[CooperTune]

After looking for a 4.5 qt oil pan only to find there are none. I'm thinking about making my own 5 qt pan. I just feel the system needs more oil. It's that or remote oil filter and temp control cooler. Are there any oiling issues that we are aware of?
Also I got around to checking the difference between org pistons and the aftermarket ones. On top of that after CCing the heads it looks like 9.8 to 1 is as simple as cutting .010 from block surface. I'll confirm all this when the block comes back from boring. And the 318 / 5.2 rods are .062 wider than the 3.9 rods. Steve

 

[CooperTune]

OK I lied I have even more questions. What do we know about these cranks? My book of lies says 2.124 to 2.125 rod journals. Measured all mine and no two the same none 2.124 and none 2.125. This is not all bad but all bearings are showing copper. Very likely dry starts or low oil. As for journals low 2.1242 and high 2.1248. I'd polish it but I can see shadows around the oil holes now. They will only get worse with a polish reducing surface area. If you look close it appears the cranks have rolled radius. This is something they came up with to improve crack resistance where the journal meets the cheek. The ones I have seen before grind out around .020 U/S grinding .010 should leave the rolled radius intact. This should satisfy my need for a uniform size and still have a improved shaft. Whats wrong with wanting it all? Steve

 

[RalphP]

If I understand, your rod journals are all within the 2.124/2.125 range; within .0006 of min to max.

That's not a problem for a production motor. (Yah, I'd blueprint closer if I were blueprinting one.)

RwP

 

[CooperTune]

At this point it's nothing but time and money. As I type the 8 Scat con rods are spinning around to become V 6 rods. I have resisted ordering bearings until the crank was clean and checked. Today I stood beside a ThunderBolt 427. If you don't know it don't matter. Steve

 

[RalphP]

I remember the Thunderbolt 427s.

I'm old enough to remember them first hand, not just by reading articles on the Innarwebs!

RwP

 

[CooperTune]

As we know there are differing opinions on KEG mods. I'm game to see if there is anything there to be had. I'm not 100 per cent behind the design. So far I have two hours milling machine time and a hour of cardboard templates. I suspect another hour more likely two of hand port work an both ends. Clean, clean, clean tack the plates in fill with foam seal with silicone and go back to work. I have some pictures. Steve

 

[CooperTune]

As you suggested, if I were still working the counter at a machine shop I'd point out the sizes as measured and I'd let the customer decide as for a street std polish crank, hone block rebuild it would be fine. Only someone wanting the best result in spite of a few dollars would go this far. Once I find someone willing to receive text pictures and post them this story will become more interesting. Steve

 

[CooperTune]

It looks like I'll receive the rocker pivots direct from MOPAR today the new intake and exhaust valves tomorrow from the left coast. All that is left is the drop ship piston rings from the factory. I'm sure issues of the last year is why there are so many shorts. Several of the performance items from Summit and Jegs have been drop ships. It's bad enough to be working on a unit that has almost no support then have issues getting rings and bearings. Steve

 

[CooperTune]

Pop question for 10 points. What percentage of reciprocating weight is used in making bob weights for the 3.9 V6 Dodge? OK second question, The flywheel is quite heavy at around 38 lbs. Considering the low RPM expected the flywheel could be safely lightened a few lbs. Would removing those few lbs have a negative effect on smoothness? Steve

 

[RalphP]

Pop question for 10 points. What percentage of reciprocating weight is used in making bob weights for the 3.9 V6 Dodge? OK second question, The flywheel is quite heavy at around 38 lbs. Considering the low RPM expected the flywheel could be safely lightened a few lbs. Would removing those few lbs have a negative effect on smoothness? Steve

First question - I have NO idea; that's why I take engines to professionals to rebuild. But I could find out if I wanted to, I'm sure.

Second question - Yes, it will. How negative will depend on how much weight you remove. Being lighter it will help the engine rev a bit easier, too.

RwP

 

[CooperTune]

There you go, there is life here. The reason I ask is there are different schools of thought on balancing a split pin V6. Depending on degree of split and some other black magic as to percent. I have no idea how many V8s I balanced and always used the 50% rule. We never invested in bob weights for the V6 so it never came up for me. I have reduced the weight of the reciprocating mass which I want to benefit the balance.

Yes, I understand the relationship of removing weight to ability to rev. There is a formula weight reduced rotating mass equal to weight removed from load. Wondering if the weight is there for another reason. Think I'll leave it for now. Steve

 

[CooperTune]

Been away for a few days, as it turned out the first flywheel I got from a junk yard was for a 10.5 inch clutch in a early 3.9 V6. The correct 11.5 / 12 inch clutch flywheel is about 3 lbs lighter. Kind of nice to find the factory part that does what you'd like to do. Location of the weight must have a lot to do with it. The larger dia pressure plate moves weight further from center line. And the flywheel has 3 lbs removed as close to the center line as possible. Funny the things you learn by mistake. Stteve

 

[RalphP]

Yah.

"Eureka!" doesn't precede most scientific discoveries, but instead, "Well, that's strange."

RwP

 

[CooperTune]

OK maybe one more question. Very early on asking around of machine shops I was told all 3.9 V6 heads are cracked. When I stripped my core engine I removed the valves and wire brushed the chambers. I did not see the very tiny hair line cracks and went on cleaning, removing rust, and porting. It was good practice and I better know what can be done. The reason the valve seats are cracked is there is no water in the area. If these cracks never got any worse I'd have no issue doing a valve job and going on. When I pull the current engine if it's heads have the same hair line cracks they will all get a valve job. Has anyone run into cracked cyl heads? Steve

 

[CooperTune]

I placed an order yesterday for a pair of new cyl head castings. Oddly I have wanted new casting all along but figure if not cracked there was no reason. Once I found both my heads cracked I hurried to get home and place the order. I will get pictures and share them. Steve

 

[CooperTune]

I always have another question to ask. Shopping sensors ( all of them ) for my 3.9 V6 engine build. Starting to wonder if there is a good, better, best provider? I'm beginning to notice that I'm starting to like it when a part is made in Mexico. Steve

 

[RalphP]

I always have another question to ask. Shopping sensors ( all of them ) for my 3.9 V6 engine build. Starting to wonder if there is a good, better, best provider? I'm beginning to notice that I'm starting to like it when a part is made in Mexico. Steve

Most of the sensors that Mother Mopar uses are longer lasting than the after market.

And yes, "Henco en Mexioco" sure beats "Made in China" for parts IME.

RwP

 

[CooperTune]

I have had to replace the crank position sensor twice on my truck. It's not in a great place to get in the truck. I spoke with a couple people about installing them. Both had a different idea of how they are set. On the back side of the flywheel there is what I call a reluctor ring. I more less understand what and how it does it's job. With the engine on the stand I can see the location. I'm just thinking there is a spacing that is correct, I can see and measure it and I imagine there is a way to adjust the spacing. I'm still looking for a Chrysler crank position sensor. Any thoughts on spacing or source please share. Steve

 

[CooperTune]

Oh yeah, I have been talking with some informed people? My next big purchase will be injectors. A good friend recently retired from the Conti tire owned plant where injectors are made. Talking with him I'm a little better informed about sizing. Having ask what the std lbs per hour rate on stock injectors is, three ask all different answer. Roughly 239s, 318s and 360s only make about 30 HP per cyl. It seems the answer depends on HP per cyl. Engine rated at 195 HP give or take, my target has been 230/240 about the same as a V8. That should be around 40 HP per cyl. It was suggested I install the orgin injectors dyno the engine with wide band O2 and if it leans at higher RPM increase injector size. But beware of over rich idle issues. Steve

 

[RalphP]

IDEALLY, you would use larger injectors with a known good and smooth transfer curve, and reprogram the ECU to work with them.

For things like that, books like Greg Banish's books and (for those of us with Fords!) Dan LaSota's books are perfect.

Also, info can be picked up at efidynotuning.com 's forums. (decipha, the guy who runs the site, likes the 80lb Deka (but only genuine ones!) because they have such a good transfer curve, easy to tune, and you can tune down if the opening curve isn't too abrupt.)

RwP