Hey guys, I need your advice. A friend just called me and asked what I would do if I had a binding wrist pin .He also sent me some pics I´ll attach below. His LS6 BB in his 66 Bel Air swallowed a little carb bolt, so my buddy pulled the engine to see what caused the noise and found the rest of the bolt in one of the cylinders. Now checking for further damage,he found that the piston that munched the bolt has a binding wrist pin where the other are perfectly smooth. He has to use both hands to move both hands and wedge the rod against the bench to move the pin. He used a heat gun to warm the piston to about 180°F and it moves a lot easier when it is warm, but still not as easy as the others. Here are some pics, you can see the mark were the piston was wedged against the cyl wall. Should he get a new piston ( if availible), or should he try and remove it from the rod and ream or poilsh the wrist pin bore? The piston is looking good otherwise, it is not cracked or damaged other than the bolt imprints on top. What would you do?
Jim , I was hoping you see this post and chime in. Do you think the binding came from hitting the bolt or would it just start to bind accidently? He shut off the engine immediately when he heard the noise and towed the car home.To me , the polished area in the bore looks like the piston might have been binding longer than for just a couple of revolutions. Damir, my friend, said that he thinks the 454 might be an 80s or 90s GM Performance LS6 type crate engine...I hope they still make replacement pistons for them.
My first task would be to have the rod checked for being slightly bent/twisted when it tried to compress the bolt......something had to give besides just denting piston and smashing bolt. Also, is the wrist pin actually bent/distorted ?
Yes that´s probably a good idea. I´m sure he´ll have to check the rod alignment once he removed the piston . The pin will be replaced along with a new piston. PS: Anybody has a GM TRW 3963550 piston for a 454 BB? Looks like none of the usual places has one...
Fwiw, I agree with Jim, I think the pin bore is probably distorted. I have had some experience in this area, and a tight pin is definately bad news, and has to be dealt with. I have seen the pin bore distort due to the heat to the point where the spiro-loc came out and the pin damaged the cylinder wall to the point where the block needed a sleeve. I realize this has press-fit pins, but IMO this has gotta be fixed. And I agree with carefully inspecting the rod before it is re-used as well.
I agree with all of the above regarding Jim & George's thoughts on this. But, let me add this for your consideration. If this was my Engine the Rod, Piston and Pin would be set up on the shelf for permanent display. You will always be "Wondering" about that hole, and with the cost of Engine parts if anything lets go you will kick your ass about it forever. New parts in that hole and you can cruise and abuse it to yout hearts content with no nagging doubts. Best of Luck with it!
I've re-used some crap that would scare the SHIT outta a lot of guys. But I would check that rod VERY carefully to make sure it isn't twisted or bent.
Dirty little secret. Bbc, broke the head off an intake valve, pieces of it went through the next four cylinders in the firing order. Holed one head, cracked two cylinder walls, and locked up so hard a third cylinder wall had a deep divot and a broken skirt (forgings, not hypers), had to sleeve those three holes, replace a head, and we replaced all the pistons. But after careful inspection, I re-used all eight rods! But yes, absolutely check the rod over CAREFULLY, and if there's any doubt, chuck it.
Whether you find a piston or not you will need to take it to an automotive machine shop and have them refit the pin and check the rod. The rod needs to be heated a little to remove or install the pin. If it has been tight on the pin for a while, the skirt might be too small but they can be knurled.
Penny wise and dollar foolish comes to mind on this type of post, new piston, pin and rod only way to go, proper head repair, valves, valve train inspection, also needed, a LS6 BBC is a valuable engine, not some junkyard crap thrown together, rebalance and have checked, crank etc or you will have pieces(junk). High compression, RPM engines, in fact ALL engines need to be correct or poor results are your destiny, junk. These are the FACTS.
Hey Baumi, thanks for this thread. Thanks all of you guys answering. It´s my engine this thread is all about. The more I think about it the more concerned I´m about it. First I thought it doesen´t look that bad, but you are all right. A skrew this size came out that flat, needs force to flatten steel this much. I will take my time to check all parts carefully. Next Thing is, I can´t find a Piston with that number new, I´ll take some time to search for one. It seems that the replacement Piston for my TRW GM 3963550 would be Speed-Pro L2349F? But I would really feel better with a original part, who knows, maybe I´m in luck and find one. Do you guys think the crank might be hurt, too?? I shut it up as soon i heard the noise, but that happened on the Highway at 3000rpm so it still turned a couple times. Bearings don´t Show unusual wear
I know a lot of HAMBERS don't like E-Bay, but currently, there are single L2349F's avaiable for $69.99, and there are two complete sets of stock rods/pistons ($600 and $800). Are the ring lands still good, the rings still slide smoothly around the ring grove? The rod can be checked/rebuilt. Even the pin can be reused IF it's straight and not all galled up (pin is stronger than the piston). Same with the piston, IF the pin bore can be refinished (oversize pins are also available). It comes down to, how much do you want to spend, and how big of a risk are you willing to take? You actually got by very lucky; the screw could have punched a hole through the head, piston head, or even the cylinder wall. Me? I'd probably have everything checked out, see if things can be refinished/repaired, and go from there; especially because of where you are located, and the difficulty in finding replacement parts. Good luck. I am Butch/56sedandelivery.
Ringland might be hurt, too. I didn´t check it right yet but I think I remember that the rings didn´t move all around freely but moving around one Point Sorry, my english is bad, hope you got what I try to explain
I think understand what you mean, but we speak the same kind of English, hahaha. You mean that you may have a tight spot in one of the ring lands so that the ring pivots around? Maybe you can find out if the sealed power L2349F is the same piston as your stock TRW .( I think TRW actually makes all the sealed power/ Speed Pro Pistons)And from what I read yesterday on Summit Racing site, the L2349F has 30.6cc dome volume, which is just the same as the stock LS6 pistons. Maybe you can call summit and ask about the weight of a L2349 F,or maybe it´s even oon their website, then weigh your TRW piston and if you are within a few grams I think you are golden....
Exactly. Contacted summit tech help already, waiting for snswer. I just don't know if all LS6 pistons were same? There was the closed chamber version from 1970, open chamber 1971 and later crate engine version with the 990 casting heads which I have. 118cc combustion chamber advertised to be about 10.2 to 1 CR I'm no expert!! Was there only one piston design or did they have various LS6 pistons?? Internet says the L2349 piston is a LS6 replacement and the dome looks same, can I be sure? Still would prefer an original piston. Just because;-) But I'll get over it.
I'm betting the bind was caused when the pin was pressed in If any damage to the piston crown is causing binding the rings would also bind. Check for cracks and rod straightness. If Ok then hone out the wrist pin bore That piston looks reusable
Damir, I googled" LS6 piston dome volume" and all I found was 30.6cc on every site that had LS6 pistons advertised. The lower CR on your engine is most likely achieved with the open chamber heads.
This is what it told me "The TRW-L2308 is either a ZL1 or L88 427 piston ID today as “Speed Pro ZL2308AF” worth approx $63 ea. The ZL1 was nearly identical to the production L88 aluminum head version of the 427, but featured an aluminum block. I believe the Compression ratio was around 11.4:1 with a 119cc Semi open chamber head."
The aluminum piston is the weakest or softest link in the system so it usually absorbs the most damage. It looks like the rings might be sticking in the photos but carbon can cause that too. The ring groove can be cleaned up with a small file. I've seen brand new pistons with tight grooves. The main things to check for are piston cracks and rod straightness. A lot depends on what you plan to use the engine for. Engines are built differently for different applications.
Damir, don't you think the rod can be straightened? I think so. Just in case you can not find a new one...have you got any response to your piston search yet?
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