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Roller Rocker Tappets


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A previous owner of my 5 fitted roller rockers, amongst many other mods. During this lockdown I thought I’d set the tappets as they are very noisy. Would the gap be the same as a standard rocket shaft? I’m not sure which cam is fitted but I would guess at a sporty version. 
thanks Paul 

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Hi Paul

i think you should try to find out what cam you have and the correct settings for it.

clearances vary a lot, my cam needs 24thou all around which surprised me

steve

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Paul/Steve, this is a dilemma close to my heart as my TR6 PI also has a fast road cam fitted I believe, but have no idea which one. Tappets seem "very cattery" and need to check/set the correct gaps etc. Is there a way to measure and determine which cam it is or at least work out the specification without removing the head, camshaft or other major components?  A discussion on this would be very useful.

Regards, Colin. 

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I’m pretty sure my cam was fitted by Racetorations in the 90’s. I have a lot of old paperwork and I know they rebuilt the engine around this time. 
I found reference to the MU been sent away to calibrate it to a 777-1 camshaft. But I’ve searched and can’t find any info on it. 

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11 minutes ago, paul7 said:

I’m pretty sure my cam was fitted by Racetorations in the 90’s. I have a lot of old paperwork and I know they rebuilt the engine around this time. 
I found reference to the MU been sent away to calibrate it to a 777-1 camshaft. But I’ve searched and can’t find any info on it. 

Then give Racetorations a ring and ask them for information .

Stuart.

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18 hours ago, paul7 said:

 I thought I’d set the tappets as they are very noisy. 

First thing I'd do is check the lift, take a cursory measurement of each valve's stroke. When mine got noisy it was due to lobe wipeout, a common occurrence with cams produced since the engines were in production. Unless all due diligence is done failure is likely. Plenty of press given to this topic on this forum.

I have (2) engines in service on my '250s. The driver's has always been a bit noisy but now has 130,000 miles on it with no change, CP cam in it, 10 thou clearances. The other has a ferocious cam with 292 degrees duration and 0.504" lift, clearances 14/16 thou. Quiet as a mouse!

 

Tom

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1 hour ago, paul7 said:

I’m pretty sure my cam was fitted by Racetorations in the 90’s. I have a lot of old paperwork and I know they rebuilt the engine around this time. 
I found reference to the MU been sent away to calibrate it to a 777-1 camshaft. But I’ve searched and can’t find any info on it. 

Paul take a look at this 

https://www.tr-register.co.uk/forums/index.php?/topic/62237-tr6-camshaft/&tab=comments#comment-531660

777  timing 30 70 30 70 lift .327 tappets 0.24 duration 280 install figure 107 

Edited by Graham
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25 minutes ago, Graham said:

 

  timing 30 70 30 70 lift .327 tappets 0.24 duration 280 

High lift/duration ratio with corresponding high acceleration forces on the valve train. A common recipe for failure; countervailing testimonials of long life welcome ^_^.

 

Tom

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Graham that sounds like to one. 0.024". Later in the week Ill take the rocker cover off and see what they are currently.

Stuart Ive contacted Daryl I'm waiting for him to get back to me.

 

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1 minute ago, paul7 said:

Graham that sounds like to one. 0.024". Later in the week Ill take the rocker cover off and see what they are currently.

Stuart Ive contacted Daryl I'm waiting for him to get back to me.

 

With roller rockers that is correct, the problem with some cams was simple made of cheese and incorrect oil journals common problem at the time ( depends when that was) you could cut one in half with a basic hacksaw with ease seen it done by a supplier.

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Darryl has just been in touch. To add confusion they produced 2 slightly different 777-1 cams in the 90’s. One set at 0.022” inlet 0.024” exhaust the other later one 0.016” and 0.018”. Darryl suggests the later gaps. I’ll measure as is now and take it from there. 

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