Tallboy

a guys got sum crower rockers that were on an LT1 that he is selling and i was wondering if they would fit on tbi heads or any 3rdgen head 4 that matter...............

thanx 4 reply

mrr23

yes

Tas

They won't fit older heads. I forget the cut off year exactly. Pre '87. I think have guideplates. after that chevys used self aligning rocker arms.

Tallboy

okay
so u guys say they will fit on 87+ heads?
what size r the stud on 3rd gen heads?

what do u guys think of crower rockers?

mrr23

self aligning will work on older heads. the non-aligning will not work on newer heads. the reason why is the pushrod slot is larger in the heads. which will make the rockers walk sideways. in older heads, the slot is just big enough to let the pushrod through. that is what kept the rockers from moving sideways.

fast_broker

iTrader: (1)

self-aligning rockers will work WITH or WITHOUT pushrods and will work with any head combo you have, old or new, independant of head pushrod slot size. If you use pushrods, you just won't make use of the self-aligning feature, that's all. Non-self aligning rockers should only be used with guideplates!!! No matter how large the slots are inthe heads for the pushrods!!!

The problem arises if you use non-self aligning Crowers without guideplates. The rockers could walk off the valve stem tips and even if they don't, they'll take a beating and wear prematurely. You DO NOT want your pushrods touching the head pushrod slots, either. If they touch, you should use guideplates and hardened pushrods for proper valvetrain geometry and wear characteristics.. DO IT RIGHT!

Damon

You don't need hardened pushrods or guideplates if your (old style) heads have the narrow pushrod holes. Yes, the pushrod will rub on the sides of the hole but there will be no appreciable wear on even non-hardened pushrods and no further aligment method is needed or wanted on these heads (guideplates).

The cast iron material of the cylinder head is MUCH softer than the steel used in non-hardened pushrods. Plus there is a large contact area unlike guideplates which are like rubbing a knife edge against the pushrod by comparison.

You want to use only ONE method of aligning the rocker on the valve stem tip. Using 2 or more raises the possibility of having the various methods "fight" with eachother and then you WILL have problems with parts wearing quickly.

Putting self-aligning rockers on an older head that never used them is usually a safe bet, however, since there is a fair bit of "slop" in the self-aligning slot in the tip of the rocker and it rarely "fights" against guideplates and other alignment methods.

mrr23

i don't think rockers arms work without pushrods. and if non-selfaligning rockers should only be used with guideplates, then why do stock heads not have guideplates? jusy trying to figure out what you are getting at. i think you are talking about selfaligning rockers working with or without guideplates.

fast_broker

iTrader: (1)

Keep your engine at 6000rpm for 10 minutes a day with your non-hardened pushrods rubbing on the heads. Not my pistons that are gonna get wacked when your valvetrain sheets the bed.

Bottom line, you want the valvetrain lined-up vertically with no slop to either side and with no head-hole rub. c'mon, do you think that is right??? Flopping back and forth to either side of the hole??? g-plates are pretty cheap.

Non-self aligners cannot keep themselves on top of the valve stem, so the need guidelates.

Self aligners have little ridges/steps/washers on the sides that will hit the valve stem tip and not allow the rocker to fall off the side of the stem. They can be used withut guideplates for this reason, but of course can also be used with guideplates as well, the self-aligning ridges not to be used.

Guideplates and hardened pushrods are the only way to truly keep your pushrods/valvetrain absolutely vertical all the time without excessive rubbing/heat. Rocker choice depends on whatcha got.

Tas

I was talking to an engine buider that droped in at work and he was saything that you could run self aligning rockers with aguideplates but that its a bad idea because since they are both doing the same job they can work against eachother. You're better off going wiht one or the other. Non hardened pusrods (like the ones that come with self aligning rockers) will also cause lots of metal chips if used with guideplates. They aren't strong enough to handle the constant rubbing against the guideplate.