Cam options ...

[FOMOGO]

 Since I discovered that the cam plug in my newly acquired F-250 was installed backwards I've decided it would be a good excuse to upgrade the cam. Engine is a fresh 390, street dominator intake(have a spare RPM I could use), Ed 600cfm carb, headers 1 3/4" primaries, 2 1/2" duals/H-pipe , will be adding Ed heads with bowl work and minor runner work on the short turn, Blend guide bosses, etc.. Haven't pulled the heads yet, but lets assume for the moment cast flat top builder pistons and static cr of 9.5:1. F-250 4x4, 5000#, TKO 600, 4:10 Dana 60 rear, Dana 44 front, 35" tires. I was thinking 270 solid flat tappet. Will be a daily driver, spirited back road driving and occasional light towing. This is going to be a temporary engine but it will be in there for probably two years until I finish up some other projects and build a 445 for it. Thanks, Mike
Da Beast

the offending plug

dialing in the new bell for the TKO

[e philpott]

Comp 270S sounds like a good choice to me too ...... I will also be dialing in my QT bell this week , familar picture . lol  ....

[jayb]

Cool truck.  I'd be looking at a Comp 282S for that engine.  It matches up to the rest of your components better than a 270 duration cam, and will get you a lot more midrange, 2500-5000, especially once you get the Ed heads on there.

[Drew Pojedinec]

ok Jay.  You have me curious.  for an obnoxiously heavy truck with a 390, why would you think a 282 would do better than the 270?

I'm only asking because I was about to throw a 270 in mine with a similiar engine and 2000lb lighter truck.

[jayb]

I'm looking at the single plane intake and mildly ported Edelbrock heads, and figuring that those are going to work at a higher engine speed than the 270 duration cam is ideally suited for.  Not that the 270 cam would be a problem; I just think that that 282 would be better.

I have a friend with a 390 in a 70s pickup.  He put the 270 cam in there.  Now he wants more cam 

[FOMOGO]

 thanks for the input guys. I won't be back home until April, so I have some time to ponder. Has anyone here done a power steering conversion on one of these? It has a 79 Dana 44 up front. I picked up a rebuilt 79 P/S gear and pitman arm. Looks like I will have to box the inner frame to attach the gear, shorten the steering shaft, and and cut and reorient the drag link. Hoping maybe someone has been down this road and has some tips. Thanks, Mike

This is the stock manual gear.

this is the gear on the 79 pitman arm donor

this is my truck with the manual gear.

[rcodecj]

Since I discovered that the cam plug in my newly acquired F-250 was installed backwards I've decided it would be a good excuse to upgrade the cam. Engine is a fresh 390, street dominator intake(have a spare RPM I could use), Ed 600cfm carb, headers 1 3/4" primaries, 2 1/2" duals/H-pipe , will be adding Ed heads with bowl work and minor runner work on the short turn, Blend guide bosses, etc.. Haven't pulled the heads yet, but lets assume for the moment cast flat top builder pistons and static cr of 9.5:1. F-250 4x4, 5000#, TKO 600, 4:10 Dana 60 rear, Dana 44 front, 35" tires. I was thinking 270 solid flat tappet. Will be a daily driver, spirited back road driving and occasional light towing. This is going to be a temporary engine but it will be in there for probably two years until I finish up some other projects and build a 445 for it. Thanks, Mike
Da Beast

the offending plug

dialing in the new bell for the TKO

I vote for the 270, mostly because of the 4.10's and 35" tires, heavy weight, occasional light towing and 600 cfm carb.
With 35" tires, that thing is actually high geared.

Edit to add:
I first assumed an automatic, I now see it is a manual, depending on the first gear, you might get by with the bigger cam, but I would still go with the smaller cam.

[FOMOGO]

 Tires may actually be 33", can't check them now to see, but your right about the gearing. Considering the 4:10's  it's much happier at highway speeds than our 66 with the same gears and 265-16's. First gear on the TKO is 2:87 and the O.D. .64 Which I think should be fine, especially once the 445 goes in. Big torque will definitely be my friend. Decisions, Decisions. Mike

[rcodecj]

Are you going to use the same cam in the 445?
That might sway my vote towards the bigger cam.

[FOMOGO]

Are you going to use the same cam in the 445?
That might sway my vote towards the bigger cam.

 No, Will be going with a hyd. roller on the new one. Mike

[plovett]

I vote 270S based on the cubic inches, weight, and gearing.  That said, I've never driven a combination just like this.

paulie

[68fecyclone]

I think I would opt for the 282s also, but since you live at somewere around a 6000 foot elevation, that may be too much cam. With your first gear ratio and tall tires, it might be a real dog to get it rolling, especially with a load on the truck.                                                                                                                               
     Does any one have some real world data as to how much altitude effects actual cylinder filling and dynamic compression, I am curios about that because I live at about 3300 feet.
    About your steering box conversion,  I have a friend who had a 70 done and has a 77 that was done also, if you want I can get some pics of his stuff and post or send them to you.  Rob

[FOMOGO]

 My place is at 7200ft and the majority of my driving will be 6000 and up. That is one of the reasons I was thinking 270. Not really stuck on the solid, it,s just been a long time since I've run one and I thought this would be a good opportunity to try one. In a hyd. maybe something like a 274xe would make a nice compromise. Also thinking I should run the RPM intake instead of the dominator thats on there.Yes, pics of the conversions would be great. Would especially like to see what he came up with for the drag link. Thanks, Mike      e-mail is:   magi1951@hotmail.com

[machoneman]

There are calculators on available on the 'Net that do delve pretty deeply into dynamic c/r's, humidity, barometric pressure, etc. and altitude...but they ain't free!

Wallace Racing's site has about the best set of general automotive calculators on the 'Net:

http://www.wallaceracing.com/braking-hp.php

A 300 hp engine at 6,000' loses 54 hp simply due to altitude. A more (much!) sophisticated calculator can be found here and I think it's still about 80 bucks:

http://performancetrends.com/drag_racing_analyzer.htm

On edit: forgot to mention the PT analzyer can be downloaded for a one-time test for free. But IIRC, you'd better have all the data at hand when giving it a one-time spin as you only get one chance! 

[68fecyclone]

  Mike, I will get some pics probably this weekend or early next week, he was not home today when I was out there. When I see him I will get as much info on his conversions as I can.  The one truck actually uses a 2 wheel drive steering box, but its set up the same as the other.

   Machoneman, thanks for the links on the c/r calculators, I'll have to look into that when I have some free time to mess around with them.  Thanks Rob