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Old 07-05-2005, 04:06 AM   #1
carls47807
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hydraulic valve lifters

I'm in need of desperate help after countless hours trying to adjust the lifters in my 65 corvair.

It seems if i use chevy service manuals and do 3/4 after 0 lash it will pop through the carburetors. If i adjust them to exactly 0 last and leave them there it will pop through the exhaust. Anywhere inbetween will cause it to pop through both.

The car has absolutely no power, but runs good despite the popping. It has all new lifters and i just refaced and lapped the valves.

I have done a lot with hydraulic lifters and haven't had any problems in the past but this has me stumped. Could one of them be bad? All of them stay pumped up overnight except for two (weird). Is there an easy way for me to tell if some of them are bottomed out?

When i adjust them i notice the valve moves in instead of the lifter collapsing, and i can't tell if the lifter eventually collapses or not. So what am i missing? I need help!

Thanks.
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Old 07-05-2005, 04:13 AM   #2
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Wally - do you have any ideas?
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Old 07-05-2005, 04:13 AM   #3
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when you put the new ones in did you soak em, maybe they havent pumped up yet, first i would start from scratch, is the cam flat or do you know the condition of the cam, if not check your lift height, then you have to turn it off take off covers when it's warm preferably, i could be wrong and if you have all the other steps then correct me, actually i dont even know what motor you got but on mine i had to go on compression stroke of #1 and do a uh #1 intake #3 intake and so on and so on, then turn it over again and do the others to proper spec, it should be good but if excessively noisy they say run it hot pull the covers and while it's runnin lossen off till clatters then turn in like 1/4 but i didn't haave to go that far and hot spraying oil sucks, is a meesy job, gimme engines spec i'll see if i can find the proper setting for yours
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Old 07-05-2005, 04:18 AM   #4
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well that's the thing, it's a f'ud up motor. it's a horizontal 6 so you can't adjust them with it running. what i do is wait till i see a valve go in and then i know that the other valve on the clyinder is completely shut and i adjust them all in that manner. I have adjusted many corvair valves before and i am positive i am doing the sequence right. I think my problem lies in my inexperience with how hydraulic valve lifters work. I didn't pump them up before putting them in but i never do and they have always pumped up before. the cam was mic'd and within tolerances. how can i measure my lift height accurately? and should i do it with the rocker nuts loose? thanks for the help.
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Old 07-05-2005, 04:49 AM   #5
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yeah I use an oil can to prime them first, then pour oil conditioner over them.


OK the real problem is backfiring which might be something other than the lifters (eg valve stem seals, worn rockers, worn rod balls, etc).

Any way you know what you are doing, but need a sounding board, so here goes:

do you think the lifters are hydraulic locking and staying pumped up? Are they flat tappet or roller lifters? Roller lifters need a more aggressive cam profile.

3/4 turn is probably alright for UNC pitched threads, but have you checked the actual takeup is between 20 and 60 thous? You can do this easily by scribing the rod when its lazy in the lifter and comparing it's push travel when lashed down.

Are you certain the pushrods are on the base circle when adjusting, because they may be flanking a bit if you are 360 out.

My guess is you camshaft is out of whack with your crank so the valve timing is out.
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Old 07-05-2005, 06:04 AM   #6
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Quote:
Originally Posted by Wally
yeah I use an oil can to prime them first, then pour oil conditioner over them.


OK the real problem is backfiring which might be something other than the lifters (eg valve stem seals, worn rockers, worn rod balls, etc).

Any way you know what you are doing, but need a sounding board, so here goes:

do you think the lifters are hydraulic locking and staying pumped up? Are they flat tappet or roller lifters? Roller lifters need a more aggressive cam profile.

3/4 turn is probably alright for UNC pitched threads, but have you checked the actual takeup is between 20 and 60 thous? You can do this easily by scribing the rod when its lazy in the lifter and comparing it's push travel when lashed down.

Are you certain the pushrods are on the base circle when adjusting, because they may be flanking a bit if you are 360 out.

My guess is you camshaft is out of whack with your crank so the valve timing is out.

..and maybe try setting them at 0 and checking the timing... then readjust. check the point gap, too

ps: welcome back, carl. haven't seen you for a while...
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Old 07-06-2005, 04:09 AM   #7
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hmm

do you think if i was 1 tooth off on the gears that the vehicle would still start, and run like it is? i think i'm starting to lean toward that.

the lifters are regualr small block chevy lifters (sealed power). I almost think they are staying pumped up and they aren't allowing for the proper 20 - 60 thousands displacement when i give them an extra 3/4 turn. any way to *deflate* them (pardon my terminology). my book says 3/4 turn is ~25 thousands. when i look at the rocker studs after adjustment some are noticeable protruding more at the rocker nuts than others, but all were adjusted at what i thought was zero lash. I even loosened all of them up for a week and let them sit. should i tighten them down all the way and let them sit to try to start with bottomed out lifters?

p.s. regular rocker arms and studs. me and my old man rebuild the motor last year and he is a stickler for checking tolerances so i'm pretty sure it's not an issue with wear. i'm leaning toward a mistimed cam if you think it would still even start (back me up!)

thanks guys.
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Old 07-06-2005, 11:45 AM   #8
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Quote:
Originally Posted by carls47807
do you think if i was 1 tooth off on the gears that the vehicle would still start, and run like it is? i think i'm starting to lean toward that.

should i tighten them down all the way and let them sit to try to start with bottomed out lifters?

i don't think so...

i'd start out loose on all the rockers...
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Old 07-07-2005, 12:25 AM   #9
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Yeah I think your valve timing is out. Check the sprockets are aligned or at least put a pair of solids in No1 and see if the valves are in synch with the crank.
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Old 07-07-2005, 02:37 AM   #10
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Quote:
Originally Posted by Wally
Yeah I think your valve timing is out. Check the sprockets are aligned or at least put a pair of solids in No1 and see if the valves are in synch with the crank.

isn't the tooth (degree) spacing on the gears such that it wouldn't run at all if it was off a tooth?
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Old 07-07-2005, 03:59 AM   #11
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Well I don't know what sprocket you have and the number of teeth or whether the chain is stretched and retarded the valve closing event.

Jumping a tooth can still let an engine run, just that is has buggerall power and backfires through the carby and given enough raw fuel into the exhaust manifold some decent muffler damage.


Did you say you have checked compression? Other things you can look for is a manifold leak weak or broken valve spring(s).
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Old 07-07-2005, 04:15 AM   #12
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checking compression will tell alot in my opinion try that first
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Old 07-08-2005, 01:24 AM   #13
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i did the compression test i get 150 on all cylinders. a guy i talked to told me it may not be a valve problem at all and to start leaning towards the carburetors. so i have them all backed off to zero lash.

I'm going to throw another set on tomorrow and see what happens. If that still doesn't work i'll pull the motor and let you all know what the problem was. Thanks for the help guys. possibly a misaligned gear like wally said or ?burned valve seat?
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Old 07-08-2005, 04:02 AM   #14
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150 all around sounds promising, are you sure your not a tooth out on the distributor
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Old 07-08-2005, 04:08 AM   #15
carls47807
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if i were a tooth off couldn't i make up for it by turning it? i know it's not 180 degrees off for sure.

do carburetor problems sound promising? or is this guy bullshitting me? the problem is whenever i throw a motor together it starts up and runs beautiful. this whole corvair thing is a new animal to me. it has a carb on each side and they are a bitch to synchronize.

mehhh. i'm 2 months on this engine.
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