Rebuilding the motor for the second time in 9 months
04-04-2008, 08:02 AM
#1
Rebuilding the motor for the second time in 9 months The motor we put together last summer started making rattling and squeaking noises two Fridays ago, after around 7000 miles.
Last year, a lifter spun in the bore, flat-spotting the Comp OEM lifter, lifter bore, and damaging the cam lobe.
This time, long story short, one of the rev-kit pieces cracked at the mounting bolt. I'm not sure if it was from improper installation or machining, or not being tested on street motors, or a flaw, etc.
My friend Robert (mrr23 here) pulled in sequence the serpentine belt, the tranny, then clutch, then checked the cam retainer bolts. Everything fine yet noise was still there. Then pulled motor and I took it over to sponsor Mike Norris for R&R. He's real close to the machine shop and I won't have to take as much time off from work as a result.
So far, the Caddy lifter on #3 was gouged and/or stuck in the bore. The rest of the lifters appear fine, which is odd because I have a badly worn cam lobe on #8.
The pan didn't show any big flakes or crazy bearing wear. Possible accelerated wear due to not being clean enough at assembly. Crank showed wear to the under material. Three of the cylinder walls have pretty good scuffing, not enough to warrant block replacement. Will need to measure piston-to-bore clearance.
The cracked rev-kit was on #2/#4. The rev kit bolts into the stock location, and the ends appeared to be bowed up .005-.010", possibly due to the spring pressures. The one that broke was much higher when we pulled the heads.
So we still don't know definitively what was making the squeaking noises. Mike didn't get to hear it.
So we're going to have the machine shop disassemble and clean the heads, flow an intake & exhaust port, test the spring pressures, and maybe get a valve job. Based upon the flow results, we'll try to pick a cam which isn't as aggressive as the LSK cam Patrick G spec'ed for me spring of '07.
I'm sticking with a NA 347, and it's a daily driver. Using a LS6 intake, I want a minimum of 350rwtq from 3000RPM to as high as possible. Undecided if I want to stick with the Caddy lifters. There are a few reported problems with them, but I don't know if I can afford Morels. What do the new Crane lifters cost?
The guy who makes the rev-kit is in the hospital due to a recent heart attack. So it's difficult to find a work around for the broken rev-kit. I suppose I'll need to go back to the OEM plastic retainers and just risk a lifter turning again?
Last year, a lifter spun in the bore, flat-spotting the Comp OEM lifter, lifter bore, and damaging the cam lobe.
This time, long story short, one of the rev-kit pieces cracked at the mounting bolt. I'm not sure if it was from improper installation or machining, or not being tested on street motors, or a flaw, etc.
My friend Robert (mrr23 here) pulled in sequence the serpentine belt, the tranny, then clutch, then checked the cam retainer bolts. Everything fine yet noise was still there. Then pulled motor and I took it over to sponsor Mike Norris for R&R. He's real close to the machine shop and I won't have to take as much time off from work as a result.
So far, the Caddy lifter on #3 was gouged and/or stuck in the bore. The rest of the lifters appear fine, which is odd because I have a badly worn cam lobe on #8.
The pan didn't show any big flakes or crazy bearing wear. Possible accelerated wear due to not being clean enough at assembly. Crank showed wear to the under material. Three of the cylinder walls have pretty good scuffing, not enough to warrant block replacement. Will need to measure piston-to-bore clearance.
The cracked rev-kit was on #2/#4. The rev kit bolts into the stock location, and the ends appeared to be bowed up .005-.010", possibly due to the spring pressures. The one that broke was much higher when we pulled the heads.
So we still don't know definitively what was making the squeaking noises. Mike didn't get to hear it.
So we're going to have the machine shop disassemble and clean the heads, flow an intake & exhaust port, test the spring pressures, and maybe get a valve job. Based upon the flow results, we'll try to pick a cam which isn't as aggressive as the LSK cam Patrick G spec'ed for me spring of '07.
I'm sticking with a NA 347, and it's a daily driver. Using a LS6 intake, I want a minimum of 350rwtq from 3000RPM to as high as possible. Undecided if I want to stick with the Caddy lifters. There are a few reported problems with them, but I don't know if I can afford Morels. What do the new Crane lifters cost?
The guy who makes the rev-kit is in the hospital due to a recent heart attack. So it's difficult to find a work around for the broken rev-kit. I suppose I'll need to go back to the OEM plastic retainers and just risk a lifter turning again?
04-04-2008, 11:37 AM
#4
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I had a couple lifters turn in my motor (at the same time). They destroyed my cam and I later spun a bearing. Had Comp Rs now I have extended cranes to hopefully help prevent the turning of the lifter. Because they were non standard they were expensive as well. Never really had a good explaination as to why it happened. It sucked.
04-09-2008, 11:57 AM
#5
How much spring pressure would be considered too much for lifters or a cam lobe? If I had ~400 open pressure from the valvespring, and an unknown amount of spring pressure from the rev kit, could the combination of those spring pressures have caused lifter and/or cam lobe wear problems?
04-09-2008, 01:13 PM
#6
I thought that rev kit was only 60 or so pounds, which when added to the spring loads back through the rocker is 740 which I think is within the capability of a Morel lifter.
To me, that rev kit looked to be highly dependent on block/head/gasket tolerance stack-up and I felt it would be difficult to get it set up correctly.
To me, that rev kit looked to be highly dependent on block/head/gasket tolerance stack-up and I felt it would be difficult to get it set up correctly.
Last edited by vettenuts; 04-10-2008 at 07:16 AM.
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04-09-2008, 08:51 PM
#8
How much spring pressure would be considered too much for lifters or a cam lobe? If I had ~400 open pressure from the valvespring, and an unknown amount of spring pressure from the rev kit, could the combination of those spring pressures have caused lifter and/or cam lobe wear problems?
04-10-2008, 07:14 AM
#9
See link: Link
I screwed up my calculations in my original post and went back and fixed it.
Last edited by vettenuts; 04-10-2008 at 07:28 AM.
04-10-2008, 09:52 AM
#10
I thought that rev kit was only 60 or so pounds, which when added to the spring loads back through the rocker is 740 which I think is within the capability of a Morel lifter.
To me, that rev kit looked to be highly dependent on block/head/gasket tolerance stack-up and I felt it would be difficult to get it set up correctly.
To me, that rev kit looked to be highly dependent on block/head/gasket tolerance stack-up and I felt it would be difficult to get it set up correctly.
04-14-2008, 04:19 PM
#11
I picked up the old cam and lifters today. The worn lobe is the 3rd from the rear. I can't get my cheap digicam to focus well enough at a close distance to show the wear clearly. You can slightly feel the wear running the finger 90* perpendicular to the lifter path. Nothing real rough, but visually it appears to be in the early stages. Still waiting for the heads to be flowed and the runners to be cc'ed before picking a cam, then once we have the cam specs we'll check the current springs to determine if they have sufficient pressure.
