8-105 Engine Tick Under Load Only

  • curtiss
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12 Dec 2017 00:39 #33851 by curtiss
curtiss replied the topic: 8-105 Engine Tick Under Load Only
OK, I know this is an old one but still working on the fix :)

I have tried many things and the problem is now more easily repeatable but still there. I adjusted the lash, changed oil, ran some marvel in it, checked for a broker valve spring and still there.

I can now recreate the symptom by warming the engine a little than while sitting still rev it to 2000 or 2500 for about 2 to 5 mins then it will start ticking and it will have a miss but as soon as I let off the gas it normally goes back to a normal running engine.

At this point I am suspecting it is an exhaust valve since it is not backfiring or spitting from the carb side. I am thinking one or more of my valve guides is too tight and when the valve heats up it is expanding and sticking. I am to the point that I am going to pull the head and the valves out to see if I have a tight guide. I may go ahead and get a guide reamer and run it through each one.

My question is around tools, what valve spring compressor will work on the flat heads and is there anything I should be aware of tackling this?

Thanks,
Curt

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12 Dec 2017 04:59 #33852 by mikespeed35
mikespeed35 replied the topic: 8-105 Engine Tick Under Load Only
I use the reg. "C" type valve spring compressor used on overhead valve heads. The lifter should be adjusted to give the most clearance to get the spring out once released. I use a screwdriver to bend and pry the spring put. I would avoid running the engine at 2000 to 2500 under no load for two to five minutes though. You may hear more than ticking!
CORDiallyMike

Mike Huffman

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12 Dec 2017 20:35 #33853 by Ivor
Ivor replied the topic: 8-105 Engine Tick Under Load Only
Hello Curtiss, It is very easy for the valve stem collet's to fall into the sump when removing the valves, to prevent this fill the area around the cam follower blocks with rag or cushion foam. Don't forget to remove it after the work .

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12 Dec 2017 20:40 #33854 by curtiss
curtiss replied the topic: 8-105 Engine Tick Under Load Only
Thank you for the advise, I will do that!

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13 Dec 2017 00:33 #33855 by 1748 S
1748 S replied the topic: 8-105 Engine Tick Under Load Only
If and when you pull the head to "check" the exhaust valve springs and guidea might be a good time to remove the oil pan and pull the pistons and rods. Look for a cracked piston. Your in for a dime and going the extra is a cost effective way to remove doubt.

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13 Dec 2017 01:02 #33856 by RandyEma
RandyEma replied the topic: 8-105 Engine Tick Under Load Only
Hello. Also look at the cam followers as the cast heads do come loose from the stems. R

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