Roller Rockers

Head rebuild upcoming, should I upgrade to roller's or stick with stock? If upgrade then which vendor? Again, thoughts, experience and suggestions are being sought.

More important than the rockers is the headwork it will take to get any benifit from other mods.Larger valves and porting lay the ground work for HP. I would suggest at least SOME porting for a mild street prep. If you are replacing valves, go bigger. The stock motor needs more compression, and head milling is a quick way to get it. Also the goodparts tricarb set-up is a hot lick, love mine!
MD(mad dog)

Hi,

I've been planning to put roller rockers in my TR4 engine, but realistically I'm looking for quieter running and less wear and tear on the valve train, not any sort of significant performance increase out of the rollers themselves.

I've heard that there are some pretty bad rollers out there, don't hold up well, at least in the 4-cylinder motors. Many of the TR vintage racers have reported problems with roller rocker installations. I am trying to find out now what's reliable and what's not.

One thing seems true for the 4-cylinder engine, perhaps for the 6-cylinder as well. There is little sense in going to an increased ratio roller rocker. The cam is a better place to design in some increased lift. In fact, increased ratio roller rockers might do more harm than good. Most TR cams appear to be designed without any increase in mind, and broken valve springs, or worse, could be the result.

I agree with the other response. First spend your money on a good cam. Then head milling, porting and valve work. Next dial in the carbs and exhaust. Then look at the ignition. Overall, hotter motors generate more heat, so make sure the cooling system is in good order and possibly add an oil cooler. Maybe then roller rockers, if you want to do things in a sequence, not all at one time. After all, roller rockers are largely a bolt on modification, can be done after all else is back together and running, maybe a change of pushrods will be needed.

Depending upon how you want to use the car, be careful not to get too extreme with modifications. Too radical a cam, too big valves, too much carb, too light a flywheel might all make a car a blast on a race track, but less than fun on the street. I think many "tuners" get carried away and end up with a car they don't enjoy as much as they thought they would.

Cheers!

Alan

Having a midget with a 1500, I have been quite happy with TSImportedAutomotive's roller rockers which go on the stock rocker shaft. They have held up well so far, for about 2000 miles, many of which were 'sporty.' They held up better than my pushrods, which needed replacement after only 1200 miles ... guess they weren't that great! Incidently, they're 1.55:1 ratio instead of the stock (for Spit/Midget) 1.45:1. I assume the TR-6 motor has the same rockers. The Moss/VB rockers include a new rocker pedestal and are extremely expensive for only .1 on the ratio.

Matt

Matthew, funny you should write and mention TSI. I met Ted Schumacher, MR. TSI, at Road Atlanta yesterday. An interesting and very knowledgeable fellow. I believe TSI is redistributing Harland Sharpe rollers at $30 per unit which is the cheapest I've seen them. These appear high quality, 1.55 ratio and run on a bronze(?) bearing, not needle bearings like Goodparts product which cost substantially more. What rod replacement did you choose.

Hi again,

Ted & TSI are one of the better recommended sources of roller rockers I've heard mentioned. Because I work on 4-cylinder TRs, I really have no experience with Goodparts and can't comment out their stuff, mostly 6-cyl. oriented AFAIK.

One key recommendation I've seen mentioned several places is that it's a very good idea when installing a new set of rollers to also replace the rocker shaft. Even imperceptible wear in the shaft can lead to problems. Makes sense to me. And, sometimes there are hardened versions of the shaft, or it might be possible to have one nitrided locally. For bushing-type roller rockers, I imagine that's mostly for initial break-in purposes, much like camshaft and crankshaft hardening. However, it appears mandatory that a hardened shaft be used with needle bearing roller rockers.

BTW, a little more food for thought. Shopping around it appears the "latest and greatest" roller rockers for V8s use bushings instead of needle bearings! Just the opposite of what I expected. The explanation of the "problem" with needle bearings in this application is that they need to reverse direction with every stroke. The concern is wear and early failure of the needles and/or shaft they ride upon and a potential for binding. So, bushings are being touted as "better" by some manufacturers.

But, how much of this is marketing hype and how much is truth I really don't know. I would speculate there is little real world difference in a car that spends it's life operating under 6000 rpm, like our TRs generally do. If you are building a car to run regularly at 8000 rpm, this might be more of a concern.

If you go with any increased ratio, just be very sure to spec your cam lift accordingly and double check for valve spring binding.

Tubular pushrods are recommended for additional strength, reduced flex, lower weight and easier modification to the correct length, if needed.

Still in the valve train area, one weakness of the TR4 setup is the cantilevered shaft at either end, serving the last two valves. A strengthening upgrade is available in the form of special front and rear pedestals that better support the entire length of the rocker shaft. I don't know whether or not this is an issue with the 6-cylinder motor, too.

Cheers!

Alan

I actually had a custom set of hollow pushrods which were about .1" shorter, but they failed due to a head oil problem. I figure the gasket or some debris interfered with oilflow to the head. After one pushrod failed, I tested and found that oil would take an extremely long time to reach the head, despite the fact that the pressure was excellent. I installed the auxillary oil feed and replaced the hollow pushrods, which showed signs of failure on others as well (the cups were spreading, making the valves very loose). I used the stock pushrods (one from my spare engine, as apparently one of the old ones from my current engine got bent somehow). The bearings (not roller) on the rockers had slight evidence of scarring, but it was very slight, despite the unfavorable operating conditions. There is no harm in using this type of bearing so long as there is adequate oil flow. Why else would they use it for main/big end bearings? Now the rockershaft drips with oil and I have had absolutely zero problems in the valve-train department. My trans/rear axle is a different story as of a week ago Sunday ... hehehe ... too much racing!

Matt