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Did a search but couldn’t find exactly what I was looking for. I have a 1998 Formula with 160k miles on it. No mods daily driver. I recently pulled the engine to replace oil pump and give it a once over. Ended up giving the short block to a local machine shop to clean up and check over for me.
They said the cylinders are showing .003-.004” wear and I can either re-ring it or bore it out and get new pistons. I don’t plan on modding the car and will likely see some daily driver use for a couple more years. Has anyone just ran new rings without issues? If I did decide to bore it out, what’s the next piston size up? My shop is telling me it’s a .020 oversize which seems like a lot. The 1998 blocks has the thinner sleeves so not sure if that is a good idea.
Basically looking for some input on what I should do. I don’t want to spend more money than I have to considering how much money has gone into replacing suspension parts, AC, cooling etc. Thank you.
How much do you trust what they are telling you? Frankly I have a hard time trusting anyone with my engine but at this point it certainly makes since to re-ring your pistons. Just like it makes since to go back through the cylinder heads with a new valve job, seals, springs and retainers. At 160,000 miles your cam bearings may be showing significant signs of wear and need to be replaced. If your in this far go ahead and install an LS2 timing cover and timing chain and while your at it throw in some new lifters. But if you want to just put a (xx:xx) on it then put it all back together and just run it!
Hi Rocky, I can supply Forged Pistons at +.006" AND use +.005 rings.
DO NOT WASTE money for a Bore job.
Lance
Thanks for the tip. Will send you a private message.
Originally Posted by 01CamaroSSTx
How much do you trust what they are telling you? Frankly I have a hard time trusting anyone with my engine but at this point it certainly makes since to re-ring your pistons. Just like it makes since to go back through the cylinder heads with a new valve job, seals, springs and retainers. At 160,000 miles your cam bearings may be showing significant signs of wear and need to be replaced. If your in this far go ahead and install an LS2 timing cover and timing chain and while your at it throw in some new lifters. But if you want to just put a (xx:xx) on it then put it all back together and just run it!
I probably should have included a bit more details about what else I’m doing. I got a set of 241 heads locally for free that had about 20k on them. Nice and clean and figured I will give them a light lap job at home and be good. I’m replacing all the wear items while I have the engine apart. Ordered new lifters, new timing chain, oil pump etc. Gave the short block to the shop to deal with the cam/main bearings and pistons/rings. Just wasn’t sure at what gap the pistons must be replaced as this is my first time diving into an engine and the shop I’m dealing with really isn’t a speed shop. Thanks.
A shop need not be a speed shop to know basic engine assembly/machining operations. Speed shops sell performance parts. Any engine shop they have would have the same capabilities as any other engine machine shop. As long as the shop you are using knows how to assemble an engine you should be OK.
Reading this excerpt below has got me thinking I should just get new rings and a light hone being that mine is a 1998. And it's got me a little worried the shop is even suggesting a 0.020 oversize piston
The blocks are actually cast in place around these liners (rather than the normal practice of pressing the liners into the block after it has been cast). On the very earliest LS1 blocks produced in 1997 and 1998, the sleeves may not always be positioned 100 percent perpendicular within the block casting, meaning that the final-bore sizing and honing process left one side of the walls thinner than the official engine design specs called for. Therefore, 1997–1998 LS1 5.7L aluminum blocks can only be safely honed (not even bored!) just 0.004-inch over the stock bore diameter. Improved liner positioning in 1999-and later 5.7L LS1 blocks and all LS6 blocks permit boring up to 0.010-inch oversize. Either way, you are SOL at wanting to go 0.020-over for a reliable LS1 aluminum block rebuild.
I would be more worried about someone pulling a 160k mile engine apart that doesnt plan on modding the car.
Or am I missing something here? Replacing oil pump??? Just because you wanted to or because it was having issues?
These engines in stock form will go 300,000 miles with nothing more than a lifter tap. With proper oil changes of course
The shop may have suggested.020 if it has an older boring bar. It can be hard to center in a worn cylinder to cut .005 of each side all the way down. I do agree with getting the .005-.006 over pistons because you can throw it in a hone and clean it up and know you’re gonna seal new rings.
I would be more worried about someone pulling a 160k mile engine apart that doesnt plan on modding the car.
Or am I missing something here? Replacing oil pump??? Just because you wanted to or because it was having issues?
These engines in stock form will go 300,000 miles with nothing more than a lifter tap. With proper oil changes of course
I too wonder why urgency to open up the engine? I daily drive my 332,000 mile TA and the only thing that I have done engine wise is replace the oil pump (it was tired at around 280k and the pressure was under 20 at hot idle.) While there I replaced the timing chain and sprockets. I am using a quart of oil between 3k oil changes, but I still am gonna just drive it.
Come on guys, if I was smart I’d have sold the car a long time ago lol. Most of the what I’m doing is just for my own learning and I’m probably doing stuff that isn’t needed. I have a 90 Iroc and 09 vette which will be a proper project car in the future. This is just a learning excercise and an expensive one at that.
The oil pressure had been dropping steadily for about 12 months, and combined with all the oil leaks the car had I figured I would just drop the cradle so I didn’t have to work on my back. Had been seeing a little milkiness in my recent oil changes and had a set of newish 241 heads so off my old heads came. Once I saw all the crud I figured a hot tank was in order. At that point it’s at the shop so might as well throw in some new bearings and inspect so here we are.
I guess an option I still have is to just leave everything as is and reassemble with some new bearings. I can’t find a set of non-forged 3.903 pistons so I’m leaning towards just replacing the rings. I was hoping someone with experience could tell me if this is a really bad idea or I should be ok.
I will be posting more pics later but here are some showing the block. Haven’t always been on top of my maintenance and it shows.
Ooof. Yeah, she’s gonna need a hot tank. Make sure the shop your using has a torque plate for the LS engine. Believe it or not, 21 years later, some shops still don’t have one.
I don't see why you couldn't you just go through the cylinders with about 7-10 strokes of a FLEX ball hone to get some cross hatching in it and then clean everything up really good and reassemble with new rings and bearings.
I don't see why you couldn't you just go through the cylinders with about 7-10 strokes of a FLEX ball hone to get some cross hatching in it and then clean everything up really good and reassemble with new rings and bearings.
Because he secretly wants to have a completely rebuild engine and is trying his best to justify it in his mind.
I don't see why you couldn't you just go through the cylinders with about 7-10 strokes of a FLEX ball hone to get some cross hatching in it and then clean everything up really good and reassemble with new rings and bearings.
I guess this is what I was asking for some input on. If I had one of the newer blocks, I think I would just hone it to 3.905 and get new pistons. Mine being a ‘98, I’m thinking of going the route you mentioned. It won’t be any worse off than it was before I dropped it off. A little piston slap and oil consumption let’s me know she’s there.
Originally Posted by Ls7colorado
Because he secretly wants to have a completely rebuild engine and is trying his best to justify it in his mind.
I will try and make better life decisions in the future.
Keeping stock cam for now. I have an A4 and was planning on keeping TC for now. Stock TC stock cam. Only things I’ve got lined up are ARH lt headers and LS6 intake mainly cuz I wanted to ditch the EGR/AIR. Nice dd car with a lil punch I hope.
I guess i'll do it. Take that aluminum block and put it in your garbage disposal. Aquire an lq4/lq9 and put that in there with your accessories. Get it tuned and you will still have $ left over and a better engine. If the 100 lbs difference is too much go on a diet. At lowe's they have some nice aluminum looking paint if you want to keep the stock look.
So the machine shop is finally getting back to my block. They are able to source some new forged Wiseco ProTru 3.903 pistons for me for very cheap (300usd) from one of their other customers. These are +4cc dome pistons which would push my static compression to roughly 10.8:1.
I know it's dynamic compression which is what matters but I can't find any detailed specs on my stock 1998 cam (ABDC?) and I've searched a lot. Any thoughts on running ~11:1 static compression on 91 octane with a stock cam? My other choice will probably be to trade my 241s with some 317s that would take my compression back down to 10.1 based on the calculators I've used.
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New rings or replace pistons 
