School me, 3.79 strokers

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DrEamer

DrEamer

I suffer from cars on the brain!
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I'm not thinking about doing one, but the 3.79 based stroker is something that I do not know the history of. it started when I found some pistons for a 3.79 on eBay a few months back, but noticed that they were fairly old stock. My guess is that the early stroker were regular cranks, with the rod journals offset, and turned to accept a Chevy rod. Add custom pistons, and your have a 3.79 stroker? If I am wrong, please let me know, I'm just trying to learn here.
 
Your wrong they were custom forged cranks from MoPar that used upgrades MoPar rods. But you could use stock rods.
 
Did anyone back in the day do a 360 stroker by milling stock crank and using Chevy rods? I always heard about it in the 80's but never really read anything on it. Just curious now that you brought it up.
 
A local machine shop here in CT did a few. He knew I was a MoPar nut and let me watch.

Basically he used Chevy rods and off set ground the cranks and used a piston with the pin bore higher up in the hat. This allowed for a longer stroke but the 360 cranks were cast so they would not last so he stopped building them. He tried to get me to use a ford rod in a /6 to pull the same thing. But I knew the /6 had limited port flow and would not be worth all the work. I was at one show “Papa’s Dodge when it was held at the Farmington Polo grounds and there was a Barracuda -68 if I remember correctly that had this done. Damn thing ran low 10’s in the quarter but sounded like a pop corn machine when he lit off this drag car.

The owner said 500hp from a /6 but I was only like 20 and had no idea if that was true.

Sorry for going off the rails on you. All I can say in the 80’s... there was a lot of experimenting going on. Some worked... a lot did not.
 
I never heard of such work when I was a kid except the 360 crank in the 340 trick which you can get as a brand new crank now in cast or forged
 
rumblefish360 said:
I never heard of such work when I was a kid except the 360 crank in the 340 trick which you can get as a brand new crank now in cast or forged
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Rumblefish360- Yes, you offset grind the 360 rod journals to give to a diffrent throw and the Chevy rods use a smaller bearing than the 360.
I'm going back to the 80's so either this stuff is odd or it just was too much trouble than it was worth I am assuming.
This shop - TLB in Norwich, CT (i think out of business now) was putting the 360 crank in an over bored 318 to make like a 380 or maybe a 348 motor. Again trying to remember 30+ years ago for that kind of detail is tough... too much brake cleaner i guess. LOL!
 
Syleng1 said:
Rumblefish360- Yes, you offset grind the 360 rod journals to give to a diffrent throw and the Chevy rods use a smaller bearing than the 360.
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I don’t know how far you can off set grind the 360 crank or what rod is out there to allow more than what a Chevy rod can give you. This is mad scientist stuff I like but never looked into back in my po-boy racing days.



was putting the 360 crank in an over bored 318 to make like a 380 or maybe a 348 motor. Again trying to remember 30+ years ago for that kind of detail is tough... too much brake cleaner i guess. LOL!
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Yes, a 348-ish sized mill with the 3.58 stroke in a 318, we had a few fellas here do that. I’m not amused with this particular mini stroker trick. No pistons for it on the shelf, low cube return, still a small bore, my least favorite combo.

I do like the 360 stroke in a 340 or larger bore block so much I picked up a forged crank for this. Luck would be with me, I found one on sale. It was $425 delivered to my door. That’s a home run! Now I’m just sonic checking blocks.

A 340 @.030 & a 3.58 crank equals 372, @ a 4.100 bore, it goes to 378. A 4.125 would require a MP race block and return a sweet 382.75. cubic inches.
Live the big bore for that top end pop!
 
DrEamer said:
I'm not thinking about doing one, but the 3.79 based stroker is something that I do not know the history of. it started when I found some pistons for a 3.79 on eBay a few months back, but noticed that they were fairly old stock. My guess is that the early stroker were regular cranks, with the rod journals offset, and turned to accept a Chevy rod. Add custom pistons, and your have a 3.79 stroker? If I am wrong, please let me know, I'm just trying to learn here.
Click to expand...
FWIW, the 4.00 are stroker would be easier and cheaper being more popular. MoPar also used to have a pretty good verity of stroker cranks. A popular trio is/was the NASCAR 3.5 area cranks.

IIRC, I could be wrong here, but *I Think* they were available for the 340 & 360 journals. These 1043 forged cranks could be a available at a reasonable price BUT pistons may end up being expensive and custom. Also, IIRC, there 8 bolt flanged.
 
rumblefish360 said:
FWIW, the 4.00 are stroker would be easier and cheaper being more popular. MoPar also used to have a pretty good verity of stroker cranks. A popular trio is/was the NASCAR 3.5 area cranks.

IIRC, I could be wrong here, but *I Think* they were available for the 340 & 360 journals. These 1043 forged cranks could be a available at a reasonable price BUT pistons may end up being expensive and custom. Also, IIRC, there 8 bolt flanged.
Click to expand...

I only asked asked because I found the pistons, plus while looking at cranks, I noticed that Molner makes a 3.79 crank. Both the piston and crank are to Chevy spec, so I assumed that is why they started making them that way from the beginning. I know of a local machine shop used to do Ford stroker engines using a mopar rods back when I was racing in the 90's. Like it has been mentioned, there was quite a bit of experimentation back then. As far as doing a stroker for myself, I would just go ahead and do the 4.00 crank based stroker. Like you said, the parts are off the self, and far less money to do.
 
I’m actually planning to one day build a 3.79 based stroker with a solid cam . I already have a 408, but maybe the 3.79 will RPM a little better?? Something about a better rod ratio that I know nothing about. LOL.

I think out of a 340 it makes 372ci.

Pistons might need to be custom, I’m okay with that. I’ll hit up Brian at IMM for the build.
 
The aftermarket parts are very good and strong.
Some people like the 3.79 crank better than the 4.00.
 
mopardude318 said:
I’m actually planning to one day build a 3.79 based stroker with a solid cam . I already have a 408, but maybe the 3.79 will RPM a little better?? Something about a better rod ratio that I know nothing about. LOL.

I think out of a 340 it makes 372ci.

Pistons might need to be custom, I’m okay with that. I’ll hit up Brian at IMM for the build.
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388.67 cubes on a stoke bore, 396.47 @ .030 over.

Calculate Cubic Inch Displacement
 
Oooooo, custom slugs, might wanna price check that with a few slug manufacturers
 
Hot rodding was born by guys swapping parts around to go faster. Guys used to race Model T Ford's with Chevy heads back 95 years ago.

I don't like the 4" arm... not a good history on oval tracks at 7,000 rpms. My SB has a 3.79... I don't like spinning any engine over 7k since I'd go broke trying to repair it...doing that right now .
 
Under $500 for custom 4032 forged from RaceTec.

There isn't any good race engine that can't benefit from a customer piston.

I could never understand guys putting $10g's in paint and DooDad's but won't spend the money under the hood...mostly Chevy guys.
 
mopardude318 said:
I’m actually planning to one day build a 3.79 based stroker with a solid cam . I already have a 408, but maybe the 3.79 will RPM a little better?? Something about a better rod ratio that I know nothing about. LOL.

I think out of a 340 it makes 372ci.

Pistons might need to be custom, I’m okay with that. I’ll hit up Brian at IMM for the build.
Click to expand...

Because of rod ratio, issues with feeding a 420 inch motor with available heads( without going exotic) the 3.79 stroke combo is probably the best option out there in many cases.
Less side loading, will rev better and higher more easily and intake port sizes commonly available are a better fit
For instance, even a well done W5 head on like say a 422 shortblock is “ one size to small” Been there, done that, seen that. With 4 inch or bigger tractor crank
I didnt like the fact Mopar 3.79 offerings were 1053, not 4340 forgings.
Think the 3.79 crank came out prior to any 4 inch stuff.
As well it probably should have, 3.79 arm suited W2/ W5 stuff better.
Talked to a lot of savvy smallblock guys over the years. Lot of them think the 3.79 deal is the way to go.
 
Modifying a crank takes hours of time. For a what you get for time/ cost, buy a manufactured one. This took me about 7 hours to whip up, 318 mains, LS 4.8l Chev rods (same as SBC journal diameter) Ford piston. Really not worth it unless you are/can be doing it for yourself.
100_1981-jpg.jpg
 
Before 4" cranks became readily available I offset ground a mopar 3.79 crank to 3.91 stroke. I also had custom rods built to a 6.4 length. The compression distance on the pistons was 1.22. It all worked great. One thing to consider I believe all of the mopar 3.79 cranks had 8 flywheel bolts which will require extra $ to convert. I had this done better than 20 years ago and just used the same crank in a blower motor I built.
 
B3422w5 said:
Because of rod ratio, issues with feeding a 420 inch motor with available heads( without going exotic) the 3.79 stroke combo is probably the best option out there in many cases.
Less side loading, will rev better and higher more easily and intake port sizes commonly available are a better fit
For instance, even a well done W5 head on like say a 422 shortblock is “ one size to small” Been there, done that, seen that. With 4 inch or bigger tractor crank
I didnt like the fact Mopar 3.79 offerings were 1053, not 4340 forgings.
Think the 3.79 crank came out prior to any 4 inch stuff.
As well it probably should have, 3.79 arm suited W2/ W5 stuff better.
Talked to a lot of savvy smallblock guys over the years. Lot of them think the 3.79 deal is the way to go.
Click to expand...


This post should be made a sticky with bold capital letters. 100% facts.
 
B3422w5 said:
Because of rod ratio, issues with feeding a 420 inch motor with available heads( without going exotic) the 3.79 stroke combo is probably the best option out there in many cases.
Less side loading, will rev better and higher more easily and intake port sizes commonly available are a better fit
For instance, even a well done W5 head on like say a 422 shortblock is “ one size to small” Been there, done that, seen that. With 4 inch or bigger tractor crank
I didnt like the fact Mopar 3.79 offerings were 1053, not 4340 forgings.
Think the 3.79 crank came out prior to any 4 inch stuff.
As well it probably should have, 3.79 arm suited W2/ W5 stuff better.
Talked to a lot of savvy smallblock guys over the years. Lot of them think the 3.79 deal is the way to go.
Click to expand...
Thanks for that. Was lookin at molnar or dragon slayer crank. They have em in 6 bolt
 
I think Rocket may have a lot of info on the 3.79 strokers. He was selling parts. I believe he raced them. Maybe he will chime in. Kim
 
604B1duster said:
I realize just a typo but 394.47 cubes,
I have one, but I remember them being referred to as 392s, guess it sounds better
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I call my 360 crank in a .030 over 340 a 373.

When some A-hole corrects me, for the actual 372, or dead nutz 372.61 I just roll my eyes and say what ever. Only A-holes pick this **** apart as if there is a royal holy dynasty to up hold. It’s just amazing how some assholes freak out because you rounded up or down.

392/394, a matter of a .030 vs a .040 or less? IDK
I get the general idea and I’m good with it. I can always ask a question on actual BxS cid.
I don’t care, saying I have a (LA) 392 is cool.


Edit-spelling
 
Last edited:
rumblefish360 said:
I call my 360 crank in a .030 over 340 a 373.

When some A-hole corrects me, for the actual 372, or dead nutz 372.61 I just roll my eyes and say what ever. Only A-holes pick this **** apart as if there is a royal holy dynasty to up hold. It’s just amazing how some assholes freak out because you rounded up or down.

392/394, a matter of a .030 vs a .040 or less? IDK
I get the general idea and I’m good with it. I am always ask a question on actual BxS cid.
I don’t care, saying I have a (LA) 392 is cool.
Click to expand...

Best laugh I had all day, thanks !
 
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