41 Plymouth SB Mopar Engine Swap

I've tuned a lot of Edelbrocks and have all the parts. This one is definitely a little lean on part throttle. Interesting that SBC's like the std. jetting. I will double check the oiling but I'm pretty sure that is ok. Had to drop the pawn and put some etc on the gasket to try to stop a leak at the front corner. Hopefully, that worked.

 

Ok, I'm beyond frustrated. The 360 Dodge engine that I built for my 41 Plymouth runs like Jack the Bear but it leaks oil out of the front pan seal. When I built it, I put a new design one piece seal. It leaked, so I replaced it with a 4 pc. seal and glued everything down. It pulled up straight and was in perfect position. After a short, spirited drive, I smelled oil again. I put it on the lift and it has sucked both of the top sides of the pan gasket seal in and pulled the little tits that hold it in place off while doing it.

I checked the breather and it is unrestricted. There is lots of vacuum to the PCV and it it new, as well. Anybody got any ideas? This is a real pain in the ass as I cannot completely drop the pan and I really dont want to take the entire front end of this car off and remove the engine. I can get several inches of clearance in the rear and about an inch or so in the front. Any helpful ideas are appreciated.

 

You have too much vacuum, Either the PVC system doesn't have enough air coming in, or your ring seal is bad and your sucking too much air past the rings on the intake. I hope its a PVC issue. You either need to reduce the vacuum your PVC can pull, or get a PVC valve with less flow capacity, or you need to add another breather to bring more air into the system. As long as there is more vacuum then there is air coming into the system, it will suck in the weakest gaskets at there most stressed location.

I had the opposite problem on one motor, it was creating too much pressure and would blow the gaskets out. That one turned in to being a plugged breather, the pvc couldn't suck out the pressure because it couldn't get any air into the system. The PVC system is pretty picky about the flow through the system. Gene

 

I am about convinced that it's a problem with the Dorman rear sump oil pan I'm using. I had trouble just installing the first attempt at the 4 pc seals. The PS of the front seal kept pulling inward, so I got another seal and glued it in and let it set overnight. This is a fresh engine that is strong and not smoking at all. The breather is brand new and unredtricted. I will double check the PCV in the morning to make sure it isnt stuck but it also is brand new. Right now it feels like a pan problem.

 

Lookin good rock. Any one know what ever happened to farmer12?

 

Does sound like a PCV system problem, but if you're convinced it's a pan problem go to the junkyard & pull a pan off a 360 in a Van or pick up.

 

I don't know what happened to Eric but Id like to know.

After getting the pan off, I don't see anything wrong with it. To me, it looks like a vacuum problem. I guess it could be poor assembly technique since I only had about an inch of clearance to work with. Now that I have it off, I will do better and double check the vacuum on the crankcase.

 

Anybody tried the one piece Fel Pro gasket?

 

I have, on a small block Chevy. It worked very well.

 

So far, so good. I installed it today but due to the approaching hurricane, I only got to drive it a few miles. So far, no leaks. Fingers crossed.

 

I'm getting there. Waiting on the headlights to come back from the platers. Got it aligned today and took the tech for a "road test". When I shifted to 2nd and nailed the throttle, the right rear tire started spinning and he said, "You need some "oh shit" handles in this thing!" I haven't put the seatbelts in yet. Still gotta paint the rims body color, too. Waiting on the upholsterer now.

 

Long time coming, but it's looking REAL GOOD, rockable!
As far as paint matching the wheels, I kind of like the bright Orange.
It says (to me) Hot Rod, where if they matched, it would be more subdued.
Quick, ugly paint of the wheels

 

I want to put in a plug for Chris and the crew at Advanced Custom Chrome in Erie, PA. These guys do a great job and they make sure you are happy. I had a couple of fitment issues after trying to assemble my lights and they took them back, stripped them, fitted them and rechromed them at no extra charge to me. They do great work and will continue to be my plater of choice. I always say, "Cheap chrome ain't good and good chrome ain't cheap." These guys do excellent work on diecast potmetal and everything else and good platers are hard to find. Advanced Custom Chrome : Home

 

One headlight installed!

 

Very Nice!

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Here is how I got turn signals in the small parking light housing. I believe these are twist in receptacles for instument lights but they work well with the flasher.

The front end looks complete now.

 

Ooh. My upholsterer finished my seat. I built plywood frames for the seat and used extra firm foam to create an original looking but good sitting seat.

 

Ok, Mopar gurus, I need some help. I did the AX-15 transmission swap using the 3.9 flywheel and clutch, as recommended in this thread. (https://www.jalopyjournal.com/forum/threads/dodge-la-5-speed-transmission-options.486239/page-3) When I built the engine, I had it balanced using the same balancer, flywheel and clutch that is installed in it.

I have a vibration that starts at about 1500 rpm and builds as rpm increases. Of course, the frequency changes as the rpm goes up. The engine idles as smooth as glass but when rpm builds, it vibrates. I've double checked the firing order and looked at the plugs. I'm convinced there is no misfiring.

What might be the problem? How do I troubleshoot this? Removing the engine is going to be a real pain, so I hope that is not got to happen. As always, thanks for your help.

 

A manual trans should allow you to diagnose if it's the engine ONLY or if the rest of the drivetrain is a problem. You say the engine vibrates. So it will do this with the trans in neutral and the clutch in?
If it's driven down the road and you shut off the engine in neutral, there is no drivetrain vibration?

Now, a 360 is externally balanced (balancer and flywheel/flexplate have offset weights). The flywheel/flexplate can only be installed one way. That leaves either the balance job or the harmonic balancer. The stock ones have been known to 'slip' where the rubber is between the inner and outer rings. If the timing marks align properly (find TDC and check the marks), that would show it's correct.
Flywheel description with picture HERE
https://www.forbbodiesonly.com/mopa...tion-internal-verses-external-balance.100142/

Note that it appears that the 3.9L engine is internal balanced.
http://stores.hi-potek.com/damper/
They only mention the 360 being external balance here.
So I'll have to read through the thread to see if this is addressed (using neutral balance flywheel/clutch on external balance engine).
EDIT: The balance issue was brought up by you and answered that Yes, the 360 is external so you need that. The question is; Did the balance job take this into account, using a 3.9L neutral flywheel on the back of a 360 external balance engine? The picture in the previously mentioned thread shows 3 15/16" holes. That would be my first check (or memory nag).


Stock balancer here (aftermarket ones have a slot cut out on the back). This can be checked without removing anything.

If it vibrates coasting, it's probably a driveline phasing issue. The other things to check are driveshaft balance, bent axles, bent trans shafts and wheel/tire issues.
You seem to be a smart cookie, so you probably know all this. Just trying to list the typical stuff.

 

Yeah, you are confirming my thoughts. It idles smoothly in neutral and the vibration starts to build around 1500 rpm. I just put a new driveshaft in and that is what caused me to focus on the vibration. I was trying to make sure the driveshaft was ok. There may be a problem with it but until I get the engine smoothed out, it will be hard to discern, except by coasting.

The flywheel was drilled to accommodate external balance, then everything was balanced with the clutch. The guy who did it is an experienced machinist who only works 2 days a week. I know he knows how to do it properly.

I'm going to check the balancer and timing advance first. I have "gotten on it" several times, so maybe it's the balancer. I've put over 300 miles on it and I think I would have noticed if it were this bad when I started. It seems to have gotten worse, which kind of points to a slipped balancer. I hope that's it.

 

A longer shot, but I’ve seen a fan mounted a little off-center due to oblong holes cause a vibration issue.

 

I have an electric fan. Thanks anyway.

 

Well, I used a piston stop and checked the balancer. It is ok. Also, there are no external rotating pieces that are eccentric or wobbling, including the flywheel/clutch parts I can see. I also changed plugs and checked the timing, just to try to make sure it wasn't a high speed miss. No luck.

I'm sick. This thing is almost finished and now im looking at possibly having to disassemble the front end and remove/disassemble the engine. Anybody got a match?

 

Is the vibration there if you bring the engine rpm up to 1500 while the car is sitting still? A motor balance will occur at the same rpm, weather the car is moving or not. If there is no vibration by just bringing the motor rpm up into the vibration range, its not from the motor.

The next thing to do is drive the car up to where the vibration is the worst, then shove in the clutch pedal and let off the gas. Is the vibration still there? If the vibration is still there, its not from the motor. Then the question is do you feel the vibration through the seat, or through the steering column. Vibrations are sometimes difficult to locate, hang in there, it will be OK. Gene

 

Unfortunately, yes. It's there whether it's sitting still or moving and it's there with the clutch is engaged or not. I
isolated the transmission and the driveline. It's not there. This definitely points to the engine.

I'm trying to think if I did anything wrong but the only thing I can think of is maybe I didn't number the piston and rods the way the machinist did. Don't they get all of them to the same weight before balancing the assembly?

 

This is a really good, but long video on balancing an externally balanced engine. I took the balancer, flywheel and clutch to my machinist when he did the balancing. It's hard to see how he could have screwed this up. He's been doing it a long time. So, the question now becomes what is screwed up? Is the pressure plate out of balance? Maybe he didn't include it when balancing the assembly?

Could it be an ignition problem? Jeez, I really don't want to take this engine apart.

 

You changed the plugs but how about the wires?

Use a quality ohm meter and check resistance on each wire as you wiggle them around a bit.
Also, they can fail as voltage pressure increases.

.

 

The car is looking great Rock! Just hope you can sort out the vibration problem....

 

Thanks, Eric! I take one step forward it kicks me back two steps....often. I will get there, however.

 

They are new but I will check them. Also, I'm going to try to get someone to test my new distributor. Any other ideas?