Jon,

Thanks for the info on cams... learned something new today.

WRT this subject... would there be any advantage to using a DLC (casidium) on the cam lobe?

-Mindgame

 

You guys never fail to make me learn...lol

I asked my Machinist about the welding on cast and he said HE didnt want to do it he might ruin, he is looking now into oversized thrustsurface bearings.

The reason I wanted to save this crank, even though the initial outlay was 200$ I spent a good 300$ in extra machining on it. It has all rod throws drilled, lightened and knifeedged counter wights, surfaces were nitrided (I know that will have to be redone after the regrind). then it was internally balanced for my set-up.

I think if we cant find the right bearings I'm just going to go with a new forged crank.

The crank has really performed well though, I still have it running in my car now, but it has a mystery noise. When we discovered the extra clearance we replaced the main bearings and it put it on the very extreme side of the clearance spec. We are not sure what made the beaing wear the way it did (car is an auto), but the bearing wore down to the steel backing and basicly re ground the trust surface. I took it into him a while back and against his advise I repolished it with emery and reinstalled it with new bearings.

I have gritted my teeth long enough and m getting it fixed ASAP...lol

 

I'm not sure if DLC is used on Cup lifter faces or not, but I think yes. Assuming the lifter face is slightly spherical as most are, the loading approaches point loading. Lifter faces are very hard material anyway so they don't deflect very much under loading. I think virtually any "deflection" would crack the DLC. Also there is lots of impact loading when the lifter lofts and comes back down on the lobe, as well as when the valve bounces on the seat which may be multiple times per cycle.

The lobe has to be about as resistant to deflection as the lifter face, which means a relatively thin hard case with a typical core hardness of carburized 8620 steel isn't strong enough. My guess is that the built-up hard face might be maybe 3 mm thick. I could be wrong here because I'm just guessing.

So, if DLC is used on lifter faces, you probably don't want it on the mating part. You do need to keep the mating surfaces compatible with each other.

Of course, if someone has developed lifter and lobe coatings which work, they may not say much about it. I think most, but not all Cup cams come from the same company. Off and on Cup teams seem to buy cams or grind their own. I don't know who's doing what this year (or this week). It could be that teams grind their own dyno test cams, but use purchased versions for the race where million rev durability is important. Again, this is mostly conjecture, but it seems feasible.

 

400 block cranks are made to fir 2.65 dia. journals though if my memory serves me correctly. wouldnt that require align boring the caps and block inoreder to use a crank from the 400 sbc?

 

Bunny,

IF you do a 383 the old way with a 400 crank you will grind the journals on the mains of the crank down.... to get the "Medium" journal size (2.450") You can put the medium journal cranks in a 400 block if you have bearing spacers.

Good finish to that JB.

Bret

 

i gotcha now...i just went back to the beginning of the thread and read it over...that explains why he wants to grind down the journals. ive heard of the spacers being used before but that wouldnt be a very good idea in my book. unless there isnt THAT much strength difference.

 

Good stuff guys.

Continued education

CT interviewed Chris Brown, VP at Comp Cams for that one. Pretty interesting article if you're interested in cams and valvetrain stuff. Which I know none of you guys are.

edit: LT1bunny, is that a desert or a dessert between those two mountains? Or maybe my eyes are just playing tricks on me?

-Mindgame

 

Thanks for the link.

The best part of the link (IMO) is Billy's explanation of nitriding. He is one of the most knowledgeable people about a very wide variety of subjects that I have ever met. He's also a great teacher.

There is probably way more to the subject of Cup cams than any of us here know. We've hardly scratched the surface. (pun intended )

 

Nice link Mindgame...acyually its a beach, you really cant see the water though but you can see the island across the way

 

Looks like dessert to me?!?!

 

lol...dude i just notice that! Man I must have been slow yesterday but I just notice the two ss's and the one s! Dessert man, every night!

 

Don't sweat it, I have used a wire feed to fix damaged journals on a cast crank and never had a problem.

 

Just to clarify. The crankshaft I was talking about, at the beginning of of this thread, has the standard SBC 350 (Large), journal size, it isn't a 400 block crank. The balancing problems stem from the balancer that it was manufactured for, which is a "400 style" counter-weighted balancer. A true 400 style crank would require some of the machine operations discussed in this thread to be adapted to a 350 style block.

 

Yes, I understand completely now! In the beginning I though you got a crank out of a 400 sbc...which would require all that machining. But when I went back and read it over again I assumed it was a 350 crank. I just was wondering cause if you did do all that machining I dont think it would be worth your time because I do believe (not exactly sure) that putting spacers on the bottom end would weaken it a lot. How much I'm not sure but I never seen a racing engine with the spacers in it and if it did I dont think it would last very long. Maybe a year??

Anyone...more input on using spacers; good or bad or doesnt really matter?

 

I will say yes Diamond Like Coatings (DLC) can be used on almost any application where friction and wear are a concern. The technology has advanced enough to be used on practically any application including high impact.

"may not say much" more like under contract to say nothing.

There is multiple sources for anything in the racing industry as there is in almost all industries.

If you want to DLC coat a part as the company about the application and see what they recommend, they will know best.

Edit: DLC coatings are usually between 2-5 microns thick (.000002"-.000005")
http://www.applieddiamondcoatings.co...teristics.html