Burton BF134 timing issues

[kliobas]

I bought a Burton BF134 camshaft which came in Kent box (however got a "bf134" stamp on the back), they advise such figures:

Valve Lift: 0.460"
Duration: 266°
Timing Figures: 23/63/63/23

However I tried to measure these figures and got different results. I set valve clearances as required, used 0,25mm checking height and at first 0 deg on cam pulley. The results on inlet were 12/71. Then advanced 4deg and got 20/63. the duration is very similar to Kent FR34. Then advanced to 5 deg on cam pulley and got 22/61 as it should be on FR34, but the exhaust showed 62/6. So the exhaust duration is only 248 deg??? Am I missing something while measuring, or something is wrong with the cam? Valves are standard by the way so the rocker geometry should be fine.

Also I checked the valve lift, my indicator cannot measure that precisely but I got definitely more than 11,8mm which is more than it should be on BF134. It looks like this cam is more similar to Kent FR34 but exhaust duration is quite short (checked on 3 cylinders). Now I'm not really sure how to set cam pulley as well.

Thanks,

[Graham]

Heaps of fun,

kent grind burtons cams so that explains the box.

First off cams almost NEVER give the timing advertised, and its very unusual to get exact lift, and just because the valves etc are standard doesnt mean the geometry is right! if you get a bit more lift dont worry thats a good thing.
timing checking is usually done at 0.5mm lift not 0.25, but when it comes to actaully timing the cam ignored the stated opening and closing points, its too difficult to accurately determined them.

time the cam so the inlet has full lift 110 degrees ATDC that will be spot on or very close to what the engine actually wants

[kliobas]

Many thanks, Graham, I have seen information on this forum that exact figures are not achieved but different duration somehow confused me. I will set the timing as you suggest, thanks once more.

[Miniliteman]

The Kent Cams catalogue states that timing figures are checked with 0.25 mm checking height.
If you find it somewhat difficult to get the full-lift timing at 110 degrees ATDC you can also set the cam so that both inlet and exhaust valves are open the same amount at TDC.

[Dyno]

Let us not start the discussion a camshaft can be wrong grind so because we are 100% sure about the grind, timing will be very easy.

Don't try to measure anything at 0.25 , 0.50 or anything else. Fit the camshaft and measure the lift for both inlet and exhaust valve at TDC when symmetric installed. You should normally find a number close to 1 mm for this cam (really depend on who is grinding the ERSON 134 and also how short or long are you valves). Mine normally correct installed measure less than 1 mm. OK, id does not matter here. let say, you find 0.9 mm

This means you adjust the camshaft until both inlet and exhaust are at the same lift. Now you advance the cam until you find little more lift for inlet as for exhaust at TDC. Numbers like 1 mm inlet - 0.8 mm exhaust or 1,1 mm inlet and 0,7 exhaust are all fine. You can check max lift after TDC for inlet later as a reference but it is of no real use. The most important stetting is done and can only be fine tuned at a dyno but believe me it will be rare to find anything better.

This is the best installation guide for any camshaft grind with almost identical inlet and exhaust profile and both inlet and exhaust on a fixed shaft.

PS: shorter valve stems can give more lift as advertised, it will also give wider lobes and that's 2x good news.

[Flighter]

Also I checked the valve lift, my indicator cannot measure that precisely but I got definitely more than 11,8mm which is more than it should be on BF134.
Thanks,

I'm in the middle of setting one of these up too, and found exactly the same thing.

[kliobas]

So I ended up with 3 deg advance on a camshaft pulley to have approx. 110 deg ATDC of inlet valve full lift, seems to be reasonable. Will see how it goes, many thanks !

[Dyno]

Did you measured the lift at TDC for both inlet and exhaust? This more important than the 110° you are now talking about.

BTW, if you only measured the full lift for inlet (110°) and not measured the full lift for the exhaust you still don't know anything because it's so easy to change the LC if the geometric is incorrect setup.