You're not measuring the piston in the correct location/ measure point. Measure close to the bottom of the skirt, maybe about 1/2 inch up from the bottom.
Mopar 350 Stroker
- Thread starter Racingcowboy89
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Racingcowboy89
Well-Known Member
Okay let me remeasure them again
Racingcowboy89
Well-Known Member
You can’t accurately measure a piston with calipers. Damn.
You need help from a machinist. You are incapable of taking critical measurments.
Just friendly advice.
Racingcowboy89
Well-Known Member
Well no offense but nearest machines is 45 miles away so I am trying to do what I can from home.
Then spend the money to buy a set of MICROMETERS and learn to use them. Throw those calipers in the drawer and only use them when the **** you are measuring doesnt matter.
And make sure the micrometers have standards in the set.
https://www.amazon.com/Anytime-Tools-Micrometer-Machinist-Precision/dp/B000JMW4AS/?tag=fabo03-20
Here you go. 0-6 inch micrometers with standards. This is what you use when **** matters.
Right. What are you, four pages in and NO ONE here told you the truth? Lots of “pros” on here who should have told you from the first 5 posts you’re using the wrong tool.
So skip it. Don’t buy the proper tools. Just keep struggling.
Edit: cranks are cheap enough today that turning the mains down on a 360 is just dumb. Even if you already have the crank.
Sell it buy the right ****.
Racingcowboy89
Well-Known Member
318 LA & 340 crank will handle 6500 rpm's??? If so then I got a 318 cast crank instead of a 360 crank.
Ive turned 273 cranks to 9k on occasion and 8500-8800 every gear change. Buy a quality damper.
Edit: and NEVER broke a crank.
gzig5
Well-Known Member
Why would you think the shorter stroke crank would not handle the RPM, but the longer stroke would? Several important differences in 318 and 340 cranks even though they share stroke and bearing diameters.
33IMP
Well-Known Member
Turk is right. The proper tool for what you are doing is a mic. And the mic set he mentioned is a bargain! (A single Starrett is probably more money)
But, you can get within a few thou with a caliper, enough to see if you have standard pistons or .030s or .060s.
You can also get a good idea about your rod dimension with your caliper.
But this thread has helped you learn where to measure stuff, and how to calculate what you need.
In other words.... measure a piston on the skirt (I usually measure center of pin high, with a mic) and piston deck height is top of piston to top of pin hole, PLUS half the diameter of the pin.
Next step is calculator, to see how it all might go together, what crank you need, and what needs to be done to it.
By the way, where's Buckeye? I'm in tri-state AZ.
But, you can get within a few thou with a caliper, enough to see if you have standard pistons or .030s or .060s.
You can also get a good idea about your rod dimension with your caliper.
But this thread has helped you learn where to measure stuff, and how to calculate what you need.
In other words.... measure a piston on the skirt (I usually measure center of pin high, with a mic) and piston deck height is top of piston to top of pin hole, PLUS half the diameter of the pin.
Next step is calculator, to see how it all might go together, what crank you need, and what needs to be done to it.
By the way, where's Buckeye? I'm in tri-state AZ.
I shifted a reworked 73 340 (cast crank) at 6700 with a bell and trunnion 833 in the late 80's with a stock damper...Not knowing any better. When we freshened the short block she needed the piston pin bores oversized from the abuse...Badger cast pistons no less!
In fact one of my fondest memories is street racing a 327 Chevelle who pulled a rod cap trying to match my 2-3 gear shift timing...
All of us started somewhere
Racingcowboy89
Well-Known Member
Buckeye is in the West Valley, West of Phoenix heading towards California.
Racingcowboy89
Well-Known Member
Say I used a 340 or 318 crank for drag racing instead of a 360 crank, with using the Chevrolet small block connecting rods, and those pistons?
33IMP
Well-Known Member
Cast pistons and cast crank at 6700?!? YIKES!
I had a malfunctioning tach cost me a cast piston 327 once. Piston head separated from the skirt, skirt dissolved and the pin put four lovely grooves into the water jacket.
Tach said I was shifting at 6000, solid lifter z28 cam, should have been good to 6500.(with the engine laying down at 5500, wtf?)
Real shift rpm was high side of 7500. Resulting in OOPS!
Racingcowboy89
Well-Known Member
I know stroker 4.000 cranks could handle probably 7,000 rpm's but I would think with the Chevrolet small block connecting rods, and those pistons would put my pistons over the deck?
Early 3.31 (273/318) stroke steel cranks are around. If you’re running an automatic you’ll need to machine the register for the torque converter pilot.
I believe the Chevrolet connecting rod with is slightly wider than the small block Chrysler. You’re gonna wanna confirm that additionally you’ll need to turn down the rod journal diameter for that connecting rod.
If I recall correctly, the article I posted on the 470 hp 318 build the engine builder use the Chevrolet connecting rod.
When you’re running a small cubic engine, the lighter, you can make it reciprocating assembly the more you’re gonna get out of the combination.
Newbormb will likely chime in on the Chevrolet connecting rod application.
Take into account that the 318 has the lightest duty main cap out of the 318 340 and 360 engines. I believe North Carolina engine builder posted some photos of this a couple months ago.
33IMP
Well-Known Member
That's why I said it's calculator time.
Try to find if the block has been decked. You might have to take it to a machinist to find out.
But you can still use published specs to figure out where you probably are.
Take a proper measure of
your piston deck height. Add the length of your chevy rods (center of pin to center of big end)
Subtract that number from block deck height. Result will be HALF of the stroke length you need.
OR: you can assume a 318 stroke, divide by two, and add rod length and piston deck height, and subtract that from block deck to find out how far down in the hole your pistons will be.
AGAIN, assuming you block hasn't been decked excessively.
Read below
MoPar used to sell rotating assembly parts to have their engine restroked to fit into the old class racing rule of a max of 355ci.
In my particular case, I needed bearing spacers for the small journal (340 sized) crank into the large journal (360) block.
The 360 was bored .030 for the forged flat tops and the crank is a 3.45 inch stroke for 352ci.
No. Slick workings can turn down a 360 cranks journals to fit the smaller journals of the other 3 engines. Over boring the 318 to whatever was needed or desired now requires ether a custom piston or the use of a flat top where valve notches need to be cut in for valve clearance. There are a lot of factors to what is needed for this operation.
I turned my cast crank 318 to 6800.
Okay, plenty of input happening while I been typing this, so there’s some redundancy. If you use the SBC rods, the big ends are wider (.940) than Chrysler rods (.925). The rods you have may have already been dressed down to fit Chrysler journal width, but oftentimes the rod journal cheeks are ground to fit the rods. More things that need to be properly measured. And if you get precision tools, you should also invest in a dial bore bore gauge, too. And educate yourself about engine blueprinting from the resources at hand. Plenty of YouTube videos about measuring things properly. But, before offering too much advice, we should be asking “What’s your proposed budget, and kind of heads are you planning on using?” If you use those pistons and rods, then you’d have to have the rod journals cut down to the probably 2.1 inch sbc size and measure the rods to see if the cheeks of rod journals need to widened to the aftermarket rods. Actual compression height is 1.7905 from the center of the piston pin, so a .030’ish cut from the block decks would yield a zero deck. That doesn’t account for the way the blocks came, which was usually somewhat above the 9.60 deck height spec on all the ones I’ve checked, as well as out of square and off from one end to the other. It’s probably already been done, but that’s something that you won’t know for definite until either putting the rotating assembly in, or having the deck height of the block measured at your machinists.
33IMP
Well-Known Member
If you have something close to 318 piston, a 4" crank will push them roughly a half inch OUT of the hole. Real hard to bolt cylinder heads on that way.
Hard for the pistons to go back down the hole when the rings go past the top of the deck, too.
If you’re on a budget, you should scour the ads and wrecking yards within your vicinity for a donor 273 that has the adjustable rocker arms. You could use the crank and the valve drain off it and throw the rest in the dumpster.
Well, you can usually sell the later 273 234 or 920 casting number heads here pretty easily.
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