4” stroke clearance? Lt1/lt4 Block difference
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Intermediate
Joined: Jun 2017
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4” stroke clearance? Lt1/lt4 Block difference
4” stroke clearance? Lt1/lt4 Block differenceHad 2 questions:
What if any clearance modification needs to be done to the block for a 4” stroke crank
Anyone know what the difference in the lt1/lt4 BARE block?
Lt1 part #: 12619171
Lt4 part#: 19329617
Thinking about a winter project if I keep the car and wanted to see if anyone can help me answer these 2 last points.
Lastly, aside from on the loose side of spec, does anyone have any bearing clearance, ring gap recommendations for ~15-18lbs of boost? Thanks
What if any clearance modification needs to be done to the block for a 4” stroke crank
Anyone know what the difference in the lt1/lt4 BARE block?
Lt1 part #: 12619171
Lt4 part#: 19329617
Thinking about a winter project if I keep the car and wanted to see if anyone can help me answer these 2 last points.
Lastly, aside from on the loose side of spec, does anyone have any bearing clearance, ring gap recommendations for ~15-18lbs of boost? Thanks
Heel & Toe
Joined: Aug 2007
Posts: 16
Likes: 2
From: Maryland USA
I'll take a stab at answering a few of the questions.
LT1 / LT4 blocks are very much the same. Probably exactly the same as in dimension inside and out. All LT4 blocks are 4-bolt. All Corvette LT1 blocks are 4-bolt.
Stroker clearance for 4" cranks depends on the rods. Eagle rods are the worst...i.e. require the most clearance. To helps ease the worry of having to clearance until into water jacket....Epoxy fill the bottom of the water jacket up to the freeze plugs, (the lowest freeze plug). Then you can clearance right into the water jacket.
You'll need to clearance inboard at the cam tunnel too, (if your rod has a parting line shoulder bump out).
Also will need to clearance at the oil pan rail. (Unless it's a custom crank with small rod journals).
Really, if you get a set of rods where the bolt heads are not poking out too far, (such as Callies Ultra I-beams) then you might not even hit water jacket.
.0025" main bearing clearance is a target. Rods from .0020 to .0025"
Rings need to be as per ring manufacture spec or a pinch wider but not one bit tighter.
If you have the budget then a Callies Magnum crank with 2.000" or 1.888" rod journals would make for much less block clearance work.
LT1 / LT4 blocks are very much the same. Probably exactly the same as in dimension inside and out. All LT4 blocks are 4-bolt. All Corvette LT1 blocks are 4-bolt.
Stroker clearance for 4" cranks depends on the rods. Eagle rods are the worst...i.e. require the most clearance. To helps ease the worry of having to clearance until into water jacket....Epoxy fill the bottom of the water jacket up to the freeze plugs, (the lowest freeze plug). Then you can clearance right into the water jacket.
You'll need to clearance inboard at the cam tunnel too, (if your rod has a parting line shoulder bump out).
Also will need to clearance at the oil pan rail. (Unless it's a custom crank with small rod journals).
Really, if you get a set of rods where the bolt heads are not poking out too far, (such as Callies Ultra I-beams) then you might not even hit water jacket.
.0025" main bearing clearance is a target. Rods from .0020 to .0025"
Rings need to be as per ring manufacture spec or a pinch wider but not one bit tighter.
If you have the budget then a Callies Magnum crank with 2.000" or 1.888" rod journals would make for much less block clearance work.
Thread Starter
Intermediate
Joined: Jun 2017
Posts: 28
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Karl appreciate it, most informative post! Yeah it seems I had some back info on the block part # and this helps clarify things.
As far as rods and rod journals, personally I would want to stick to a 2.100" rod journal size, knowing on the aftermarket cranks I would have to most likely run a narrow rod bearing due to the fillet designs and do the clearance work for better oiling and more bearing surface.
I did confirm I would have notch the cylinder and tweek the squirters or plug them. I didnt know about the cam tunnel, I have to look into that. if you have any details on where, that would be great.
clearance looks normal for what I would have gone for, just wanted to know if these bottom ends had anything out of the ordinary to look out for. Work I have done in the past has been mostly imports and german.
what are you thoughts on the Manley crankshafts? significant price difference between that and the Magnum. I can guess offshore vs domestic forging, but I don't know if 2x the price justify 2x the crank....
BTW we are talking about gen 5 LT right? lol
As far as rods and rod journals, personally I would want to stick to a 2.100" rod journal size, knowing on the aftermarket cranks I would have to most likely run a narrow rod bearing due to the fillet designs and do the clearance work for better oiling and more bearing surface.
I did confirm I would have notch the cylinder and tweek the squirters or plug them. I didnt know about the cam tunnel, I have to look into that. if you have any details on where, that would be great.
clearance looks normal for what I would have gone for, just wanted to know if these bottom ends had anything out of the ordinary to look out for. Work I have done in the past has been mostly imports and german.
what are you thoughts on the Manley crankshafts? significant price difference between that and the Magnum. I can guess offshore vs domestic forging, but I don't know if 2x the price justify 2x the crank....
BTW we are talking about gen 5 LT right? lol
Last edited by Goohead; Oct 24, 2019 at 06:52 PM.
