Any love for a 373 SB

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The stock 340 stroke of 3.31" is plenty good for revving the crap out of....it's the valvetrain, and other parts, that will be your limitation.
 
Nat said:
well you guys got me interested in this build for my 340 block , my 5 mpg 426 stroker is getting out of hand have to fill the tank twice a day , **** that . tinking about this molnar crank
MOLNAR FORGED CRANK: SB CHRYSLER 340 3.790" x 340M x 2.100"(EACH) - 340-3790EB6F
with matching molnar h beam rods be cheaper to do this than drive the car as is , $140.00 a day in gas more if i use race gas which is $25.00 + a gallon 372 sounds lika a good compromise between mpg/hp
Click to expand...
So what combo makes yours a 426?
 
rumblefish360 said:
I remember the article reusing the OEM stock parts for the build. That’s all there was back then. I’m not sure there were any stroker kits or just stroker cranks back in the 70’s at all. It was a smart move to look at all the parts and think about how they can be repurposed.
Here are a few of today’s options from Hughes engines.
They are all cast crank and Hyperutecic pistons for a closer direct comparison of parts used. The last one is the cost jump of forged crank & pistons as well as additional stroke.
Hughes Engines
372 = $1596
Hughes Engines
340 - 416 =$1676

Hughes Engines
360 - 408 = $1781

Hughes Engines
340 - 435 = Ka!-Ching!!!!!
Click to expand...
i like the 372 kit , if only it had a forged crank and pistons with H beam rods ,, it's sure cheap with the cast crank
and hyper pistons , but I hate doing things 3/4's the way , i don't care much for looks but want bullet proof internals as i go well over 7500 rpm because i forget to shift out of 2nd at the track , getting old and forgetful
 
Nat said:
Funny you should mention the destroked 340 to 5.0 litres , i was thinking about doing that , having an engine i could rev the crap out of , might be the way to go , as all i have now is a block heads and intake , how hard would it be to get 400+hp out of that destroked 340 . I'm looking for something different that if driven with a light foot like highway driving will match the mpg of my 340 about 22 mpg and pull low 13 in the 1/4 mile . i drive the car 120 miles a day so mpg matters , also ;l still like to have a bit of hp for some track time
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Don’t bother with a destroked 340. It’s going backwards for the most part. You want a mileage car that runs 13’s? Take that 340/360, add a small cam with a 4bbl, run an OD trans with 4.10’s. Enjoy…..

Your next post is confusing since you want an engine turn 7500+. That makes no sense to running the above ET. Over reving? Rev limiter. The engine stutters, you shift. Problem solved. Case closed.

You also need to turn the right rocks over to find the parts you need for a all forged 372. It’s not that hard to do. Expensive that way. Part by part.
 
K.O. SWINGER said:
How do you feel about the old 373 build? Which is the old 340 block with a 360 stroke crankshaft. It's one of my favorites I just love the bore stroke ratio ,piston speed and other dynamics of the combo. It is falling out of Grace with the low cost 4 in strokers what's your opinion?
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If it's an old Mopar V8 or slant 6, I like it. End of story.
 
Cliff Ramsdell said:
Rumble,
The car is a restored, stock 1968 Dodge Dart GTS. 340, 4 speed, 3.23’s. Firestone E70-14 redline tires. It’s a matching numbers car so racing is out but keeping the stock motor is in. The motor has a set of TRW forged pistons and an MP P4120231 cam that I installed in 1983.

The car had leakdown issues and my son Chris and I pulled the motor this weekend and tore it apart. Looks like some bore wear and crank wear will require a bore and grind.

I like the 372 package and have no concerns about the cast crank with a car like this. My plan is to reuse the MP cam package and swap in 3.55’s or 3.91’s.

I’m not looking to make 500 hp or run 10’s and I’m not wanting to swap to W2’s, eddys, or any of the other aftermarket heads. I want the car to look stock still. The wallet isn’t as fat as before, 4 kids, 6 grandkids and close to retirement, I don’t spend that kind of money on cars anymore but I want it nice.

Cliff Ramsdell
View attachment 1715669620 View attachment 1715669621
Click to expand...
Skip the 3.55's go 3.91's!
 
Nat said:
find me a made in USA MP crank and i'll buy it , hate spending money on crap made in China , would spend double to have made in US products any day all day
Click to expand...
I have one leaning against my living room wall circa 1993...
 
66fs said:
Why spend money to turn a 340 into a 360? Just get a 360. Do you know what .040 is on a 4.000 diameter?
Click to expand...
The larger bore makes more HP... My 360 block is only 4.040... I wish it was 4.1 or more.
 
Yup!
340 w/360 crank = 367. A 22 cube gain.
367 -> 378 = 11 cubes.
Grand total over the 340 to 378 = 38 cubic inches larger over where you started.
4.04 vs 4.1
4.00 stroke, 410 - 422.
4.15 stroke, 425.69 vs 438.33.

Pick your parts and to play. What ever suites you.
 
rumblefish360 said:
Yup!
340 w/360 crank = 367. A 22 cube gain.
367 -> 378 = 11 cubes.
Grand total over the 340 to 378 = 38 cubic inches larger over where you started.
4.04 vs 4.1
4.00 stroke, 410 - 422.
4.15 stroke, 425.69 vs 438.33.

Pick your parts and to play. What ever suites you.
Click to expand...

4.000 ID vs 4.040 ID + $ for 340 vs 360 + special crank
 
Krooser said:
The larger bore makes more HP... My 360 block is only 4.040... I wish it was 4.1 or more.
Click to expand...


I was told, which means it was probably BS, but I was told all the 6 bolt MP cranks were Scat China cranks. I was told all the 8 bolt forged cranks were USA cranks but I forget who they told me made those 8 bolt cranks.

That may or may not be true.
 
The one advantage I see of using a 340 main diameter crank at 3.58 stroke would be the ability to keep bearing speed lower than the 360 main version... that can be beneficial in higher rpm situations
 
rumblefish360 said:
Don’t bother with a destroked 340. It’s going backwards for the most part. You want a mileage car that runs 13’s? Take that 340/360, add a small cam with a 4bbl, run an OD trans with 4.10’s. Enjoy…..

Your next post is confusing since you want an engine turn 7500+. That makes no sense to running the above ET. Over reving? Rev limiter. The engine stutters, you shift. Problem solved. Case closed.

You also need to turn the right rocks over to find the parts you need for a all forged 372. It’s not that hard to do. Expensive that way. Part by part.
Click to expand...
i don't want an engine that yurns 7500 , i'm just saying i forget to shift out of 2nd at the track and it hits over 7500 i want something that will take it without breaking when i do forget to shift . i just figure with the 372 i could make more power easier and still get the mpg . the hughes kit you posted looked right except for the cast crank and hyper pistons , i always go overkill on parts want the lightest forged parts , why not it's just money . besides the 426 was costing over 800.00 a week in gas money 2 weeks of gas money for parts is money well spent
 
Well I can’t yet but I just finished assembly of my 372” 340.

Installed and running I’m still breaking it in right and tuning the car. So far, super happy with it all.

Cliff Ramsdell
9EFED18B-11B5-44B5-934F-61A5CD43C999.jpeg
81A2BE9D-BEE1-4316-8541-53492125ED93.jpeg
16A23CC1-E6F3-4E6B-AB5C-9F87E32F423B.jpeg
DDA93FF7-A8E6-43F0-B825-88086AD8D32E.jpeg
 
66fs said:
Until the cylinder walls don't seal, then you make less. .06 of an inch? with the same heads, really?
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340 vs 360... virtually every SBC I see on my regular Saturday night haunt has a larger bore than our 360's can manage. There is a reason for large bores.

I am going to keep the rpm below 7500. My buddy turns his 362 SBC 7800... some do 8500. The Fords will stick together at 9K if the right guy built the engine. My crank is 20 lbs. heavier than most I see so....
 
Last edited:
rumblefish360 said:
Yup!
340 w/360 crank = 367. A 22 cube gain.
367 -> 378 = 11 cubes.
Grand total over the 340 to 378 = 38 cubic inches larger over where you started.
4.04 vs 4.1
4.00 stroke, 410 - 422.
4.15 stroke, 425.69 vs 438.33.

Pick your parts and to play. What ever suites you.
Click to expand...
so what i have is a .30 over 340 block all i need is the crank rods , pistons and a decent cam , cam is always where i **** up
Cliff Ramsdell said:
Well I can’t yet but I just finished assembly of my 372” 340.

Installed and running I’m still breaking it in right and tuning the car. So far, super happy with it all.

Cliff Ramsdell
View attachment 1715751626 View attachment 1715751627 View attachment 1715751628 View attachment 1715751630
Click to expand...
car looks great ! what pistons are you using ?
 
66fs said:
Why spend money to turn a 340 into a 360? Just get a 360. Do you know what .040 is on a 4.000 diameter?
Click to expand...
because I have a good 340 block with the right date code for my car. that and i've had bad luck with 360 blocks in the past
 
a friend campaigned a 340 duster that ran mid 11's
stroked it to 372 changing only the rotating assembly.
new times were mid 10's shifting at 7800.
 
Krooser said:
340 vs 360... virtually every SBC I see on my regular Saturday night haunt has a larger bore than our 360's can manage. There is a reason for large bores....
Click to expand...

Do you realize that .040 is, the difference between a 360 and 340, almost nothing in a 4.000 bore. I am not interested in SBC engines, I rebuilt too many of them. How many Chevy parts are in those motors? My friend ran a 350 and I always teased him that he spent $10,000 to make his SBC into a stock SBM. Bore size is not where the power is, it is airflow through the heads. Why do Super Stock Class cars run almost the same times whether a 273, 340, or 360 using the same heads?
 
Nat said:
because I have a good 340 block with the right date code for my car. that and i've had bad luck with 360 blocks in the past
Click to expand...

It is your time and money. God Bless America! We all get to do what we want, within reason. Not what I would do, but I have no problem with you doing it.
 
66fs said:
Do you realize that .040 is, the difference between a 360 and 340, almost nothing in a 4.000 bore. I am not interested in SBC engines, I rebuilt too many of them. How many Chevy parts are in those motors? My friend ran a 350 and I always teased him that he spent $10,000 to make his SBC into a stock SBM. Bore size is not where the power is, it is airflow through the heads. Why do Super Stock Class cars run almost the same times whether a 273, 340, or 360 using the same heads?
Click to expand...

Large bore unshrouds the valves... most aftermarket blocks are cast to go 4.1 to 4.250 or more depending on application. That's where the HP comes from. Pistons are lighter than cranks... light pistons and light cranks.

My deal was originally built for the 1994 racing season. My cranks is 63LBS.!!! Yikes! I found a nice used set of Crower rods to replace the 340 rods that were in the engine. Just a little insurance. I could never afford a quality US made lightweight cranks so I'm sticking with my old MP crank.

All that rotating weight doesn't seem to bother the BBC's that run oval track so I am likely rebuilding this engine with a bit of overkill. But I have always been conservative with my RPM's. Small wallet if you know what I mean. But I did invest in lighter valves with 11/32 stems instead of our normal 3/8" things.

My heads flow a bit short of 300 CFM on the intake... I could spend another $1,200-2000 to open them up for more HP but, again, no $$$ in the till. New Brodix B1-BA-MC's could up my HP by 50-75. No cash for that stuff.

I'm shooting for 600-625HP. About what my other poverty goverened racers have in their SBC's. The well funded teams are running $40,000 bullets and spend $7-10K to refresh after 2000 laps. I can't afford that.

Right now I'm just hoping to stay upright in order to race... old age is a killer!
 
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