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Thread: Engine Block Cracked

  1. #21
    Senior Member Carroll Shelby Fbody383's Avatar
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    Quote Originally Posted by 39PitCrew View Post
    trans fluid in it and we kept getting different readings on the dial depending on if we spun the shaft or not? If I recall, it made 1-2 thou difference in the measurement.
    I think that's right... after we moved everything around whatever was in bearings/spacers/etc. would move some oil around and change the readings.
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  2. #22
    Member Rookie fscott's Avatar
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    Quote Originally Posted by 64GunPilot View Post
    Has anyone ever tried brazing? I am thinking to open up the cracks with a dremel, and then braze with Muggyweld SSF-6 brazing rods specifically for cast iron using a torch. Maybe I can preheat the assembled engine from the side using a propane IR heater so there wouldnt be any shock heating/cooling.
    I've TIG welded cast iron once, using specialty rods. I got away without preheating. The trick there was to put down some weld, and then immediately grab a hammer and punch and start beating on the weld bead as it cools. Then repeat as needed until done.

    When you weld cast iron, the weld shrinks enough to pull away from the base metal, which is why you normally preheat the entire workpiece. But by peening the metal as it cools, you're forcing it into the gap that's trying to open.

    I agree with others, a new block is probably better. But I thought you might want to know this trick in case it ever comes up.

  3. #23
    Senior Member Rookie 64GunPilot's Avatar
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    LM7 5.3 Engine, intake manifold, throttle body, injectors, exhaust manifolds, and T56 transmission all bought and paid for. Still needing a lot of other stuff, the $$$ is starting to add up and Im starting to think maybe I would have been better to just do a new 305 shortblock. I enjoyed being slow with the 305 TPI, at least I had an excuse. But after an LS swap I wont have any excuses. I'll just be slow and broke LOL.
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  4. #24
    Senior Member Carroll Shelby Supercharged111's Avatar
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    Still gotta do the oil pan, accessories, cheater short 5th, and electronics. It's all on my white board and it makes me throw up in my mouth. After Hallett I seriously question if it's worth it.
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  5. #25
    Senior Member Rookie 64GunPilot's Avatar
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    So, after a complete teardown of my junkyard 5.3 I've measured the bores after ball honing. Im 0.0015 out of round (1.5 thousandths) and the piston to wall clearance is about 0.005. New standard pistons should bring it down between 0.002 - 0.003 but thats the best Im gonna get before having to go full bore and upsize and rebalance at the machine shop.

    Anyone here think 0.0015 out of round is a problem? New pistons (hypereutectic) and send it?
    Last edited by 64GunPilot; 08-01-2021 at 06:18 PM.
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  6. #26
    Senior Member Carroll Shelby Supercharged111's Avatar
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    I think you should have left the pistons in the holes, checked a couple of bearings for copper, and sent that lump. There's plenty of money to spend elsewhere in the swap. They usually out down around 275whp junkyard fresh.
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  7. #27
    Senior Member Rookie 64GunPilot's Avatar
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    Quote Originally Posted by Supercharged111 View Post
    I think you should have left the pistons in the holes, checked a couple of bearings for copper, and sent that lump. There's plenty of money to spend elsewhere in the swap. They usually out down around 275whp junkyard fresh.
    I don't think this engine was gonna last very long based on what I see. I can tell you a cam lobe was eaten by a bad lifter, cam bearings were shot, and the heads had some exhaust bolts snapped off. So thinking the eaten cam metals might have damaged the lower end bearings, I decided a full teardown was in order. The lower end was amazingly in like new condition.

    So thats where Im at. Full bore, or just slap in some new stuff and send it or does anyone think original pistons with 5 thou PTW clearance is ok? Send it?
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  8. #28
    Senior Member Carroll Shelby Supercharged111's Avatar
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    Take this for what it's worth: back in 2015 I found I'd wadded up a rod bearing. My motor is a 93, I believe it was 95 when they changed the rotating assembly but don't quote me. I nailed a late LT1 crank on Craigslist and had it polished. I found a set of stock takeout pistons and rods on eBay. I installed new rings and bearings, gave the bores a 3 stone hone job 320 grit with moly rings. Didn't measure a damn thing and that's the motor you saw my car run at Hallett. On a motor that needs to be restricted, perfection isn't really necessary IMO. Mine made 292whp unrestricted in 2016. I'm 1 plate size larger than I was then. Is it the book answer? No. But to an extent, good enough is good enough in our class. YMMV.
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  9. #29
    Senior Member Rookie 64GunPilot's Avatar
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    Im not looking to build power obviously, just reliability. Im not usually a lucky person, so putting it together without taking measurements, my luck something would be x10 beyond a tolerance and the engine would self destruct on the dyno. Problem is I never done this before, and I don't know typical limits of what is normal.

    I just ordered a kit with new pistons. Will throw it together and see how it turns out.
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  10. #30
    Senior Member Rookie 64GunPilot's Avatar
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    Jealous not being able to come and attend Hallett this year.

    Being deployed I have too much time to think about racecar stuff. Ive been building a 5.3 and getting ready to do the swap. I came across a good deal on an LT1 complete turn key with accessories and T56 trans and bought it. The trans needs rebuild, but was thinking about what if I bolted up the LT1 to the T5 currently in the car. Would the T5 survive? Most seem to think it would not survive behind the 5.3. I would assume the same behind an LT1. Just asking what ya'll think. Some other forums have folks who thrash on the LT1/T5 and say it seems to survive but thats probably on street tires and street conditions. The LT1 would be so much more simple in terms of engine mount, trans bolt up, driveshaft mod ect. (Ive read plenty about the optispark issues and torqhead is an expensive fix).

    Im still planning to do the 5.3 but just window shopping other ideas.
    Last edited by 64GunPilot; 06-06-2022 at 01:45 AM.
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