LT-4, motor and trans out, what now?
06-24-2019, 05:15 PM
#1
LT-4, motor and trans out, what now? Turns out my cyl. 1 noise was rod bearing. We pulled the motor and trans (cuz you have too). Car only has 57k miles, so its strange, but now im going to rebuild the motor and put a new clutch in while the trans is out.
It has excellent oil pressure, and I only run Castrol Synthetic, so im puzzled! Would a higher volume pump be a good idea? Was this an issue on these motors?
If I remember right the dual mass delete is as simple as getting LT-1 Camaro clutch parts correct?
Im going to go with bigger cam and long tubes, but I dont want to go crazy, so thats about it besides the obvious (for me), new pistons and rings (11:1 most likely), valve springs, seals and all new gaskets. The crank is likely turnable, so ill keep it and the rods since both are forged in these no?
Is it still a good idea to get rid of the sodium valves even if they look fine?
It has excellent oil pressure, and I only run Castrol Synthetic, so im puzzled! Would a higher volume pump be a good idea? Was this an issue on these motors?
If I remember right the dual mass delete is as simple as getting LT-1 Camaro clutch parts correct?
Im going to go with bigger cam and long tubes, but I dont want to go crazy, so thats about it besides the obvious (for me), new pistons and rings (11:1 most likely), valve springs, seals and all new gaskets. The crank is likely turnable, so ill keep it and the rods since both are forged in these no?
Is it still a good idea to get rid of the sodium valves even if they look fine?
06-24-2019, 11:12 PM
#2
11 Second Club
Sodium valves? Is this an LT4?
06-25-2019, 10:15 AM
#4
Would a higher volume pump be a good idea? Was this an issue on these motors?
If I remember right the dual mass delete is as simple as getting LT-1 Camaro clutch parts correct?
The crank is likely turnable, so ill keep it and the rods since both are forged in these no?
Is it still a good idea to get rid of the sodium valves even if they look fine?
If I remember right the dual mass delete is as simple as getting LT-1 Camaro clutch parts correct?
The crank is likely turnable, so ill keep it and the rods since both are forged in these no?
Is it still a good idea to get rid of the sodium valves even if they look fine?
the rods & crank are not forged but very good. Crank can be turned .010 under and rods can be resized and fitted with ARP fasteners
If valves are still good the machine shop can lap them. Get new valve springs
Not sure if the DM flywheel can be resurfaced but you can replace it with a standard LT1 FW and then run a sprung hub disc clutch
DM FW LT4 used a solid disc vs sprung
06-25-2019, 11:21 AM
#5
So ordering a complete clutch assembly, (flywheel, disk, pressure plate assembly) for say a 96 Camaro LT-1 is all I need to do? No issues with clutch slave or T/O bearing?
06-25-2019, 01:51 PM
#7
This car is low mileage and well kept, Castrol synthetic oil. My concern is that the #1 rod is the last to receive oil so I suspect a lubrication failure, not abuse that caused the spun bearing. I dont want to rebuild this thing only to have this happen again so I need to nail down the cause 100%.
The rod did not show any heat discoloration (it shouldnt have anyways as the bearing only rotated slightly, it did not "spin") there is no obvious damage to the big end so I do intend to re-use both.
I understand this, my question was should the valves be replaced since they are hollow intake, sodium exhaust. I had heard rumors they were prone to failure. If I put solid stainless in there im not gaining anything but durability, as they will be much heavier requiring stronger springs. The only benefit is if I get under cut stems and I dont even know if these heads will like that all that much. The cam will be relatively mild by comparison to my LSA motor, so maybe?
Yeah im 0% interested in leaving that heavy lump in there. If the only conversion part is a single mass LT-1 flywheel then im there!
So ordering a complete clutch assembly, (flywheel, disk, pressure plate assembly) for say a 96 Camaro LT-1 is all I need to do? No issues with clutch slave or T/O bearing?
The rod did not show any heat discoloration (it shouldnt have anyways as the bearing only rotated slightly, it did not "spin") there is no obvious damage to the big end so I do intend to re-use both.
I understand this, my question was should the valves be replaced since they are hollow intake, sodium exhaust. I had heard rumors they were prone to failure. If I put solid stainless in there im not gaining anything but durability, as they will be much heavier requiring stronger springs. The only benefit is if I get under cut stems and I dont even know if these heads will like that all that much. The cam will be relatively mild by comparison to my LSA motor, so maybe?
Yeah im 0% interested in leaving that heavy lump in there. If the only conversion part is a single mass LT-1 flywheel then im there!
So ordering a complete clutch assembly, (flywheel, disk, pressure plate assembly) for say a 96 Camaro LT-1 is all I need to do? No issues with clutch slave or T/O bearing?
IDK if the sodium filled valves are any more prone to failure that solids. Their intent is to reduce valve train weight. 11/32 valve stem is stock size I have Ferra solid valves in my ported LT1 heads 2.02/1.60 FWIW. Get the Lunati spring kit for LT1 73925K5
Yes a stock LT1 FW & clutch kit is plug & play. The clutch will come with a new T.O. bearing. It is advised to replace pilot bearing on clutch swaps also
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06-28-2019, 01:08 PM
#8
Just a quick update:
ONLY rod #1 was spun, but ALL rod bearings were in bad shape. All mains looked pretty good. The cylinders dont look great but the piston skirts all still show machining marks. So definitely oil starvation issues (possibly before me?). Drivers side freeze plug with the oiling hole in it is cocked a bit sideways, not sure if this had any effect.
That weird harmonic pulley hub thats balanced has severe seal grooves, is there a better option? Its balanced so im not sure if it has to be mounted to the damper pulley in a proper orientation?
ONLY rod #1 was spun, but ALL rod bearings were in bad shape. All mains looked pretty good. The cylinders dont look great but the piston skirts all still show machining marks. So definitely oil starvation issues (possibly before me?). Drivers side freeze plug with the oiling hole in it is cocked a bit sideways, not sure if this had any effect.
That weird harmonic pulley hub thats balanced has severe seal grooves, is there a better option? Its balanced so im not sure if it has to be mounted to the damper pulley in a proper orientation?
06-28-2019, 02:45 PM
#9
Replace the hub, ideally with a keyed hub. The "damper" would be neutral balanced. If its the original replace both damper and hub
07-01-2019, 11:14 AM
#10
07-02-2019, 03:26 PM
#13
Oil pump advice - don't bother with a HV pump. Numerous reasons:
1) takes more power to turn with no real benefit
2) is taller than std volume pump, drops pickup 1/8 - 3/16" lower and reduces pickup to pan clearance in a stock pan (restricting oil flow into the pump)
3) sucks the sump dry faster than oil can return (crank/rod big end oil starvation)
4) more pressure is what you can really benefit from. GM 'white' spring is part # 3848911.
1) takes more power to turn with no real benefit
2) is taller than std volume pump, drops pickup 1/8 - 3/16" lower and reduces pickup to pan clearance in a stock pan (restricting oil flow into the pump)
3) sucks the sump dry faster than oil can return (crank/rod big end oil starvation)
4) more pressure is what you can really benefit from. GM 'white' spring is part # 3848911.
07-03-2019, 05:01 PM
#14
Oil pump advice - don't bother with a HV pump. Numerous reasons:
1) takes more power to turn with no real benefit
2) is taller than std volume pump, drops pickup 1/8 - 3/16" lower and reduces pickup to pan clearance in a stock pan (restricting oil flow into the pump)
3) sucks the sump dry faster than oil can return (crank/rod big end oil starvation)
4) more pressure is what you can really benefit from. GM 'white' spring is part # 3848911.
1) takes more power to turn with no real benefit
2) is taller than std volume pump, drops pickup 1/8 - 3/16" lower and reduces pickup to pan clearance in a stock pan (restricting oil flow into the pump)
3) sucks the sump dry faster than oil can return (crank/rod big end oil starvation)
4) more pressure is what you can really benefit from. GM 'white' spring is part # 3848911.
07-03-2019, 07:57 PM
#15
Village Troll 
iTrader: (2)
If it’s internally balanced then a keyed hub is not necessary. You can most likely run a stock damper depending on your RPM level. I think Jegs sells a damper that is relatively inexpensive. Search “LT1 damper” on their site.
07-03-2019, 09:34 PM
#16
The pulley is what concerns me, since they are mated together, no?
07-04-2019, 10:57 AM
#17
Just buy a keyed hub for a LT1 F body since your hub is scored. If the damper that bolts to the hub is original or has 100k mi on it than just replace it with a new hub & damper (aka balancer)
the hub & damper on LT1 & LT4 motors are already "neutral" balanced. If your motor is being rebuilt than it likely will be a "internal" balanced motor which means you need to buy a new "neutral, aka zero, balanced FW or flexplate as stock LT1/4 motors are "externally" balanced from the rear. You can have a stock LT1/4 FW or flexplate neutral balanced at a machine shop typically for around $40-$50 if you want to reuse your existing one
07-04-2019, 11:40 AM
#18
Village Troll
iTrader: (2)
Is the pulley a smaller diameter than the pulley? I used to have an underdrive pulley that was an interference fit over the damper. I think it was made by Mallory. The belt fit around the U/D pulley and the damper sat on the outside. In ether case, just get rid of it and get a stock/ish damper.
07-06-2019, 11:05 AM
#19
TECH Resident
