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Triumph TR6 - roller rockers

HAS ANYONE INSTALLED ONE OF THESE AND IS IT A WORTH WHILE IMPROVEMENT? CAN BE EXPENSIVE IF YOU GO WITH THE GOODPARTS ONE? SOMEONE TOLD ME THEY THOUGHT YOU COULD MODIFY A CHEVY ROLLER ROCKER TO WORK ON A TR6?
ian white

I would say Roller rockers would be very last on my list to do. If all the other mods possible are done and you have a lot of toonies burning a hole in your pocket then go for it.
DON KELLY

Hi Ian,

I put 1:55 ratio roller rockers into my car. I cannot comment on their road performance as the car is yet to hit the road. Nevertheless, if you have recently fully rebuilt your head it may be a worth while pursuit; the conventional rockers run steel on steel and exert side thrust on the valve stems cause frictional losses and premature guide wear. A roller rocker with minimal increase in ratio (1:5-1:55) will increase lift ,thus VE, and will decrease valve guide and rocker-shaft wear. I would advise the use of a bronze-lite bushing over the needle bearing centers as the bronze will last at least as long and does not require the use of a tuff-trided rocker shaft. The fore and aft support pedestals may require a slight modification for clearance and can easily be accomplished in a minute or two with a die-grinder.

Although I have not driven the car on the open road, the engine revs considerably quicker and there is a more aggressive note than that of a stock TR6. I do not recall the vendor I purchased from but the cost was about $330 US two years ago.

No idea about the chevy rollers... I think that they are stud mounted and would require at least significant machine mods to the head before mounting.

Cheers, Rob
Rob Gibbs

Thanks Rob,for your advice Iam assuming that you rebuilt your head? What changes did you make to your head? Bigger valves,compression, porting etc
Thanks Ian
ian white

Ian,

the head was rebuilt with new guides , hardened seats, 3 angle grind, decked about .030" or 1mm off, port matched and a modest amount off porting mostly to remove irregularities. Valves and dual springs were replaced with stock sized units. A new rocker shaft, roller rockers and a top feed oil line were installed. I capped it off with an alloy rocker cover having an O-ring groove CNC cut into the bottom edge.... it works great. I did not want to make a race engine but one that would deliver a moderate improvement to performance and having greater durability/longevity.

Rob
Rob Gibbs

Rob, what year is your -6 and what Compression Ratio did milling 0.030" get you?
db
Doug Baker

I ran across this javascript application while looking for something else. A compression ratio calculator can be found at:

http://www.csgnetwork.com/compcalc.html

Lots of other neat stuff at the base web site as well.
SteveP1

Doug,

I regret that I did not cc the combustion chamber and so cannot calculate the CR. I wanted to moderately increase the CR from the low stock 7.75:1 closer to 8.75:1. The head and engine I am using are from a '74 car... my car is a '76 and had the engine changed out by a previous owner. The pistons are +.020" oversize. I wanted to use regular low grade pump gas and not have to worry about pre-ignition problems... no 10:1 ratios wanted. Reading what other guys had done to increase their ratios to varying degrees made me conclude that .030" decking would be "safe" for my purposes. Some fellows were removing over .100" to achieve the high ratios... the danger here is not only the pre-ignition problems, cranking difficulties, etc. but also the possibility of cutting into the water jacket and destroying the head during the removal of so much material. I figure if I want more zoom later I can always pull the head again and re-deck it another mm or so.

Regards, Rob
Rob Gibbs

Thanks Rob,
Mine is a 71 and already at 8.5:1 and with Steve Pike's counsel and advice, I'm sneaking up cautiously on 9.5:1, but like you, am fearful of taking too much off and inviting too many other issues. I've cc'ed my combustion chambers (after a fashion) and have determined that they are stock at 51.5cc and with a block height of 3.46" it looks like I'll need to shave about 0.047" to get to 9.5:1 but I've got to do some more figuring. Steve's discussion of swept and unswept volumes leaves my head hurting! I've got 0.010" lip on the block and many recommend a flat block, but messing with both increases the risk of errors to both. Thanks for your response.
db
Doug Baker

This thread was discussed between 31/03/2009 and 14/04/2009

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