Brian Builds the Kerzel Hit and Miss I.C.

[Brian Rupnow]

Just tossing this one out there but could the valve springs be to light. If the spring pulled a little harder maybe the valves would seal some more.

Could the exhaust valve be being pulled open on the intake stroke? I dont know!!

Nope---Checked that.

 

[tel]

 

[stevehuckss396]

Here i go again!!!


I can't remember but did you cut the seats into the head or did you use a cage. If cage then could the valves be sealing but the leak be between the head and the cage? Wouldn't know how to check for that but I have heard of it happening.

Again just trying to think of something. Sorry if i'm pestering! Not that i'm going to stop! :big: :big:

 

[kcmillin]

Nope---Checked that.

Perhaps it could be that the intake valve is too strong, and the intake valve is not opening long enough or not enough height. (actually it vibrates, I took high speed video of mine while running) I had a lot of trial and error getting the spring to work, but then again that does not solve the compression issue.

I don't know, I'm just thinking out loud now.

Kel

 

[Brian Rupnow]

I used cages and loctited them in. The intake valve spring is very light---i can see the intake working llike crazy when I am running it with the drill motor and when its running on its own.

 

[Brian Rupnow]

Tel---I love it!!!

 

[stevehuckss396]

Well I move that Brian start over completely from scratch and make a whole new one.

All in favor say I!!!


That's all I can think of. Best of luck and if something hits me i'll try again.

 

[bearcar1]

What about the height of the fuel tank. You mentioned that it acts like it 'runs out of gas' after a short period of time when you remove the drill. Like Steve, just spit ballin'.
I like Tels' product in a can. Pretty much says it all.

BC1
Jim

 

[metalmad]

Hi Brian
i guess u did the spark timing as well as the valve timing ?
running right way?
is the fuel any good?
so close Mate

 

[Brian Rupnow]

Whatever is going on, its going on with my intake valve. I have a VERY light spring on it, and its opening under engine vacuum while the drill motor is turning the engine. However, if I flip the engine over by hand, I feel no compression. BUT---and its a big BUT--If I fiddle a bit with the intake valve with one hand while trying to turn the engine over with the other hand, I can get a really good compression kick back. The valve stem seems to be a bit undersize---I can wiggle the stem in the guide. The conundrum of course, is that if I put in a stronger spring, the engine isn't able to pull the valve open. If I leave the current light spring in there, the valve isn't sealing consistently. I find it very encouraging though, that I am getting compression kickback under some conditions. That tells me that the exhaust valve with its stronger spring is sealing adequately. Maybe on Saturday, I'll make another intake valve and lap it in, see if I can't get it to deal consistently.

 

[bronson]

Good to hear you are narrowing down the issue i was just about to see if you did the leakdown test that was posted before. I find that to be a very helpful test being a tech. I hope that the intake valve fixes the issue.

 

[stevehuckss396]

I have a VERY light spring on it, and its opening under engine vacuum while the drill motor is turning the engine. However, if I flip the engine over by hand, I feel no compression. BUT---and its a big BUT--If I fiddle a bit with the intake valve with one hand while trying to turn the engine over with the other hand, I can get a really good compression kick back.

Make a new retainer thicker than the present one, so the spring is compressed more and see if a bit more spring pressure helps or hurts. Again, maybe you just need to pull on it a little harder. Better yet, make one thick as he!! and then keep facing off a little at a time and see if that makes any difference.

 

[Lakc]

Make a new retainer thicker than the present one, so the spring is compressed more and see if a bit more spring pressure helps or hurts. Again, maybe you just need to pull on it a little harder. Better yet, make one thick as he!! and then keep facing off a little at a time and see if that makes any difference.

Time for the old "stack of washers".

 

[stevehuckss396]

Time for the old "stack of washers".

In a manner of speaking.

 

[jpeter]

I test my valve seating success by sealing the combustion chamber, then blowing into the sparkplug hole with my breath while the valve assembly is under water. I have a length of silicon tube attached to a motified sparkplug for the test. If a bubble appears more often than every 4 or 5 seconds my valve work isn't good enough. Early in the hobby I didn't know how good valve seating had to be and thus I had lots of difficulty getting my engines to start and run well. I still make leaky valves I just find them and fix them quicker. My engines with bad valves would run at high rpm, generally hot. They'd not idle well at all. Same result for a bad fitting piston/cylinder. Now-a-days I know what to look for. Try the bubble test. If nothing else you'll learn a lot.
BTY, if your cam is like your drawing shows and the rise area is truly a straight line like the drawing and the follower is flat faced you're accelerating the hell out of the valve train. Its gonna pound the system to death. Most cams I've seen are more pointy with the rise and fall lines, although slightly curved to provide a reasonable acceleration, almost perpendicular to each other. Seems to me you've got an extremely long dwell period when the valve is open. Excuse me if I'm wrong I'm just trying to be helpful.

 

[fcheslop]

Hi Brian,I had a similar problem with Little Angel and found that the inlet valve was under size on the valve stem and believe it was sucking air down the valve stem instead of through the carb remade the valve and away she went.The inlet spring was a swine to set up just enough to seat the valve but still allow it to open. Not trying to tell my granny how to suck eggs just a suggestion.Best of luck
regards Frazer

 

[cfellows]

Hi Brian,I had a similar problem with Little Angel and found that the inlet valve was under size on the valve stem and believe it was sucking air down the valve stem instead of through the carb remade the valve and away she went.The inlet spring was a swine to set up just enough to seat the valve but still allow it to open. Not trying to tell my granny how to suck eggs just a suggestion.Best of luck
regards Frazer

I had this same issue on my plumbing parts engine, but it was only a problem when I had the carb throttled way back. If your carb is wide open, I don't think a loose inlet valve stem will be a problem and it's easily overcome by richening up the mixture.

Chuck

 

[NickG]

I think the loose valve stem problem may be causing it not to seat correctly as Brian said when he fiddled with it, compression came back. If he doesn't get compression it'll never run. Think he's on the right track. Brian there was some good dialogue around valve seats in the Tiny I.C. post, a good suggestion was to use a counter sink and make a very narrow valve seat. Alternatively, the way you mentioned leaving the topslide at the same setting to make the cutter and valves.

Nick

 

[Brian Rupnow]

I'm just tickled pink to have good compression and "kick back" on the engine--even "sometimes". Its something I have never previously felt at all. Like I said, that pretty well confirms that the exhaust valve is seating correctly and consistently. Its not a big deal to remake the intake valve. Thats a Saturday morning job.

 

[ozzie46]

Brian, sorry I don't have the knowledge or expertise to advise on what to do but I'm rooting like all get out for you to find the problem and come to a successful solution.

However I'm learning quite bit from all the feedback. Sorry it's at your expense though.


Fingers, toes and eyes crossed here. Good luck.

Ron