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SB 4125 K1 CRANKSHAFT

Posted By: moparmacka

SB 4125 K1 CRANKSHAFT - 11/29/10 08:07 PM

Has any one fitted one of these 4.125 cranks to an engine. What sort of quality are they? Any reliability issues with this stroke? Also what is the best length rod to use? I was thinking 6.200". Chasing around 440 cubes from a siamese 340 resto block. Comments please.

Thanks
Macka
Posted By: Leon441

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 08:35 PM

6.375" for running Normally aspirated with a W style layout intake valve at 2.10 diameter and 4.125" bore.

6.200-6.250 for running nitrous with a larger than 2.15 valve diameter and bore starting at 4.155".

The deciding factor will be the valve layout on your heads and the bore of the piston you run. You can run .060" Valve pocket to ring groove NA. You need to be around .150" if you are running a power adder. This Valve pocket to ring groove is everything on the small block.

Leon
Posted By: Quicktree

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 08:37 PM

I have one, I think ask Dan he should be setting mine up to fit my block
Posted By: Quicktree

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 08:55 PM

sorry Dan AT Performance Only thats his screen name.
Posted By: AndyF

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 09:51 PM

I started a huge thread on here last year on that subject. I've also written some magazine articles on the same topic. So there is lots of info on here on the topic.
Posted By: Performance Only

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 10:40 PM

Quote:

Has any one fitted one of these 4.125 cranks to an engine. What sort of quality are they? Any reliability issues with this stroke? Also what is the best length rod to use? I was thinking 6.200". Chasing around 440 cubes from a siamese 340 resto block. Comments please.

Thanks
Macka



the quality from K-1 has been exceptional from what we've personally seen. rod length is subjective to the builders thoughts but we do prefer to keep it in the .6.2-6.3 range.
we won't sell a product that we know has QC issues, and believe me, there's plenty of that stuff out there. we've been a distributor for K-1 almost since their beginning and couldn't be more happy with the product or their customer service.
Posted By: Scamp408

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 10:43 PM

Dan is the MAN
Posted By: Moparnut426

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 10:51 PM

Cheeres to Dan The MAN!!

Very helpfull guy!!

Posted By: fishy340

Re: SB 4125 K1 CRANKSHAFT - 11/29/10 11:09 PM

4" crank w a 4.185 bore is what i have =440 ci sb
Posted By: Hitman340

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 01:14 AM

BPE also offers a crank in that stroke.You may ask Rod about a combo and a price before you buy.It will will be well worth your time to ask.
Posted By: BPE

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 01:20 AM

We use a 6.200" rod, it still gives you enough room to keep the pin out of the oil ring. It also allows plenty of skirt on the piston to keep it stable in the bore. Keep in mind that K1 is not the only one to offer that stroke combination. I also have those available for less. Check out my add in the new products section.

Rod
Posted By: Leon441

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 02:00 AM

Quote:

4" crank w a 4.185 bore is what i have =440 ci sb



He is looking at using the K1 4.125" stroke. With a 4.125" bore it is 441 CID. Built one. First stroker for me 15 years ago. Screen name Leon441 had that for 15 years also. 4.100" bore will give you 435 CID. 440 just sounds cooler to some.

Nothing wrong with running the pin in the oil ring. In fact I prefer it. Just don't necessarily like to get above the groove.
Posted By: sixpackgut

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 02:30 AM

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



A HA!! i knew you were up to something with all the smack talk
Posted By: poisondart2

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 02:44 AM

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



A HA!! i knew you were up to something with all the smack talk



Ray did you miss he had a block at Dans? Have you ever seen the size of the steam rollers on his car? Bigger engine was needed to turn them, plus I think Tony is going to set Dans pinion angle in trade and possibly put a 9 inch in.
Posted By: Quicktree

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:05 AM

Quote:

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



A HA!! i knew you were up to something with all the smack talk



Ray did you miss he had a block at Dans? Have you ever seen the size of the steam rollers on his car? Bigger engine was needed to turn them, plus I think Tony is going to set Dans pinion angle in trade and possibly put a 9 inch in.

I wouldn't touch Dans pinion angle with a 10 pole
Posted By: cheapstreetdustr

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:11 AM

Quote:

Quote:

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



A HA!! i knew you were up to something with all the smack talk



Ray did you miss he had a block at Dans? Have you ever seen the size of the steam rollers on his car? Bigger engine was needed to turn them, plus I think Tony is going to set Dans pinion angle in trade and possibly put a 9 inch in.

I wouldn't touch Dans pinion angle with a 10 pole



lol..

cheapst
Posted By: sixpackgut

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:20 AM

Quote:

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



A HA!! i knew you were up to something with all the smack talk



Ray did you miss he had a block at Dans? Have you ever seen the size of the steam rollers on his car? Bigger engine was needed to turn them, plus I think Tony is going to set Dans pinion angle in trade and possibly put a 9 inch in.



i made a comment in that post and Quicktree lied like a grudgracer
Posted By: Quicktree

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:21 AM

Quote:

Quote:

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



A HA!! i knew you were up to something with all the smack talk



Ray did you miss he had a block at Dans? Have you ever seen the size of the steam rollers on his car? Bigger engine was needed to turn them, plus I think Tony is going to set Dans pinion angle in trade and possibly put a 9 inch in.



i made a comment in that post and Quicktree lied like a grudgracer

not me
Posted By: Performance Only

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:23 AM

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



yes, i have yours and a couple others. we've already had yours in the grinder to check index, stroke, taper and out of round. i don't see how any crank could measure any better than this one did. K-1 is doing an outstanding job on their stuff.
aside from a litle extra time to check it all out, they really make my job a lot easier when it comes to putting all the pieces together.
Posted By: Quicktree

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:27 AM

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



yes, i have yours and a couple others. we've already had yours in the grinder to check index, stroke, taper and out of round. i don't see how any crank could measure any better than this one did. K-1 is doing an outstanding job on their stuff.
aside from a litle extra time to check it all out, they really make my job a lot easier when it comes to putting all the pieces together.

thats great but im still not messing with your pinion angle
Posted By: Performance Only

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 03:31 AM

Quote:

Quote:

Quote:

I have one, I think ask Dan he should be setting mine up to fit my block



yes, i have yours and a couple others. we've already had yours in the grinder to check index, stroke, taper and out of round. i don't see how any crank could measure any better than this one did. K-1 is doing an outstanding job on their stuff.
aside from a litle extra time to check it all out, they really make my job a lot easier when it comes to putting all the pieces together.

thats great but im still not messing with your pinion angle



thank goodness for that.
Posted By: moparmacka

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 04:58 AM

Leon, why do you prefer to have the oil rings at the pin height. Will it matter that this engine will see alot of street miles also....I heard that the 4.125 doesn't offer the duarbility of a 4.000??????
Posted By: moparmacka

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 05:01 AM

Andy can you point me in the direction of that info?

Macka
Posted By: AndyF

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 06:32 AM

Quote:

Andy can you point me in the direction of that info?

Macka



http://www.moparts.org/Tech/Archive/smallblock.html
Posted By: AndyF

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 06:38 AM

Quote:

Andy can you point me in the direction of that info?

Macka



Search is your friend!

https://board.moparts.org/ubbthreads/show...part=1&vc=1
Posted By: kielbasa

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 07:18 AM

Yes, I've also been curious as to how durable these strokers will be for street life. 5K, 10K, 50K miles?????? I understand there are a ton of variables to answer that question, but if one is to drive these for 5k street miles a year (along with the occasional blast down the strip), how long before the piston skirts etc. get clapped out and time for a rebuild?
Anybody here with firsthand experience that's run one for a few miles?
Posted By: moparmacka

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 08:02 AM

Thanks, I will have a read
Posted By: moparmacka

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 08:09 AM

Do you think durability may be an issue with the long arm??? Again a fair few street miles will in order with this too. I'm starting lean toward the 4.125 stroke and 4.125 OR possibly bigger bore with 6.200 rod. What is the absolute max with these siamese blocks? i like the idea of oil pump and pick up clearing the 4.125 with the chev journal too.
Posted By: AndyF

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 05:18 PM

I don't see why durability should be much of a factor. What you're building is similiar in dimensions to a Chevy 454. That Chevy 454 combination was used for millions of vehicles ranging from street cars to pickup trucks.
Posted By: kielbasa

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 07:23 PM

454 has either 9.8 or 10.2" of deck height vs 9.6 for sbm, throw in a 6.2 rod (vs the 454's 6.135) - i would think the 454 will have a taller, more stable piston, yes?
Posted By: moparmacka

Re: SB 4125 K1 CRANKSHAFT - 11/30/10 09:31 PM

That is exactly what friend said to me yesterday!!! I was thinking along the lines of the smaller piston though.

Thanks
Macka
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