comp cams 851-16 hyd. roller lifter issues?

igotaneed4speed

igotaneed4speed

Club Member
Who has these in there cars? any problems reving over 6400?

Have a set in a car and can't get it to go over 6400 in first or 6200 in second cars loses its head and floats the valves im starting to think its the lifters collapsing and going into valve float.
 
igotaneed4speed said:
Who has these in there cars? any problems reving over 6400?

Have a set in a car and can't get it to go over 6400 in first or 6200 in second cars loses its head and floats the valves im starting to think its the lifters collapsing and going into valve float.
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u get it goin or somethen without tellin us?
 
jordanbmx said:
u get it goin or somethen without tellin us?
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nope.. I shifted it at 6000 when i raced ur dad. :icon_wink



But its getting tore into today, found out the issue and a the fix. Finally it might run some good numbers...

I was told it should pick up about two tenths :seizure:
 
Sean said:
Whats the rest of the valve train got for parts and what are the cam specs ?
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sry can't say cam grinder would prob shoot me, plus I don't give out specs to any cams in a car thats not mine.


But I will tell you its a hyd. roller under .650 lift, all good stuff the problem is the lifters not springs or rockers or push rod length..

I had to rule out everything else before I tore into it, so i did now it time to fix the turd.
 
Well lift would have been fine. Don;t be so sure on the springs. To heavy and to stiff on a hydrualic roller will spell doom.


Sean


igotaneed4speed said:
sry can't say cam grinder would prob shoot me, plus I don't give out specs to any cams in a car thats not mine.


But I will tell you its a hyd. roller under .650 lift, all good stuff the problem is the lifters not springs or rockers or push rod length..

I had to rule out everything else before I tore into it, so i did now it time to fix the turd.
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Sean said:
Well lift would have been fine. Don;t be so sure on the springs. To heavy and to stiff on a hydrualic roller will spell doom.


Sean
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its pretty aggressive but the springs are only a 455in lbs spring there not over kill at all.

Its collapsing the lifters a lil handy work and it'll be good to go.
 
455inch lbs whats the install height and seat pressure. The Ford lifters can take about 175-185 seat at 475 but if the seat is to high it will blow down the lifters. Check the preload. If these are the lifters I think they are you could have a problem with to much preload.
 
Sean said:
455inch lbs whats the install height and seat pressure. The Ford lifters can take about 175-185 seat at 475 but if the seat is to high it will blow down the lifters. Check the preload. If these are the lifters I think they are you could have a problem with to much preload.
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I know its not the pre-load already went thru that, every position from here to the moon and no change. The lifters are bleeding down and collapsing and making it float happens at 6400 in first and 6200 in second.

The springs are 173 on the seat and 458 @.600 lift or so
 
Hows the oil pressure ? Any signs of oil foaming ?


igotaneed4speed said:
I know its not the pre-load already went thru that, every position from here to the moon and no change. The lifters are bleeding down and collapsing and making it float happens at 6400 in first and 6200 in second.

The springs are 173 on the seat and 458 @.600 lift or so
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Sean...my 4.2 uses 5.0 style hyrd. lifters also.I run comp cams 918 springs that have 130 seat pressure and like 300 open.Is that too much for the lifters? I have some nasty valve train noise right now that I am looking into.I do know that my pushrods are too long right now.
 
Could be the lifters are fialed and or damaged by now. You can run the restricted tip pushrods to keep the lifter pressurized with more oil. I love and hate that approach though. I always worry about spring and rocker cooling when using that fix.


OrangeF150 said:
Sean...my 4.2 uses 5.0 style hyrd. lifters also.I run comp cams 918 springs that have 130 seat pressure and like 300 open.Is that too much for the lifters? I have some nasty valve train noise right now that I am looking into.I do know that my pushrods are too long right now.
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