Problems with rebuild
Thread Starter
Instructor
Joined: Mar 2006
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Problems with rebuild
Alright This is an older corvette motor with the 4 bolt mains and its been in my boat for a few years now, and just recently I spun 2 main bearings, so i tore it all down and rebuilt it had it line bored and reconditioned completly had it decked added a bigger came some 202 heads, a weiland high rise holley carb, and kept the flat top pistons. So i got it back togeather took it out to get it timed right and it was running fine. I fine tuned the timing and it was good. I ideled it out for prob about 20 min or so then i took off not hard on it or anything and drove to my fishing spot. went fishing, which was good, then left. On the way back it started sounding like it did when i spun the bearings but only not nearly as loud. so i opend the engine lid and it was smoking out of the valve covers, I have breathers that go to the carb from the valves, it was smoking out of these. So yeah im getting ready to pull it back out and look it over. What do u guys think? and advice is apreciated.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by HighHeat303
Alright This is an older corvette motor with the 4 bolt mains and its been in my boat for a few years now, and just recently I spun 2 main bearings, so i tore it all down and rebuilt it had it line bored and reconditioned completly had it decked added a bigger came some 202 heads, a weiland high rise holley carb, and kept the flat top pistons. So i got it back togeather took it out to get it timed right and it was running fine. I fine tuned the timing and it was good. I ideled it out for prob about 20 min or so then i took off not hard on it or anything and drove to my fishing spot. went fishing, which was good, then left. On the way back it started sounding like it did when i spun the bearings but only not nearly as loud. so i opend the engine lid and it was smoking out of the valve covers, I have breathers that go to the carb from the valves, it was smoking out of these. So yeah im getting ready to pull it back out and look it over. What do u guys think? and advice is apreciated.
Thread Starter
Instructor
Joined: Mar 2006
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hmm
im pretty sure its not a rocker arm, and what do u mean by break in, I've only put one hr on it yet so i wouldnt really consider it broken in. I just pulled the motor out today, and the main bearings had some uneven wearing on them, and after one hr i dont think they should really have any where near this kind of wear, and it should be at least even. On some bearings one side was warn and the other side of the same bearing was not touched at all. Im thining that the machine shope did not line bore it properly, Im getting some opinons on it. im kind of depressed about the whole thing. I figure I should have just got a new block Im not really a fan of line boreing, I guess thats just what i get for taking other ppls advice. I'll update when i know whats goin on. thanks for any and all advice.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Originally Posted by HighHeat303
...I ideled it out for prob about 20 min or so then .
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Tom454
Unless you have roller lifters, cam/lifter break-in procedure normally is to run it somewhere between 1500 & 2000 rpm for 20 minutes.... not idle. ???
So he should have tooled around the lake for 20 minutes at a 2000+ RMP?
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Originally Posted by Durango_boy
So he should have tooled around the lake for 20 minutes at a 2000+ RMP?
(Take the prop off.)
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Thread Starter
Instructor
Joined: Mar 2006
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lol
by edeling out i ment at 1500 rpms, high idel for a car but not for a boat, it doesnt even hardly move unless your idleing atleast at 1000 RPM. But i took it to some other machine shops and showed them and they said that it may have been line bored a lil off and that it might just wear in. So i figured o well. Im putting it in and if it spins the bearings ill throw the block out and get a new one and put everytthing on that, new crank though, and thats kind of a bummer cause they arent super cheap. O well we'll see what happens. The motor should be running around 400 hps though i think ne way. I'll let ya guys know how it goes im putting it back in tomorrow.
Thread Starter
Instructor
Joined: Mar 2006
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hmm
well i replaced all the gaskets, and the block should be good cause i sent it in had it inspected baked and decked. So i really just have no idea any more, and like i said if it blows up whole new block time.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by HighHeat303
well i replaced all the gaskets, and the block should be good cause i sent it in had it inspected baked and decked. So i really just have no idea any more, and like i said if it blows up whole new block time.
You're a 'Glass Half Full' kind of guy and I respect that. Let us know what happens.
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
It could also be a bent or mis-ground crank causing uneven bearing shell wear. If it's a flat tappet cam and you didn't break the cam in for 20 minutes at around 2K, you may have lobe damage making the noise and debris may have damaged the bearings. I hope not - good luck.
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
One of the valve cover lines should go to the air cleaner (or have a open breather) the other should go to the large carb port to draw the air through the eng
Would assume it should have it hooked up just like a cars PCV (postive crankcase ventilation) system or the eng compartment would fill with smoke from the eng
Would assume it should have it hooked up just like a cars PCV (postive crankcase ventilation) system or the eng compartment would fill with smoke from the eng
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Originally Posted by Fevre
One of the valve cover lines should go to the air cleaner (or have a open breather) the other should go to the large carb port to draw the air through the eng
Would assume it should have it hooked up just like a cars PCV (postive crankcase ventilation) system or the eng compartment would fill with smoke from the eng
Would assume it should have it hooked up just like a cars PCV (postive crankcase ventilation) system or the eng compartment would fill with smoke from the eng
All boat engines I've seem or worked on had a standard car PCV style setup but I don't know the industry standards.
Pro
Joined: Feb 2005
Posts: 571
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From: Harleysville pa
Well since you dont really have that much money into it and its fairly easy to pull and reinstall boat motors I would just change the oil and put it though the cam break-in procedure again. ( Is the cam a flat Tappet?) If so make sure you use oil with zinc additive in it like racing oil.. Then I would run the **** out of it.. Its a gm motor bro..
Last edited by mpett1; Aug 23, 2006 at 03:28 PM.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by mpett1
Well since you dont really have that much money into it and its fairly easy to pull and reinstall boat motors I would just change the oil and put it though the cam breakin procedure again. ( Is the cam a flat Tappet?) If so make sure you use oil with zinc additive in it like racing oil.. Then I would run the **** out of it.. Its a gm motor bro..
If it blows smoke again or throws something...you only lost the time if you were gonna buy a new block anyway. Flog it like it just violated your daugter's honor. 
Burning Brakes
Joined: Feb 2005
Posts: 1,235
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From: Mesa AZ
i'm guessing you didn't plastiguage the crank when you put it in?
like the others said, you need to run the engine at 2K for twenty minutes to break in the cam.
if your going to buy a new block, just run it till it blows. but make sure you have a way to get back to shore.
like the others said, you need to run the engine at 2K for twenty minutes to break in the cam.
if your going to buy a new block, just run it till it blows. but make sure you have a way to get back to shore.