Bill Ball

Argh! I'd be concerned about the lifters too and metal in various places, especially if the bearings are worn as well. 5W40? I trust it wasn't raced on that. Did Ernest ever report back the oil analysis? It could be helpful as to Dave's concern about the bearings and how far the motor needs to be torn down. Argh!

heinrich

Mark unless someone made a GT with auto box, then GT cams come on 5spds lol.

GregBBRD

Virtually all of the GT engines ran with just the oil cooler that sits under the radiator, which means that most all ran extremely high oil temperatures, especially when subjected to "American" traffic.

I figured that a lot of this damage occurs at higher mileage, but I took apart one of Marc Thomas's stroker engines that used a brand new set of GT cams, which only had 5,000 miles on it. There was an amazing amount of wear on these virtually brand new camshafts. Certainly, the engine was running very rich and had quite a bit of fuel in the oil. It also had stock valve springs with the significantly heavier 968 valves. There was also no effort made in increasing the oil cooling ability.

Now, I'm not sure what causes this damage or how soon it occurs.

The one thing that should absolutely be done in the GT engine in which these cams came from, would be to take a look at the rod bearings.

terry gt

just have Colin get them re ground , or get a set of new ones . This is not the first set of GT cams to have this issue . When Colin install the stage 11 triflow cams in my car , and pulled out the GT cams , you could see a very slight pitting on 1 or 2 lobes . My car has 70,000 on it and all the records , showing it using good 20/50 oil .

SMTCapeCod

bad things. Good luck with the repair- you know you're going for the big cams now....:-

https://rennlist.com/forums/showthre...ferrerid=33949

Alan

H - that really sucks - when will you ever get to drive the thing...

Rick Redpath had some excessive wear on his GT cams also - did a pretty big rebuild - I wonder if the GT cam profile creates some extra wear - or maybe its just that GT's just tend to have lived a harder life...?

Wise insurance might be to plumb a rad side tank in after the air/oil cooler. I did that to keep my oil temps under control - I also switched to AMSoil 20w50 - doing both really was required to solve it for me. Car was never really fully happy on Mobil 1 15w50. I know I know - more $$$

Alan

123quattro

I don't think oil is to blame for that wear/failure. My A6 4.2 runs on M1 0W40 with a similar valve train. It has a lot more miles and is perfect.

ROG100

I plan to protect my S3 street grind cams in my GTS by adding a hose kit from Greg Brown that will include both the air (under rad) and water (in rad) coolers. Already fitted a Behr two cooler rad in anticipation. I am also pleased that Greg will allow me to sell the hose kit as well.
Already use RP 20W 50.

GregBBRD

Sometimes...not always.

The process of grinding "smears" metal, which will hide defects.

For example, grinding a flywheel does not remove all those ugly hard spots....it just smears the surface so that it all looks the same. The first couple of times a clutch disc hits that new surface...all the old "defects" will show up.

The same thing can happen with grinding a cam.

If there isn't enough material ground away from the top of the lobe to get down to good base metal, the defects will simply be hidden and will immediately reappear once the cam hits a lifter a few thousand times.

If the base circle gets reduced by .040", that doesn't leave very much at the top of the lobe, to "find" good base metal.

Since magnafluxing a piece of csst iron is virtually a complete waste of time, die penetrant crack checking works fairly well in a freshly ground surface to see how much "damage" lies below that surface. However, cam grinders tend to apply a coating of "break-in" material to "hide" any defects. If you've ever had a set of "Web" cams, with the uber thick coating that they apply to "hide" the defects (and you take time to remove this thick coating), you will instantly know what I'm talking about.

The cams, in these pictures, have some significant wear, which is going to have stress cracks deeper into the base material. Regrinding far enough to get down to decent base material and ending up with a "GT" lobe shape is going to be a real challenge, with these cams.

Lizard928

Greg,

Shouldn't you be off enjoying your time off with the family? After all tomorrow is your bday!

What would you suggest;
New set of cams,
Good used S4 cams,
Good used set of GT cams (good luck finding them!)?

GregBBRD

That question totally depends on the "budget". My first choice would be a new set of cams with an "improved" valve spring and a set of DLC coated lifters.

Finding a good used set of GT cams is a dream. I just got information back from the factory that they had all of the GT cams "back in stock"....but I have not ordered any to confirm this. Frankly, buying a set of GT cams, from the factory, would be "silly" since you produced your cam blanks.

S4 cams, in this engine would be.....sad....since the significant price that Heinrich paid for this engine was that it was a GT and not an S4....the difference of which is the cams.

andy-gts

arghh!!!!!! I wish I could help some how. . I have a set of gts cams you could have but that wouldnt do too much. My gts engine is arriving from gregs shop friday and it has gts cams with base circle grind that with 5 psi gave me 426 rwhp on mustang dyno. I could get those off the heads if you wanted( they were dr nicks)

just thinking .

andy

redpathtribe

H, as Alan said, when Dan and I went through my GT motor there was a decent amount of wear on the cam lobes. IIRC had something to do with the lift of the GT cams and the stock springs not being able to handle it, but my memory may be off... the thread's still on here somewhere I'm sure if you want to search for it.

Anywho, had Elgin refurbish and renitride (?sp?) the cams and they came back looking good as new. I'm sure Colin can take care of that for you too. At least you have some options here, but unfortunately I'm sure none of them are what you planned on...

heinrich

Thanks very much, Guys. Yes... pondering options. Remember I bought this motor at premium price because it has gt cams which I now see are dead, and because it was an easy, reliable drop-in in, which now I see it is not.

I now have 2 broken engines in my garage, both need fixing and the gts is still without engine.

Andy thanks those cams may help. Will ponder it.

heinrich

Bill according to Aspkiller (Larry) he pulled the motor immediately and never raced it.