Guide clearance
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Guide clearance

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    Senior Member ol guy's Avatar
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    Default Guide clearance

    I hope a few of the head gurus answer this. When the heads (290) were set up all was well, now I have a valve guide holding a valve alittle tight? Bronze wall (not inserts). I have never seen a bronze guide tighten up like this. The valve is straight. IDEAS????? M

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    Senior Member lbhsbz's Avatar
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    Oil cooked and cokes the guide?
    GN7: "If you were to have ever had two brain cells you could rub together and make heat, you be dangerous"

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by lbhsbz View Post
    Oil cooked and cokes the guide?
    My temp never gets that high, oil or water. I just got home from my nights work and I will measure both and random samples to narrow down were the issue is! Thanks for the response. For what its worth it is an exhaust valve/guide that is hanging up! M

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    Senior Member ol guy's Avatar
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    Come-on gn-7. I was hoping for your'e opinion on this. We may argue about ring gaps and stuff but PLEASE don't take it personal I value alot of what you post and what's your'e thought? Never a problem for probably 40 hrs run time and now 1 valve hanging up. M

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    Boat Nut sleekcrafter's Avatar
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    Stainless valve? Inconel would be better, were the guides reamed to size after install? My brad new heads were taken apart, guides were reamed, and new Ferera inconel exhaust valves installed. The exhaust can hang up if they get hot, even worse if the engine suffers from reversion.
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    steelcomp was here
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    Old...how are you checking your guide clearance? Then only accurate way to check guide clearancess is with the proper bore gauges and a C mic that reads in tenths. Bronze guides will definitely grab abvalve if too tight...they're no less prone to this than anything else. You also need to make sure you're running chrome stems. Marine apps...absolute min. 0015 intakes, .0017 ex. Blower apps, .0019-.002 ex. I've never been able top ream a guide acurately ane be done with it. It always requires honing for the final fit.
    When you say "290", what 290 are you talking about?
    Last edited by scott foxwell; 08-07-2011 at 11:39 AM.
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    Senior Member ol guy's Avatar
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    Thanks for the responses guys! Steel when I said 290 that was the cast heads I am running, with alot of work done. The valve guide tightened up at the last 1/2 inch in the combustion chamber, so it could be heat related? When they were put together every thing was fine for quite awhile. I am running good stem seals and now thinking of loosing them on the exhaust side only. M

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    Senior Member wagspe208's Avatar
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    Personally I don't run exhaust seals on fresh guides. At the first freshen up, it depends on application.
    Now, how were the guides sized? Meaning were they broached (not if thick walls), reamed, or honed with a sunnen guide hone? And with SC... I use a Sunnen gauge. It is fast but also takes a little practice.
    The failure I had with the guys engine was with used valves and some taper in the stem (like .0002")
    I am not a fan of reaming for tons of reasons. Honing takes some skill to get them straight. Not rocket science, but not tear down guy easy either.
    Wags

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    gn7
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    Quote Originally Posted by ol guy View Post
    Come-on gn-7. I was hoping for your'e opinion on this. We may argue about ring gaps and stuff but PLEASE don't take it personal I value alot of what you post and what's your'e thought? Never a problem for probably 40 hrs run time and now 1 valve hanging up. M
    Been alittle busy a busy with the races at Long Beach with my own issues

    I don't get into valve clearances and seat width much. I leave that to the head gurus. But what caused it to tighten, thats hard to say. More curious why you say its in the last half inch on the chamber side. Like Steel said, measuring guide clearances accurately take some specialized measuring tools that most us do not have, and have little use for to justify the cost. Not to say you couldn't see it was tighter in one area using nothing more than a ball gauge, just hard to tell the exact size, just that its tighter.

    I would think galling the guide could tighten one up in a given area, but that would be pretty easy to see.
    Never seen one tighten up that wasn't damaged, but then I haven't seen everything.



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    Senior Member wagspe208's Avatar
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    Quote Originally Posted by gn7 View Post
    Been alittle busy with my own issues.
    Fixed it for you GN7. I am glad to see you are finally getting help!
    ROFL
    Wags

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    Quote Originally Posted by wagspe208 View Post
    Fixed it for you GN7. I am glad to see you are finally getting help!
    ROFL
    Wags
    sounds like cheezy rope deflectoritis to me... just sayin..

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by gn7 View Post
    Been alittle busy a busy with the races at Long Beach with my own issues

    I don't get into valve clearances and seat width much. I leave that to the head gurus. But what caused it to tighten, thats hard to say. More curious why you say its in the last half inch on the chamber side. Like Steel said, measuring guide clearances accurately take some specialized measuring tools that most us do not have, and have little use for to justify the cost. Not to say you couldn't see it was tighter in one area using nothing more than a ball gauge, just hard to tell the exact size, just that its tighter.

    I would think galling the guide could tighten one up in a given area, but that would be pretty easy to see.
    Never seen one tighten up that wasn't damaged, but then I haven't seen everything.
    Thanks gn7. I have the gauges and mic's. I have pulled both heads and will recheck clearances to see if it is typical through-out the exhaust side. if so I am going to loose the seals on that side only. I have a strong idea it is heat related with a touch of dry guide. Thanks again guys, I think I over thought the obvious Mark

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    Boat Nut sleekcrafter's Avatar
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    Old Guy, when I had my heads done, the builder popped off the springs when I dropped them off, and proceeded to empty the head. He had a full set of go-nogo gauges for the guides.
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    Senior Member ol guy's Avatar
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    Quote Originally Posted by sleekcrafter View Post
    Old Guy, when I had my heads done, the builder popped off the springs when I dropped them off, and proceeded to empty the head. He had a full set of go-nogo gauges for the guides.
    Sleek, I have a set of ball-snap gauges down to 1/4 inch. I am going to recheck the person who set up these heads and hone to work proper. on reassemble I will be loosing the exhaust seals. On a qwik check about an hour ago, the guides have a slight taper at the last LOWER portion! So now its time to dissassemble both and fix with a hone. I wish I had the old head bench from years ago but now it will be work with what I have. If this were a race deal I would be cutting down the guide and blending, but its just a budget project and we will see! M
    Last edited by ol guy; 08-09-2011 at 05:10 PM. Reason: addition

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