Good morning guys. One question on a cam that was installed in my 400. The numbers are 484/510 204/214 with straight up timing chain. I understand that this is not a large cam but was told it is like an RV cam whatever that means. I did not want a large cam just something that was a little better than stock. Can anyone tell me what I should expect out of it. The motor is in my 55 F-100 with FMX trans and a 3 20 something rear. It is more or less a daily type driver. In a previous post I had a vacuum leak and we found and corrected that so now it idles and runs nice. I have not had it on the road yet. Thanks

 

Something like this:

https://www.crower.com/camshafts/for...-cam-282h.html

Short duration, higher lift. Get the cylinders filled and close the door so you don't bleed off cylinder pressure at low revs. That is the ticket for low compression engines.

Low to mid range, all done around 4 to 5500 rpm is the way I read these.

Depending on what else was done to the 400 it could be a reasonable improvement.

 

Only other change is a straight timing chain. Thanks

 

I've run Summit's P/N 5200 cam in a 400 and it was a definate improvement over stock.. Same duration, slightly different lift specs.

 

I hate that people still use the term "RV cam" anymore! It's got such a wide range of possibilities it's too hard to narrow down by that name. With your exact numbers though, that tells the tale.
I think most cams that fall into the RV category tend to be too big for happy idle and street use. But yours sounds like it's going to be sweet! Can't wait to hear how it runs down the road.
Let us know when you take it out for it's maiden voyage.

Thanks

paul

 

Where did the term RV cam come from. I would assume that it is little better for larger vehicles ? I did drive it home from the shop though not a far distance . It ran well and idles with just a tad bit of bump to it. I am happy.

 

It was coined by the cam companies for cams that were in between stock and "high performance" cams back in the 60's & 70's to improve the performance of towing vehicles.

 

Nowadays when people say RV you automatically think motor home. Back in the day RV meant "Recreational Vehicle" in the more general terms - anything Off Highway Vehicle (OHV), and likely not emissions compliant. Think off-road trucks and jeeps, mild street/strip cars, etc.

 

The 2 engine builders I use that have been in the business for 50 years, "REMEMBER" The days of hot rodding, multi carburetor induction systems, High compression, poor flowing castings and poor flowing manifolds, both intake and exhaust, and before diesels were doing anything, towing was a big deal. towing camper, towing construction equipment, towing cattle, towing boats, towing race cars. Now this meant that a (for the time) high horsepower cam shaft like a boss engine or CJ engine might have, would tow fine but be VERY VERY sluggish to get a large amount of weight moving from a dead stop, like a boat climbing out of a boat ramp or a backhoe loaded on a trailer towing up a driveway approach to the hiway, This necessitated a LESS than high performance/hi rpm, but there was gains to be had over the original.

This meant that a cam was selected that was smooth idle, good vacuum retention, low overlap,often split pattern like marine to get rid of exhaust in poor flowing castings, and slightly more lift. traditionally around 500 lift was the guidelines. The several engine builders always spoke of "RV" cams and "MIDRANGE" cams. A rv (recreation and/or work) meant we were after STRONG off idle performance, predicated into helping get that intake charge moving and into the cylinder more efficiently at lower rpm, but not creating overlap which relies on scavenging properties of escaping exhaust helping charge intake. A RV cam was never offered by any local engine builder to be much over a 262-265 grind that made 500 lift.

The RV grinds were made to idle around all day picking up hay, feeding cows in winter, idle around the mountain jeep roads all hunting season, with out loading up, without losing vacuum, and just idle around and be able to lug all the way out of a canyon with a load of firewood behind it. A traditional RV cam would be like a comp XE256H (212/218... .493lift) crower 15965 (.477/.486 lift 258/264 duration) or And I would say the ABSOLUTE CEILING of the RV cam territory in these applications would be a crower 15240 (.486/.510 lift, 270-276 duration) or comp xe262 (262/270, .413/.520)

I have ran several similar grinds to these and these grinds, and currently run a crower 15975 in a very well tuned and built up 400. It is VERY flat on the bottom. Almost can't even pull itself through the ditch with a load of fire wood with 410s and low geared c6. I accidentally ordered the wrong cam and installed it, I MEANT to order the 15240 but the lift was so close I overlooked that. My engine runs very strong throughout the advertised powerband, but needs way more bottom end to be practical. I know. I speak from experience.

Now, RV cams were installed regularly for framers, ranchers, construction workers, loggers, hunters, outfitters, Fire departments, all for the simple reason to improve what they had. A 390 ford with a comp 256 is an absolute animal. a ford 460 with dove-c castings and a similar 260-ish cam would walk away from an early 12v or 7.3 or 6.5 turbo. It would run to the barn and hide in those old scenarios with less gears (4spd vs 5spd) but much more than the 260s and they suffered from a dead stop, especially if going up hill.

Many rear axles and many many clutches and u joints scattered over the hiway with trailers behind them and a heavy foot with those old big blocks and a RV cam. In the later years RV has pretty much been replaced across the board by calling it a "mild" grind. No self respecting pickup truck owner ever wanted to be beat off the line with a trailer behind by the guy in a chevy or the guy in a dodge, or even a diesel. Then the 90s were over and pickups soon had hundreds upon hundreds of horsepower. That was the end of the RV camming days, noone wants to mess with it anymore.

 

That cam is probably an Engine Power cam. They are sold by many companies such as Summit or Erson. Some of them are really pretty nice grinds actually that are quiet and work pretty well. BUT. A lot of them are ground on really weird wide lobe separations which don't work well in low speed low compression engines. Most of the time that cam is ground on a 112 sep and put in on a 106 to 108. MUCH better would be to use the intake lobe on both sides on about a 107 in on 105.