My engine is a L48 "72". I am going to put off any major engine mods for a while but I may go ahead and put some headers on this winter. I thought I would check the condition on my valve springs and rocker adjustments as well. (While the plugs are out it is easy to turn engine to do this) I saw some stamped style rocker arms that had a ratio greater than 1.5 (stock). Is there any benefit to go to a higher ratio rocker? I know I would have more lift but I have never seen these talked about on the forum before. Is this just a Gimick?

 

Yes, you can get 1.6 ratio rockers for your small block. What they don't tell you is that you have to have the heads machined for them to work. Take a look at 1.5 ratio roller tip rockers. They will help some without having to have the heads machined.

 

There will be a small difference in power using 1.6 rockers, but not really enough to notice. The different geometry may cause interference between the pushrod and slot in the head, so be carefull. I would suggest not doing it, but putting that money towards a new cam and springs instead. This will gain you a lot more power than a rocker arm change. 1979toy's idea is a good one too. The roller tip rockers are 1.52 ratio and are much more precise than any of the stamped ones. The ratio of the stamped ones can vary by quite a bit. The only down side of these is the cost. They go for about $130. A new cam will be cheaper than this.

Tom

 

But don't roller type rockers require guide plates because they are not self centering? I have been told guide plates require threaded studs. This would also mean the heads will have to be removed and machined. Think I will stick with stock 1.5 stamped.

 

Hey Steve,
We exchanged some postings about heads. I have looked into Vortec heads and it seems like a good deal. CR is 10:1 though but I have been told because of "fast burn" charateristics it will not be a problem with 93 octane. The show stopper for me at least for now is the intake for those heads by Edelbrock does not support a divorced style choke. It will take some effort for me to convert my Q-Jet. First I will have to convert it to a hot air non-divorced stile..then convert it to electric. ... :crazy:
Or just buy a new Carb$$$$. I think I will wait a year or so, pull the engine and do a complete rebuild. I am to old to be hanging over the fender changing the cam anyhow.

 

Guide plates are not needed. The push rod slot in the heads acts as the guideplate. However, if you chose to go with the 1.6's, then the slots may need to be enlarged, which would require you to add guideplates.

 

I'm going to try & see if 0.10" longer pushrods would give me the needed pushrod-hole clearance for 1.6 rockers. If it works on Sportsman IIs, it might work on other heads too. I'll post my findings when I get around to doing it.

 

This is the 64 dollar question. I have destroyed a lot of expensive parts over this. My 993 GM castings were not opened up by the machine shop since I was using 1.5 roller rockers. Screw in studs were installed, but not guideplates. After bending pushrods, having the pushrods beat up the roller rockers and lifters I started e-mailing cam manufacturers, roller lifter manufacturers, and the 2 major speed shop mail order houses that I deal with. The results were: 3 said guideplates were not required, three said that they were. Real bottom line? There's only one way to find out if your heads have the proper clearance for pushrod travel with roller rockers and it may be real expensive. Smarter choice is to use guideplates from the start. In my case I'm going to have to remove the heads again to have them machined for guideplates, different studs, new roller rockers, new pushrods, new lifters and possibly a new cam.


[Modified by 1979toy, 4:13 PM 11/8/2001]

 

In my experience over the years, I have found that using a set of quality hardened pushrods will prevent a lot of damage and/or wear. I was having problems with my push rod slots enlarging on my fuelie heads. This would allow the rocker to slide off of the end of the valve. :smash::smash: :eek: It was happening often enough and I got tired of messing with it and bought a new set of heads. Within a year, I noticed similar wear in several of the slots on the new heads. I was using factory type pushrods with cheap Summit stamped rockers. I finally relized that the stock soft pushrods were flexing under load and wearing the slots out over time. This would eventualy cause the pushrod/rocker/valve stem geometry to progressively get worse adding even more stress to the pushrod ,causing it to bend severely.This combination of crappy parts cost me a bundle of $$$. I now use fully hardened pushrods and roller tip rockers on both my Vette and streetrod and have not had anymore problems. I did end up putting guideplates on the Vette heads since these slots were already worn too much. The steetrod does not have guide plates, but has always had hard pushrods and the roller tip rockers. This motor sees 7500+ somewhat regularly and the slots are still in great shape after alll of these years.
With that said, the factory slots are good enough, but guide plates will add a piece of mind.

 

If I switch to hardened push rods, do I also have to replace the lifters? I am planning on doing the cam next year and will deal with the lifters then.

 

So It sounds like if I go to roller rockers 1.52 I still may be assuming risk if I don't use guide plates even if they are not required. If I stay with stamped rockers @ 1.5 w/ hardened rods, I should be ok. Romoving the heads and machining for guide plates is beyond the scope of what I want to do. I will be replacing the heads in the future anyway.

 

No. Replace cam & lifters together. You can go to Comp Cams 1.52 roller tip fine. If you want to go to 1.6, then Comp Cams sells the Louis tool for elongating the pushrod slot.

 

Thanks Ganey!! I am assuming if I replace the heads next year, I can just remove the new rockers from my old heads and use them?

 

Like I said in my earlier post, I use the hard push rods and roller tips in my street rod with only the cast-in slots to guide them(NO guideplates). This has worked well for me over the years. Regarless of whether you use the stock slots or guideplated, the danger of bending pushrods is still there. The use of high quality parts(ie, hard pushrods ) goes a long way to prevent future problems. For your fairly stock motor, I don't know that it really matters. When you begin reaching higher rpm levels and must use stiffer valve springs, then hard pushrods become more important. Much of it depends on how you drive you car. I tend to be a little hard on things. I like to run it through the gears often. My driving style puts a lot more stress on things than a more conservative driver. If you plan to drive it like this, than use the "good stuff" in your motor.

Also, you do not need to replace lifter if you change the pushrods. Only replace lifters if you change the cam.

1979toy, Are you using hard pushrods? I would be very surprised if you are having all of those problems with hard pushrods.

Tom

 

tsw71 - The parts that I used were; Comp Cam XE262 cam, Comp Cams lifters, Crane pushrods, Erson roller rockers, Summit springs.
The pushrods contacted the guide hole in the head at the closest point to the stud which would indicate that I should have checked the geometry of the parts. In measuring the pushrods that were available to me at the time I found that not everybodys 5/16th rods measure 5/16th. The Crane rods were 5/16th, the factory rods were 17/64ths. The factory pushrods might have worked in view of the limited interfearance that I got. These heads had been used with the factory pushrods, the same roller rockers, and a milder lift cam.

 

KJL,

I agree the others to stay with 1.5 for your choice of ratios for the roll rockers.

I am using 1.6 because they are reguired with my heads, and are self aligning.

My advise to you is that going cheap when purchasing them is a real mistake. If one fails and the parts get into the engine it is a major problem!

I am using Crane Gold Race and the quallity is excellent and I have had zero problems with them.

They also clear stock valve cover.