Hi, recently a stock rocker stud with a stock rocker on it broke off in my head, while driving. (completely stock engine) All of my mods sofar have been bolt-on's and suspension. CAI, Air Foil, ceramic coated hooker long tubes, y-pipe, 3" pipes, electronic cut out, a highflow catalytic converter, and a Flow master to finish the exhaust. I basicly have the entire BMR catalog, K-member, upper and lower A-arms, subframe connectors ect.
and now that I've got some head problems... its time to get in the engine.

I dont really want to spend a lot of money on fixing stock heads that I dont want, and not to mention, that same head has a heli-coil in it from when I blew a plug out of the head a few years ago.

I would feel much better spending that money on some ported AFR heads, a badass valvetrain, and MAYBE cam.... I say maybe because Chris at Speed Demon Motorsports, in Houston TX told me that they have had a lot of problems with new cams in LT1's. He says they are prone to spin cam berrings; and that he recomends pulling the engine and replacing the cam berrings (and basicly a full rebuild) if I wanted to put a new cam in.

Is there any truth to this? has anyone out there replaced their LT1 cam's and left the bottom end stock; and had it run w/o problems for a long time? or has anyone done this with disasterous results?

I am thinking about some ported AFR 220's with a ported LT4 intake (all used) I like the idea of a revkit, even if I'm not drag racing every day, that will on ly help reduce any valve float(plus I will have the rev-kit for when I do a full rebuild and will actually "need" it); and also a 58mm TB or a monoblade if I can find one reasonably priced. So, obviously with this new top end, I will benefit from a new cam... is it safe to do a cam swap w/o changing the cam berrings?

I am thinking about a GM 846 cam, with 1.6RR's if it would be a good idea. or if not, I will save the money for my big rebuild later on, and run 1.7RR's with my stock cam. Any thoughts on that?

One last thing.... I have read that you need ShaftMount Rockers for AFR 200's. Yet, the man I am thinking about buying these heads and intake from, says he ran Crane Gold Race aluminum 1.6:1 roller rockers with guide plates... I can use regular 7/16's ARP hardened rocker studs and regular 7/16's Roller Rockers right? Like the Scorpion 1.7's from Flatlander

Thanks for reading all this
-waylow

 

Many people have done cam swaps with over 100k on them with no probs. Did any metal cycle through when rocker broke? I;m sure some did. If you do the swap or have it dodne I wold check the bearings before puttin new cam in. Also, you can replace cam bearings without doing complete rebuild.

 

yea my engine has like 120,000 miles on it. Mobile one oil and mobile one oil filter, every 2,000 miles since new. well taken care of. I blew the tranny, and it sat for almost a year and a half before I could fix it. and it hasnt been running long at all, and now the damn rocker stud snaps... about metal... I'm not sure.. I sure didnt see any, and the stud looks like it snapped close to flush, so I dont think much if any metal woulda got in the oil, but thanks for the heads up.. I'll change the oil asap, before I forget.

I cant check Inspect the cam berrings with the engine in the car, can I? I dont think so... how much would labor be to pull the engine and to replace my cam berrings? and crank berrings for that matter.

 

Yeah I can name 3 people off the top of my head that spun a bearing after a cam install on an LT1. Doesnt happen to everyone but its common enough that I would recommend new bearings.

 

I'd say you could check the first few cam bearings with the engine still in the car. Might not be the easiest thing to get down there and look at but it's doable.

And from personal experience, it's much cheaper to rebuild it BEFORE spinning any bearings..

 

lol True Dat. Thanks for the input.

 

Thats what I was afraid of. Thanks for the input.
I dont think I want to risk replacing it yet. looks like I'll just get bigger rocker's for now.

 

Oh darn... Bigger Rockers

 

As far as having to use shaft rockers with AFR 220's that's not true now the 227's yes but not the 220's. Although the intake rockers will sit offset on a 220 but the geometry is fine.

 

If nothing else, at least do a new oil pump. I didn't believe the myth the first time, and spun a bearing :-( This time, I put in a new oil pump to be safe, and knock on wood, no problems, and I turn 6600+ rpms.

 

What if you're using a cam that only spins to 6000 rpm? Like a Lingenfelter 74211, for example... Wouldn't be a problem for the bearings, would it?

Snausman

 

Thanks for the Info. Glad to hear it.

That is something to consider, I may install a new oil pump, even if I dont put a new cam in the engine.

Thanks for all the Info everyone!

 

I spin it to 6200 with the stock cam and 1.6 rr.

 

Damn, glad I decided to install the arp rocker studs for insurance!

The factory helicoiled the LT1 aluminum heads, and they left the "tang" in near the bottom of the thread. You need to remove this tang in order to properly install the arp fasteners. You can do this with small needle nose pliers by moving it back and forth, fatiguing it.

The standard 3/8" arp fasteners are chromoly steel and have a tensile strength of 170,000 psi The factory ones are probably around the 125,000 psi range.