3.9 Stroker

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67autocross

67autocross

A new iron curtain drawn across the 49th parallel
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Did they ever make a 4 inch stroker crank for the 3.9 ...I went to start my 89 Dakota after it has been sitting for a few years and the engine is stuck...got me thinking that if I have to pull it for a re-build it would be interesting to pump up the torque a bit...
 
might want to pull the acc belts off , maybe a/c or alt is froze and wont turn over that way??
what year is the dakota?
 
It's stuck internality...I already had the big pry bar on the crank bolt to see it would budge...pulled the plugs last night and sprayed in the penetrating oil...it's a 1989 Dak
 
67autocross said:
Did they ever make a 4 inch stroker crank for the 3.9 ...I went to start my 89 Dakota after it has been sitting for a few years and the engine is stuck...got me thinking that if I have to pull it for a re-build it would be interesting to pump up the torque a bit...
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No
 
At one time there were heads / cranks /cam and other but i do not think any one building that stuff any more call hughes engine at one time they had stuff for them. Email: [email protected]
 
It already has a carb,intake,headers…and orange box MP ignition…all that is left is the stroker
 
The 5.2 would be just fine in front of the ax15 and even stock is much better than the 3.9. As long as you’re not racing it side stepping the clutch it’ll be ok.
 
Jadaharabi said:
I thought the transmission used behind the 3.9 was the same as the one used behind the 5.2.
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I don't really want to turn this into another project...I just figured if I had to pull the engine a stroker crank would be a nice addition....plus the 3.9 it already has intake, headers ect
 
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more POWER !!!!
 
67autocross said:
It would kill the 5 speed….
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I've been running a mildly warmed over 5.9 in front of the original NV2500 in my '88 Dak for a few years now, no issues. I've kept an AX15 in reserve as a backup, but so far it hasn't been necessary.
The 5.9 bolted right in using the V6 mounts (and a Durango oil pan), just had to rebalance the flywheel. With a 5.2 you wouldn't even have to rebalance, since the V6 and 5.2 are both neutral balance.
 
67autocross said:
I don't really want to turn this into another project...I just figured if I had to pull the engine a stroker crank would be a nice addition....plus the 3.9 it already has intake, headers ect
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Thought mopar used to sell some heads for those and what not ...that would really wake it up. Or weld up the crank and cross your fingers every time the tach hits 6000 rpm..or..
Just do like drill press bore job guy... buy a stroker crank, cut and weld the nose back on and re machine.. probably
040 or .050 under to get it straight. Lol
Hell just run a bolt all the way through it while your at it..
 
Well if I end up pulling it for sure it will get some flat top pistons…head valve job and mild porting…reground cam…. I will also chan my user name to 75%of318willrun
 
A stroked 3.9l be slightly bigger than a overbored 273, a 273 would be better with 8 intake & 8 exhaust ports over 6 & 6.
 
273 said:
A stroked 3.9l be slightly bigger than a overbored 273, a 273 would be better with 8 intake & 8 exhaust ports over 6 & 6.
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Lots of things would be better… but I want want to keep the truck true to its original state…,

0E267A2F-CD99-4D03-9DE3-750F7E668563.jpeg
 
Have you considered a 3.6 pentastar?

I don't know squat about this company, just a minute with google.

prodigyperformance.com

3.6 Pentastar Performance Parts | Prodigy Performance

Prodigy Performance is the ONLY Manufacturer of Forged Internals for the 3.6L Pentastar which includes Pistons, Rods, Headstuds and Block Guard for Forced Induction applications
prodigyperformance.com prodigyperformance.com
 
Again I don’t want to change the soul of the truck… it was factory ordered with the 3.9 and a 5 speed, 3.91 gears, sure grip and no AC with no power windows and the sport package… soon after the EFI was pulled off and replaced with an M1 intake, 650 carb, electronic ignition and headers… and a big stereo for listening to punk rock…

4F03F7ED-35DD-4D11-A758-455C7A4863F8.jpeg
 
I called a few places about a crank….they all hung up on me…the dream has died and I’m going back to seeing if I can bust it loose
 
67autocross said:
Did they ever make a 4 inch stroker crank for the 3.9 ...I went to start my 89 Dakota after it has been sitting for a few years and the engine is stuck...got me thinking that if I have to pull it for a re-build it would be interesting to pump up the torque a bit...
Click to expand...
Lacquer thinner mixed with transmission fluid (or better yet super creep) sprayed into the spark plug holes with an oil can.

Maybe, additionally, pull the oil pan and spray up into the rotating assembly. Should loosen things up. There are automotive ‘snake-oils’ that are so thin, they soak into porous metal, and that would loosen things up.
 
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