Syclone#2960
What ever it takes!!
Anyone ever tried running LS7 lifters? My engine builder is telling me they will work. They ran them in a 383 without any problems. Could be a better solution then the comps.
LS7 lifters?
- Thread starter Syclone#2960
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Syclone#2960
What ever it takes!!
Re: LS7 lifters?
Did a little more research & it appears they will work. Going to guinea pig a set.
Did a little more research & it appears they will work. Going to guinea pig a set.
Bad Ass Black Trucks
New member
Re: LS7 lifters?
How did they work for you? I am exploring options right now and heard good things about them.
How did they work for you? I am exploring options right now and heard good things about them.
Re: LS7 lifters?
I have the LS6-LS7 roller lifters in my 1991 S10 4.3L engine. The engine has a Comp Cams 09-412-8 camshaft, Comp Cams 983 valve springs with 105 lb. seat pressure 310 lb. open pressure. The engine has about 9,000 miles on it and I also have no complaints. I set the lifter preload on the engine stand and have never had to readjust them.
GM part #12499225 is for 16 lifters.The optimum preload for these lifters is .083" from zero preload (about one turn) using ARP 100-7201 fully adjustable 3/4"-24 rocker studs with ARP 200-8551 hardened washers under the studs. The preload range is .070" - .090", however, do not estimate the the amount of turns for lifter preload by the 24 threads per inch of the rocker stud, you must also consider the rocker arm ratio. The lifters in the 16 lifter package are the same lifters as GM part #17122490 for the individual lifter. The 16 lifter package cost 1/2 as much compared to buying them individually. The LS6 - LS7 lifters have restricted oiling for high RPM with full roller rocker arms. They also have a high check ball and metering plate for reduced lifter pump up at high RPM. According to my engine builder, the revised LS6 - LS7 lifters alone are worth an additional 500 RPM.
GM Roller lifters:
1986-2004 4.3L V6 .... GM-17120090, low check ball
LS1 - LS6.... GM-5234890, low check ball
LS6 - LS7 (revised).... GM-1249925 (16) , GM-17122490 (1), high check ball
2004 -up Cadillac CTS-VR..... GM-88958669 (16) , light weight ceramic check ball
I have the LS6-LS7 roller lifters in my 1991 S10 4.3L engine. The engine has a Comp Cams 09-412-8 camshaft, Comp Cams 983 valve springs with 105 lb. seat pressure 310 lb. open pressure. The engine has about 9,000 miles on it and I also have no complaints. I set the lifter preload on the engine stand and have never had to readjust them.
GM part #12499225 is for 16 lifters.The optimum preload for these lifters is .083" from zero preload (about one turn) using ARP 100-7201 fully adjustable 3/4"-24 rocker studs with ARP 200-8551 hardened washers under the studs. The preload range is .070" - .090", however, do not estimate the the amount of turns for lifter preload by the 24 threads per inch of the rocker stud, you must also consider the rocker arm ratio. The lifters in the 16 lifter package are the same lifters as GM part #17122490 for the individual lifter. The 16 lifter package cost 1/2 as much compared to buying them individually. The LS6 - LS7 lifters have restricted oiling for high RPM with full roller rocker arms. They also have a high check ball and metering plate for reduced lifter pump up at high RPM. According to my engine builder, the revised LS6 - LS7 lifters alone are worth an additional 500 RPM.
GM Roller lifters:
1986-2004 4.3L V6 .... GM-17120090, low check ball
LS1 - LS6.... GM-5234890, low check ball
LS6 - LS7 (revised).... GM-1249925 (16) , GM-17122490 (1), high check ball
2004 -up Cadillac CTS-VR..... GM-88958669 (16) , light weight ceramic check ball
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Syclone#2960
What ever it takes!!
Re: LS7 lifters?
No problems in the V6. I did however install a couple of washers inside each lifter to mimic a solid lifter. I'm getting ta few knock counts and suspect the modified lifters. Going to take out the shims & check if it solves my knock counts.
I do believe these lifters have a larger fulcrum then the comps.
No problems in the V6. I did however install a couple of washers inside each lifter to mimic a solid lifter. I'm getting ta few knock counts and suspect the modified lifters. Going to take out the shims & check if it solves my knock counts.
I do believe these lifters have a larger fulcrum then the comps.
Re: LS7 lifters?
My engine builder explained the difference in the "revised" LS lifters.
The dimensional measurements of the LS lifters are the same. However, the revised LS lifters have a stronger check ball spring, the piston spring is 50% stronger and the metering plate does not have a oil hole. My machinist also mentioned that the pushrod cup is .020" deeper in the lifter body which requires a longer pushrod when used with non-adjustable net lash rocker studs. The lifter preload adjustment range of .070" to .090" can compensate for the lower pushrod seat when used with fully adjustable rocker studs such as ARP 100-7201. or more expensive Crower 88419-12 rocker studs.
The stronger internal check ball spring and metering plate are designed to resist lifter pump up at higher RPM. The stiffer internal piston spring resists lifter collapse when using high load valve springs that are normally used with high lift camshafts that have more aggressive cam lobes. Only use the revised LS lifters with valve springs having less than 350 lb open pressure.
My engine builder explained the difference in the "revised" LS lifters.
The dimensional measurements of the LS lifters are the same. However, the revised LS lifters have a stronger check ball spring, the piston spring is 50% stronger and the metering plate does not have a oil hole. My machinist also mentioned that the pushrod cup is .020" deeper in the lifter body which requires a longer pushrod when used with non-adjustable net lash rocker studs. The lifter preload adjustment range of .070" to .090" can compensate for the lower pushrod seat when used with fully adjustable rocker studs such as ARP 100-7201. or more expensive Crower 88419-12 rocker studs.
The stronger internal check ball spring and metering plate are designed to resist lifter pump up at higher RPM. The stiffer internal piston spring resists lifter collapse when using high load valve springs that are normally used with high lift camshafts that have more aggressive cam lobes. Only use the revised LS lifters with valve springs having less than 350 lb open pressure.
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Re: LS7 lifters?
The Chevrolet 4.3L V6 engines are limited to using camshafts having no more than .350" tappet lift. and a cam lobe base circle no less than 1.170" diameter. I am confident that you will not find a "off the shelf" camshaft for the 4.3L V6 engine that will exceed those limits.
If you ever plan to use a camshaft with a tappet lift from .320" to .350" (.480" to .525" valve lift), you should use Comp Cams 875-12 Pro Magnum "R" roller "limited travel" hydraulic roller lifters. Limited travel lifters (flat or roller) only have .070" of plunger travel and must be set at no more than .004" preload using a feeler gauge. I just used a "slight flick of the wrist" preload adjustment with my 1970 Pontiac Ram Air 4 engine. On the Chevy 4.3L V6 engine, you can learn by my mistake after I used the GM LS7 lifters with a Comp Cams 09-412-8 camshaft that has .333" tappet lift (.500" valve lift). Stock lifters, including the GM LS7 lifters, will be noisy with a camshaft with from .320" to .350" tappet lift. When using a GM lifter with .070" to .090" preload, the roller "lofts" over the nose of the lobe and smacks cam lobes on the return flank, even with more than 300 lb. open spring pressure. Since the Comp Cams 875-12 "R" roller lifters do not have but .004" (1/8 turn) preload, they can follow a more aggressive cam lobe, similar to a solid roller. In fact, if the 875-12 lifters are set correctly, they are .004" away from being a solid roller. Be advised, when using Comp Cams 875 lifters, the push rod seat retainer can be ejected if the correct preload is not locked and maintained precisely by using poly locks with full roller rocker arms or new OE lock nuts with stock or roller tip rocker arms...
If you don't mind the noise and have disabled the knock sensor, the LS7 or OE hydraulic roller lifter noise that accompanies a high lift camshaft will not be a problem. I knew this was true with a hydraulic flat tappet camshafts but I did not realize it also applied to a roller tappet camshaft as well, so be forewarned. I will be changing my LS7 lifters to the Comp Cams 875-12 Pro Magnum "R" lifters when I get tired of the noise.
The Chevrolet 4.3L V6 engines are limited to using camshafts having no more than .350" tappet lift. and a cam lobe base circle no less than 1.170" diameter. I am confident that you will not find a "off the shelf" camshaft for the 4.3L V6 engine that will exceed those limits.
If you ever plan to use a camshaft with a tappet lift from .320" to .350" (.480" to .525" valve lift), you should use Comp Cams 875-12 Pro Magnum "R" roller "limited travel" hydraulic roller lifters. Limited travel lifters (flat or roller) only have .070" of plunger travel and must be set at no more than .004" preload using a feeler gauge. I just used a "slight flick of the wrist" preload adjustment with my 1970 Pontiac Ram Air 4 engine. On the Chevy 4.3L V6 engine, you can learn by my mistake after I used the GM LS7 lifters with a Comp Cams 09-412-8 camshaft that has .333" tappet lift (.500" valve lift). Stock lifters, including the GM LS7 lifters, will be noisy with a camshaft with from .320" to .350" tappet lift. When using a GM lifter with .070" to .090" preload, the roller "lofts" over the nose of the lobe and smacks cam lobes on the return flank, even with more than 300 lb. open spring pressure. Since the Comp Cams 875-12 "R" roller lifters do not have but .004" (1/8 turn) preload, they can follow a more aggressive cam lobe, similar to a solid roller. In fact, if the 875-12 lifters are set correctly, they are .004" away from being a solid roller. Be advised, when using Comp Cams 875 lifters, the push rod seat retainer can be ejected if the correct preload is not locked and maintained precisely by using poly locks with full roller rocker arms or new OE lock nuts with stock or roller tip rocker arms...
If you don't mind the noise and have disabled the knock sensor, the LS7 or OE hydraulic roller lifter noise that accompanies a high lift camshaft will not be a problem. I knew this was true with a hydraulic flat tappet camshafts but I did not realize it also applied to a roller tappet camshaft as well, so be forewarned. I will be changing my LS7 lifters to the Comp Cams 875-12 Pro Magnum "R" lifters when I get tired of the noise.
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