im having lifter issues
Thread Starter
Launching!
Joined: Feb 2009
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im having lifter issues my lt1 has a comp custom cam 242 with a 577 lift for some reason my lt1 wont stop braking lifters at wot. i even replaced all the with ls7 lifters. every month i average least 2 lifters a month. can any one explain what is causing my lifters to brake? i have full roller rockers and valve springs, part # on the valve springs are Crane Cams 10308-1. can it be possable that these are the wrong springs?
The 10308 part number you indicate is actually the part number for the spring, retainer, lock, and seat kit. The actual springs you are talking about are p/n 99893.
What exactly is breaking? Are they collapsing? Are your pushrods the correct length? Do you have good oil pressure? How much preload are you running? Lots of questions to answer...
What exactly is breaking? Are they collapsing? Are your pushrods the correct length? Do you have good oil pressure? How much preload are you running? Lots of questions to answer...
Thread Starter
Launching!
Joined: Feb 2009
Posts: 201
Likes: 0
I have a new motor just got rebuild 400 miles ago,my oil pressure is perfect, I'm running stock push rods bc mines a 93 and already came with harden pushrods. In this case I think its my springs ill post up cam specs but I've already changed cams due to lifters scuffing the cam.
I would not use stock pushrods on a cam aggressive enough to hit .577 lift. They can act like a pole vaulter's pole and be a spring in the middle of your valvetrain.
The Crane springs are a decent part, it is just that since those were popular cams have gotten a fair bit more aggressive and there is more to spring choice than just lift capacity.
Also I thought the plunger depth on the LS7 lifters was a little different than stock so if you have stock pushrods with them that could cause some valvetrain funkyness.
The Crane springs are a decent part, it is just that since those were popular cams have gotten a fair bit more aggressive and there is more to spring choice than just lift capacity.
Also I thought the plunger depth on the LS7 lifters was a little different than stock so if you have stock pushrods with them that could cause some valvetrain funkyness.
Sounds like the 242/248 xfi cam and you will most likely be getting valve float with those springs. If it's breaking lifters your cam is probably all chewed up as well which would be sending metal through your engine.
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Measure the correct pushrod length. If those stock ones are flexing then it is beating the hell out of your valvetrain. A quality PR is not very expensive and they will make you valve train more reliable, but honestly measure to find what you need.
The engine builder adj. the rr but this wasn't the 1st time and several others have adj. them. I don't think backlash is the problem. They have been given from 1/2 to 1/4 turn and still break. I think he is gonna change the pushrods to 7.150 from stock at this point and see how that goes. Biggest fear is getting the lifters stuck and having pull the cam again.
Thread Starter
Launching!
Joined: Feb 2009
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TECH Veteran
Joined: Apr 2008
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OP
do you have a "XFI" Comp cam?
given the condition of those lifters...I would SERIOUSLY look at the cam lobes to see if you gauled or wiped a lobe(s)
if cam is ok replace lifters, springs (depends on wtf cam you have) and get ..080 wall hardened PR (trick flow) measured to whatever length you need
do you have a "XFI" Comp cam?
given the condition of those lifters...I would SERIOUSLY look at the cam lobes to see if you gauled or wiped a lobe(s)
if cam is ok replace lifters, springs (depends on wtf cam you have) and get ..080 wall hardened PR (trick flow) measured to whatever length you need
