Robedom
Probationary Member
- 10
- 11
- Apr 12, 2023
-
Vista,
California
Looking for some advice from the DSM community because I’ve gotten myself into a pretty frustrating situation with this rebuild.
My 1996 Eclipse GSX has been at a shop in California for quite a while getting rebuilt. We started by completely rebuilding the 1G big-port head with upgraded valvetrain, titanium components, cams, etc. After dealing with some problems there and replacing a bunch of parts, we discovered that one of the cylinders in the block was badly scarred.
We pulled the engine, sent the block to the machine shop, had the damaged cylinder sleeved, and had the block completely machined and cleaned up.
Then we discovered there was also a problem with the crankshaft. My builder told me I had a 6-bolt, so I purchased a forged 6-bolt crank from STM Tuned and had it balanced and polished. I also bought Wiseco forged pistons and Manley H-beam rods. At this point I figured I was building a bottom end capable of handling far more power than I would ever actually use — potentially an 800-hp-capable motor even though that isn’t my goal.
Then last night I found out that the block that has been in the car this entire time is actually a 7-bolt.
So now I have a freshly sleeved and machined 7-bolt block, but a brand-new forged 6-bolt crank and H-beams that obviously aren’t going to work with it.
The car only has about 42,000 original miles, and the original block damage appears to have been related to crankwalk/thrust bearing failure. That leaves me trying to decide what direction makes the most sense from here.
Do I:
My concern with staying 7-bolt is crankwalk. I have a pretty aggressive clutch/master setup in the car, and from what I’ve been reading, clutch pressure/load may have contributed to the thrust bearing failure in the first place.
That said, the actual goal for the car is only around 450–500 hp on E85. I have absolutely no intention of racing it, launching it repeatedly, or trying to make 800 hp. This is basically a weekend car that will probably see 1,000 miles or less per year.
So am I overthinking the crankwalk issue? With a properly machined/rebuilt 7-bolt, good forged rotating assembly, correct clearances, and only 450–500 hp, would you guys have any hesitation running the 7-bolt in this application?
The other consideration is what to do with the parts I don’t use.
If I go 6-bolt, I’ll have a completely cleaned, machined and sleeved 7-bolt block available that has already had all the machine work done.
If I stay 7-bolt, I’ll have a brand-new STM Tuned forged 6-bolt crank that has been balanced and polished, along with the 6-bolt Manley H-beams, that I’ll need to sell.
Is there much of a market for either setup? I’d obviously like to recover some of the money I’ve dumped into this because of the 6-bolt/7-bolt misunderstanding.
One last piece of context: this isn’t really a “build the fastest DSM possible” project anymore. This particular car was featured in Sport Compact Car back in 1999, and my goal now is to restore it into something resembling a period-correct time capsule. I want it fast and reliable, but I don’t want to turn it into a modern 800-hp race build with a bunch of modifications that wouldn’t have made sense for the car in that era.
Given that goal, 450–500 hp on E85, very limited annual mileage, and no racing, would you finish the 7-bolt that I already have fully machined, or would you use this opportunity to go 6-bolt?
Interested to hear what the DSM community thinks.
My 1996 Eclipse GSX has been at a shop in California for quite a while getting rebuilt. We started by completely rebuilding the 1G big-port head with upgraded valvetrain, titanium components, cams, etc. After dealing with some problems there and replacing a bunch of parts, we discovered that one of the cylinders in the block was badly scarred.
We pulled the engine, sent the block to the machine shop, had the damaged cylinder sleeved, and had the block completely machined and cleaned up.
Then we discovered there was also a problem with the crankshaft. My builder told me I had a 6-bolt, so I purchased a forged 6-bolt crank from STM Tuned and had it balanced and polished. I also bought Wiseco forged pistons and Manley H-beam rods. At this point I figured I was building a bottom end capable of handling far more power than I would ever actually use — potentially an 800-hp-capable motor even though that isn’t my goal.
Then last night I found out that the block that has been in the car this entire time is actually a 7-bolt.
So now I have a freshly sleeved and machined 7-bolt block, but a brand-new forged 6-bolt crank and H-beams that obviously aren’t going to work with it.
The car only has about 42,000 original miles, and the original block damage appears to have been related to crankwalk/thrust bearing failure. That leaves me trying to decide what direction makes the most sense from here.
Do I:
- Keep the freshly machined and sleeved 7-bolt block and buy another forged crank and H-beams for the 7-bolt?
- Find a good 6-bolt block and finish converting the car from the original 7-bolt setup to a 6-bolt?
My concern with staying 7-bolt is crankwalk. I have a pretty aggressive clutch/master setup in the car, and from what I’ve been reading, clutch pressure/load may have contributed to the thrust bearing failure in the first place.
That said, the actual goal for the car is only around 450–500 hp on E85. I have absolutely no intention of racing it, launching it repeatedly, or trying to make 800 hp. This is basically a weekend car that will probably see 1,000 miles or less per year.
So am I overthinking the crankwalk issue? With a properly machined/rebuilt 7-bolt, good forged rotating assembly, correct clearances, and only 450–500 hp, would you guys have any hesitation running the 7-bolt in this application?
The other consideration is what to do with the parts I don’t use.
If I go 6-bolt, I’ll have a completely cleaned, machined and sleeved 7-bolt block available that has already had all the machine work done.
If I stay 7-bolt, I’ll have a brand-new STM Tuned forged 6-bolt crank that has been balanced and polished, along with the 6-bolt Manley H-beams, that I’ll need to sell.
Is there much of a market for either setup? I’d obviously like to recover some of the money I’ve dumped into this because of the 6-bolt/7-bolt misunderstanding.
One last piece of context: this isn’t really a “build the fastest DSM possible” project anymore. This particular car was featured in Sport Compact Car back in 1999, and my goal now is to restore it into something resembling a period-correct time capsule. I want it fast and reliable, but I don’t want to turn it into a modern 800-hp race build with a bunch of modifications that wouldn’t have made sense for the car in that era.
Given that goal, 450–500 hp on E85, very limited annual mileage, and no racing, would you finish the 7-bolt that I already have fully machined, or would you use this opportunity to go 6-bolt?
Interested to hear what the DSM community thinks.
