I know the Crane and Comp Cams roller rockers are good. Anyone know anything about the Summit Racing rockers? How about Scorpion? Just researching brands.

I have centerbolt valve covers, what do I need to look for to make sure they will fit properly with my valve covers? With 1.6 ratio rockers will I have any clearance issues with standard aftermarket Chevy valve covers?

Also what is the major advantage of the bigger rocker studs? I bought a set of used heads and they already have them installed. If I find a smokin' deal on a set of 3/8 stud rockers is it possible to go back to that size? Or is that not a good idea?

 

The CC ProMagnums have lower rotating mass (less valve train inertia) and are stronger than Al RRs so they are my #1 choice when going to 1.6:1 ratio.

When installing RRs onto the #113 heads ('88-'91) you will need to pull the factory non-hardened guide plates, which requires removal of the rocker studs. For me this made it a no-brainer to go with 7/16" studs and matching RRs. These thicker studs reduce deflection at high rpm and so maintain full valve lift.

Also, since the OEM guide plates are comming our anyway, just go with hardened guide plates & push rods and get non-self aligning RRs. These are only $260 compared with over $300 for self aligning, so about the same either way.

Also install new valve springs and machined keepers and set seat force to around 110lbs (stock was around 85lbs!!).

 

Smokey Yunick once explained the disadvantages of an aluminum rocker arm.
He said that while they are lighter (have less inertia) than a steel rocker...including the cast steel roller rockers...they have lower fatigue strength. This means that unless you plan to replace them regularly (which is what the race teams do), you risk losing one. For street use, ol' Smokey liked steel units.

Hey, he said it...not me.

The seller should be able to tell you which valve covers his rockers are compatible with. If he can't, find another source.

Larry
code5coupe

 

I don't know who makes Summit's RRs. If they won't tell you, I wouldn't buy them. If they're Proforms they're junk, run the other way! Comp Cams Pro Magnums are hard to beat for street cars.

 

Oops, missed the question about valve cover fitment.

I had to reduce the height of the drip tabs in my stock '88 valve covers as well as narrow the bolt towers to get the valve covers back on over the ProMagnum 1.6:1 RRs. But that's no big deal with only a Dremel tool.

 

Are there any 1.6 roller rockers that will fit under stock LT-1 valve covers? What about 1.5 roller rockers?

I like the idea of roller rockers and heard 1.6 ratio on an otherwise stock engine makes virtually no difference. So maybe I'll pick up a set of 1.5 if I don't need to cut my valve covers.

Thanks

 

I missed it too but then he didn't mention exactly what year/ engine either. Oh and hz900, if you're buying rockers anyway, might as well stick w/ the 7/16" studs. There's no disadvantage fitment-wise with the Pro Mags, they make them for both stud sizes.

I'm told the 1.6 Pro Mags will fit the later LT1 (composite) covers (like your '95 should have) w/o even shortening the drip tabs. But mine were already cut because I had aluminum RRs on the engine before I switched to Pro Mags. Who told you 1.6 RRs wouldn't make a difference on a stock engine? They are FOS! It will make a difference you can feel. However, a valve spring upgrade is highly advisable. The LT4 springs will do nicely for this and are only about $40 new. They can be had with their own retainers but will also work fine with the LT1 retainers.

 

Thanks CK! If they do in fact make a difference then this mod moves to the top of my future mods list! I still don't like the idea of cutting my drip tabs so that's good if they'll fit under the composite covers. Does anyone know for sure?

Thanks

 

So you'll know, the drip tabs are not needed for RRs, they oil internally. The tabs are to provide the stock stamped rockers with a little extra insurance.

 

[QUOTE=I'm told the 1.6 Pro Mags will fit the later LT1 (composite) covers (like your '95 should have) w/o even shortening the drip tabs. But mine were already cut because I had aluminum RRs on the engine before I switched to Pro Mags. Who told you 1.6 RRs wouldn't make a difference on a stock engine? They are FOS! It will make a difference you can feel. However, a valve spring upgrade is highly advisable. The LT4 springs will do nicely for this and are only about $40 new. They can be had with their own retainers but will also work fine with the LT1 retainers.[/QUOTE]

Comps Hi-Tech and Pro Mags, Crane Gold, Crower SS and of course the GM LT4 rollers aka Cranes will all fit without any issues under the composite LTx valve covers. Scorpian, Pro-Form, Summit are chinese rockers, also there are the CAT rockers now that copy the Comp Hi-Tech SS rockers, these are also Chinese. I can tell you that the copy is very good as far as visually goes, they look nearly identical to the Comp Hi-Tech which goes for nearly $400 but they sell for nearly half of what the Comps sell for. But for me I wouldn't risk a big dollar engine with a $200 savings for cheap rockers that may or may not break. At least not until they are proven to me that they are OK.

I often wonder what the acronym CAT means......Chinese Auto Tech maybe Not saying anything bad about Chinese, obviously I am Chinese, only that I have worked in China and have seen how cheap and how crappy their QC is, but at the same time I have also seen parts equal or exceed that of US made parts as well.....

 

Yes, and it's not like you can't buy good AND junk parts made in the USA too. But definitely don't scrimp here. I saw a set of Proforms begin to just fall apart after only a few thousand street miles. They were properly installed and adjusted in an otherwise healthy engine and did not see excessive RPMs.

 

Thanks TJ. What do you recommend? What's the best bang for the buck?

Also, a related question, does the LT4 springs (oval section) require a special valve seal? I'm thinking not but I just want to confirm my assumption.

Thanks

 

When I installed my LT4 hot cam kit, I tried to use my stock '95 valve covers, but they did not completely fit. I bought a pair of the '96 valve covers which eliminate these tabs to clear the LT4 rockers. If you are using a set of the Comp stainless steel rockers, those may be smaller and can fit... Just have to try it out I guess.

 

If you are using the LT4 HOT cam springs that comes with the GM kit you can use the standard replacemen valve seals with the springs. The best bang for the buck would be the Comp Pro Mags or the Crane Gold race rockers, or the GM rockers which are identical to the Cranes except that they are silver and have a little bowtie stamped on the body. I think that you can get the GM rockers cheaper than the Cranes if that is the case I would go with them unless you can get the Comps at a better price. Any of the three would be a good choice. If you were going with a high lift cam, hotter duration and heavy springs I would go with the Comp Hi-Tech or the Crower SS versions. These are extremely durable rockers next to going with shaft mounts, and that is another can of worms and not worth the money or the headaches in a street engine. One problem I did run into with the Comp rockers is clearance issues using a 1.50" to 1.55" spring, we had to use a slightly longer push rod to get the added clearance so that the retainer would clear the rocker. Crowers gurantees clearances up to 1.55"

 

Crower stainless steel rollers, and they are rebuildable.

 

Is that installed height? I plan to replace my springs with the LT4 springs, GM pn 12551483. I read the installed height is 1.78" and 101# seat pressure. So I should be Ok with the Comp rockers right?

 

I believe that is spring diameter. That is larger than the stock springs, likely due to dual springs.

 

Yes, that is correct the Comp Hi-Tech rockers and most likely the Pro Mags has a clearance issues with the larger OD springs. Comp says no but I have found it on two occasions. With the standard LT4 springs or other springs less than 1.50" OD you will not have a problem.

 

Why don't you use beehives?