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Coyote Jack

Coyote Jack

Member #55, I'm old
FABO Gold Member
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May 22, 2004
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I got the 360 apart today. I lucked out. After wiping 2 cams I couldn't find any damage to the mains or connecting rod bearings. There was one minor scratch on one cylinder wall. I'm not going to worry about it as I have seen worse in perfectly good engines. The scratch was only about 2 inches long and barely noticable. I had to have my glasses on to see it. Pistons and rings were perfect. So I have put the bottom end back together.
What I did find that worries me a little is that all of the cam lobes that had damage are on the intake valves on the drivers side of the engine.(both cams). I am taking that head to a local shop to check out the sping heights, pressures, and guide to retainer clearance's. Maybe there is something there.
Going through the spec's of the engine build they used a .026 head gasket and the pistons are .020 in the hole. Other than that nothing stands out as to a cause for these cams dieing. Jim, at Racer Brown didn't think that the 15 seconds it took for the engine to really fire up should have caused the problem but stranger things have happened.
One other thing I noticed was the thick sludge in the bottom of the oil pan. I figured that must be the remains of the GM EOS. Nasty looking stuff. LOL
It was also amazing the amount of crap, ie: silicone that had got caught in the oil pump screen.

Anybody got any thoughts on this? Just something that I can ask the local shop to check.

Jack
 
If it's all the intakes on one side, that's not a fluke. I would very carefully check the stem heights on it. Even a straightedge would help accross all the valve tips. If the intakes are higher, that could be enough to put too much preload on those lifters. Also, the head gasket is about .020 thinner than the factory would have used, so you're loosing some there too. I'm beginning to think you may need shorter pushrods, I cant rtecall if you had adjustable valvetrain or not tho... You will, in any case, want to set the lifter preload without the intake on when it goes back together, and make sure every lifter has what it should (between .010 and .030").
The thick sludge is a mix of iron particles (run a magnet thru it...), moly from the cam and assembly lube, the silicone that may have been over-used, and the EOS...lol. It's all had time to settle out, so it's all there. That would be why they say drain the break in oil and change the filter immediately after the cam break in, while it's all still hot and all that crud is suspended in the oil. When you drain it, it has a strange sheen and color to it too.
 
I just got back from the local shop. Here are the answers to some of the questions.

Retainer to guide clearance was good. No scarring on any parts.
Installed height was 1.623 I think. anyway it was within .003 of spec.
Installed closed pressure was 125 lbs

My rockers are not adjustable.

How do you set the lifter preload with these rockers? You just torque these down as far as I know.

I have been thinking that maybe my pushrods are to long. I would love for that to be the case. They are cheap. LOL

Jack
 
!.623 is .020 short of 1.643. Not that it should matter that much, if anything, the seat and open pressures are a tad higher. Not a big deal. But, in terms of preload. There are always to adjust it. The best way to determine what you need is bolt it all together, sans the intake. The cam should be degreed, and the lifter rotation verified by this point. (so that particular lifter is staying in that particular bore) Then use a wire feeler gage to check how far down the plunger of each lifter has been pushed by the torquing down of the fulcrum. The distance between the plunger and the retaining clip is what you need to get. For each lifter, when the lifter is on the base circle. (lifter not on any part of the lobe, only the flat of the journal) If you have more than .010, but less than .030, you should be fine. You may fine you have .040 or more. Too much preload can lead to probelms, and wiped lobes. You may also find that some may have .025, and some have .055 (I'm assuming the plunger can travel that much). If that were me, I'd adjust that to even things out better. In terms of adjustments, if there is too much, you can get shorter pushrods, or get adjustable roller rockers. If there is not enough, you can go longer pushrods. There should be enough room in the lifter motion to get a shelf available push rod to solve any problem. But, you may need to buy them seperately, instead of a full set. Adjustable rockers may solve the preload issue, but may not give the best rocker geometry.
 
you can change the preload on non-adj rockers with different thickness shims. these go between the shafts & pedestals. you can get them from Hughes Engines.
 
O.K. moper, I understand what you are saying. In simple terms, it is possible that my pushrods are compressing the plunger in the lifter to much before I even start the engine. And now I know how to check it. The final installed height was supposed to be 1.640 and was actually 1.643. Close enough that I don't think that is causing the problem. I had the numbers writen down in my truck and I went and checked them.

mike, I had thought of using shim stock under each rocker, especially before the next attempt at break-in. Much easier than changing the valve springs out to lighter ones.
 
Mike, Magnums dont use shaft rockers..they have fulcrums. Like a GM..in fact, I'm pretty sure some GM rockers fit, and cost a boatload less...
 
Yep! Crane sells a kit that contains the screw in studs (moper uses 5/16" threads in the head verse GM's 3/8") and guide plates for the conversion, $89 at Jegs. Then use 1.6 ratio sb chevy rockers.

I plan to do this next winter. I will get the kit from Jegs and go shopping for used rockers at the Thompson Speedway fall racers swap meet.
 
Let me get this right. You are saying that you can toss the solid mounted rockers, then install the studs from Crane, then run the Bowtie rockers that you adjust at the rocker. If this is so then I would say you are getting the best of both worlds as far as flat tappet cams go.

Jack
 
moper said:
Mike, Magnums dont use shaft rockers..they have fulcrums. Like a GM..in fact, I'm pretty sure some GM rockers fit, and cost a boatload less...
Click to expand...
I'm sorry, I thought we dealing with the older heads.
 
Another update.

I took the valve spring from the worst lobe to another shop.
Here are thier pressure's.

seat pressure - 110 lbs
.500 lift - 280 lbs
.516 lift - 290 lbs (this was the total lift of my cam)

These are not out of line, at least not enough to do the damage by themselves.

With this and all the other info I have I believe that my push rods are to long.

I will be talking to Jim at Racer Brown tonight and maybe we can get this resolved.

Jack
 
Coyote Jack said:
Let me get this right. You are saying that you can toss the solid mounted rockers, then install the studs from Crane, then run the Bowtie rockers that you adjust at the rocker. If this is so then I would say you are getting the best of both worlds as far as flat tappet cams go.

Jack
Click to expand...
While this sounds like a great idea I have heard it isn't really due to differences in the length from the rocker fulcrom to valve and fulcrom to pushrod of a chevy vs. a mopar. Their close enough to work apparently because they sell the kit but it puts undue load on things. I read an article about a month ago I believe from Harland Sharp about this and he had all the figures but for the life of me I can't find it or I'd post it here. Dang me for getting on too many boards!!!!
After reading this article my suggestion is to keep your stock rockers and check the lifter preload like Moper said and get the correct length pushrods.
 
There was someone posting about this in the past couple of weeks and I don't recall where. They cited Harland Sharp saying the difference is significant.

My comment to that is Harland Sharp has a vested interest in promoting that difference to sell their product just as much as Crane and Comp have a vested interest in down playing the differnece to sell their product.

I have enough confidence in Crane or Comp that they would not suggest that you use a Chevy rocker if it was significant enough in the long run to make a difference. Likely the difference is you will wear out the guides in 150,000 miles with Chevey rockers verse 200,000 with Harland Sharp.

I would put this issue in the same category as the superiority of the cams designed to take advantage of the larger mopar lifter diameter. In theory it's true but in practical application it's not significant.
 
Well, I think the Harland Sharp idea has merrit. but, to be honest, most guys dont need roller rockers, and aluminum rockers of any sort will break eventually. For a street car, where budget and mild cams take precidence, the Chevy parts are fine. They do adda a certain amount of stress to the stud. as you can see in the pics, the factory has a flat to flat joint, with each 1/2 helping to stabilize the other. I think using guide plates and hardened pushrods would do a very similar job, even under abuse. But, the pedestal style fulcrum will be ultimately stronger. Question is, is the $2-300 difference in price worht the stability? That depends on budget and usage.
 
I think it also depends on what you are working with to start with. I will say that after checking the conversion out I will not be going that route. It states right in thier literature that it is for mild applications only. I wouldn't want to push the envelope. And for the $2-300 dollars I can go a proven route.

Jack
 
if this had happened twice who is putting your motor together. you are the mach. shop? if they are. Are they covering your cost? i have a mag head 360 and had the pushrods all the magazines said i needed for the build. when trial fitting we found out they were no where close. as others have said this has to be checked. if you change one thing it has a effect on soming else.now if you're paying someone to check all this do not let them play it off.the best shops i have found are guys who build motors for round track guys.go to the local track see who wins and find out who builds there motors even if its a chevy or ford.
 
dartbob,

The engine was a rebuild I bought from a 3rd party. I checked the engine out when I bought it and everything seemed good. The engine only had dyno time. It then sat for 2 years in my garage. Stupid me, didn't take the intake off and relube the lobes before I started it up. The second time around I put a bigger cam in and was pushing the limits on all of my valve train. Lesson learned big time. I am now checking and double checking everything. I believe that the 3rd time will be the charm and I will be up and running soon.

By the way, when I took the engine apart, all of the things that had been told to me before I bought the engine checked out. I will have a strong runner soon.

Jack
 
I'm pretty sure I found the problem. I re-assembled the the top end today, put a couple of rockers on and measured my lifter pre-load as best I could. By that I mean I didn't have a feeler gauge wide enough that would fit in at the lifters with the pushrods in. I measured .045 and still had lots of play. I'm am just guessing but I would bet that there was at least .080 of pre-load.

I figure there are 2 ways to cure this. Shorter pushrods or adjustable rockers. Anybody got any other ideas?

Jack
 
I'm with Moper too. Alot cheaper than adjustable rockers too. And if you have everything correct there's no need for adjustable valve train anyway.
 
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