So a little back story. First I never rebuilt an engine so I'm lost on all the technical language but i have replaced parts on cars and know how to torque them right by reading the manuals. Well my brother passed away 6 months ago and he had an 05 z71 that was sitting because the motor had a hole in the block. This truck had a l33 in it with 799 heads. I want to get the truck running in remembrance of him. I know the l33 is aluminum block and they are hard to find with a big price tag. So since money is very tight I had a friend give me an iron block lm7 which looks exactly the same. Will everything mount up to this block (799 heads, crankshaft, cam ect)? I am going to replace all seals, gaskets, piston rings, hone the piston walls, crank and cam bearings. The lm7 block has a cam and crank in it but I think the l33 had different ones so I'm going to use the can, crank and pistons from the l33 unless there's a reason not to. Any and all comments welcome in helping me achieve my goal on getting my brothers old truck back to life. Thank you.

 

I'm sorry about your Brother's passing. 🙏

I think you have a good project going.

I would say that since the original engine had a hole on the block, it's very likely something went wrong with it, so careful inspection of the internal components is going to be key. Hopefully everything is still reusable. Have you taken the engine apart yet?

 

Yes I did. Cylinder 1 threw a rod. The rod broke off on top and bottom and threw the entire piece into the block. The bearing and piston clamps were still on the crank so the crank looks good where the bearings go. A big chunk of the block on piston 1 on the bottom is broken and the hole in the block is all i see. I took the motor fully apart and after the rod busted the block it blew a bit hole into the oil deflector and layed into the oil pan. The crank looks good with no scarring on the bearing spots. Heads seems good and passed water pressure test. Oil pan has no dents or holes. Cam has no scarring. Anything else I should look for?

 

Ok, sounds like you are doing a good job checking.

Are you planning on checking bearing clearances? I think Plastiguage will work and is inexpensive. Check main and rods.

 

Thats where inexperience comes into play. I was just going to order regular stock bearings and put it together. I just figured if there was an issue the machine shop would tell me when they clean the block, hone, change cam bearings and ensure and cut block if needed to ensure its straight. How would I check the piston rods since they attached to the pistons besides cracks and not bent? That brings me to another question, the block that was givin to me has pistons that looks the exact same as the l33 pistons. Do I reuse these or can I use the 7 good pistons from the l33 and one from this block? Again thank you for all information to help me achieve my goal on getting the truck back on the road.

 

I'm just a hobbyist myself learning the craft, so I can't answer all of your questions. Someone please chime in.

Do you have a micrometer? You should be able to do a visual inspection and take some dimensions to determine if the pistons are good. Are the rods the pressed-in type? I thought on the later LS Gen III the rods were the floating style held with the little clips? Or, I think you are asking about the LM7, then correct? Those are probably pressed in.

 

I'm not sure about the pistons in the lm7 because I haven't removed them and sent in the block yet. But from what I read those are pressed and the 7 good ones from the p33 does have the clip. That's why I wasn't sure to use the 7 and one from the lm7. I'm not even a hobbiest lol. I'm just a guy with tools and changes stuff when they break. I can pick up a micrometer and check before I order the parts. I decided to ask the guys that knows what they doing first before I send the block and order all parts to try to rebuild my first motor.

 

Use what’s with the iron block. If you try and switch 7 from here and use another from a different engine, you could run into balance issues. The Lm7 bottom end is fine, so keep it as a unit. I’d use the heads and intake from the l33. The L33 was considered the HO 5.3 (high output) so the camshaft might be a tad better than the LM7 camshaft. Your machinist will be able to help you get the correct bearings for both mains and rods. If the lm7 needs bored, he can also help you with pistons and rings. You’ll need new head bolts, because the LS engines headbolts are a “one time use” fastener, although I’ve seen guys re-use them without issue. While your there grab a new oil pump and timing set. There are vendors here that sponsor the site, who can help you with every bit of this. I’ve used WS6Store a few times in the past for stock/mild rebuilds and their prices and customer service is top notch. Good luck and don’t be afraid to ask for help.

 

That's alot of help thank you for the information. So would it be good to use the l33 cam?

 

As long as it’s not damaged, absolutely. It will keep you out of getting a tune done as well. Use the L33 intake and injectors also.

 

The more you mess with in the bottom end the more magic you let out. And as funny as that sounds, there's truth in it. The best bet is to leave the rotating assembly alone. If you want to swap the cam I would recommend doing at least a stage 1 cam while you are in there to make the time and effort worth it.

Pulling the l33 all apart and the lm7 to swap a stock cam in that will likely give you around 5 hp isnt worth it in my opinion. And again, it introduces variables that wouldn't other wise be there.

Putting anything from a blown up engine onto another engine is very risky. Metal fragments and shavings go into the strangest places.



So, my recommendation is pull the heads off the l33 and send them out for cleaning and inspection and broken exhaust bolt removal (surely there are some broken off in the heads).

Then put them on the lm7 and slap it in the truck and be good to go. Or get a small cam and put it in while you have everything apart. Be a good time for some long tube headers and new motor mounts also. Long tubes provide good gains (in combo with a good flowing cat back of course)

 

Thanks for the information. That was recommended to just use the lm7 parts and reuse the heads. That is the rought i am going to take. The block and heads was dropped off yesterday and when theu come back im hoing to order the new rings, gaskets ect. I was going to order them beforw but descided not to just in case they have to bore it.

 

Man that's awesome your way ahead of where I thought you would be. I got lost and saw your thread here going and let the other people put there 2 cents in and you actually already have a block chosen and dropped off nice. I'm not familiar with the Gen III personally. Have you selected an online supplier? Being new here I won't give any advice I'm rebuilding something after not working on anything in years last time I changed some heads was 5 years ago on a v6 saab lol. I bought my 08 6.0 2 years ago replaced a lifter initially in California with a bare set of tools to get back to Texas was sloppy work and probably contaminated the oil in the top end because a number 4 cam bearing took a **** 35k later or it was the race car way I had been driving the truck nearly redlining way too often lol. Also rebuilt the 4l70e a year ago never been so covered in fluid which was dumb now I buy gloves don't cancer yourself. But I did a great job put 20k on it since. Today's lesson for me is make sure you have enough workspace. I put the driver head on torque the head bolts moved on to the left side putting the lifters in get to noticing I have one left. I panicked I quickly grabbed a push rod started poking the head installed checking all the holes and none gave showing lifters. I then took the assumption that I had to have switched one of the old ones in one grabbing them out of the box because I did have one old one in there and my thought I probably put it in the bucket and it's probably installed underneath the head but fortunately enough I looked over at the passenger lifters I just put in and one had a gold clip out of all my morrel lifters indicating the ls7 style lifter did get swapped in. Swapped out and both my heads are torqued need to go finish and give it a shot. You will have a couple phases of ordering good to order what you can now make sure it fits so you can eliminate it off your list and I just barely thought of it that way myself. What was your brother name? I've never had siblings but I've lost a few close friends and it takes time to feel like you have recovered from it so it's ok when your not buddy hang in there. Again awesome job delivering to the machine shop they give you a time frame?! Apologize for the grammar errors

 

My brothers name is Troy. I hadn't found an online supplier yet but I am looking. Now if anyone has any thoughts I have another question. The oil pickup tube have very little shavings on the screen because I think the rod blew when trying to start so is that something I can just clean instead of replacing and when I took the oil pump apart I found no scarring, no wear on the gear and not much shavings. Can I just clean up the oil pump and pickup tube e and reuse them? I am doing all the bearings, timing gears and chain, rings, and motor mounts. I think the head bolts are tty but not sure. If so, would it be a good idea to replace them?

 

Pickup tube and screen will clean, no problem. You can actually carefully unfold the metal seam around the screen itself, and clean it the right way. It comes apart pretty easy. Give WS6Store a call if your interested in a full kit with headbolts. I’ve bought a few from them for mild builds and they are great. They are a site sponsor. Great guys. The kit will come with a new oil pump as well as everything you need to rebuild your engine. Best prices and great service.

 

Getting his truck running definitely seems like an awesome commemoration. Let me know if your local to Texas if you would need a hand.My gaskets I get all locally from oriellys for this build not sure if there is a go to online that isn't outrageous either. I paid nearly 100 for my intake gaskets and 60 for a valley cover gasket which I thought was insane. WS6 carry ARP headbolts? I used the TTY's for years even reused them once 2 seperate times. Ordered ARP's for my current truck and I'm really happy I've heard 5x reused is ok and for the bit more I paid it's worth it. I finally drove it today and I'm kinda speechless don't wanna speak too soon before I put a good drive on it. Sorry if I wrote a story last time just didn't want you to think I forgot about you didn't realize I talked about my stupidity so much but it's a learning process.

 

Yeah I am in the Houston area. I am getting the head bolts from oreillys. I'm orange the gasket kit from online. The kit has good reviews and a lifetime warranty. The timing chain and timing gears from Amazon (alot of good reviews). The machine shop said since it was my brothers truck and he died in my arms 7 months ago and the reasoning why I'm building it they are going to rebuild my heads with new seals, clean and paint them for no charge and also clean the cam, crank and pistons at no charge. So all I'm paying for is the block cleaning, honing, cam bearings and block and heads smoothing or whatever it's called if it needs it. So next week when I get it back all I have to do is put it together.

 

Well the world gets smaller and smaller. I'll be headed home to Corpus Christi here in a week or so if things work out right and maybe I can head up there.

 

A little update and I broke it. Got it back from the machine shop. Everything looked good and he found no faults. Recieved my parts and went to put it together. Crank went in good and got it torqued to specs. Put on my piston rings and clocked them. Went to out I. The first piston and kept popping out the sleeve. Well on the last ring it popped out and the piston broke. So I'm guessing to use a piston from the l33. I still have to clean it but what's everyone's thoughts? Will it be ok?

 

No it won’t work. The broken piston is a dished piston. The good piston in your pictures is a true flattop. You can not mix them. I see a C-Clip holding the pin in the picture of the broke piston. Does the other engine have C-Clips that hold the pin in? If so, you could swap all 8 pistons over with their rings, and hope for the best on a balance job. You need to buy a tapered ring compressor for 3.78”, which is what you doing here. It will make your life soooo much easier. Here’s a link for that $30 tool.
https://www.summitracing.com/parts/s...SABEgL1GfD_BwE
Take your time here. If something won’t go smoothly, there’s a reason. Look for the obvious. Don’t force anything. With the tapered compressor, you can knock all 8 in the holes on a few minutes.