Fevre

A topic was started a few days aga about roller tip rockers and many people chimed in included myself. I have roller tip rockers and put them in my new LM1 crate engine and thought nothing of it. They rested nice on the valve stem and my engine ran pretty good after tuning and such but I knew I had to check the valve lash sooner or later just to be safe. I AM GLAD I DID. I wish I had taken a picture so everyone could see. Every rocker tip was off center and the push rods were resting against the holes in the head. I tried centering them and they just snap from one side to the other.

I decided right away to put the factory ones back on a couple at at time so I could adjust the lash for two instead of eight. I had noticed that one or two of the push rod holes in the head were not perfectly round like the rest and one had a big gap on one side. After geting the two factory rockers on I started the engine and guess what happened.... that's right, the rocker with the push rod hole gap shot opposite the gap and the push went right in the gap dislodging the rocker of the valve stem and it was resting on the spring cap. I shout it down and replaced the rest of the rockers.

So if you have these reockers without guide plates do yourself a favor and pull your rocker covers and make sure your tips are centered. If they aren't I would suggest replacing them ASAP. I am not sure if my valves stems are convex or what but something caused those rocker tips to move off center.

I feel very lucky I decided to check them today and I suggest you do the same.

Chris

BTW I got it running even better after carb adjustments but that is another thread.

Brutus

Makes me glad that my AFR 180 aluminium heads came with guide plates already fitted.

SharkAttack

Note to self ... (in the event I ever install roller rockers)!

Fevre

My trick flows have em too.

Wrecked82

House of Speed and I learned that the LM1 takes a special rocker. They are some sort of self-aligning rail type so the push rod stays inside the rail of the rocker - or should I say the rail keeps the rocker centered. If you want 1.6 stamped ones, they are made by Speed-Pro. If you want roller tips, Comp Cams makes some that have "washers" on the sides of the roller tips to keep the rockers in line. You can get either from www.goautocenter.com. Send them an email and inquire. I had to return to my stock rockers for the exact same reason. Luckily, only one rocker developed a problem and that was addressed before any problems.

Fevre

Larry

Thanks for the info. Did you install the LM1 in your vette? I got it to use for a temp and to maybe keep as a spare engine. I put a little bigger cam in it so it has some spunk. I am just glad I caught those rocker before something major hit the fan.

tsw71

I have had a lots of experience with this problem of the rockers sliding off of the valve. This was BEFORE I switched to the roller tip rockers. In fact, the reasons I ended up buying new heads two years ago was to eliminate this problem. Many of the pushrod slots in my old heads were in very poor shape and had so much slop that a rocker would slide off monthly. A while after I replaced my heads, I noticed the same problem with the pushrod slots in the new heads :confused: To get me by until I could later install guideplates(did that last year) on the heads, I switched to hardened pushrods. The stock pushrods deflect under load and create lateral pressure agasinst the side of the pushrod slot as it slowly laps out the hole. It also eventually bends when the lateral load gets to be too much and then allows the rocker to slide off the valve stem. I can tell you that it does not sound good when that happens :eek: :eek: Once I made the switch to the hardened pushrods, this problem did not re-occur.
I also run the roller tip rockers in my streetrod's 350 without guideplates. This engine sees 7500 regularly, and I have never had any problems. Again, I believe it is due to the hardened pushrods that I have used on this engine since day one.

Fevre

I now see the need for the guideplates to control lateral movement after seeing the one deflect total off the valve right in front of my eyes. It was a real eye opener. I think there are some applications would be OK without guide plates but I would be very carefull and check them often for a while to make sure no rockers are straying from center or just buy ones that are self-centering. Since this engine is super hi-po I think i am going to run the stock rakcers. I can always slap on the trick flows if I want need more power but i am saving them for my 383 rebuild.

Fevre

corrections

the engine is NOT super hi-po + ROCKERS(sp)

I hate typing. :mad

Wrecked82

Yes, the LM1 is in my Vette. I like it. Nice improvement in power over the stock L83. Wanted the 1.6 rockers till I ran into the problem. House of Speed reinstalled my 1.5 stock ones, and still had an improvement since they made sure they were adjusted properly - which they were not from factory.

Fevre

I snuck a little bigger cam from Summit in it. I have to believe it helped with power. I saw a company offering a LM1 with a GM cam with the same specs and it dyno'd at 289 horse (with headers and 750 carb) which ain't to bad. Guess I am at about 260 horse but more torque down low. Not a bad engine for the price. I paid $1369 delivered to my plant.

SteveG75

Small block Chevys use one of two methods to keep the rocker arm centered on the valve. The old method was either using the pushrod slots in the head or pushrod guide plates to keep the rockers centered. The new method (including the new crate motors) is to use a rail type rocker that has the guides on the tip so it does not move off the valve. To prevent pushrod binding with this method, the pushrod holes on the heads are opened up.

So, if you put non-rail rockers on a new engine there is no way to keep the rockers centered on the valves. Conversely, if you put rail-typr rockers (roller or on) on an engine with pushrod guideplates, you have a tailor-made recipe for binding.

As an aside, I have guideplates and some of my Comp Cams roller tip rockers aren't perfectly centered but the tip isn't off the valve stem. :smash:

Fevre

I all my tips where on the stem tips, but not by much, but all push rods where against the push rod holes in the head. I am just glad I checked the valve lash or i may have f'd up the engine. This time it would have been 100% me.

rod73vette

Hey,

I stopped in tonight to ask if anyone had had problems with roller tip rockers interfering with stock valve covers and found THIS instead! I've got a stock L-48 in a '73 with regular pushrods. I recently put roller tips in, but haven't started the motor yet (still finishing). I'm wondering how concerned I should be? I don't race my car and I don't have pushrod guideplates. Looking at the stock rocker arms I don't see any kind of "centering" device and they work fine (obviously). The roller tips have the same kind of insert and locknut so what's the big deal? It seems that as long as your lifters are correctly adjusted to keep pressure on the end of the valve stem (no slop) then the tip shouldn't wander too far? Any more input?

Thanks,
Rod Hisle
Louisville, KY (Derby City)
:flag

Corellian Corvette

Rod I have the exact same setup with my stock 73 L48. I think the key is that the original poster has a different engine. Assuming that your pushrod holes were thin, vertical and oblong, we're in good shape. I've been running mine for a couple months with no problems.

rod73vette

Thanks CC!

I appreciate the feedback on your similar engine setup. Yes, the pushrod holes are as you described.

Have A Great One :cheers:

Rod

Corellian Corvette

No problem Rod!

How original is your engine? I'm looking for some good, high quality pictures of a correct engine compartement for a '73. Is yours pretty stock?

If so, I'd love it if you could snap some good pics!

Thansk!

LS1-Corvette00

Call me crazy but one thing that I have known for quite some time now is
that when using non self aligning roller tipped rockers you must use bolt
on pushrod guide plates (of course this also means you must use screw in
studs which is not a bad idea as I have seen pressed in studs unpress themselves!)

Or you could forgo the guide plates and use a newer set of self aligning
roller rockers. I used these on my 95 LT1 and they worked great.

Good thing you caught this when you did!

Jvette73

Im using comp cams magnum roller tip rockers on my cast iron 64cc heads. when I first did research before buying them I did not see any warnings or requirments to use guide plates. It wasnt untill I opened the box and a little piece of paper fell out and and noted that guide plates must be used. Im glad I saw it and went ahead and added the guide plates as well. The problem I had was that the pushrod slots in the head did not line up perfectly with the slot in the guide plate. When adjusting the valves it caused the pushrod to bind against the guide plate. It was then nessisary to remove a small amount of material from the guide plate slots in order to prevent the binding. So far so good. Had I failed to correct this problem, the pushrods would have been seroiusly chaffing on the guide plate slot to an extent that it would have maybe sliced right through them.

427V8

I hope you guys are running hardened push rods with them guide plates!