TR2/3/3A Camshafts and Valve Settings Conundrum?

[karls59tr]

Hello All I asked this question years ago but am looking for new insights. Here are the specs for a Shadbolt 518 fast road cam: 227 degrees @.050"..... 280 degrees cam lift ........420" valve lift on 109 degree lobe c/1 The cam supplier is no longer available so I can no longer get the correct valve gap specs from him. I believe I have been running the car with the valve gap at at the stock .010 and it seems to run well enough but I would like to try and set the valve gap closer to the correct valve gap that the cam needs. I have heard that for a 270 cam I should run .014 intake and .016 exhaust? I have also heard that the cam I have is similar to a Kastner D grind cam which should be set at .014 Hot? As well specs are possibly similar to an Erson149 cam? Should I try .012 inlet and .014 exhaust to see what that is like???????

 

[CJD]

The .010" will be easiest on your drive line, so long as it's running well. The manufacturer grinds the lobes with a short "entry ramp", which takes up the slack in the valve train before the lobe starts the aggressive valve opening. Setting the valve clearance smaller will normally give the best performance and ensure you are not getting past the entry ramp on the lobe. With too much gap...past the entry ramp...the valve train gets hammered pretty hard. The worry about too little clearance is the chance that the valves are not fully closing, which will burn the exhaust valves in short order, and results in a terribly running engine.

So...always go with the manufacturer specs. But, if they are not available, I think you will be fine with .010 to .012" range. Check them once warm, just to ensure there is still some clearance when the valvetrain is hot.

 

[Stevenry]

My BP270 cam (in a TR 2-4) from British Parts Northwest is .012 intake and .014 exhaust.

Steve

 

[karls59tr]

My BP270 cam (in a TR 2-4) from British Parts Northwest is .012 intake and .014 exhaust.

Steve

Thanks Steve Do the specs from my cam look similar to yours? The "270" part sounds encouraging.

 

[charlie74]

This is from the Newman Cams website which my BP 270 cam from BPNW is a Newman cam. Presumably by the descriptions of the cams mine is the first one and valve clearances are listed although they are all the same. This being for a TR6, mind you…

 

[Hamish Racing]

my old 87mm engine ran 12-14 gaps
My new engine has similar to the 300 cam spec and runs 14-16 gaps
So very cheap engraving place created this for the top of the rocker box

 

[karls59tr]

This is from the Newman Cams website which my BP 270 cam from BPNW is a Newman cam. Presumably by the descriptions of the cams mine is the first one and valve clearances are listed although they are all the same. This being for a TR6, mind you…

View attachment 76349

Thanks for the info most appreciated.

 

[karls59tr]

my old 87mm engine ran 12-14 gaps
My new engine has similar to the 300 cam spec and runs 14-16 gaps
So very cheap engraving place created this for the top of the rocker box

My engine is basically stock except for an exhaust header and a TR4 intake manifold so I am going to set the gaps at 12-14 and see how it sounds.