340 Build Advice

[mopowers]

Upgrading the 904 to a 998 or an 999 (2.47 1st and 1.55 second) with six thin clutches in place of 5 with a custom converter and a Trans-Go TF3 manual valve body kit would make it perform like you want. It's the route I would take if I kept it at a stock stroke. 3.58 inch stroke is also a good option for 367-379 inch combination. I do like a four speed for auto cross though.

Do you know what yrs and models one could find a 998 or 999?

 

[Garrett Ellison]

I have an a999 from a 1989 318 dodge truck. They can be converted to non lockup by swapping the input shaft (maybe some other parts involved, I'll have to research it again before I go through mine to confirm, @#!% Covid Fog!), but you can also have a custom performance converter built without the lockup clutch assembly installed in it. The same gear sets and five disc clutch front clutch drums are in a999 500, 42RH and 42RE transmissions, and I have heard there were some 360 a 998s in the seventies with 5 drum clutches.
Here's some information from Wikipedia, FWIW. I'm sure there are probably exceptions to what's listed here, but this should hit the high spots.
A998 (31RH)[edit]
The A998, later renamed 31RH was a medium-duty, narrow or wide-ratio version of the small-frame A904 transmission for use with medium-power V8 engines and the 3.9 L V6 engine. It was equipped with four direct friction plates. This transmission differed from the A904 by having a reinforced case and internals. Narrow ratios are 2.45/1.45/1.00:1 and wide ratios are 2.74/1.55/1.00:1.

Uses:

• 1984-1989 318 (2-bbl)
• 1972-1988 AMC 6 cylinder and 304 V8 engines
• 1987-1988 Dodge Dakota

A999 (32RH)[edit]
The A999 (later renamed 32RH) was a heavier-duty, wide-ratio version of the small-frame A904 transmission for use with medium-power V8 engines and the 3.9 L V6 engine. It was equipped with five direct friction plates. These automatics had lower first and second gear ratios to allow the lower-powered engines to provide better acceleration without sacrificing highway fuel economy. Frequently used today in drag racing.

Uses:

• 1975-1980 360 (2-bbl)
• 1984-1989 318 (4-bbl Police)
• 1994-2003 Dodge Ram Van B150 with Magnum 3.9L V6 engine
• 1994-2003 Dodge Dakota with Magnum 3.9L V6 engine
• 1987-1995 Jeep Wrangler YJ with 6-cylinder engine.

• 1997-2002 Jeep Wrangler TJ with 6-cylinder engine.
• Jeep Wagoneer/Grand Wagoneer with the 258ci (4.2L) straight-6

 

[MOPAROFFICIAL]

Are you not wanting any money for your labor and machine work ? I see at least 5 grand in parts for a running 500 HP engine.

Outside of the machine work* anyone with a good book and a torque wrench can assemble an engine, and should!
Sure it's good to have experience and to have the extra tools to check and verify the machine work.. but if the work was done right you wouldn't have to do/check anything you could put a blindfold on and simply have somebody set the wrench and listen for Clicks.. and the motor would run fkn grrreat. . . well..almost..lol
I can do it cheaper where I'm at.
So I'm like..10k for an engine?? most of the time fkn car ain't worth ten grand 'by itself' lmao..

 

[Bewy]

The difference between when the 340 came off the production line.....& now......is the plethora of stroker kits available. And cheap too. For me, it is a no brainer....

 

[Alexhetti]

Upgrading the 904 to a 998 or an 999 (2.47 1st and 1.55 second) with six thin clutches in place of 5 with a custom converter and a Trans-Go TF3 manual valve body kit would make it perform like you want. It's the route I would take if I kept it at a stock stroke. 3.58 inch stroke is also a good option for 367-379 inch combination. I do like a four speed for auto cross though.

After speaking with @replicaracer43 I’m thinking of doing a 4” stroke engine. What trans combination would you suggest if sticking with the 904? I’d like to go 4-speed ideally but incase that doesn’t work out

 

[Alexhetti]

The difference between when the 340 came off the production line.....& now......is the plethora of stroker kits available. And cheap too. For me, it is a no brainer....

that’s the direction I think it’s heading!

 

[goldduster318]

I have a stock crank 340 build, it made 470.9hp and 455 lb-ft on the dyno with a 750 DP but it has MPFI now, a little more expensive to pull off.

'70 Block and Crank, 0.040 over.
Edelbrock Heads, valve job (they were used), Comp Beehive springs and retainers
Custom pistons, (flat top w/reliefs, Racetec), 9.75:1 CR
K1 H-beam rods
Lunati 227/231 duration at 0.050, 0.530/0.530 lift, 110 LSA Hydraulic roller
Crane Gold Roller Rockers
Kevko oil pan with built in crank scraper
When dyno'd it had an Edelbrock Air Gap, currently has an Edelbrock Super Victor EFI
Currently has Megasquirt 3 Pro EFI with Coil Near Plug and GM LS D585 truck coils and a Holley 1000 cfm throttle body

I have a T56 magnum in the car, 3.23:1 rear end gears, the engine will pull a hill at 1400 rpm without problems and it pulls hard, I only turn it 6200 rpm max. I typically get about 14-16 mpg and that's almost always short trips. Great engine for a street car. Other than swapping the intake to do the EFI I've never messed with it since it was built in 2013. This was built to be a street engine over all.

 

[512Stroker]

After speaking with @replicaracer43 I’m thinking of doing a 4” stroke engine. What trans combination would you suggest if sticking with the 904? I’d like to go 4-speed ideally but incase that doesn’t work out

If you are going to spend the $money to build up a shifter car I would go with a 5 speed. The overdrive gear for highway cruz'n and it would be great behind a 416 at an autocross event.

 

[AJ/FormS]

How are you gonna deal with the massive tirespin that even 280hp brings?
A streeter with street gears, and an automatic transmission is a two gear/one shift car.
With 3.91s and a 5500 shift, your speeds at the shift are about;
42/71/103. When you shift into Second at 42mph (no tirespin) the Rs will fall to about 3250, with a typical street stall. What good will your 500@5000/5500rpm engine be, at 3250? You won't get to the power peak again until say 5000/65mph. Which is good gearing, but the tirespin will kill your ET. You might as well have half the power ...... and not have to deal with as much tirespin.Jus saying

 

[Alexhetti]

How are you gonna deal with the massive tirespin that even 280hp brings?
A streeter with street gears, and an automatic transmission is a two gear/one shift car.
With 3.91s and a 5500 shift, your speeds at the shift are about;
42/71/103. When you shift into Second at 42mph (no tirespin) the Rs will fall to about 3250, with a typical street stall. What good will your 500@5000/5500rpm engine be, at 3250? You won't get to the power peak again until say 5000/65mph. Which is good gearing, but the tirespin will kill your ET. You might as well have half the power ...... and not have to deal with as much tirespin.Jus saying

I run 3.55 gears and I'm even considering switching to 3.23. There's really no need for me to run anything like 3.91, I'm not drag racing the car. It's a driver and may see occasional autocross. Do you think the car is gonna spin out the tires that much? I run one of the widest tires a non-tubbed/spring relocated dart can, 15x8's.

 

[goldduster318]

I don't think it will spin that much, but I also have a 6-speed so no converter action there. I built a stock stroke engine partially because I thought the extra low end might be a bit much to get traction on the street. But its a lot more than 280hp. I'm making 400 lb-ft at 2800 rpm and it can hook up fine. But I don't have M&S radials like BFG Radial T/A's or Cooper Cobra GTs like a lot of people have. Those spin really hard. I used to have 225-60-15 BFG G-force sports and I could spin those pretty hard, my friend has them on a 71 Demon with a 318 Magnum with a small cam and a stock 904 and it only spins a little usually after it rolls out a bit, now I have 275-35-18 Continental ExtremeContact DW and as long as its over 50F it doesn't spin so much unless I'd get aggressive on the clutch. A little spin on the 1-2 shift but I basically shift from peak HP to peak torque since a 6000 shift gets me to 4400.

Moral of the story, Tires matter a lot, compound as much if not more than width.

 

[AJ/FormS]

I run 3.55 gears and I'm even considering switching to 3.23. There's really no need for me to run anything like 3.91, I'm not drag racing the car. It's a driver and may see occasional autocross. Do you think the car is gonna spin out the tires that much? I run one of the widest tires a non-tubbed/spring relocated dart can, 15x8's.

Like @goldduster318 says. it depends on your tires.
Now, the following is/are my experiences, and are my opinions.
But 255 streets are a waste of time at even 300hp.
My current car is a 1968 Barracuda 367/A833Commando/3.55s, and she goes 93 in the Eighth at 3467 pounds/me in it. The Wallace makes that to be 433 hp.
It spins 295 BFGs, or Cooper Cobras, or even 325/50-15 BFG-DRs right thru 2 gears, and more. With 3.55s in the back 6800 in Second is 80 mph. On the shift, into Second-over (GVod) the Rs fall to 5300, and guess what, that is just a wee bit over the power peak of my 230*cam, so ....... sometimes it just keeps on spinning........
And that is just what you are looking at with a goal of 400 to 500 hp, on 255s. or on any street tire that fits inside the factory tubs, for that matter.
Someone here on FABO, recently stated that it would cost over $3000 to fix that, by mini-tubbing, moving the springs, narrowing the rear, and installing some sticky fattys on appropriate wheels. I dunno if that's enough. Actually I doubt it.

In fall of 1970, I purchased a nearly new 70 Swinger340/A833/3.55s , and drove it until 1975. I can tell you without reservation, that car, on the factory tires, was the sickest-handling performance car ever brought to market, EVEN WITH the rally suspension. I was only just 17, the car looked awesome in PantherPink, but what a pos it was, as to handling; even just switching lanes a lil too abruptly could send it into a tizzy. That is the car I learned to drive in and after five years and many many sets of tires, I was still learning,lol. And that was with a pure-stock 275hp-advertised 340 that went 14.4 in the qtr spinning a very long way, on the PolyGlass E70-14s. It also easily laid rubber thru two gears with bias-ply G60-14s, or later, on radials. Not a hope in heck would I myself, with over 50 years of bag-driving street-experience, try to autocross that Dart on factory suspension with a stock 340 never mind a mean 340; No matter what tires are in the stock tubs. IMO you will get black-flagged for spending more time off-track than on.
But I can tell you another thing about that Swinger. Given a big open parking lot and a few strategically abandoned shopping carts, late at night, me and my younger brother, would have a chitload of fun, "testing the limits"! lol. Good times! Little Brother is gone now..... all I got are the memories.

Ok so like I said, those are my experiences.
The 340 was totally stock including the exhaust..
The 367 is a high-compression, eddy-headed, pussy-cat with a Hughes 230/237/110 cam in it, plus all the usual bolt-ons.

Dare I say this: if your stock 340car, on stock suspension, on the street, cannot spin street tires, in the stock tubs, to; right thru First gear and at least part way thru Second with 3.55s, then, either;
1) that 340 is sick/way out of tune, or
2) you got a pair of fantastic tires, or
3) IDK, maybe yur running downhill? .....
4) I would not install low-profile tires, on hi-dollar wheels, on any Street Dart that gets driven because the curbs will eat your expensive wheels. Just one hit in today's world is likely to ruin your summer.
IDK, maybe I'm just a crusty old man, I dearly loved that car. I wish I would have had it 20 years ago, and did it up like I did my Barracuda. Such is life.

 

[goldduster318]

I dunno, 72blunblu probably drives his car more than almost any of us and has 18's. The thing is, nearly all of these tires have "inset beads" so you'll not hit them with a casual rub, you'd have to hit pretty hard. I'm going on year 7 -> maybe 10k on it and I live in SE MI which is not a place with good roads and haven't damaged any wheels. My DD's even have 17" wheels with the same rolling diameter and have never damaged them. These days it is the difference between having crap tires like Radial T/As or Cooper Cobras and tires that can put power down (and go around a corner). You don't buy 400 treadwear M+S tires with "A" traction rating and expect them to be very good. Tire tech has come a long way. The 200 treadwear stuff you can buy in 17s and 18s are wildly sticky in comparison.

Other thing I know is the rear suspension setup varies for a lot of people. I have stock height ESPO 6 leaf springs with a stock height pinion snubber and the hotchkis rear sway bar, poly bushings and nothing else. I feel like the jacked up rearend crowd or the tall MP pinion snubber doesn't help. Those springs will be 20 years old this year. they always worked well and no wheelhop at all. My friend has the same on his Demon so maybe other setups don't perform as well for traction either.

 

[Scody21]

I agree on the tires. I’ve been too cheap to buy a set of rims. The ones on there are 16’s the PO put on. The selection of 16’s tires suck so I’m kinda stuck with Falken Azents 615 which are a 200 tread AA temp that are sticky as heck when hot. Im running 225/50-16’s which is the widest for 16’s. Have Firmfeel SS springs, sway bar and RCD billstines. I can / do steer it with the go peddle and have no problems taking corners. I’m planing on a panard bar when I finely get to some wanted upgrades. A few buddies are running BFG’s/ Cobras and those cars handling in poor at best…

 

[Rat Bastid]

I agree on the tires. I’ve been too cheap to buy a set of rims. The ones on there are 16’s the PO put on. The selection of 16’s tires suck so I’m kinda stuck with Falken Azents 615 which are a 200 tread AA temp that are sticky as heck when hot. Im running 225/50-16’s which is the widest for 16’s. Have Firmfeel SS springs, sway bar and RCD billstines. I can / do steer it with the go peddle and have no problems taking corners. I’m planing on a panard bar when I finely get to some wanted upgrades. A few buddies are running BFG’s/ Cobras and those cars handling in poor at best…

26/11.5-16LT

Here you go. 16 inch wheel and all the bite you could want.

 

[Rat Bastid]

26/11.5-16LT

Here you go. 16 inch wheel and all the bite you could want.

Here is a 16 inch drag radial of you hate yourself.

275/55R16

 

[Scody21]

26/11.5-16LT

Here you go. 16 inch wheel and all the bite you could want.

Want road race slicks, not drag slicks ​

 

[fishmens67]

Want road race slicks, not drag slicks ​

You're probably going to need a rain slick on the coast.

 

[Scody21]

You're probably going to need a rain slick on the coast.

LoL. I want to find some 14” sand paddles for my 73 Ratty Swinger so I can blast it down the beach.

 

['Cuda_ragtop]

Bought the car in 1987. Stroked it in 2013

480HP @ 5700, 511 Torque @ 4300
488 torque @ 3100, where the dyno started measuring
418 C.I. stroked and poked 340
10.5:1, 92 octane unleaded pump gas.
Crane Camshaft: SR246/362-2S-8IG , .543/.561 L/S: 104 Int. C/L: 108
Full roller, solid lifters, LD340 intake, QF650 DP, Edelbrock heads straight out of the box.
Just a street car... Pulls way harder than the mostly stock 340 did before stroking it.
A833 4-speed, 3.55, 8.75 Sure Grip
Running Mopar HiPo 340 exhaust manifolds too.
A single Plane intake and long tube headers would most likely get it to 500+ @ 6000+ RPM
Just runs out with the dual plane intake and manifolds, which is still fine with me.


17" Year One Rallye wheels, 275/40-17x9 rear, 245/45-17x8 front
Firestone, Firehawk Indy 500 Wide Ova, Ultra High Performance Summer Tires.
They hook really well. Can still fry them at will but really surprised at how well they hook up.
Ride nice too, not too harsh and handle well. Bilstein RCD shocks on all 4 corners.

Have been looking at the Continental Extreme Contact as possible replacements.
Thought about 285/40 but the recommend minimum wheel width is 9.5" and my rear wheels are only 9 inches wide. “¯\_(ツ)_/¯“