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TR2/3/3A Street cam again and Valve gap?

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karls59tr

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Could someone who is familiar with camshaft speak advise me on what valve gap I should be using with this cam. Here are the specs as written on the bill
M518 Cam...duration 227" @.050"(280"advertised).....280"cam lift....420"valve lift on 109"Lobe C/L
I've been running this cam for years and the engine pulls strong but I've just kept the valves gapped at the stock .010 ......I think I researched this years ago as I found a piece of paper where I marked down to set the intake and exhaust to .016? Anyone knowledgeable in these things think I should open up the gap to .016? Anyone running a similar cam on their TR3?
 
Many times they recommend a slightly larger gap with performance cams, but I have no idea how this is arrived at or calculated. I might open up the gap a couple more hundredths and call it good if I didn't have the specs that were provided with the cam (if any). But that is just a shade tree mechanic aw shucks golly durn approach, maybe others can provide a more precise answer.
 
So if I opened up the gap by another .004 would the there be a noticeable improvement in performance? Would I have to make timing and carb adjustments? Should I leave well enough alone?:eagerness:
 
I have an Erson 149 grind (from British Frame & Engine), and it has figures very close to yours and the recommended gaps are 0.016" (intake) and 0.018" (exhaust). I also have a list of almost 50 TR3/4 cam specs, and all of the non-stock ("performance type") cams have increased valve gap specs, anywhere between 0.012"-0.022". Unfortunately, my list does not include a cam of your exact specs, but all of the similar cams have valve gaps listed between 0.013"-0.018". I would go with the info on that piece of paper...0.016". There's a reason you have it.
 
I am no cam expert but with my old motorcycles and sometimes unkown various high performance cams I usually go by the hot clearance.All the specs are cold clearance for the obvious reason of ease of checking and adjusting,but the end goal,I believe, is minimum clearance at maximum temp.So a quick check of a couple at temp shoud give you an idea if they are to tight.Too loose you will probably hear.
Tom
 
karls59tr said:
So if I opened up the gap by another .004 would the there be a noticeable improvement in performance? Would I have to make timing and carb adjustments? Should I leave well enough alone?:eagerness:
Click to expand...
Should you or shouldn't you ?
Take this into consideration. The larger the gap, the longer the valve will rest on it's seat. The longer on it's seat, the more it can cool down. That's an important aspect especially concerning exhaust valves.
 
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