Hey all. Ok so this is basically an extension of my other post about the horse power of a 1978 Lin 460.

If you haven't read that post yet, the engine is in a 1990 F250HD with a C6 and 4.10 gears. This is be a tow rig / Huller.

So my question is if I change cams, would this cam be a good choice?

It's a Summit SUM-K3500 Summit SUM-K3500 - Summit® Cam and Lifter Kits - summitracing.com

The specs are: Rpm range - 1500-4000
Duration at 050 inch Lift: 204 int./214 exh
Valve Lift with Factory Rocker Arm Ratio: 0.479 int./0.504 exh. lift
Lobe Separation (degrees): 112

would this be a good choice for a mild cam just to add a little bit more lower end? Or would it not be worth installing this cam?

Also, If i do in fact buy that one, would you recommend installing new cam bearings, or no? engine mileage is unknown, but I would guess at least 80,000 + miles.

Thanks a bunch for all your guy's help.

Justin
New Baltimore, MI

 

Is it fuel injected ?

 

I've had both the 3500 and the 3501.

The Summit cams performed well (grunty) so if what you really want is "a little bit more lower end" I would say they should work well.
The 3501 is described as a "towing" cam as opposed to a "R/V" cam and seems to 'build' power quicker. But since I've never driven an automatic I can't say what your rpm range is at freeway speeds.
(with stock tires -235/85 R16- and 4.10's behind a T-19 I'm right at 3k at an indicated 60mph)

 

393Stroker - The engine is carbed

ArdWrknTrk - So would you say go with a better cam, or stick with the summit ones. I'm not looking to make this a race truck, all I want is just a little more bottom end when I"m hulling stuff.

As far as speeds or RPM's...The calculator I used says with stock tires (235/85) with 4.10's and a 1:1 trans I"d be going 60 MPH at 2650 and just about 65MPH at 2800. Does this seem right?

Thanks for your input.

Justin
New Baltimore, MI

 

No, I'm saying this is a good cam for your purpose.
Some people don't want to buy a 'cheap' cam but I've had no problems in many miles with the summit cams I've used in my truck.

You seem to be revving a little less than I do with your transmission.
What I was saying was that the 3501 'seems' to make a little more power and I don't know how much you're hauling.
With an automatic you have no choice about your shift points.

As has been said the biggest difference will be seen by going to a straight up timing set.
The 460 has plenty of power. You will understand once you start using it .

 

Good to know that Summit cam is ok, cause thats what I used in the RV.
Cant remember the part number of what I got, it was #35 something, but has .484/.509 lift.
On mine, I set the new timming set at 4* advance instead of straight up, taking a chance I guess you could say, but dont seam to have hurt anything.

With the M/H & trailer together, loaded, I'm pulling around 23,000lbs.
This past Saturday, was the first trip pulling out on the road after getting the top end back together. Was around 50 miles one way & the route we took, there a hill just before we get to where we go & normally like before the engine would pull down far enough to get into passing gear, which is at 45 mph. This time, same amount of weight, NO passing gear. The engine pulled down some, I didnt expect it not to & was around 55 mph at the top.
Being the first trip out, still a little adjusting I need to do. Nothing been done to the dist far as the timming advance springs I see some of the guys talking about on here & I still have stock exhaust system on it.

Quite a bit of difference in what you rpm might be compaired to mine. At 65mph, my 460s turning around 4800 rpm. If the paper works right in the R/V, according to that the diff has either a 4.56 or 4.63 gear which is god awfull crazy, but I guess to pull that load its probably about right.

Keep a check on the heads, those valve seats, cause this cheap unleaded gas we got to pay through the nose for causes a lot of chamber heat & will beat those seats out if not carefull, at least did on mind.
Neil

 

That does not sound right.

When I plug a 31" tire (235/85/16) with 4.56 gears at 4800 rpm into the calculator it comes out to 97mph. A more reasonable 3000 rpm would put you right at 60mph with 4.56 gears. A 4.63 drops you by about 1mph at 3K rpm.

You would need to be running a 21" tall tire to get your 4800 at 65mph.

 

R/V I have has 19.5" rims & cant remember the height of the tires but are bigger that the 16" rim tires.
Crazy thing about this rv, I could check the ratio by turning one rear wheel & counting the rotations of the drive shaft, but the parking brake is on the end of the tail shaft & would need the engine running & trans in netural to release the shaft so it could turn.
I'm kinda shakey about crawling under an 18,000 lb vehicle with the engine running & in netural with one side jacked up.
Neil

 

or just disconnect your drive shaft from the axle yoke/flange. Should be fairly easy. . .just be sure to securely shock your wheels

 

As I said T-19 = 1:1 , 4.10's, 235's .......3k at an indicated 60.

Something is wrong with your calculator....

 

MPH = (tire dia / 336) * (engine rpm / gear ratio)

That isn't a formula that I invented - that is a very well known speed calculator.

You are actually doing about 67mph if you are running a 235/85/16 (approx 31") tire with 4.10's at 3000rpm. 4.56 would put you right at 60 mph.


C-leigh - rim size does not matter, just overall tire diameter. Again, there is no way you are turning 4800rpm at 65mph with the gearing you stated. If your tires are even taller than I used in my calc, then your rpm is even lower than I stated.

 

Justin check your email.

Paul E.

 

Were getting a little off track here, sorry about that 460/F250.
Tach I have, works off of the wire from the dist to the coil, maybe thats hooked up wrong ??? dont know.
Measured tires, 33".
Neil

 

No problem guys, As far as the RPM range...I dont see why I would need to go any higher then say 4000 Rpms...Maybe 4500 at most, but would there really be any reason to rev it to say 5000 or 5500? Like i said I dont care what this truck does in the 1/4 mile, I rather be able to rip a house down lol.

ArdWrknTrk - So you say stick with the 3501? It sounds like a nice decent cam, and its only 100 bucks. I do have a question though. Will I have any issues using the stock springs or pushrods with this cam?

paganit2 -Got your email...I'll certainly think about it...But i'm working with a VERY limited budget. lol.

Thanks all again

Justin
New Baltimore, MI

 

When you talk to Summit, be sure to ask them about the rocker ratio.

When I was ordering mine, I was going to get the K-3501, but in talking to the guy there, the rocker ratio was listed wrong on their sheets once he got to checking the specs.
Best I can remember from him checking close, the lift specs on that cam were from their listing 1.65 or 1.70 ratio rocker which if what everybody is saying the 460s have 1.73 ratio.
1.73 is what I based my thinking on reason I listed the K-3500 with .484/.509 lift. Once the ratio deal was found, he said I probably should get the 3500 instead of the 3501 just to be safe.
My engine is an 87 model with E6TE-DA heads & 1.65 exhaust valves.

I can only wonder what the K-3501 cam would have been like, but the K-3500 I did install, engine sure feels a good deal better than what it was before the top end repairs were made.
Neil