replicaracer43
Grumpy Old Man
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And was just a .060 over 360 correct?
Any love for a 373 SB
- Thread starter K.O. SWINGER
- Start date
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RAMM
Well-Known Member
Yes. J.Rob
gregcon
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Around 1983-84 I put together a 373. Used a 360 block with a 360 crank and .030 over 340 pistons. Had to mill the pin bosses for clearance (found that out only after first try at assembly...).
The 360 block was .070 over...it was an early block with thick enough walls.
The 360 block was .070 over...it was an early block with thick enough walls.
Cliff Ramsdell
I'm just a guy.
This is a timely thread. I have been looking at the 372 kit from Scat, 1-98001bi for my 68 GTS.
Car is stock except for a MP 284/484 cam so limitations will be intake and exhaust.
Looks like I might need to bore the std block and grind the crank, also std. Motor was freshened up in 1983 and not touched since except being returned to stock. By the time you figure pistons, resize rods, rod bolts, grind the crank and add rings and bearings & balance this kit is a deal.
Thoughts on head limitations with this size engine? I don’t think too much given the fact the 360 uses a lesser head.
Cliff Ramsdell
Car is stock except for a MP 284/484 cam so limitations will be intake and exhaust.
Looks like I might need to bore the std block and grind the crank, also std. Motor was freshened up in 1983 and not touched since except being returned to stock. By the time you figure pistons, resize rods, rod bolts, grind the crank and add rings and bearings & balance this kit is a deal.
Thoughts on head limitations with this size engine? I don’t think too much given the fact the 360 uses a lesser head.
Cliff Ramsdell
Hey Cliff. My thoughts on the cylinder head situation are at a stand still due to lack one thing, answer these questions to shed some light on the matter.
What is it you want from the car?
How heavy is it?
What trans, rear end ratio and tire size are in use?
How thick is the wallet?
What I mean by the last one is, can there be new cylinder heads in the future? This can be a pricey expenditure if the wallet is on the thin side.
Also, even stock small heads can perform great if you’d not pushing the heads performance level. Like looking for 575 hp from a stock port and valve 1.88/1.60-360 head. It’s just really feasible or wise to do so. Unless this is a FAST car bracket racer?????
Cliff Ramsdell
I'm just a guy.
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
If you can rescue that cam it would be a real coin saver! This is how I feel about the stock heads and exhaust manifolds. Don’t even worry about it! Just run it. Like you said, kids with grandchildren and the best one of all, (congratulations!!! 5 months to go for me!) retirement!
When the cubic inches are 360 plus, for the most part, torque production isn’t the issue. One of the reasons the 360 is a street guy’s favorite for decades now. Adding another 12/13 in bore size just adds to the mix.
The camshaft can use an improvement. Since the exhaust manifolds are the biggest issue being the cork, should a new camshaft come into play, look for more exhaust than a normal split duration can which is 4*’s. 8*’s should be enough to help get rid of the exhaust gasses.
On gear ratio, 3.55’s allow interstate driving, not so much a/3.91’s. Even more so with the stock tire size. While the 3.55’s are t the huge torque gain a change to 3.91’s offer, those stock tires are just going to give up the ghost at heat any speed your traveling at. IMO, it’s just to much torque release. Stay with 3.55’s. MAX, IMO.
Enjoy!
When the cubic inches are 360 plus, for the most part, torque production isn’t the issue. One of the reasons the 360 is a street guy’s favorite for decades now. Adding another 12/13 in bore size just adds to the mix.
The camshaft can use an improvement. Since the exhaust manifolds are the biggest issue being the cork, should a new camshaft come into play, look for more exhaust than a normal split duration can which is 4*’s. 8*’s should be enough to help get rid of the exhaust gasses.
On gear ratio, 3.55’s allow interstate driving, not so much a/3.91’s. Even more so with the stock tire size. While the 3.55’s are t the huge torque gain a change to 3.91’s offer, those stock tires are just going to give up the ghost at heat any speed your traveling at. IMO, it’s just to much torque release. Stay with 3.55’s. MAX, IMO.
Enjoy!
gregcon
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With those scrawny and short tires, I wouldn't even use 3.55's unless I spent 90% of my time driving on small roads.
The 340 manifolds are pretty good for being manifolds. That said, it's an age-old story....once you start modifying the engine, where do you stop? The old formula of cam/carb/headers is a pretty good one, still. But frankly...headers have gotten so out of hand cost-wise, I'm not that keen on them for a relatively stock car.
This is just me, but using a cast crank in any 69 Dart, especially with a 4 speed and 340, would create a lot of balance and failure issues. My guts would go out of balance, and my bowels would fail to hold it in.
Numbers matching....the bane of the hobby.
The 340 manifolds are pretty good for being manifolds. That said, it's an age-old story....once you start modifying the engine, where do you stop? The old formula of cam/carb/headers is a pretty good one, still. But frankly...headers have gotten so out of hand cost-wise, I'm not that keen on them for a relatively stock car.
This is just me, but using a cast crank in any 69 Dart, especially with a 4 speed and 340, would create a lot of balance and failure issues. My guts would go out of balance, and my bowels would fail to hold it in.
Numbers matching....the bane of the hobby.
Cliff Ramsdell
I'm just a guy.
I have been down this road with the car in the past. When I built this short block it also had an LD340, holley 3310-2, MSD-5C, Headman headers, 2.5” exhaust and 4.30 gears. That and a G70-14 tire and I drove the car everywhere within a 300 mile radius with never a care and it ran a best 13.92 just like that.
The 372 is a consideration of the current state of the engine and where I might need to go. As Rumble stated the cam package is big coin and my son Chris @TurboGLH has pointed out also that a split pattern would be great but if a nice clean up on the heads along with a fresh valve job and the current cam package will work I’ll move that way but I have time to work on it.
@gregcon As for a cast crank, I knew that would come up. I have no issues using one. I built some pretty stout turbo dodges for years. Cast crank, forged piston and 20 lbs of boost in my 2.5 made 372 hp and 417 ft lb at the tires. I built quite a few of the cast crank, TII rod (think 340) and forged piston motors and never a single crank failure. 20 years as a Chrysler mechanic and still no failed crankshaft.
I bought this car from the original owner in 1980 and I’m happy it’s a matching numbers car. Maybe a bane for you but I’m just happy to have the car
Cliff Ramsdell
The 372 is a consideration of the current state of the engine and where I might need to go. As Rumble stated the cam package is big coin and my son Chris @TurboGLH has pointed out also that a split pattern would be great but if a nice clean up on the heads along with a fresh valve job and the current cam package will work I’ll move that way but I have time to work on it.
@gregcon As for a cast crank, I knew that would come up. I have no issues using one. I built some pretty stout turbo dodges for years. Cast crank, forged piston and 20 lbs of boost in my 2.5 made 372 hp and 417 ft lb at the tires. I built quite a few of the cast crank, TII rod (think 340) and forged piston motors and never a single crank failure. 20 years as a Chrysler mechanic and still no failed crankshaft.
I bought this car from the original owner in 1980 and I’m happy it’s a matching numbers car. Maybe a bane for you but I’m just happy to have the car
Cliff Ramsdell
K.O. SWINGER
Meeting in the alley since 1976
The 284 Mopar hydraulic is still in my humble opinion a awesome 340 camshaft. But it likes gears and it needs to breathe a mismatch for stock manifolds. As good as the 340hp manifolds were they're still a major cork as the RPM range climbs the problem becomes more pronounced. I would keep the cam lose the manifolds and run a 355 with the 26-in tire. But really better yet a 391 yes it'll be whining a little bit at 65 to 70 mph but for a 340 that's just a sweet song . But if you move to the 358 stroke rear end gears 355 no problem great combo. Also by moving to the longer stroke you will raise the compression enough that a ironhead will be needing a spot on tune and good fuel! The 340 stroke and the same setup will be quite a bit more forgiving and premium pump gas friendly.
EddieSketti
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3.55 gears are the best of both worlds best thing i did to my car
gregcon
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My comment on numbers matching is just that....no one should really care. But, the Chevy boys have bled over into our hobby and now everyone wants to get wet about matching numbers. A 340 Dart is a 340 Dart, no matter if the numbers match or not. I can live without the snobbery of numbers. I do place value on a period-correct engine with the proper casting look and accessories....I don't like a 1978 440 in a 1968 Super Bee because it start to look wrong.
My 70 Dart Swinger, 1990-ish. I bought this from the original owner in 1983. 132K miles, loose but not worn out. 727, 3.23SG, buckets, console, no AC. Bone stock mechanicals, ran 13.8's in the quarter on more than one trip to the drags.
My 70 Dart Swinger, 1990-ish. I bought this from the original owner in 1983. 132K miles, loose but not worn out. 727, 3.23SG, buckets, console, no AC. Bone stock mechanicals, ran 13.8's in the quarter on more than one trip to the drags.
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
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
Krooser
Building Chinese Free Engines since 1959...
I wont spend that on ethanol for a month.
I think Tom Molnar has the nicest ChiCom cranks available… Mine is a US made billet deal from MP Performance but Molnar will walk you thru the whole deal. He is also a buddy of one of my machine shops.
Good luck on your build.
I think Tom Molnar has the nicest ChiCom cranks available… Mine is a US made billet deal from MP Performance but Molnar will walk you thru the whole deal. He is also a buddy of one of my machine shops.
Good luck on your build.
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
Tat is a great time for a stock 340 what tires out back to run a 13.8 , best i ran was a 14.01 @99mph with 235-14. bfg tires and stock engine smoked the tires trough 2nd gear .
SS Lancer
Well-Known Member
Do we have past posts for all the possible combinations using LA blocks & cranks ?
I find those very interesting and many folks are still interested in the old Formula's .
SS Lancer
Well-Known Member
Great article and thanks .
K.O. SWINGER
Meeting in the alley since 1976
So I will be most likely going through my 69 340 this winter, here is my parts list. Nothing is in stone except for the camshaft and six pack & lifters which I have. 1969 340 block,TA six pack, procomp as cast heads competition valve job,MP solid lift camshaft 525 lift 284 duration on a 108, 4.080 icon Pistons and Scat 358stroke and other goodies . 4 speed car with 391 rear may change gear.street car.
ir3333
Well-Known Member
The below picture is out of the last MP catalog and I think it does not include the very short stroke crank for Trans Am racing where the 340 gets destroked to the 5.0 Ltr. limitation of the Trans Am series racing.
(I forget the stroke of that crank.)
It also does not include the latest cranks of greater than the 4.0 from various places. IIRC, there was a 4.15, 4.17 & a 4.25 available at one point. There may have been others as well as custom one off cranks home builders thought up and actual super duty race cranks from such race supply houses like Winberg.
(I forget the stroke of that crank.)
It also does not include the latest cranks of greater than the 4.0 from various places. IIRC, there was a 4.15, 4.17 & a 4.25 available at one point. There may have been others as well as custom one off cranks home builders thought up and actual super duty race cranks from such race supply houses like Winberg.
Locomotion
Well-Known Member
I'm pretty sure it was a 2.96" stroke crank.
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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