Stroke with only Pistons and Crank?

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33IMP said:
I believe in K.i.s.s. You used to have to piece a stroker together. No reason, in my humble opinion, not to use a kit now, and as complete as possible.
I understand financial considerations, but I think I would save till I could afford the kit, rather than invest in individual pieces.
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That's exactly what I did.. I just saved $100 $50 or whatever it took to add up. It's funny how over the last 8 years of my first stroker I've seen people pop in with all these different old engines they've reworked and cleaned and bought little parts for then spent money here and there and still have cobbled together old crap. Well the last 8 years I've had a superb running Stroker motor... Remind you the slowest on the internet but still I'm happy with it LOL... I don't know if you want to call it cry once or do it right the first time but either way...
 
Rat Bastid said:
The OP wants to stroke his engine and use the OE connecting rods. It’s cost ineffective to do that. By the time he buys a decent bolt, gets new bushings (the bushings should almost always be replaced) and rebuilds the rods he could have a set of aftermarket rods that have 7/16 cap screws rather than 3/8 bolts and nuts, plus a better grade of steel and a better design. It makes no sense to use OE rods any more.
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agreed.
 
B3422w5 said:
I wouldnt even remotely consider using stock rods. Better off buying all new stuff in a kit. Pricewise likely little difference
Stock rods, no matter how much purists try to make them seem like Oliver Rods, are friggin 50 years old.
I would use a new Scat H beam rod WAY before stock rods, no matter how much they were upgraded with new bolts, etc, etc…. And not think twice.
Did i mention 50 years old…
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How old are the blocks most of us are using? ....and that's different how?
 
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j par said:
That's exactly what I did.. I just saved $100 $50 or whatever it took to add up. It's funny how over the last 8 years of my first stroker I've seen people pop in with all these different old engines they've reworked and cleaned and bought little parts for then spent money here and there and still have cobbled together old crap. Well the last 8 years I've had a superb running Stroker motor... Remind you the slowest on the internet but still I'm happy with it LOL... I don't know if you want to call it cry once or do it right the first time but either way...
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for someone running a street stroker under 475 hp, a 4” Cast Crank, internally balanced kit will work fine. That situation won’t turn over 6200 rpm.

if you are just building something under 1hp/1cu like 350-400hp, even cast pistons are fine. Might even be a stock 340 cam and heads scenario. You’ll definitely feel the extra 76 cubic inches over a stock 340.
 
One other thing not touched on... most all 4" arms using stock rods require notching the block for rod bolt/shoulder clearance.

As others have mentioned, by the time you clean, prep, install new bolts, resize you are just about in the range of new rods depending on your location/machine shop pricing.

Pick your parts, pay your money.
 
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j par said:
I invite you to tell us how many strokers you've built with stock rods and what it cost to have the rotating assembly balanced you did... ZERO...
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Scat rods are far superior and lighter than Factory 50-year-old stuff..
You'd probably be $350 into Mallory just trying to counterbalance those heavy Factory rods that aren't as strong or as precision made...
I've learned a lot from you but sometimes in life you have to realize you don't know it all...
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Even for 50 yr old factory stuff, MOPAR rods were usually much better then the competitions rods. All that said, regardless of the brand name on them, rods were factory tested and rated for cycles, the number of times they could be stressed to the max before the material itself failed to return to its original dimension. I've run factory MOPAR rods in small and big blocks to over 7k with no issues. Now in the case of most small blocks the front of the block cracks at the oil passages to the main bearing bore before rod failure many times. But cracking here is not as noticed as a failed rod. Knowledged machinists can tell you a large portion of 340 blocks were taken out of service because of this issue but it works the same with any LA block, likely even others. The fact is when a rod fails it takes the block out with it so those cracks are not even searched for.
 
Bret Tschacher said:
Even for 50 yr old factory stuff, MOPAR rods were usually much better then the competitions rods. All that said, regardless of the brand name on them, rods were factory tested and rated for cycles, the number of times they could be stressed to the max before the material itself failed to return to its original dimension. I've run factory MOPAR rods in small and big blocks to over 7k with no issues. Now in the case of most small blocks the front of the block cracks at the oil passages to the main bearing bore before rod failure many times. But cracking here is not as noticed as a failed rod. Knowledged machinists can tell you a large portion of 340 blocks were taken out of service because of this issue but it works the same with any LA block, likely even others. The fact is when a rod fails it takes the block out with it so those cracks are not even searched for.
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you have any test data to support your claim that the factory rods are better?
 
Bret Tschacher said:
Even for 50 yr old factory stuff, MOPAR rods were usually much better then the competitions rods. All that said, regardless of the brand name on them, rods were factory tested and rated for cycles, the number of times they could be stressed to the max before the material itself failed to return to its original dimension. I've run factory MOPAR rods in small and big blocks to over 7k with no issues. Now in the case of most small blocks the front of the block cracks at the oil passages to the main bearing bore before rod failure many times. But cracking here is not as noticed as a failed rod. Knowledged machinists can tell you a large portion of 340 blocks were taken out of service because of this issue but it works the same with any LA block, likely even others. The fact is when a rod fails it takes the block out with it so those cracks are not even searched for.
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All great information but maybe falling a little short of the original point... The op was looking for Budget minded help with building a stroker... You're going to obviously have to get a new crank for a stroker and obviously a new set of pistons and a new set of bearings and a new set of rings...
Now do you buy a kit which is slightly discounted when all package together...
Is this where the op will save $100 by using the old rods ...?.. or will he actually spend more money getting the whole assembly balanced?..
I've got two sets of rods in my shed that I probably won't be able to get 10 bucks for at the swap meet this year... I didn't even remotely cross my mind to use them when all this is readily available...
 
70aarcuda said:
you have any test data to support your claim that the factory rods are better?
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I was thinkin maybe he meant better than factory Chevy, Ford and other's rods. I would agree with him there.
 
Why are we adding tungsten to an assembly that has LIGHTER PISTONS? The bobweight of an Eagle cast or forged stroker crank is ~2050g. Way over what the stock rods and smaller lighter stroker pistons weigh when balancing. Your gonna be removing weight for sure unless your going to heavy pistons.
 
Back in the mid-1980's when building strokers was beginning to take off, the late, great John Lingenfelter did a Hot Rod magazine article on his "budget" 496 stroker for his race car hauler. It involved welding a steel 454 crank and stroking it to 4.250". Pretty impressive article for the time. A friend that was my optometrist and had deep pockets decided he was going to do one exactly like the article. Several key points the article omitted, but he didn't realize until he'd already had the crank welded and reground and pistons bought, was that with the stock length rods and the extra stroke, the pistons hit the counterweights big time at the bottom of the stroke. So after throwing the crank back into the crank grinder to remove nearly a 1/4" from all the counterweights on a fully counterweights crank. It took almost 23 pieces of Mallory to now balance the crank since so much counterweight was removed. Most stroker cranks today have counterweight clearance for longer than stock connecting rods, so shorter rods could cause an issue in some cases just like it did my friends. So before you pull the trigger on the crank, trust, but verify you don't paint yourself into a corner.
 
340inabbody said:
What are your thoughts about stroking my 340 with pistons and crank only and using my original factory rods? Will that work? Will that save me money? I would think the factory rods assuming that I have factory rods are as good as most current stuff out there??

Thanks and Merry Christmas guys!
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It will generally put the wrist pin into the oil control rings, but depending, it could only require pistons with less deck height.
 
Confusedoldman said:
It will generally put the wrist pin into the oil control rings, but depending, it could only require pistons with less deck height.
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That tends to be an issue with a low deck BB set up needing the support.

A 4" arm, stock rod length, SB std OEM deck height isn't an issue with the oil rings. It does start to get tight if you go with more than 4" stroke.
 
340inabbody said:
Good inputs here guys. I would like to maintain the internal balance.

Question about the balancing of the rotating assembly. Is the crank the only part dynamically balanced and the rods and pistons just weighed and made all the same?
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Yes, that is correct. Note however, the rods are weighed on both ends and fussed with until all weigh the same on both ends. Then a bobweight can be calculated and added to the throws on the crank for the dynamic crank balance procedure.
 
CNC-Dude said:
Back in the mid-1980's when building strokers was beginning to take off, the late, great John Lingenfelter did a Hot Rod magazine article on his "budget" 496 stroker for his race car hauler. It involved welding a steel 454 crank and stroking it to 4.250". Pretty impressive article for the time. A friend that was my optometrist and had deep pockets decided he was going to do one exactly like the article. Several key points the article omitted, but he didn't realize until he'd already had the crank welded and reground and pistons bought, was that with the stock length rods and the extra stroke, the pistons hit the counterweights big time at the bottom of the stroke. So after throwing the crank back into the crank grinder to remove nearly a 1/4" from all the counterweights on a fully counterweights crank. It took almost 23 pieces of Mallory to now balance the crank since so much counterweight was removed. Most stroker cranks today have counterweight clearance for longer than stock connecting rods, so shorter rods could cause an issue in some cases just like it did my friends. So before you pull the trigger on the crank, trust, but verify you don't paint yourself into a corner.
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I stroked my 454 1971 vette to 496 with solid lifters that thing dynoed in the car at over 600ftlbs and 500hp. Flat torque curve from 2000rpm to 5000. Wish I still had it……
 
pishta said:
Why are we adding tungsten to an assembly that has LIGHTER PISTONS? The bobweight of an Eagle cast or forged stroker crank is ~2050g. Way over what the stock rods and smaller lighter stroker pistons weigh when balancing. Your gonna be removing weight for sure unless your going to heavy pistons.
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That might be what Eagle says ...but...I have had 5 4 inch cranks balanced.....all using Scat I beam rods weighting around 580 grams...Pistons are usually right around 500 grams plus the pins....Everyone has taken Mallory metal...Mine are not eagle cranks 3 are Scat forged steel...1 is a K1 forged steel and 1 is a MP (Scat) Cast crank...

Even the 318 that i stroke with MP cast crank ...Scat Rods and KB Icon pistons weighting 450 grams took a slug of mallory....So that is my real life experience....
 
That's not uncommon as you have experienced. Other stroker cranks for Ford and Chevys also have to do that. Its nothing to do with the rods and pistons being lighter than stock as much as the cranks have too much counterweight removed from Scat or Eagle.
 
Here is my $0.02. You could you use stock rods, but I would think you would want to have them magnafluxed (they are 50 years old), resized and new bolts. Since the engine is apart, and the crank and pistons are new, I would buy new rods too. I hear what RRR said about trusting the 'prebalanced' thing, but if I am going to trust the parts, I think I will trust the balance also.
 
harrisonm said:
Here is my $0.02. You could you use stock rods, but I would think you would want to have them magnafluxed (they are 50 years old), resized and new bolts. Since the engine is apart, and the crank and pistons are new, I would buy new rods too. I hear what RRR said about trusting the 'prebalanced' thing, but if I am going to trust the parts, I think I will trust the balance also.
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Yeah I hear what your saying. Makes good sense because there is a lot of trust in all this work. If any of the machining isn’t right that can lead to critical failure. You have to trust someone at some point. I probably will go with new rods as in the end I won’t have to worry about metal fatigue and not really saving any appreciable money. I also don’t have a shop yet to work with. I WILL however have the balance checked out before I use anything as that to me is an investment in good judgment. Pay me now or pay me later…..
 
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