Do these engines spin a rod very often?
10-25-2007, 08:21 PM
#1
Race Director
Thread Starter
Do these engines spin a rod very often?
I am wondering if it would be wise to replace the rod bearings. I would do this with the engine in the car. I run the car pretty hard for HPDE use, is spinning a rod likely? Bearings are very inexpensive but I have not done this project before. Which is part of the appeal, it sounds like fun and I like to learn. Any advice?
A coated bearing costs quite a bit, are they worth a minor gain?
A coated bearing costs quite a bit, are they worth a minor gain?
10-25-2007, 09:00 PM
#4
Team Owner
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St. Jude Donor '05
PITA when in the car. Easy to nick the crank with the threads and God forbid the caps arent seated just right beofre your torque them down.....Ask me what happens when you fire it up 
10-25-2007, 09:34 PM
#5
Le Mans Master
I've done it before on an 86; not a big deal at all.
Run your fingers along side the parting line between the cap and the rod to make sure they are level.
Use several, at least four, torque sequences. 10 or so ft lbs of torque on one, then 10 or so on the one on the opposite side. That'll pull them up square.
Be sure not to put the cap on 180 degrees out.
LT1s are know for spinning rod bearings, but I believe it's because the clearances or so tight.
Jake
Run your fingers along side the parting line between the cap and the rod to make sure they are level.
Use several, at least four, torque sequences. 10 or so ft lbs of torque on one, then 10 or so on the one on the opposite side. That'll pull them up square.
Be sure not to put the cap on 180 degrees out.
LT1s are know for spinning rod bearings, but I believe it's because the clearances or so tight.
Jake
10-26-2007, 01:41 AM
#7
Le Mans Master
My vote is that excessive RPM is the most significant culprit in cases
of spun rod bearings.
Loads increase as the sq of the increase in speed and at some point
the rod bolts stretch. If you can keep the RPM's below the critical
speed, then the rod bolts will essentially have infinite life.
Is your auto modified with a shift kit? Do you hold gears manually?
What RPM do you shift at on the track?
.
of spun rod bearings.
Loads increase as the sq of the increase in speed and at some point
the rod bolts stretch. If you can keep the RPM's below the critical
speed, then the rod bolts will essentially have infinite life.
Is your auto modified with a shift kit? Do you hold gears manually?
What RPM do you shift at on the track?
.
10-26-2007, 04:12 AM
#9
Safety Car
I would get the tool to turn the flywheel so you can stay under the car.
Remove the trans converter pan and remove the spark plugs and you can be an expert in a couple of hours.I replace mine every 6 mths NBD.
Spend what ever you want on bearings.I use the hardened race bearings and they look like they have already been run in the motor and
spunn in the motor.Just make sure you wipe the crank and rod down with Aceatone,bearing .I use assembly bearing lube to put it together.Only put the lube on the inside of the bearing ,not on the rod or back side of the bearing.I would get some gas line hose and when you get the cap off slide the hose over the rod bolts.The bearing has upper on the top and lower on the other,don't mix them up.Don't put your finger print on them eather.
Remove the trans converter pan and remove the spark plugs and you can be an expert in a couple of hours.I replace mine every 6 mths NBD.
Spend what ever you want on bearings.I use the hardened race bearings and they look like they have already been run in the motor and
spunn in the motor.Just make sure you wipe the crank and rod down with Aceatone,bearing .I use assembly bearing lube to put it together.Only put the lube on the inside of the bearing ,not on the rod or back side of the bearing.I would get some gas line hose and when you get the cap off slide the hose over the rod bolts.The bearing has upper on the top and lower on the other,don't mix them up.Don't put your finger print on them eather.
10-26-2007, 06:14 AM
#11
Le Mans Master
"Spun" rod bearings are usually a result of not enough oil. Stock engines with stock oiling systems run hard are inviting this due to insufficient oil control in the oil pan. Oil runs away from the pickup during hard cornering, braking, etc. Add factory bearing clearance tolerance to this and likelihood for failure increases for rod bearings on the tight side of the acceptable range. With interrupted oil supply aggravated by tight factory clearances bearing quickly overheats and fails immediately. Running a stock engine hard is like rolling the dice. You might make it and you might not.
10-26-2007, 07:39 AM
#12
Melting Slicks
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16-'19, '21-'22-'23-'24
Just two cents from a noob:o....I've never done what you want to do but it seems like it would be easier to pull the motor & do mains + rods as you road race your car. I would look into a road race oil pump + pick-up + road race pan?? I'm saying this as I agree with Greg about oiling issues on a motor that is used the way you use yours. JMHO.
I know that chevy's old "off-Highway Parts" catalog from the 70's offered a road race pan for a sb motor & I bought one for my C3/ LT-1 and it had very visable differences in baffling besides 1 qt more pan capacity.
Tom
I know that chevy's old "off-Highway Parts" catalog from the 70's offered a road race pan for a sb motor & I bought one for my C3/ LT-1 and it had very visable differences in baffling besides 1 qt more pan capacity.
Tom
10-26-2007, 08:06 AM
#13
Race Director
From what I have observed from the numerous threads on spinning bearings, most are done after upgrading the top end of a LT1/4. I mean replacing the cam, heads and intakes along with a reprogrammed chip allowing higher RPM. There is a reason why GM put a limit on RPM on these engines.
I, also agree with pulling the engine to do work on the bearings, less chance of messing something up and you can be more accurate and clean.
I, also agree with pulling the engine to do work on the bearings, less chance of messing something up and you can be more accurate and clean.
10-26-2007, 08:16 AM
#14
Pro
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First things first,
Purchase a roadrace oil pan. I have and like a Canton because it is made specifically for a corvette. A Moroso will work as well but it hangs WAY too low for me & does not provide a plug for your oil temp unit.
You may want to check a bearing or two while changing the pan but chances are they are good.
A good pan will prevent oil starvation & is cheap insurance.
For even more protection an Accusump is a good idea too.
In short: High G's at sustained high RPM's (i.e. long fast sweeping corners) will kill a motor with a stock oiling system. It is just a matter time
Purchase a roadrace oil pan. I have and like a Canton because it is made specifically for a corvette. A Moroso will work as well but it hangs WAY too low for me & does not provide a plug for your oil temp unit.
You may want to check a bearing or two while changing the pan but chances are they are good.
A good pan will prevent oil starvation & is cheap insurance.
For even more protection an Accusump is a good idea too.
In short: High G's at sustained high RPM's (i.e. long fast sweeping corners) will kill a motor with a stock oiling system. It is just a matter time
10-26-2007, 08:38 AM
#15
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over reving the engine by bumping the rev limiters kills them.
so does oil starvation.
A road race pan, and an accusump help.
an oil cooler is also advised.
10-26-2007, 11:27 AM
#16
Race Director
Thread Starter
Thanks for all the advice.
At Road America I keep the car in D and it can see 5,500 RPM on the straights (three times per lap). I have found that my lap times are better if I hold D instead of going to OD. I do have a shift kit and governer recal. I plan to stay on street tires so I don't have to swap wheels at the track or trailer in (lowering cornering G). I have been reluctant to go over 5,500 and have not really needed to yet. Next season the car will have more power so I will be forced into more RPM or into OD. WOT OD shifts are going to wear on the trans.
May I have a part number for the pan? I was thinking I could modify the stock pan while it was off though too, is it worth it? I did modify one on my old Dodge by making a cardboard template then remaking the part out of metal and welding it in.
I am thinking the accusump is too expensive and would be out of the picture for awhile. My oil temp has not been to bad (250°) but I have been planning to install a cooler as I have not ran in really hot weather still.
There are 106,000 miles on the car now.
My father rode along and made a video, this is at Road America, closing weekend. Now for the long winter...
http://video.google.com/videoplay?do...08422587506673
The trans temp gauge is reflecting on the windshield making the HUD effect. The first lap was under caution due to the track being damp. It rained most of the day so I didn't get any really fast laps in but still had fun.
At Road America I keep the car in D and it can see 5,500 RPM on the straights (three times per lap). I have found that my lap times are better if I hold D instead of going to OD. I do have a shift kit and governer recal. I plan to stay on street tires so I don't have to swap wheels at the track or trailer in (lowering cornering G). I have been reluctant to go over 5,500 and have not really needed to yet. Next season the car will have more power so I will be forced into more RPM or into OD. WOT OD shifts are going to wear on the trans.
May I have a part number for the pan? I was thinking I could modify the stock pan while it was off though too, is it worth it? I did modify one on my old Dodge by making a cardboard template then remaking the part out of metal and welding it in.
I am thinking the accusump is too expensive and would be out of the picture for awhile. My oil temp has not been to bad (250°) but I have been planning to install a cooler as I have not ran in really hot weather still.
There are 106,000 miles on the car now.
My father rode along and made a video, this is at Road America, closing weekend. Now for the long winter...
http://video.google.com/videoplay?do...08422587506673
The trans temp gauge is reflecting on the windshield making the HUD effect. The first lap was under caution due to the track being damp. It rained most of the day so I didn't get any really fast laps in but still had fun.
10-26-2007, 11:48 AM
#17
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An accusump is less than $200 ( plus the installation ), which is a lot cheaper then an engine.
The carousel at RA is so off camber, you really want to get a road race pan on it.
Are you running race rubber?
The more grip you have the more you need it.
If your just starting out your probably safe running an extra quart, but better to be safe.
The carousel at RA is so off camber, you really want to get a road race pan on it.
Are you running race rubber?
The more grip you have the more you need it.
If your just starting out your probably safe running an extra quart, but better to be safe.
10-26-2007, 12:29 PM
#18
Race Director
Thread Starter
Just street tires for now. I have been adding the extra quart the last three years. It does use the whole quart in a track day, no oil use otherwise.
The carousel is still giving me trouble. As you can see in the video I tried going straight into it, that is really the off camber side. There is a seam in the track about in the middle and on the other side it is more flat. I think this should be a double apex corner but I need to try a different line there still. I did pass a Lotus and a C5 by there with the way I was taking the corner.
The Canton pan will fit well on my '88?
The carousel is still giving me trouble. As you can see in the video I tried going straight into it, that is really the off camber side. There is a seam in the track about in the middle and on the other side it is more flat. I think this should be a double apex corner but I need to try a different line there still. I did pass a Lotus and a C5 by there with the way I was taking the corner.
The Canton pan will fit well on my '88?
10-26-2007, 01:29 PM
#19
Le Mans Master
I am not in disagreement with Greg Gore about oil delivery, it is my #2 culprit.
I suggest that in the circles (pardon the pun) GG travels, rod prep is to a
higher standard than stock and that oiling becomes the #1 culprit. However,
for an OEM L98 rod in a high mileage engine, my vote is still that excessive
RPM is the leading cause of rod bearing trouble. Toe-may-toe :: toh-mah-toh.
Aardwolf, my vote is that **- IF -** the tach is accurate, 5,500 on stock con
rods & bolts is at the verge of shortening reliability. It becomes a matter
of when the clock runs out - the engine will last longer if periods are brief.
With an auto, missed shifts are less likely. Manual downshifts on a 700R4
can still overspeed the rotating components. Also, tachometer accuracy
can be an issue.
Options include choosing add-ons that build torque and electing to stay below
5300-5500. A SuperRam; 1-5/8 headers; small port heads and so on. The limit
here IMO are the hypereutectic pistons - greater V-efficiency increases dynamic
compression and raises prospects of piston damaging detonation
Alternatively, if more RPM is desired, a winter engine freshening could include
having the rods resized and fitted with better bolts or swapping them out for
reasonably priced aftermarket rods like those from Eagle or Scat.
My vote is that an accumulator with the optional E.P.C. pressurestat is an
excellent addition. The full install will cost way more than $200. Finding
a location for installation on a dual-purpose car is a challenge. Integrating
an accumulator with an OEM oil cooler can be a challenge.
Research oil pans carefully. The Canton 15-240T fits an '88 and can be installed
with the engine in place. Mine did not leak but more recently others have posted
about trouble. The pick-up is positioned back to the rear - I expect this works
well for high powered cars on a road course but the braking requirements of my
events needed pick-up placement further forward and different baffling.
I switched to an Armando pan - this worked well but a recent transaction for a
replacement pick-up (different pump) has not been as satisfactory. Someone else
here recently wrote about also wanting oil control under braking and they found
what they needed in a Champ pan.
.
I suggest that in the circles (pardon the pun) GG travels, rod prep is to a
higher standard than stock and that oiling becomes the #1 culprit. However,
for an OEM L98 rod in a high mileage engine, my vote is still that excessive
RPM is the leading cause of rod bearing trouble. Toe-may-toe :: toh-mah-toh.
Aardwolf, my vote is that **- IF -** the tach is accurate, 5,500 on stock con
rods & bolts is at the verge of shortening reliability. It becomes a matter
of when the clock runs out - the engine will last longer if periods are brief.
With an auto, missed shifts are less likely. Manual downshifts on a 700R4
can still overspeed the rotating components. Also, tachometer accuracy
can be an issue.
Options include choosing add-ons that build torque and electing to stay below
5300-5500. A SuperRam; 1-5/8 headers; small port heads and so on. The limit
here IMO are the hypereutectic pistons - greater V-efficiency increases dynamic
compression and raises prospects of piston damaging detonation
Alternatively, if more RPM is desired, a winter engine freshening could include
having the rods resized and fitted with better bolts or swapping them out for
reasonably priced aftermarket rods like those from Eagle or Scat.
My vote is that an accumulator with the optional E.P.C. pressurestat is an
excellent addition. The full install will cost way more than $200. Finding
a location for installation on a dual-purpose car is a challenge. Integrating
an accumulator with an OEM oil cooler can be a challenge.
Research oil pans carefully. The Canton 15-240T fits an '88 and can be installed
with the engine in place. Mine did not leak but more recently others have posted
about trouble. The pick-up is positioned back to the rear - I expect this works
well for high powered cars on a road course but the braking requirements of my
events needed pick-up placement further forward and different baffling.
I switched to an Armando pan - this worked well but a recent transaction for a
replacement pick-up (different pump) has not been as satisfactory. Someone else
here recently wrote about also wanting oil control under braking and they found
what they needed in a Champ pan.
.
10-26-2007, 01:49 PM
#20
Race Director
Thread Starter
I ran a search and bookmarked the Kevko site, it looks like they make a pan for road racing. On some of the corners I need to dump 100 MPH so how the pan handles braking is very important to me.
I don't really want to rebuild the engine till it has a serious problem. Then I would rebuild with more cubes. My thinking is that new rod bearings would help till the rings are done. I'd get my moneys worth out of the engine!
Is the accumulator install real hard? I do all my own work. My plan for the oil cooler was to ditch the stock coolant cooler and replace it with a 180° thermostat valve going to a stacked plate cooler mounted in the spare tire location.
I don't really want to rebuild the engine till it has a serious problem. Then I would rebuild with more cubes. My thinking is that new rod bearings would help till the rings are done. I'd get my moneys worth out of the engine!
Is the accumulator install real hard? I do all my own work. My plan for the oil cooler was to ditch the stock coolant cooler and replace it with a 180° thermostat valve going to a stacked plate cooler mounted in the spare tire location.