess I too should've called the comp cams for their opinion.
Good luck with whatever decision you make and safe and strong towing.

Tony

 

I have described my build several times, but the basics are bored 0.030 over, 10:1 compression, ported D3's with SCJ valves, Weiand intake, headers, roller rockers, 750 carb and the 268H Comp Xtreme 4X4 cam which is the next up from the one you are talking about. Mine is 218/226 with .515/.524 installed 1 degree advanced with an intake centerline of 106 degrees, and it has plenty down low. I think I should have gone with the next bigger cam. I've got 28 inch tires and a 3.25 locker. It'll do 55 mph in first gear (read: high geared), but it will still smoke the tires off if you start out in 2nd and nail it. It will stall my poor stocker converter up to around 2100. You might want to stay down around 9.0-9.5:1 compression which will lose a very small amount of power, but nothing that you'll ever miss. I couldn't be more happy with my combo.

JJ

 

JJ,

I am thinking of getting the Same Xtreme 4x4 Cam. The 514/524 218/226 for my 460.

The 460 is punched 0.030 over, L&L headers 2.5" duals through flowmaster series 50, C9VE-A heads w/clean up porting, edlebrook performer intake and 750 Cfm carb. The truck is a Fullsize Bronco w/c-6 and 3.50 gears. I will be towing a trailer with another fullsize bronco (my beater). 32" tires.

My MAIN concern is still having enough Low-end Grunt! Sounds like this cam will work nicely..

Any thoughts?

 

I think you will have plenty of down low torque. I truly believe I could have gone with the next larger cam and not lost any down low. The cam I used sure didn't. Let us know how she turns out.

JJ