Flathead Cam Weber F7RS

HOTROD_WILLIE

HOTROD_WILLIE

Senior Member
Got this cam the other day. It is Weber F7RS. I never seen a flathead cam w/ this much duration. Can anybody tell me anything about the cam. Thanks again for all the help.
 

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hi i have a webber f5-s doze anybody have specs on it? i will be useing it in a 8ba in my 51 hope to have it together next spring.
 
Ol' Ron said:
You can get radius lifters from Pete. But, That's not a street cam. Something for the track.
Click to expand...

Hi Ron , i doubt that , as the weber cam uses 1 inch Radius lifters
And Pete makes the 2 inch radius lifters for a 404-A (for example)
As far as i know.
 
Tim you are correct

I bought a set of the 1inch ones at LARS years ago when i was hunting for a 2 inch set
For my 404-A :-)
Found it out after i got back home ��
 
According to the site, the idea behind the radius is to allow for a more radical opening and closing ramp. Does it also make the cam "bigger" by allowing the lifter to stay of the face of the lobe longer vs. a square making contact like a "stock" style lifter?

Cams are one of my favorite subjects and would love to know more.

Also, not to start a side bar discussion, but Barney Navarro said he didn't like roller lifters for the roller would "pool" up the oil as it started to accelerate up the ramp and didn't do what it was designed to do (spin).

Not sure about all that, but I'm curious on the rationale behind a radius lifter.
 
Tim Ayers said:
According to the site, the idea behind the radius is to allow for a more radical opening and closing ramp. Does it also make the cam "bigger" by allowing the lifter to stay of the face of the lobe longer vs. a square making contact like a "stock" style lifter?

Also, not to start a side bar discussion, but Barney Navarro said he didn't like roller lifters for the roller would "pool" up the oil as it started to accelerate up the ramp and didn't do what it was designed to do (spin).
Click to expand...

It doesn't necessarily make a cam 'bigger' - the lobe profile and design of the cam determines that. What it usually does is increase the valve lift velocity in the mid-lift areas of the profile (the ramps) and deliver more area under the curve for a given velocity.

For example here are the velocity numbers for my favorite two Potvin grinds - can't really show area under the curve in 'text' :) :

a) Potvin 3/8: maximum velocity of .008512 per degree of rotation happens at .1239 of intake ramp lift.

b) Potvin 425: maximum velocity of .008519 per degree of rotation happens at .1925 of intake ramp lift.

Now, the Isky 404-A: maximum velocity of .009738 per degree of rotation happens at .163 of intake ramp lift.

Roller Lifters: I'm not going to dispute what Barney said - as I would have to know the context of his comments (cam, spring pressure, etc). What I will say is that roller cams tend to take more spring pressure to keep them tracking on the lobes . . . and "rolling/spinning" is a part of that. If roller cams didn't work, you wouldn't see them being used in just about every top-competition engine today. :)

What is difficult with roller lifter profiles in flatheads is that we do not have the added benefit of a rocker arm and associated ratio and our base circles are very small. About the only way we can achieve high ramp velocities (to say match a radius) and increase the area under the curve is by using inverse radius/hollow flank profiles. You've probably seen a few cams like this - the lobes look more like "peanut shapes". A great example of this is the top race cams that Harley used on the KR flathead and also what Kenny Kloth had made for his record setting engines for Bonneville.

One of the problems/issues with inverse radius cam profiles is that it takes SMALL cam grinding wheels to make the inverse profile with the small base circles of a stock flathead cam blank - and most of the cam grinders use bigger grinding wheels.

Solution: If you bore out the cam bores of the block, use larger journals/bearings and increase the base circle diameter of a custom steel billet core, then we have a LOT more to work with. This is what most of the high-end Bonneville guys are doing - it is the only way to get the profiles and lift that they need.

Enough of my babble . . .

Dale
 
Bored&Stroked said:
It doesn't necessarily make a cam 'bigger' - the lobe profile and design of the cam determines that. What it usually does is increase the valve lift velocity in the mid-lift areas of the profile (the ramps) and deliver more area under the curve for a given velocity.

For example here are the velocity numbers for my favorite two Potvin grinds - can't really show area under the curve in 'text' :) :

a) Potvin 3/8: maximum velocity of .008512 per degree of rotation happens at .1239 of intake ramp lift.

b) Potvin 425: maximum velocity of .008519 per degree of rotation happens at .1925 of intake ramp lift.

Now, the Isky 404-A: maximum velocity of .009738 per degree of rotation happens at .163 of intake ramp lift.

Roller Lifters: I'm not going to dispute what Barney said - as I would have to know the context of his comments (cam, spring pressure, etc). What I will say is that roller cams tend to take more spring pressure to keep them tracking on the lobes . . . and "rolling/spinning" is a part of that. If roller cams didn't work, you wouldn't see them being used in just about every top-competition engine today. :)

What is difficult with roller lifter profiles in flatheads is that we do not have the added benefit of a rocker arm and associated ratio and our base circles are very small. About the only way we can achieve high ramp velocities (to say match a radius) and increase the area under the curve is by using inverse radius/hollow flank profiles. You've probably seen a few cams like this - the lobes look more like "peanut shapes". A great example of this is the top race cams that Harley used on the KR flathead and also what Kenny Kloth had made for his record setting engines for Bonneville.

One of the problems/issues with inverse radius cam profiles is that it takes SMALL cam grinding wheels to make the inverse profile with the small base circles of a stock flathead cam blank - and most of the cam grinders use bigger grinding wheels.

Solution: If you bore out the cam bores of the block, use larger journals/bearings and increase the base circle diameter of a custom steel billet core, then we have a LOT more to work with. This is what most of the high-end Bonneville guys are doing - it is the only way to get the profiles and lift that they need.

Enough of my babble . . .

Dale
Click to expand...

Hi Dale:

Thanks for the info. Yes, I agree with what you said about rollers. There is a reason why top racing guys are using them without question.

I still kick myself for about 25 years ago I was at a yard sale. There was a brand new box of Crower adjustable roller lifters with the jig to drill the lifter bores. The guy wanted $100 for the set and I declined. I sure wish I had those in my stash now.
 
Too soon old, too late smart. The more I learn about camshafts, the less I know about camshafts. Back in the 60's we ran the 404 with the double spring package. Instolation was a *****. and the engine ran OK for a while untill one of the lifters gave up and we switched to a 400jr. Which ran much better. However we eat up a few lifters here as well. We were running 85 lbs of spring pressure as reccomended by some expert?? after that fix dropping the installed spring pressure to 65 lbs the cam and lifters lasted several seasons untill we switch ed to a Sig Errson cam. Learned allot the hard way. Nut I still say, The air pressure in the right fron and a great driver is all you need on a short track.
 
Tim Ayers said:
Hi Dale:

Thanks for the info. Yes, I agree with what you said about rollers. There is a reason why top racing guys are using them without question.

I still kick myself for about 25 years ago I was at a yard sale. There was a brand new box of Crower adjustable roller lifters with the jig to drill the lifter bores. The guy wanted $100 for the set and I declined. I sure wish I had those in my stash now.
Click to expand...

Hell, come to Columbus and I'll give yah a good kick for that one! That is about $750 worth of lifters!

The Crower roller lifters are quite heavy (just put a set in my 42 Merc engine), but they beat the hell out of making your own. If I was building a race engine for Bonneville, I would make my own - just as we did on our Flathead Cadillac engine.
 
Ol' Ron said:
TBack in the 60's we ran the 404 with the double spring package. Instolation was a *****. and the engine ran OK for a while untill one of the lifters gave up and we switched to a 400jr. Which ran much better. However we eat up a few lifters here as well. We were running 85 lbs of spring pressure as reccomended by some expert?? after that fix dropping the installed spring pressure to 65 lbs the cam and lifters lasted several seasons untill we switch ed to a Sig Errson cam. Learned allot the hard way. Nut I still say, The air pressure in the right fron and a great driver is all you need on a short track.
Click to expand...

I'm running about 95 lbs of spring pressure (on the seat) on my steel roller cammed race-style engine - as you don't want to float the rollers and bang them on the cam - breaks roller axles and then you lose the motor. As this is a custom setup, the cam has an 8620 steel core and is hardened - so it can take the spring pressure.

On a side note, FlatDog used to run the dual-spring Isky package and he and I talked a lot about it. He then switched over to the single 185-G springs on his .450 lift roller - used about 100 lbs on the seat and had no problems at all with his race engines. Man - he was a good dude . . . miss our bench racing conversations!
 
"The air pressure in the right front and a great driver is all you need on a short track."

Ol' Ron, there is a lot of wisdom in those words.
 
Bored&Stroked said:
I'm running about 95 lbs of spring pressure (on the seat) on my steel roller cammed race-style engine - as you don't want to float the rollers and bang them on the cam - breaks roller axles and then you lose the motor. As this is a custom setup, the cam has an 8620 steel core and is hardened - so it can take the spring pressure.

On a side note, FlatDog used to run the dual-spring Isky package and he and I talked a lot about it. He then switched over to the single 185-G springs on his .450 lift roller - used about 100 lbs on the seat and had no problems at all with his race engines. Man - he was a good dude . . . miss our bench racing conversations!
Click to expand...

Yeah, he certainly knew how to get a lot out of these old motors. One year, we pulled into the show out at Macungie, PA. The entire place turned around when they heard him pull in with his '34. That flathead sounded like a full race SBC. Nasty to say the least.
 
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