383 blew up.... need 402 Road Race motor... Who makes the best?
04-17-2009, 11:24 PM
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383 blew up.... need 402 Road Race motor... Who makes the best? I used to drag race and switched to AX and road racing. I had a 383 5.7 block with a Callies crank and rods, diamond pistons and 236/236/550 cam. Thing ran great for last 3 years. I have an accusump on it and canton pan to help with sarving for oil. Well,I took it out to play today on the street and I was blasting the tires off of a stop sign and KABOOOOOOOMMM! Lots of noise, pulled over and could hear **** pouring out of it. Got it home and found a hole in the pan and a cracked block. So much for racing this season........
I plan to pull the motor out tomorrow and see what all is trashed.
I am on a budget so I would like to reuse my crank if it is still good. This thing spends a lot of time in the 5500-6800 rpm range and want to buy a motor that will be built with that in mind. One issue was with the oil tending to accumulate in the heads.
I am thinking of going with an LS2 block and depending on if my ported LS1 heads are trashed.... maybe get L92 heads as well. I only want to do this once and IF I have to wait a year, then so be it. I just want something that will last LONGER than 3 years. Car only does 6 high speed AX track events and 6 parking lot events a year and maybe a 1000 miles of street duty.
I don't want to change valve springs every couple months either so I don't want a crazy lift cam. I change them every season since they are cheap insurance. Never broke a patriot gold set yet.
Any advice/info would be appreciated.
Thanks
I plan to pull the motor out tomorrow and see what all is trashed.
I am on a budget so I would like to reuse my crank if it is still good. This thing spends a lot of time in the 5500-6800 rpm range and want to buy a motor that will be built with that in mind. One issue was with the oil tending to accumulate in the heads.
I am thinking of going with an LS2 block and depending on if my ported LS1 heads are trashed.... maybe get L92 heads as well. I only want to do this once and IF I have to wait a year, then so be it. I just want something that will last LONGER than 3 years. Car only does 6 high speed AX track events and 6 parking lot events a year and maybe a 1000 miles of street duty.
I don't want to change valve springs every couple months either so I don't want a crazy lift cam. I change them every season since they are cheap insurance. Never broke a patriot gold set yet.
Any advice/info would be appreciated.
Thanks
04-18-2009, 10:42 AM
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Most LS motors that fail in RR or AX conditions suffer either from oiling problems or valvetrain failure (usually springs). You've taken great care with oiling; valvetrain will always be vulnerable to some extent.
It isn't automatically true that lower lift cams are less hard on valve springs. What fatigues valve springs most is resonance, which depends in a fairly complicated way on lobe profile, pushrod and rocker mass and stiffness, and valve weight - complicated enough that it can't be completely modeled, and has to be observed with a Spintron.
What a lot of pro engine builders do is shim the springs until they are near maximum compression at max lobe lift. Although this sounds counterintuitive, shimming like that will tend to damp spring resonance and therefore increase spring life. So, if your springs are not set up that way, lower lobe lift might actually reduce spring reliability! In the end, there is no substitute for a builder with plenty of experience on these issues.
It isn't automatically true that lower lift cams are less hard on valve springs. What fatigues valve springs most is resonance, which depends in a fairly complicated way on lobe profile, pushrod and rocker mass and stiffness, and valve weight - complicated enough that it can't be completely modeled, and has to be observed with a Spintron.
What a lot of pro engine builders do is shim the springs until they are near maximum compression at max lobe lift. Although this sounds counterintuitive, shimming like that will tend to damp spring resonance and therefore increase spring life. So, if your springs are not set up that way, lower lobe lift might actually reduce spring reliability! In the end, there is no substitute for a builder with plenty of experience on these issues.
04-21-2009, 07:22 AM
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i figured i would throw my hat in the ring.
As stated above,valvetrain failure due to bad valvetrain design(or lack thereof)kills most engines of this type.We use Gordon Blair's 4sthead software to simulate all valvetrain dynamics so we can design the proper valvetrain.You cant really just use a gut feeling when building an endurance engine-you really need the proper equipment.
As stated above,valvetrain failure due to bad valvetrain design(or lack thereof)kills most engines of this type.We use Gordon Blair's 4sthead software to simulate all valvetrain dynamics so we can design the proper valvetrain.You cant really just use a gut feeling when building an endurance engine-you really need the proper equipment.
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04-21-2009, 08:31 AM
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I managed to pull the piston out of the motor....... So far it looks like the cap on the rod may have came off?? The rod is intact.... bent like a twisler.... except for the sides of the crank end. They are busted off. No supprise there. No evidence of blueing on rod, bearing surface of crank looks good except for some dings. Still have to take more appart to check the rest of the bearings and examine the pile of pieces. The sleeve is trashed.... busted in pieces at the top and bottom.
I am hoping my crank is repairable. It was a very nice piece.
All the springs were still good, there was no evidence of piston to valve contact on any cylinders..... except for the busted one
I reviewed my tape of one of my lapping sessions and the tach is between 4000 and 6800 the whole time. What ever I end up building, I need it to have good torque from ~3800 or so to get me out of the corners. OR, I could put my 4.10 gears back in and build something that revs to 7500 or so with the power shifted up higher???? probably get more life out of a slower spinning motor.
I am hoping my crank is repairable. It was a very nice piece.
All the springs were still good, there was no evidence of piston to valve contact on any cylinders..... except for the busted one
I reviewed my tape of one of my lapping sessions and the tach is between 4000 and 6800 the whole time. What ever I end up building, I need it to have good torque from ~3800 or so to get me out of the corners. OR, I could put my 4.10 gears back in and build something that revs to 7500 or so with the power shifted up higher???? probably get more life out of a slower spinning motor.
04-25-2009, 06:52 PM
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i figured i would throw my hat in the ring.
As stated above,valvetrain failure due to bad valvetrain design(or lack thereof)kills most engines of this type.We use Gordon Blair's 4sthead software to simulate all valvetrain dynamics so we can design the proper valvetrain.You cant really just use a gut feeling when building an endurance engine-you really need the proper equipment.
As stated above,valvetrain failure due to bad valvetrain design(or lack thereof)kills most engines of this type.We use Gordon Blair's 4sthead software to simulate all valvetrain dynamics so we can design the proper valvetrain.You cant really just use a gut feeling when building an endurance engine-you really need the proper equipment.
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