OK experts - I don't have the experience to figure this out -

Rockers - are they head-dependant, or block dependant? I have a roller block (1990 LO3) - I know the blocks changed in mid-1987. I'll be installing #416 heads, which are from a 1985 (non-roller) block. Rockers - do I need self-aligning rockers, or not?

My brother has a 1987 LG4 - but it is a later '87 production, and is a roller block, and his heads are original to the engine. He just installed LT1 cam and 1.6 roller-tip rockers, but they were NOT self-aligning. He couldn't get a good valve adjustment, and after a week of fooling with it, one of the rockers broke. He was thinking that he may have needed self-aligning, and that's why it broke. Also, he reused the lifters instead of getting new lifters. Pushrod was undamaged.

Why did his rocker break?
Did he need to use new lifters?
Did he need to have self-aligning rockers instead?
What will I need, given that my block is 1990, but my heads will be 1985?

Thanks for any input.

 

I'm 99.99999999999% sure that ALL Chevy small blocks have to have self aligning rockers.

 

yeh what he said

 

um, no, that's not true. i don't know about your self-aligning rockers but i do know that you can use non-aligning rockers on pre-87 non roller setups. and yes, it was ok to reuse the lifters as long as they look ok.

 

i'm 100% sure not all SBC use SA rockers. i beleive SA rockers starter the same time as roller cam engines. rockers are dependent on the head, or more correctly the method of locating the push rod. you can tell SA rockers by the little ears, or rails at the rocket tip where it contacs the valve stem tip.
reson you broke a rocker is bad valve train geometry, and i believe you need SA rockers. lifters wouldn't matter. running the valves isn't rocket science and if he couldn't get a good adjustment ought to of tipped you off to a problem.

 

OK - he (brother) says that he never got ANY of the valves adjusted right - they all still made more noise than they should. He also said that the car did fine up to 3700 RPM's - then it just died as far as any acceleration - feels like you tossed out a boat anchor that hooks a tree. So, he's thinking that it's a bad lifter issue, and that he should have replaced his lifters - not necessarily rocker arm problem - because weak lifters will make you float valves at higher RPM's.

Does this theory work for anyone else?

 

Did your brother change his valve springs when he did the cam and rocker arm swap? If not the springs are probably the cayse of the valve float not the lifters.

 

Yes - sorry - he did put in new springs good to .490 - the lift of the LT1 cam with 1.6 rockers.

 

There are 3 systems available to locate the rockers on the valves. One, and only one, must be in effect at any one time.

• narrow slots in the heads that fit tight to the push rods, no guide plates, and non-SA rockers;
• big holes in the heads for the push rods, guide plates, and non-SA rockers; or
• big holes in the heads, no guide plates, and SA rockers.

SA rockers were introduced on the SBC in 87. Before that, from 55 to 86, nearly all SBCs had method #1. For racing, method #2 is more stable, since the guide point is moved much closer to the end of the push rod, therefore the push rod can't bend and allow the rocker to move around to somewhere it's not supposed to.

Look at the heads. If they have little slotsfor the push rods that only clear the rods by .015" or less, then you must not use self-aligning rockers. If you have the big holes, but your heads have guide plates, then you must not use SA rockers either. If your heads have big holes but no guide plates, then you must use SA rockers.

The year of the block does not matter. Whether it has the factory roller setup (or the original, correct, roller design either) does not matter. The year of the heads does matter, because they changed to SA rockers in 87; they quit using the narrow slot and went to the big holes.

He probably had no guide for the rockers at all, and they were free to go wherever they wanted to; that's probably why they broke.

He shouldn't need new lifters.

What springs did he actually use?

 

He used Summit Springs - part number SUM-G1515

http://store.summitracing.com/partdetail.asp?part=SUM%
2DG1515

There are no guideplates. The rockers are non S/A. The holes in the heads for the pushrods seemed really small (tight to the pushrod) - at least from left to right (perpendicular to rocker).

 

RB83L69, You responded to my post yesterday(5/12) about push rod guide holes and whether S/A rockers where necessary or not. I concur with your accessment. I believe I don't need S/A due to the design of the guide holes. But, therein lies the dilemma. Refering to the picture on my thread:https://www.thirdgen.org/techbb2/sho...hreadid=178784 , the casting number can be clearly seen as '14101083' which according to www.mortec.com is for 87-up - 350 - Gen.I, also used on crate motors, 285 or 300 hp, 64cc chambers, 72' center manifold bolt angles. Shouldn't my heads have the larger holes requiring S/A rockers? Not that it matters, I've got what I got regardless of casting numbers and they appear to require non S/A rockers. These heads where probably used on 350's in other vehicles such as trucks and maybe they weren't designed for S/A rockers like the third gens. I don't know but its just a thought.

 

That's about the size of it.... "looking up" stuff on web sites only takes you just so far; the parts themselves tell you a great deal about themselves, if you just open your eyes and look. Sometimes web sites and books and even GM parts listings (although very helpful in a general way) aren't as good as just looking at what you've got. In this case, regardless of the casting number, the holes certainly appear to be for the 1st design rocker system. So those heads probably came on some crate motor originally, rather than one that came installed in a vehicle.

 

Things short and simple!
Luxor,
083 castings= 64cc 350 heads found on 87 & newer engines. You will need the self aligning rockers!

camaronewbie,
Your brother should have used self aligning ones as well, that was the problem!
416 heads = pre 87 58cc 305 heads, NO need for self aligning rockers!

 

85:

Look at the pics. Come back and tell us what you see.

 

I totally agree with your statements of 3 systems available to locate the rockers on the valves.
That is strange, the pic on that link shows the 083 casting to look almost identical to 416 castings. (in pushrod holes)
I honestly have NO idea why but all of the heads I mentioned above were configured as I stated from the factory!
When I get home I will look at my 083 castings and see if it is identical to the one pictured.

RB83L69,
I must say this subject now has me wondering what is up!
Is it possible that the chevy factory centerbolt style heads just require self aligning rockers for other reasons? Such as possibly the pushrod holes being located higher or lower than the pre 87 style heads?

camaronewbie,
Possibly my statement above is incorrect. If you brothers heads had the style pushrod holes pictured on the 083 castings in that link, did he slot them to to add clearance for the pushrod angle change when using the 1.6 rockers. If not, that could have caused the problem.

 

I believe the rockers used in this case were Proform roller-tip, which should have the elongated slot.

Self-aligning did not start in '87. I have (oops, had) an '87 LB9, 72 degree center intake bolts, center bolt valve covers, that did not have self-aligning rockers - they had the pushrod slots in the heads. '88 or '89 was the intro for the SA rockers (one of the heads was actually a swirl-port 305 head, and it had pushrod slots, not circle-shaped holes).

By any chance does he have the flat-tappet length pushrods in there with roller lifters? Not sure that would do it necessarily, but it would screw up valvetrain geometry. Roller lifter pushrods are .100" shorter.

 

The block is a roller block - the lifters are roller lifters, with the retaining plate to keep them aligned - so I'm assuming they are correct length for the roller cam/lifters - he did replace pushrods, but he replaced with same length as was previously installed, and the car ran fine before his undertaking. If I remember correctly, the heads are casting #081 (maybe 801?). 0n 5/13, he replaced all the lifters with new ones, and the broken rocker, but it got dark, so I'm awaiting to see what the result is now - I'll update as I know.

 

I have a strange update, I just got back a set of 081 castings from my machinist for an engine I am rebuilding. These were a matching set, both date stamped in 1986 for the 87 model year. One of the heads has the round style pushrod holes and the other had the the different style narrow holes,(Very strange), Also, I looked at one of my 083 castings, date stamped 1988 out of a 89 model year and it had the narrow pushrod holes as well like shown in the above link. The strange thing is, These were off my TPI camaro parts cars and all of the above reguardless of hole configuration, used the self aligning rockers arms What is up with this, can anyone explain?

 

There is a certain amount of tolerance in the rails on SA rockers... I guess your motor was just lucky, that the push rod holes and the SA rockers both wanted to locate the rockers close enough to the same place that there wasn't anything binding.

Me, I'm not lucky; if I put something together like that, it would screw up for sure. But I guess GM is luckier than me. Either that, or they just swapped sloppy-built motors out in warranty until they got one into the car that just happened not to blow up.

And people wonder why their motors make strange ticking noises and eat valve train parts sometimes after they disturb something by changing a part.... maybe there's a clue in here somewhere.

 

This is brining one back from the dead lol.

I have a similar "problem".....but the thing confusing me is my 187 heads which came with Self-Aligning rockers have the "narrow" holes (not hte larger holes I would expect).......and the 416's I am putting on my car to replace teh 187's appear to have the same type of pushrod hole (small/thin)......Sooooo how is that possible since the 187's currently on my car have self aligning but the push rod holes look identical to the 416's which are suppose to be Non-self aligning.

thanks,
Dave

 

tanager11
It's like I stated above and RB83L69 backed me up on, let the parts speak for themselves. If you have the narrow pushrod slots then you don't require self-aligning rockers. They can be used but you will have to different systems trying to align the rocker, and if there is any discrepency you will have problems. When I got my motor back together I picked up a set of crane cams roller tipped rockers (non-self aligning) and haven't had a lick of trouble yet and I've got a little over 2000 miles on the motor since the rebuild. Hope this helps.

 

Cool thanks Luxor......I am in agreement after looking at this thing again last night........ let the parts speak for themselves.

1 last thing which maybe oen of you guys might know. With the rocker arms themselves......how (visually) can you tell if they are SA or Non-SA rockers. I just assumed that the ones on my old heads were SA rockers...and instead of "assuming" I want to make sure of what I have is what going back onto the car.

Thanks for all the help.

Dave

 

Self aligning rockers have two ridges on the valve end of the rocker which helps to keep in centered on the valve tip.

 

Perfect....THE BLIND MAN CAN SEE NOW!!!

Thanks a bunch LUXOR!!!

Dave

 

I just did valve guide seals on my 88 non-roller cam LG4 and I found the same thing. The pushrods look no different wear-wise than those from any guided head engine but the rockers are guided.

The tips of the valves seem worn around the edges, but not worn much dead centre.

Weird to me, since it conflicts what I'd learned previously, but it does work fine after 190k+ miles.

Maybe they were phasing out non-guided rockers and figured if they could use guided rockers across the board to save $, they'd do it and did.

-Matthew