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pvmatman
05-08-2013, 01:30 PM
Anyone have a good source for LT1 Heads? Mine overheated and blew a huge chunk out between two cylinders. I presume it cannot be repaired and that the pair should be replaced.
I plan to replace both thermostats during this rebuild. Anything else to be aware of on this motor?

Thanks

XtwentyNot
05-08-2013, 02:31 PM
Impalassforum.com is where I would start.

CC2MC
05-08-2013, 03:58 PM
Anyone have a good source for LT1 Heads? Mine overheated and blew a huge chunk out between two cylinders. I presume it cannot be repaired and that the pair should be replaced.
I plan to replace both thermostats during this rebuild. Anything else to be aware of on this motor?

Thanks

Did you just lose compression? Do you know why it overheated?

pvmatman
05-10-2013, 05:09 PM
No clue why it overheated. Impeller is new. Will be replaceing the thermostats as part of the rebuild if I can the heads for it. Will try ImpalaSS.com.

blackcreek
05-11-2013, 08:30 AM
This needs to get moved to engine forum. Any cylinder head shop can fix you up. The impalla SS used steel lt1 heads if I am not mistaken. You really just need to find the casting number on the head to match it up. LT-1 had steel or aluminum heads depending on make and model of car. http://outintheshop.com/faq/casting/heads.html

pvmatman
05-12-2013, 11:54 PM
Thanks Blackcreek. Found the casting number and got the details from the link you provided.

Casting #12551561 350 96 2.00/1.55 Gen II LT1 angle plug aluminum reverse flow cooling.

Sorry about posting in the wrong forum. any idea how to move it to engine?

JohnE
05-13-2013, 08:39 AM
Thanks Blackcreek. Found the casting number and got the details from the link you provided.

Casting #12551561 350 96 2.00/1.55 Gen II LT1 angle plug aluminum reverse flow cooling.

Sorry about posting in the wrong forum. any idea how to move it to engine?

Good luck with the repair. I moved the thread.

JimN
05-13-2013, 09:03 AM
Anyone have a good source for LT1 Heads? Mine overheated and blew a huge chunk out between two cylinders. I presume it cannot be repaired and that the pair should be replaced.
I plan to replace both thermostats during this rebuild. Anything else to be aware of on this motor?

Thanks

I'm pretty sure that didn't overheat once and do this- it looks more like the gasket was damaged and it ran for quite a while before failing or it was at high speed. If it was only one event, it was extremely hot.

Have you removed the valves in those two cylinders? Any evidence of wear to the valve or seat? Any other areas where you see melted aluminum?

Call a speed shop.

mgs96ps
05-13-2013, 12:40 PM
This post scares the pee pee out of me. Pvmatman you need to come clean and tell us the whole truth. There must have been signs and/or more to this story. Please help other LT1 owners...we need to keep this boat around as long as possible. Good luck on rebuilding of heads and keep posting.

blackcreek
05-13-2013, 08:28 PM
If I ever blow my original heads I am going to go with the steel Lt-1 heads. They flow just as good and will be far more forgiving in an overheat. Also, the water I boat in is not always 100 percent fresh and goes brackish at times. I will trade the extra weight for the added toughness of the steel heads in a marine environment.

1redTA
05-13-2013, 10:50 PM
I believe the steel heads share their port design from the vortec heads and have better low and mid lift flow. As far as the damage I've been around a lot of high horse power lt1 cars and never seen anything like that.

XtwentyNot
05-14-2013, 02:18 AM
Being an impala ss guy it's funny to me they didn't use the steel ones. They have been proven to flow better then the aluminum ones, in fact they are some of the best flowing heads GM ever produced, they are set up for more torque, and I would think they would stand up better to a marine environment.

XtwentyNot
05-14-2013, 02:21 AM
This needs to get moved to engine forum. Any cylinder head shop can fix you up. The impalla SS used steel lt1 heads if I am not mistaken. You really just need to find the casting number on the head to match it up. LT-1 had steel or aluminum heads depending on make and model of car. http://outintheshop.com/faq/casting/heads.html

I've seen numerous aluminum lt1 heads for good deals on the impala site. Stock and modified, so many impala guys are switching to ls1's they are plentiful. The boats all came with aluminum, I assumed you would be looking for aluminum replacements when I mentioned looking there.

Legolamb
05-14-2013, 07:16 AM
Here's a link to a 96 set, don't know if they are the same or not.

http://www.ski-it-again.com/php/skiitagain.php?topic=Search&category=Parts_Engine&postid=18259

pvmatman
05-17-2013, 11:25 AM
Thanks for the input from everyone. I purchased the boat in the fall last year. Had a comp test done at the dealer and all cylinders were 205-210 except #6 was at 195.
Started the engine on fake a lake in the driveway this spring and everything seemed OK. Dropped it in the water, started up, accelerated and found a definite lack of power. The temp gauge was very erratic so I limped back to the ramp and pulled it out. I'm guessing the dealer didn't quite do the compression test as they said. They have agreed to cover the cost of the repair though. I was able to locate a LT1 head at a local speed shop and am currently in the process of putting it back together. If all goes well, it should be on the water this afternoon.