getrdunn

There another one at 247/255-680/680 also???

Just a little concerned with the 247 dur 680 / .400 lobe.

getrdunn

For sure. Am gonna call anyway to see if they have any insight on that grind with similar combo/CI. Id like to narrow it down to a couple cams for when I go downstate to dyno. One hydraulic and one solid.

HaxbySpeed

Is that cam a 252/259 with a .390 intake and .380 or .385 exhaust on a 113? It's an older cam motion grind that works really well. I've used it on a procharged 540, an NA 572, and a roots blown 598. It made great power in all of them and had zero valve train issues.

articfriends

I have to dig up actual cam card to be exact but i do know its on a 114 w a tiny bit more lift on intake than exhaust, .390 intake lobe and .380 exhaust sounds right, i only made a 1000hp with it on dyno last time but the dyno we were on had a 3% correction factor at 85 to 90 degrees in dyno room plus we were sucking air off glowing hot header (operator was measuring ambient OUSTSIDE dyno room) and 90+%humidity , the only cooling water we could get for inner cooler was a garden pump running off a bucket w a little ice thrown in it, water would start at 50 or 60 degrees and before pull was over would be well over 100, among MANY other problemsw dyno setup like 10+feet of exhaust tubing same diameter as header collectors so was like collectors were 13 feet long, never bothered running smallest pulley as it was a complete cluster fuk

articfriends

.660 intake, 2.300 intake valve, have to measure exhaust valve

MILD THUNDER

Some info on cam I thought I'd add

From Harold Brookshire

Jason,

Your Schn!!der regrind is a fairly radical cam, with a seat duration, I suppose, of 268/276, or is that the .050" duration? The lobe lift is .401" on both lobes. If the seat duration is 268/276, a .401" lobe lift makes a radical cam. What was it before it was reground? To make a cam like that, a lot of metal had to be removed.
As far as the heat-treat, almost all roller cams are heat-treated BEFORE they are ever ground. The only exception is those $500-$1500 SPECIAL cams, that are not heat-treated until between the roughing and finishing stages, those made from solid round bars of steel.
Regrinding a cam only removes heat-treat, they cannot be re-heattreated, they warp too much to be straightened. Regular steel roller cams are GROUND STRAIGHT after heat-treating. After they have been run for a while, and then reground, the stress-relieving makes them warp if re-heat-treating is tried.
If the core was unsuitable for what you wanted, they should have passed on the regrind. That's what we did at UltraDyne when regrinding a cam would have destroyed it, one way or the other. There is a limit to what you can remove from a cam and still have it be a good core. No cam company warranties a regrind----Not a single one.
It sounds like they could use a course in diplomacy.......

UDHarold

MILD THUNDER

There is a limit to how far you can regrind a cam, or even the initial grind.
Cams are made to a given lift, duration, and LSA, and then heat-treated, either carburizing (8620) or induction-hardening (other steels ending in -50 or higher). How long, and how deep, the heat-treat goes is very important. Many cams have only .080" or less of heat-treat.
Cams can generally be ground +/-3* in LSA, and +/- .025" in lobe lift. These are the more important numbers.
So this means you cannot regrind a .370" lobe lift, 106 LSA cam into a .450" lobe lift, 112 LSA cam. The grinding process with go through the heat-treat on both the nose, and on the sides. You can't grind a 106 LSA into a 108 LSA, then later try for 104, or 110. You'll go through the heat-treat.
If you keep the LSA the same, or just a 1* difference, keep the lobe lift close to the original, you'll be much happier. The actual shape of the lift curve has more importance than either of those two.......

UDHarold

Full Force

OK, finally got cam #1 out, has marks as we know, I saw marks that look like little snakeskin cracking, I instantly sent pics to Kip at Cam Motion at 9:00 at night and he responded instantly saying that that can happen and immediately offered replacement, No argument about who's fault it is, or blaming other parts... just offered to make it right, talk about customer service! that's how it should be...So far Kip from cam motion and Randy at Johnson lifter have been amazingly helpful, Randy and I have become friends over all this over the last year or so... makes me feel good there are still good people in the industry...

Still need to remove the other engine from the boat and see whats happening there, another buddy told me last night if the core was soft or hardness issue I would see it digging in over the nose where pressure is highest, I am curious to see cam #2 and if there is an issue at all...stay tuned..

[ATTACH=CONFIG]560415[/ATTACH][ATTACH=CONFIG]560416[/ATTACH][ATTACH=CONFIG]560417[/ATTACH]

SB

That's cool.

I thought your lobes where grooving ?

Full Force

I have some with a little wear that's darker, nothing was grooved into it yet, but I think close, my buddys gonna look at it over weekend and check it out before I move on, I am just happy that I looked now at things, thanks Joe! lol