How much can GM roller lifters take?
09-12-2002, 03:10 PM
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How much can GM roller lifters take?
How much lift and rpm can GM roller lifters take? I heard .575 on lift, is that true? I am at 5300 rpm now and .563 lift and going to be around 5500-5600 with more then .563 lift with the new heads and cam.
thanks bro's
Travis
thanks bro's
Travis
09-12-2002, 04:06 PM
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Travis,
When I talked to someone at www.lsmeng.com about switching from my current solid roller to a hydralic he told me GM was the best lifter out there. You might want to give them a call.
also when I had my motor out we put a GM roller (GEN6 style) in my block and with my .683" lift the lifter looked like it would work. It didn't lift the tie bar or slide to far down in the lifter bore. I'm sure you would have to use a small base circle camshaft though
When I talked to someone at www.lsmeng.com about switching from my current solid roller to a hydralic he told me GM was the best lifter out there. You might want to give them a call.
also when I had my motor out we put a GM roller (GEN6 style) in my block and with my .683" lift the lifter looked like it would work. It didn't lift the tie bar or slide to far down in the lifter bore. I'm sure you would have to use a small base circle camshaft though
09-12-2002, 05:10 PM
#3
I previously ran the Crane HR-276 in my old Gen VI 454. The lift was .576 on the exhuast and it worked very well for several years. The lifters did fall well into the retainers however; enough so that I wouldn't recommend much more than this.
I now run the Crane extended lifters in my GenVI 540 with .600 lift and there's plenty of room for more. A good investment in my opinion.
Dave
I now run the Crane extended lifters in my GenVI 540 with .600 lift and there's plenty of room for more. A good investment in my opinion.
Dave
09-12-2002, 06:03 PM
#4
lifters
In your small bock or in a difrent big block. The word I got is they are to short with a small base circle camshaft. That is in BIG block aplication though not sure about small blocks. 575 lift is just were most companys like to move to the small base circle in the big blocks. What Ive heard. Charlie
09-13-2002, 07:35 AM
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Thanks boys, I'll chat it up with the GM guru's around here and see what I come up with.. I am headed up north right now so chat with ya'll on monday
Travis
Travis
09-14-2002, 11:12 AM
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Dennis, if you are still out there, maybe you could shed some light on this!
My own personal experience was with a CompCam .591/.601 lift That didn't have a clearance problem but was not able to run over 5000 rpm. Changed to The recomended Comp lifter and picked up 100 rpm! I was told by comp that when you get into the more aggresive cams with steeper ramps that the GM lifter wasn't strong enough.
Frankly I liked the stock GM roller lifter retainer system better than the link bar that the Comps have, but I don't want to loose performance either!
My own personal experience was with a CompCam .591/.601 lift That didn't have a clearance problem but was not able to run over 5000 rpm. Changed to The recomended Comp lifter and picked up 100 rpm! I was told by comp that when you get into the more aggresive cams with steeper ramps that the GM lifter wasn't strong enough.
Frankly I liked the stock GM roller lifter retainer system better than the link bar that the Comps have, but I don't want to loose performance either!
09-16-2002, 08:31 AM
#7
Hey Tom,
the Crane lifter is a direct replacement for the Gen VI roller. I'm not sure on the internals but the top is just extended to allow for much more lift and retain the same ratainer setup. Very clean setup!
Just a side note, my 540 is propped to turn 5500 rpm and haven't had any issues what so ever.
Dave
the Crane lifter is a direct replacement for the Gen VI roller. I'm not sure on the internals but the top is just extended to allow for much more lift and retain the same ratainer setup. Very clean setup!
Just a side note, my 540 is propped to turn 5500 rpm and haven't had any issues what so ever.
Dave
09-16-2002, 09:54 AM
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Nordic Heat,
What push rods did you use, the stock Gm or a replacement??
When I bought the Comp lifters I also changed the push rods to a slightly different length (I think shorter) that Comp suggested.
If you had the part # for those crane lifters handy that would be cool!
I am actually going to a custom grind CompCam that my engine builder has had great succes on 502 motors, 240/242 duration with .612/.624 lift on a 112 lsa. The way my motor is set up he tells me it will turn out over 550hp. With this aggresive of a cam I will definatly need a strong lifter!
What push rods did you use, the stock Gm or a replacement??
When I bought the Comp lifters I also changed the push rods to a slightly different length (I think shorter) that Comp suggested.
If you had the part # for those crane lifters handy that would be cool!
I am actually going to a custom grind CompCam that my engine builder has had great succes on 502 motors, 240/242 duration with .612/.624 lift on a 112 lsa. The way my motor is set up he tells me it will turn out over 550hp. With this aggresive of a cam I will definatly need a strong lifter!
09-16-2002, 10:50 AM
#9
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Lifters
Dear Tom R.
I can't help but to think that the difference in performance would be due to the bleed down rate of the lifter. With stiff opening flanks on a camshaft the stock lifter could be bleeding down a little more than the aftermarket lifter. This would mean that the full lift and duration of the camshaft is not being transferred to the valve with the stock lifter. An increase in performance could be realized by stiffer lifters.
Bleed down rate is affected by oil viscosity/oil temperature, steep camshaft flanks, rocker arm ratio and spring tension. The purpose of a hydraulic lifter is to utilize some bleed down so that the lifter doesn't hold open the valve, otherwise the valvetrain would need some lash like a solid lifter! The oil in the lifter also acts like a cushion to keep the valve from reacting to every little imperfection on the camshaft base circle (some mass produced camshafts have such an imperfect base circle that the valve will actually move while it is supposed to be closed). There is a fine line between having a hydraulic lifter that is too stiff, good for performance but bad for durability, and one that bleeds down too much, good for durability but a little less performance.
Certainly we know that if we have stiff valvesprings with standard hydraulic lifters that they will bleed down (from open valve spring tension) after the engine sits for awhile and then we will have lifter noise when we restart the engine (until the lifters refill with oil).
If we have stiff valve springs, high ratio rocker arms and steep camshaft lobe flanks combined with stiff lifters (because of thick oil or tight manufacturing tolerances) I can't help but to believe that the cushion (that the hydraulics is supposed to provide) is being limited and the base of the lifter, be it flat or roller, is going to take more of a beating. Some bleed down is good!
Hope this helps someone!
Sincerely
Dennis Moore
FAMILY AND PERFORMANCE BOATING MAGAZINE
I can't help but to think that the difference in performance would be due to the bleed down rate of the lifter. With stiff opening flanks on a camshaft the stock lifter could be bleeding down a little more than the aftermarket lifter. This would mean that the full lift and duration of the camshaft is not being transferred to the valve with the stock lifter. An increase in performance could be realized by stiffer lifters.
Bleed down rate is affected by oil viscosity/oil temperature, steep camshaft flanks, rocker arm ratio and spring tension. The purpose of a hydraulic lifter is to utilize some bleed down so that the lifter doesn't hold open the valve, otherwise the valvetrain would need some lash like a solid lifter! The oil in the lifter also acts like a cushion to keep the valve from reacting to every little imperfection on the camshaft base circle (some mass produced camshafts have such an imperfect base circle that the valve will actually move while it is supposed to be closed). There is a fine line between having a hydraulic lifter that is too stiff, good for performance but bad for durability, and one that bleeds down too much, good for durability but a little less performance.
Certainly we know that if we have stiff valvesprings with standard hydraulic lifters that they will bleed down (from open valve spring tension) after the engine sits for awhile and then we will have lifter noise when we restart the engine (until the lifters refill with oil).
If we have stiff valve springs, high ratio rocker arms and steep camshaft lobe flanks combined with stiff lifters (because of thick oil or tight manufacturing tolerances) I can't help but to believe that the cushion (that the hydraulics is supposed to provide) is being limited and the base of the lifter, be it flat or roller, is going to take more of a beating. Some bleed down is good!
Hope this helps someone!
Sincerely
Dennis Moore
FAMILY AND PERFORMANCE BOATING MAGAZINE
09-16-2002, 12:37 PM
#10
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Dennis,
First of all I am very pleased to see that you are a member of the OSO board.
I have been for a couple of years now and have found it to be very helpful as well as a lot of fun being able to talk to Hot Boat enthusiast from all over the country and beyond.
I found your book for BBC marine engines 2yrs ago this past December. I was in a Paperback Booksmith looking for a Xmas gift for my wife, bought the book instead. It has been very informative and helpful.
I have recomended it to numerous freinds who have bought it and also found it helpful!
My motor is a GenVI 502, block has been checked for square & 0 decked. The heads have been milled just enough to make them perfect (.015), mild porting and three angle valve job with the .225 intake valves installed. I run CompCams Pro-Magnum roller rockers (on adjustable studs), CompCams springs, Felpro #1047 Head gaskets (.390 compressed). I run a dart Single plane intake with a Holley 830cfm carb. I have tried a couple of different cams, GM 226/234 ( GM H.P. 502/502), Comp 226/234 With .591 & .601lft on a 112 lsa and found the latter better.
I have set up the fuel system to include a 140GPH Electric Mallory fuel pump with 1/2" line from the tank to the pump, #8 braided ss line to the 100 GPH high volume Fram filter/ seperator, #8 line to the regulator & a #6 line to each bowl.
I have lightning Headers and run the D.U.I. HEI ignition.
The motor makes 520hp with about 565lbs of torque on the dyno.
I run the motor in a 1988 28ft Scarab Excel thru a 3yr old Bravo one spinning a 25" Mirage Plus that was tuned by Bronson/Hill. The boat runs about 73mph GPS at just over 5100 rpm.
I am now going to be installing a ComCam custom grind that My engine builder tells me he has had great luck with in the 502 Marine H.P engines, 240/242 dur @ .050 with .612/.624lift on a 112Lsa.
Your explanation of the lifter bleed down was exactly what my engine builder & I suspected, infact it is what the tech at CompCams had told me would happen!
I am open to your thoughts on what lifters as well as the rest of my setup I should run with the new cam.
Thanks,
TomR
First of all I am very pleased to see that you are a member of the OSO board.
I have been for a couple of years now and have found it to be very helpful as well as a lot of fun being able to talk to Hot Boat enthusiast from all over the country and beyond.
I found your book for BBC marine engines 2yrs ago this past December. I was in a Paperback Booksmith looking for a Xmas gift for my wife, bought the book instead. It has been very informative and helpful.
I have recomended it to numerous freinds who have bought it and also found it helpful!
My motor is a GenVI 502, block has been checked for square & 0 decked. The heads have been milled just enough to make them perfect (.015), mild porting and three angle valve job with the .225 intake valves installed. I run CompCams Pro-Magnum roller rockers (on adjustable studs), CompCams springs, Felpro #1047 Head gaskets (.390 compressed). I run a dart Single plane intake with a Holley 830cfm carb. I have tried a couple of different cams, GM 226/234 ( GM H.P. 502/502), Comp 226/234 With .591 & .601lft on a 112 lsa and found the latter better.
I have set up the fuel system to include a 140GPH Electric Mallory fuel pump with 1/2" line from the tank to the pump, #8 braided ss line to the 100 GPH high volume Fram filter/ seperator, #8 line to the regulator & a #6 line to each bowl.
I have lightning Headers and run the D.U.I. HEI ignition.
The motor makes 520hp with about 565lbs of torque on the dyno.
I run the motor in a 1988 28ft Scarab Excel thru a 3yr old Bravo one spinning a 25" Mirage Plus that was tuned by Bronson/Hill. The boat runs about 73mph GPS at just over 5100 rpm.
I am now going to be installing a ComCam custom grind that My engine builder tells me he has had great luck with in the 502 Marine H.P engines, 240/242 dur @ .050 with .612/.624lift on a 112Lsa.
Your explanation of the lifter bleed down was exactly what my engine builder & I suspected, infact it is what the tech at CompCams had told me would happen!
I am open to your thoughts on what lifters as well as the rest of my setup I should run with the new cam.
Thanks,
TomR
Last edited by TomR; 09-16-2002 at 04:55 PM.
