Cast roller cam blanks

[tirod]

Having googled and read up on roller cam alloys, I get the impression that the route to better prices is getting a ready supply of cast blanks for the cam grinders to use. Nodular iron is one alloy mentioned as compatible for roller use. It seems the problem with rollers is surface cracking from high loading. Steel billet cams seem to suffer the same.

Having "grown up" in the days when remachining stock parts was common, I learned you can 1) weld up and regrind cranks - and even make stroker cranks that way; 2) weld and regrind cams to reuse.

Choosing the appropriate alloy weld rod, a good machine shop, and a cam profile that will only be just close enough, I see the possiblity of grinding a "custom" roller cam as affordable, especially compared to the total cost of a billet. No replacement distributor gear, blanks are dirt cheap, and rollers are available stock from AMC V8's, Chevy, or the 3.8 V6.

This is a theoretical discussion, of course, but real machine shop costs are just a phone call away. I'll pursue that locally - the main issue being finding a shop that can do the work, and choosing a cam profile.

The real question is whether there is a "show stopper" problem yet undiscovered.

[Flash]

The real question is whether there is a "show stopper" problem yet undiscovered

.

And hopefully 505 performance can prove that there is "NOT" one.
Or any on else for that matter


I sure would like to see a roller cam come to life.......and live, not matter what material is made off.

[Plechtan]

Most of the processes used to harden cams are developed for high production (low cost). some other (more expensive) processes might meet the requirements of hardenimg cams. I ran across the Melonite Process http://www.burlingtoneng.com/melonite.html. this uses salts to harden steel and add carbon and nitrites.

Anybody want to give it a shot?

[Flash]

Most of the processes used to harden cams are developed for high production (low cost). some other (more expensive) processes might meet the requirements of hardenimg cams. I ran across the Melonite Process http://www.burlingtoneng.com/melonite.html. this uses salts to harden steel and add carbon and nitrites.

Anybody want to give it a shot?

That was a vary interesting read, Thanks

[tirod]

The advantage of the lobe weldup process is that you get to choose the hardness and composition of the rod or wire to meet the parameters. Having worked at a plant where plain steel hammers for a feather grinder were hardfaced with high carbon rod to RC65 and above, I'm aware of the diverse results of the end product.

It was considered lobuck and hillbilly in the day to run a welded face cam or crank, but things change. Now, medium priced Kershaw knives come with a dovetailed and welded blade - ductile spring back, high carbon alloy edge. For our purposed, if it can stick to cast iron but not crack under roller loads, it may be a winner.

Googling "roller cam alloys" was interesting, and it seemed to bring up fairly simple grades. Welding on a face is probably more high tech - welding alloy is a bit more than infusing a carbon compound into the first few thousandths.

[Flash]

Just a story......kind a off the subject!

When i was young, my buddy had one of those six cylinder over head cam barrel Pontiac Firebirds(68?)

any ways the cam lobe when flat on a couple of sylinders,........he pulled the cam and with a tig welder BRAISED the cam up, ground it to look like(kinda ) like the other lobes.
Amazingly enough it ran, and ran good..............................For about a week, after he tried this the 3 time it lost oil pressure and........ ya u guest it.

What is surprising to me now, is , that it didn't fail immediately!!!!!!

[Plechtan]

The high heat involved in welding would distort the cam, straightning would be reqiured, and it is allot of work. salt nitride treatment would not cause problems because of the low tempratures involved.

[tirod]

The problem of heat distorting the cam was solved decades ago. Automated machinery does most of the work now, applying a thin buildup with a wire feed. It's a radial weld around the face of the cam while it's rotating, which is much less strenuous than a long bead commonly skip welded joining the edge of two parts.

Overhead cam motors are subject to distortion just loosening the caps inappropriately; no doubt cams aren't the hefty pieces we think they are if valve spring pressure alone can bend one by not backing off the cap bolts in the same pattern we tighten them.

Casting iron is not very precise - cranks have to be straightened, and machining is required to get all the mains and journals coaxial and indexed precisely because of the distortion in making them.

[Plechtan]

The problem of heat distorting the cam was solved decades ago. Automated machinery does most of the work now, applying a thin buildup with a wire feed. It's a radial weld around the face of the cam while it's rotating, which is much less strenuous than a long bead commonly skip welded joining the edge of two parts.

Got any pictures? What vehicles use welded cams?

[tirod]

A valid question. Most of the production was based on the resale market that existed when the home mechanic actually worked on his own car. In that day 85,000 miles was pushing it. A welded reground cam with performance profile was not uncommon in the 60's and 70's.

Now with 250,000 mile engines and a complete lack of "greasy fingernail" owners rebuilding motors, the market died. We once had 5 machine shops catering to the public, now there are three - one a franchise auto parts department, one selling to repair shops, and the last selling to the upscale hot rod market. Nobody will run a reground cam, period. None will expend the capital for the machine just to leave it idle.

Two reasons:1) warranty backup and risk - a small cam grinder has no rep to market; 2) ego - engine builders and owners sell branding. A cam has to have cache and street creds or it doesn't support the owner's effort to make himself look better.

A Comp Cams Thumper in a 350 street rod announces itself and the owner - A redneck regrind cam won't add any gloss at all when it's revealed. Today's high performance owner is much more concerned with what decals they can show off under the hood than what timing slips are actual winners.

Reground cam buyers were frugal, now hot rodding is an exercise in displaying how much money was spent. No market, no reground cams, regardless of the actual cost effectiveness. It would take a large volume of cams to generate enough business to break even - and today's buyers won't do it. It would have to be a name brand cam maker to risk it.

Good question. I'm just hoping a regional rebuilder with a cam lathe would be willing to try - otherwise, roller cams for 4.0's will probably never happen affordably.

[Plechtan]

Some people on the board have had their cams reground. If you look under stroker basics, the top thread is " how much did you spend on your stroker?" Many people have spent less than $1,000.00

Many argue that with a .904 lifter you do not need a roller cam. The market will respond to demand. currently it is difficult and expensive to install roller lifters into a jeep I6. I don't know if the cost/performance ratio is there.

[tirod]

Links to reground cam subjects:

http://www.kamsinc.com/camshaft-remanuf ... regrinding

http://www.jalopyjournal.com/forum/show ... hp?t=36558

Whether the .904 lifter is compatible to a roller grind is a good question. I don't know that the necessary limitations of a large lifter leave a reasonable working profile for a roller - but we do know that the roller can affect the dynamic compression ratio because the opening and closing can be altered. Roller cams do offer more power because they can dynamically act as torque cams at low speed and hi performance at higher rpms. You can have your cake and eat it too.

In terms of a budget stroker, the opportunity to buy a cost effective roller improves the horsepower gain per dollar. I don't see billet cams making the bill of materials under under that restriction. If parts can't be available in the same price range as if for a small block V8, it's hard to justify. It would just be a labor of love, not hard and fast total horsepower.

[tirod]

FYI another link: http://www.isuzuperformance.com/bills/engcam.html

Read down one why the welded cam offers advantages for eliminating unnecessary shimming on this direct lift cam setup. Prices don't seem to be too bad, either. They mention Web Cam grinding service who's obviously in the business. Their web site is also informative. Delta Cams also has photos, and other discussion on the web in other forums take this option as a matter of fact - any antique being restored has no other practical alternative. Cam blanks are simply unavailabable for many - so you weld and regrind.

Also consider the hard facing of cams can offer resistance to the use of a roller lifter. The industry already understands that there is a 250,000 pound limit to plain cast that requires a step up to steel (lower carbon, more ductile.) No reason that can't be done by a weld and regrind.

[Biggrnjeep97]

Most of the processes used to harden cams are developed for high production (low cost). some other (more expensive) processes might meet the requirements of hardenimg cams. I ran across the Melonite Process http://www.burlingtoneng.com/melonite.html. this uses salts to harden steel and add carbon and nitrites.

Anybody want to give it a shot?

If i had a cam that needed to be coated id do this procces. I started reading and dragged a few other machinists in our shop over. All in all we believe this would only enhance the cams life span. Welding a lope is a great idea if it werent for the heat induced into the shaft itself (causing warping) which can, in the long term, create cracks and the fact that it is VERY difficult to get most anything other than stainless rod to stick to cast anything with the reliability required of a cam would keep this as only a last resort. JMO.
-Will