LA block hunt/search maybe shift to piston hunt

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greymouser7

greymouser7

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I need another block to finish my projects.
Was trying to hunt down a standard bore 360 maybe 1970-1973, or 1988-91
I find a standard bore 340 down the road on craigslist.
I have a 3.51" (?) yellow steel 1053(?memory) alloy crankshaft sitting in the garage
would pistons be available? chevy pistons? do I have to get connecting rods again?
my cars are F or 73/74 B-bodies (street driven, no track)
 
You could do a number of things. One is a custom piston may be the easiest like a Chevy 350 piston with Mopar 18 degree valve reliefs. If it is a mild motor you may get away without changing the valve reliefs at all and run a stock Chevy piston with enlarged piston pin bore. Or you could grind the crank to Chevy 2.1 journal size and run a Chevy rod and piston. Lots of paths to follow.
 
mbaird said:
Whats the question ?
Click to expand...

Cu$tom Pi$ton$ $ound$ expensive
I was wondering if a cheap piston / rod combo from chevy that would work with the 3.51 crankshaft in a 340 block. I have heads, pumps, intake, etc. but need a block.
The 340 block is available, close, a bit more expensive, but I don't have 340 pistons or stock crankshaft.
cheaper is better, and I believe one of the machinists here said that turning down a crank a bunch is not cheap
 
Probably cheaper to sell the crank and buy a stroker kit .
Assuming you arent stuck on running 3.51 stroke.
 
It's no problem to put in a 273/318 crank with any 340 pistons, standard or lightweight, if you use SCAT I-beam rods, and you will be able to balance it by taking weight off of the crank. A lot cheaper than a stoker kit.

And if you buy the SCAT rods, they are balanced to each other and have the big end and small ends weights marked right on the box; those are the hardest numbers to weigh yourself so that makes the rest easy-peasy. Buy KB or SRP or SpeedPro pistons which are well balanced to each other, and use those piston and pin weights and the rod end weights and a few pretty standard weights to compute up the bobweight yourself. Hand that number and the 272/318 crank to the machinist and tell him to balance to that bobweight. Cheep; cost me under $100 to do this.

Let me know if you need help with the bobweight computation, but you can get the info and the formulas right off the Eagle website. Use 59 grams for 340 ring pack weights, 4 grams for oil, 4 gram for locks, and 44 grams for a rod bearing set. Or whatever you weigh to be most accurate. Then use the piston, pin, and rod big end and small end weights that you weigh or get from the date sheets. Checking the weights of as many parts as you can helps, but you'll be no worse than factory balance if you use the numbers above.

No need to be scared of this process if you can add and multiply; it is just what the machinist will do. Especially for a street motor.
 
Use the 3.51 crank and bushed 318 or 340 rods and 1972-3 340 pistons and you will be at a zero deck. Maybe have it balanced
 
Marcohotrod said:
Use the 3.51 crank and bushed 318 or 340 rods and 1972-3 340 pistons and you will be at a zero deck. Maybe have it balanced
Click to expand...
Something seems off.. .I am coming up with a +.102" deck height for that combo...??? (The CH I used is 1.824" for the Silvolite replacement units...which I thought was about right for the lower CR late 340 pistons.) Offset the bushings down into the small ends of the rods maybe?
 
.0985 additional height for 1/2 the stroke, BUT use the short 73' piston that's in the hole about an extra .100 thou, yup Marcohotrod s math works. check counter weight to piston pin boss clearance.
 
The factory 1968 -71 pistons are 1.840". 1972-3 are 1.740. Aftermarket cast pistons are compensated = about .015" less.
 
Thanks.. I could not remember what the later pistons' CH was. Sound like a good combination.

Balance should not change with this setup if the 340 rods or the later, heavy 318 rods were used. Bobweight would drop about 55 grams with the lighter 318 rods so that would need re-balanced.
 
You sure you have a 3.51" crank? That's an odd ball...maybe a 3.58? In that case have a crank shop grind the mains to 340 specs. Cheap stroker.

Call RaceTec and price out their pistons... a set of 4032 alloy will cost about $450.00... any bore any stroke any compression height. They build good stuff...no need to buy brand x anything. Talk to Randy.
 
greymouser7 said:
Cu$tom Pi$ton$ $ound$ expensive
I was wondering if a cheap piston / rod combo from chevy that would work with the 3.51 crankshaft in a 340 block. I have heads, pumps, intake, etc. but need a block.
The 340 block is available, close, a bit more expensive, but I don't have 340 pistons or stock crankshaft.
cheaper is better, and I believe one of the machinists here said that turning down a crank a bunch is not cheap
Click to expand...

Then just get a farkin 340 or 360 crank instead of that weird *** **** you always gravitate towards. That's your cheap way out. The way you should have done it to start with. Every time you try to reinvent the wheel, you end up with a square one. Every. Single. Time.
 
greymouser7 said:
I have a 3.51" (?) yellow steel 1053(?memory) alloy crankshaft sitting
Click to expand...
Nothing weird about a 3.51" stroke small mopar crank. measure the main size and stroke. 1972-3 340 cheap pistons, any cheap 318-340-360 rods, balance assembly. throw it in a 340 or 360 block and have a zero deck on a budget!
 
Marcohotrod said:
Nothing weird about a 3.51" stroke small mopar crank. measure the main size and stroke. 1972-3 340 cheap pistons, any cheap 318-340-360 rods, balance assembly. throw it in a 340 or 360 block and have a zero deck on a budget!
Click to expand...

He's trying to do this in a shoestring budget, though. All that will need balancing. Just one more expense.
 
post 15 - balance assembly . he has the crank. can use stock rods and stock replacement pistons, and get a zero deck at no extra charge
 
RustyRatRod said:
Then just get a farkin 340 or 360 crank instead of that weird *** **** you always gravitate towards. That's your cheap way out. The way you should have done it to start with. Every time you try to reinvent the wheel, you end up with a square one. Every. Single. Time.
Click to expand...

Rob, I am struggling to find an LA 360 block, nothing more. I bought the crankshaft 15 years ago. I was going to ship it to RAMM, but Canadian freight is expensive (not for my build).
I have connecting rods and all the parts to build an engine but I need a block that is .040 honed or less. I was helping out a friend and I believe that he took my 1970 stamped 360 block, so now I am searching.
I thought there might be a "weird asset way out." I hope that you are doing well.
 
greymouser7 said:
Rob, I am struggling to find an LA 360 block, nothing more. I bought the crankshaft 15 years ago. I was going to ship it to RAMM, but Canadian freight is expensive (not for my build).
I have connecting rods and all the parts to build an engine but I need a block that is .040 honed or less. I was helping out a friend and I believe that he took my 1970 stamped 360 block, so now I am searching.
I thought there might be a "weird asset way out." I hope that you are doing well.
Click to expand...

We are ok. Hope yall are too. I bet the baby is growin like a weed. How old is she now?

You should try Rodney. He may have something you can use.
 
Marcohotrod said:
post 15 - balance assembly . he has the crank. can use stock rods and stock replacement pistons, and get a zero deck at no extra charge
Click to expand...

Now he just needs a block. Tryin to help him find one.
 
Craig's list, junkyards or maybe a backroads trip can yield a treasure trove of what you need. Sometimes you have to get off the keyboard and get on the road.
 
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