roller rockers

[71tr]

Anyone have experience with roller-rockers in a TR? What are the benefits, costs, brands etc?

 

[Guest]

I put the roller rocker train in from GoodParts (same one TRF sells). I THINK I see some improvement. I have a new head (stock) and the thing never goes out of adjustment. Talk to Richard Good or read his website as to any advantages of this setup. Ex$pen$ive. Worth it? Questionable.

Bill

 

[sammyb]

No experience with roller rockers in my TR, just rock'n'rollers! /ubbthreads/images/graemlins/wink.gif (Sorry, I was just in my music room playing a little bass and drums, so it was on my mind.)

 

[LastDeadLast]

I think the answer with the roller rockers is "it depends". I'm in the middle of a fairly hot engine build (cam, compression, triple carbs, headers, and roller rockers) and I think that like most things the more you mod the motor the greater the benefit. You might feel a little difference with a stock motor.. I think Richard Good claims up to 10%.. which may or may not be true. Are they better than the stock setup? Heck yes! but on a stock motor are they THAT much better? Well it might depend on your pocket book at the time. The good thing about them is that you can install them relatively quickly and without having to rip apart the motor.

That being said, the best doller per horsepower investment you will ever make will be a compression bump. It's a little more hastle than the roller rockers, but for the same cost you could probably get a better result (assuming your current heads don't need a rebuild).

 

[SkinnedKnuckles]

Hey, 71tr

There's lots of experience out there with roller rockers. The benefits of using that as the only valve train mod, though, are small. One of the big benefits, besides increased lift, is that the GP set has roller bearings on the shaft as well as the one on the valve end. That decreases friction and the galling tyipcal of the shock set-up.

My sequence of mods was a CR boost to 8.5:1 (small but noticable power increase), 1.55:1 roller rockers (another small increase), another boost in CR to 9.5:1 (another small increase), then finally a different cam during an engine rebuild (GP-2, for info). The cam made the biggest difference, but I'm sure the other incremental improvements helped.

One thing to always consider is the total valve lift you are working on. The cams don't have bearings, but sit in a smooth machined iron journal. From what I've read if you take the valve lift above about 0.41" with performance springs, bearings are recommended. I opted for a moderate set-up that takes it up to that level, and I didn't install bearings.

 

[ALLAN]

I run Goods rockers 1.65 with 10:1 compression and headers, originaly with stock cam and stock carbs but now have webers and Goods cam. The rockers made a noticable difference,(added the rockers after adding the compression and headers). there was increased power through the entire rpm range from idle to 6000 rpm and still had alot of torque. The rockers not only increase the lift but also slightly increase duration. The rockers would probably make a little difference with a stock engine but with only a compression increase and free flow exhaust they will make a big difference. my opinion is that if you go with the rockers the 1.65 are the way to go I dont think the 1.55 will give that much to be worth the cost. Allan

 

[Simon TR4a]

First of all there are several variations:
1)Full roller rockers or roller tips only.
2)Standard ratio or high ratio.
3)Rocker arms cast iron, pressed steel or machined from billet aluminum.

The potential benefits of standard ratio rockers are obviously in the area of reduced friction to reduce wear or free up very small amounts of power.
The benefit of a more rigid rocker arm is more accurate translation of the cam contour into valve motion.It would be beneficial to use stiffer pushrods or you will simply trade rocker arm flex for pushrod flex.
Only the higher ratio sets will give a noticeable gain in power, and if you already have a high lift cam you must watch the clearances carefully (by claying the engine) during assembly.
Mainly I would say the gains would be realised at higher revs, over 5000rpm maybe, where the reduced friction and more accurate valve movement is beneficial.
Ted Schumacher at TSI is another source, especially for 4 cylinder TR motors; I believe the full roller sets require a thicker valve cover gasket to provide clearance.
Suggest you speak to Ted or Richard Good (or whatever vendor you choose) about your application, and get their advice. Good luck!
Simon.

 

[ALLAN]

The original question here was who had experience using roller rockers ( "accurate translation of of cam contour into valve motion"-- give me a break.) Richard Goods 1.65 roller rockers will give you good power gains throughout a broad rpm range when used in conjunction with more compression and a free flowing exhaust even with a stock cam. Dont worry about rigid rockers and stiff push rods unless you are building an all out race engine, The stock P.I. push rods work great for most applications when the head has been shaved for more compression.

 

[LastDeadLast]

Concerning push rods, I spoke with Richard Good after my head was shaved (he was the one that did my head work and he shaved them for 9.75:1 CR). He recommended the stock length push rods over the P.I. push rods when using his roller rocker setup. He did however tell me to use the tubular push rods instead of solid.

 

[Simon TR4a]

Allan, some of my post is obviously a discussion of race prepared motors, clearly there is little benefit for an otherwise stock motor unless you change the ratio. Reliability at high revs is improved significantly in race motors by use of stronger valvetrain components.
The original question does not tell us if its a Spitfire or TR6, or a mild or race engine.
Cam profiles are machined to tolerances of 1/10,000 of an inch, so someone must think this is important!
Simon.

 

[Dave Russell]

Simon,
I agree. While probably not noticeable on a mildly tuned engine, stroboscopic pics & even careful measurments have shown that flex in the pushrods & possibly rocker arms, as well as inadequate valve spring pressure, prevents accurate translation of the cam manufacturer intended cam motion to valve motion.
D

 

[JFS]

I have been running high lift (1.65:1) roller rockers from Cambridge in the UK on my TR3, which is quite modified for a street car, for about 12 years. They have needle bearings which slide onto the rocker shaft much more easily than the rockers from Goodparts, which I have installed on a TR6. Since the rockers combine with my Elgin cam for a .427 lift at the valves, I had to use performance valve springs from British Frame And Engine to prevent spring bind. I have been pleased with the engine's performance and roadability, although I have to give it some gas when starting out from a stop.