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Which Roller Rockers Help?

N

nsxxtreme

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I have an 87 blazer 350 vin K. Valve covers are the centerbolt version. I just rebuilt my motor and put flat top pistons and a little bit better cam in it. It's also the TBI version.

So I was thinking or replacing the rockers with roller rockers. I don't know what I need. Can someone be kind enough to pointout which version I need?

I am assuming I don't need the self aligning version because my heads have the little slots for the push rods. But I need a set that will clear my factory valve covers. I dont know anything about this so please correct me if I am wrong.

Thanks!!
 
My first guess is going to be that you'll need the self aligning rockers. Easy enough for you to figure out if you pull a valve cover. With the valve cover off, look at where the pushrod comes through the head, if its a big round hole you need the self aligning rockers, if it's a rectangal hole and the pushrod touches it then you need conventional rockers.
 
4X4HIGH said:
My first guess is going to be that you'll need the self aligning rockers. Easy enough for you to figure out if you pull a valve cover. With the valve cover off, look at where the pushrod comes through the head, if its a big round hole you need the self aligning rockers, if it's a rectangal hole and the pushrod touches it then you need conventional rockers.
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Where the push rods go through its more of an oval. Not a lot of clearance for the push rod to move around. So I am assuming I need the conventional rockers. But which rockers will clear a set of OEM valve covers? Or do I have to buy new valve covers? If I have to buy new covers then I might pass on the roller rockers.
 
I've got comps pro-magnum (steel rollers) rockers that fit under my stock centerbolt valve covers, just had to grind a tiny bit off the internal supports of the valve covers.

They aren't cheap, but I figure if going roller, might as well go all the way. It would appear to me that the major friction relieving benefit is achieved at the rocker stud, and not the rocker tip, so full roller or none IMO.
 
Well, 87 is center bolt valve covers if the heads are stock. I'm running the Comp Cams Pro Magnum rollers on mine and the stock covers will not work.
 
dyeager535 said:
It would appear to me that the major friction relieving benefit is achieved at the rocker stud, and not the rocker tip, so full roller or none IMO.
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You would be correct. The roller on the tip prevent valve wear but you don't pick up much advantage from that. I want full roller rockers.

From looking on line it seems that the self-aligning version will fit under OEM valve covers. But I dont think I need these, and the others don't say if they will fit under oem covers. I would think this would be easier then it is. I can't imagine I'm the first to want to keep my oem covers.LOL

My heads require the center bolt valve covers.

So close to having this truck back together. I have never really driven this thingyet, I bought it drove it home and tore it apart. Still have a stack of parts that need to go on. I bought 4.56 gears for the axles and ORD shackles to get rid of the blocks. I had the James Bond smoke screan efect going so I rebuilt the motor. One thing I hate is breaking down. Help me complete this thing before summer is up :D
 
I wanted to keep my stock covers but wasn't able to do so. I did find a really nice pair of covers that i'm very happy with that aren't all bling. If you don't mind spending money on valve covers also then don't be afraid to buy the roller rockers you want. Also if you said the hole are oval then you need the standard rockers.

I did find that not all aftermarket valve covers will clear either. The ones i bought are made by ProForm and are licensed by GM, they are black krinkle finish and say chevrolet on them in red lettering. They work as long as you don't install the baffle.
 
4X4HIGH said:
I wanted to keep my stock covers but wasn't able to do so. I did find a really nice pair of covers that i'm very happy with that aren't all bling. If you don't mind spending money on valve covers.
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I don't like the bling and that is one drawback. Most of the covers I have seen are chrome or aluminum. I just want black covers.

Second I dont want to spend as much on the covers as the rockers. Some of these valve covers are nuts as far as price goes.

I'm still searching.....I dont mind modifying my stock covers if they will work. I was looking at the proform rockers as well as some rockers on ebay.
 
Why won't yours fit?

I know you aren't the only one that says so, but with the same rockers fitting mine, I'm not sure why there would be any difference, unless GM changed the internals of the valve covers at some point...I have no idea what vintage my valve covers are, not sure how you'd tell.
 
dyeager535 said:
Why won't yours fit?

I know you aren't the only one that says so, but with the same rockers fitting mine, I'm not sure why there would be any difference, unless GM changed the internals of the valve covers at some point...I have no idea what vintage my valve covers are, not sure how you'd tell.
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The fulcrum portion (shaft) of the rocker would hit the internal baffling and also the center supports of the stock cover, by a TON. There was no way to even trim both the shaft or the baffling/supports to make them work with the stock covers.

Are you running the centerbolt valve covers?
 
I have a question. If this is a TBI engine with a mild cam. Why do you need full roller rockers? If you were running a high lift cam and heavy springs i could see it. But for a mild built low RPM TBI 350? Not needed IMO. Just expensive window dressing. Your money would be better spent elswhere. Like a custom chip you will need it.
BTW FYI unless you have 191 (76cc) heads. Your compression ratio with flat top pistons and 193(64cc) heads will be up close to 10 to one. That will be hard to run on the stock chip.
 
4X4HIGH said:
The fulcrum portion (shaft) of the rocker would hit the internal baffling and also the center supports of the stock cover, by a TON. There was no way to even trim both the shaft or the baffling/supports to make them work with the stock covers.
Click to expand...

Last pic here clearly illustrates what you are talking about, at least between the fulcrums of the rockers:

http://dyeager535.topcities.com/vortec.html

I can't remember since that picture is so old, whether or not the rocker cover center bolt "supports" in that photo were already ground flat or not. I think so, but not sure. The baffle for PCV is close, but no mods necessary. I've got another pair of these valve covers sitting in my garage, I suppose I could compare. They are gray, I was told they are off of a Vortec...the ones pictured are black.

The valve covers DO have to be "angled" into place a bit, they will not go straight down, but it's not an issue, even with my TPI runners bolted in place.

I'm sure this is a given, but I didn't know it right off the bat...the valve covers only go on one way...there is a top and bottom to them, since the bolts aren't dead center.

One question for all centerbolt valve cover owners...did GM ever use "locking tabs" for the gasket? I thought for certain I've either seen gaskets with tabs that would lock into milled tabs in the stock valve cover, or I've seen stock valve covers that were made that way. Just trying to narrow down vintage of these things.
 
Thunder said:
I have a question. If this is a TBI engine with a mild cam. Why do you need full roller rockers? If you were running a high lift cam and heavy springs i could see it.
Click to expand...

I think the "feel good" number thrown out for the rockers is 5hp improvement. Definitely not a good "bang for buck" improvement.

I've got a roller cam, so even though it's not high lift, it's a good load.

As you mention with heavier springs/high lift cam, improvements would be greater than a low lift cam. Still "free" power to be had, for a steep price. :)

If you are doing roller this and roller that, why not everything?! ha
 
I don't see myself spending $300 on roller rockers. I appreciate the suggestion. I think $190 is my limit. If I can't get it done for that I'll go without.

Roller rockers frees up horespower no matter which cam your running. There is a lot of friction in the stock fulcrum set up. I'm looking to eliminate that. I'm not running a stock cam, its a comp cam. Not sure the exact one machinist picked it out. I'll need to check.

My machinist that bored my cylinders and rebuilt my head, said my compression went from 8.5 to 9.0 with the flat tops. I should be fine with the stock ecu. but I may look into that later.
 
Much better off spending money on the heads and exhaust if you are going to look for real improvement, but if you've already done that, might as well go hog wild. :)
 
dyeager535 said:
Much better off spending money on the heads and exhaust if you are going to look for real improvement, but if you've already done that, might as well go hog wild. :)
Click to expand...
Exhaust might be next as the factory manifolds might be hosed.

The heads I'm leaving stock.

The motor is out, I have yet to install the rockers so this is just an easy job. That's essentially why I am debating doing it.
 
Heads and exhuast (headers) you can be talking 80+ HP even on a mild motor...torque equally impressive gains...that's not a small improvement.

It's really kind of bad to throw out numbers (I'm going conservative based on published dyno testing), you need to look at the engine as a package, if you've got a strong cam but choke it by flow, gains will be higher. But even on a stock motor, modern components make HUGE differences in the amount of power you can produce.
 
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