Starting to work on the Charger... FINALLY! Pics.

[jenkins71]

Hi guys. So, last February I picked up this 71 charger.

It has a 440/727/8 3/4 and it was used as a street/strip vehicle. I don't have a TON of info about the car as the P.O. is deceased, but I do have a lot of receipts for parts purchased and work done, and it looks like the motor was professionally built by a shop in 2000. I don't know the cam specs, or the rear end ratio, or a lot of other little things like that.

It's been sitting for almost a year, in my dad's driveway in Massachusetts while I took care of "life" stuff until eventually (3 months ago) when I got a garage.

(I've driven it here and there up in Mass, I changed the carb and did a few things here and there, new plugs and wires and such. But mostly it just sat. It ran okay, and drove ok, but it would get a little hot and sometimes backfire.)

So, lately I have been playing with ignition stuff. I replaced the dizzy that came with the Charger as it had a really racey curve and only one spring:

I wanted to just start from scratch myself, and I was able to get a stock Mopar distributor that looked basically brand new on the inside for next to nothing. It had never really been opened up, so I could start tuning with a factory clean slate.

I used a TDC tool to find TDC, and it turns out my timing mark (on what appears to be a new harmonic balancer) was dead-on.

Here's my motor I'm working on:

Long story short, I put the dizzy in and got it wired up correctly and everything, then when I ran it and check the timing, I noticed that it ran as it did before, months ago when I was playing with it in Mass and moving it into this garage. It runs good for a few seconds, and then the timing jumps wildly, and the motor surges and sometimes backfires through the exhaust!

I read some stuff online and shimmed the shaft to take out some free up-and-down play between the dizzy shaft and body. Still, same thing. I would be at about 10* BTDC and then BLAM! The timing mark would run away and the motor would shudder and sometimes make an awful pop or BANG! noise. What the hell?

After doing all that, I decided to run a compression test to see where I was at. Here are my results:

I did the test on a cold motor. Also, on the two low cylinders, #4 and #6 I did try adding some oil and the compression did NOT go up.

So, I guess I have 2 questions/concerns.
First, why is my timing so erratic? I know it's not just my timing light because to engine surges or runs rough when the timing mark jumps. Do I need a new timing chain? I find that hard to believe because I have receipts sayin the motor was built in 2000. But, apparently it was raced a lot...
Second, are my compression readings worrisome? And what do I need to do to resolve them, or test further?

Thanks for any help you guys can provide. I'm a 26 year old guy still learning.
-Sam

 

[snakeoil24]

a burnt valve or cracked compression ring. Check with vacuum gauge~!

 

[jenkins71]

with the timing jumping like that, wouldn;t it throw off any attempt at a vacuum reading???

 

[Hemi Rebel]

#6 compression is ugly. I dont like that. I would start by taking the msd off and installing a factory ignition ecu. Just for the purpose of diagnosing and getting it mechanically sound. Then you can go back and put the msd on if you wish.
But the compression all over the map needs attention. If that motor has the snot flogged out of it it needs some help. Rebuilt 15 years ago and what was done is a big ?.might as well do it right like you know it needs to be done.

 

[dieseldazzle]

If you have an msd box are you using a timing light that is compatible with multiple discharge ignition?

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Also if u use vac advance make sure you plug it when setting initial timing

 

[Hemi Rebel]

If you have one or access to one you could do a leak down test to know exactly where its losing compression. Rings/piston, valve intake or exhaust, head gasket. All the above require some level of disassembly of the engine.

 

[jenkins71]

Thanks for the replies guys. Now I'm really starting to worry! I am ok with pulling a head, but I really hope it's not the rings.
I can buy a leak down tester at Harbor Frieght easy enough, but the REAL problem is I don't have an air compressor. This might be a stupid question, but I can do anleakdown test with, say, a 12v tire inflator or a bicycle pump can I? Or, a portable steel air tank full of air?
As for the ECU stuff, I guess an orange box and the appropriate pigtail would do?
Damn, now I'm thinking this Charger wasn't such a great purchase...

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Also, I should add one small piece of information. I don't low if this is normal or not. But, with ignition ON, the purple wire from the MSD box (which translates to the ORANGE wire at the distributor) reads something like 4.5 volts. Again, not sure if this is normal, but I would have expected 12 volts. Thanks again!
Sam

 

[SublimeSixpack]

Don't get discouraged, that looks to be a pretty cool car! There's a learning curve on anything we're not familiar with. Hang in there and work through it. The issue may not be as bad as you think.

 

[poopdeckpappy]

When it comes to such a cool car that you have, coupled with the unknown screwed up things or attempts of previous owners to modify. You shouldn't chance creating further problems with your motor. That said, I would seriously contemplate pulling the motor, put it on the stand, buy or acquire everything info wise about this motor, break it down, and lovingly rebuild it! When it's back together, you will know this motor internally, and if done correctly, there will be no other ???? about what else some ding dong did or didn't do wrong before you. You will definitely appreciate and enjoy the car more. It will become a part of you! There are those that will say that if it's not broke, don't fix it. In a lot of areas I agree. When it comes to knowing your motor and having confidence in it's ability to respond when you goose her, then there's my point. Good luck in whatever you decide and I envy you for having some time to even get the hood up!!

 

[Hemi Rebel]

Worry? How can you worry? You have what looks to be a bad *** dart and you tow with a disco van. Your life is perfect compared to mine.

 

[Xp29h]

The couple posts by poopdeck..and sublime.. Are right on. I feel your pain. You just never know what a p.o. Has done or hasn't done to enhance or completely screw up these old mopars! My engine is coming out in the next couple weeks for just about the same reason. The p.o. put the motor back together way too tight. Low compression now in all cylinders. It is what it is. It's what we do. I'm actually looking forward to pulling it and tearing it apart and making right, the way it should be! Don't let yourself get discouraged, hang onto the thought of what it will be like when you're done with it! Take your time if you need to. Good luck and hang in there! We here!

 

[poopdeckpappy]

I was checking out the van too! If the van's a rockin', don't bother knockin'!!!

 

[Dennis H]

Good luck. Car is Bitchin'. You also have someone to spare an extra donut for energy.

 

[jenkins71]

Wow, thanks for the encouraging words guys. I'm having a much better outlook know! You guys rule.
Man, now I really want to pull the motor and rebuild it. The only problem is SPACE. I;m living in New York City (don't ask why, it's a bunch of BS, I'll be getting out soon) and the car can't really sit on the street while the motor takes over the tiny garage. But there is a basement I may be able to lower the motor into. That would make for a comfy winter project. The other problem is money. I figure it'll cost a lot to buy new pistons and stuff. And special tools.
I have lot to think about...
(Thanks for the complements on my van! I built it myself. Had 3.9 v6, swapped in a 360 Magnum. It's a great van. I've had a lot of fun with it, and in it.)

 

[jenkins71]

Also, from what I've read and heard, if you add oil to a cylinder with low compression and the PSI does NOT go up, it indicates that the rings are NOT the problem. Which leads me to believe that maybe I have a bad head gasket or leaky valves?
Honestly I would really prefer that... I don't know if I'm able to rebuild the whole motor right now. Even though I would LOVE to. But also, what if everything is good as far as rotating assembly? And it just has a blown head gasket. I have stacks and stacks of receipts for costly machine work on this built motor. I feel like it would be a shame to rebuild something that may be really solid. Just thinking out lout...

 

[poopdeckpappy]

Check the valves with the covers off and running. Look for oil flow problems on the inside cylinders for both heads coming to the top. Look for anything out of the ordinary. Kinda odd that your cylinders with low pressure are next to each other too. If it was one side I'd say permeated head gasket, but both sides? Maybe both gaskets? Hence the rebuild suggestions. No more questions when it's done.

 

[jenkins71]

I remember when I was turning the crank over with a socket wrench, while the spark plugs were still in, to get it lined up to TDC, and at some points there was a weird bubbling sound as some of the cylinders rotated to the top. Is that normal, or indicative of some kind of leak?
Also, poopdeck, what do you mean when you say "Look for oil flow problems on the inside cylinders for both heads coming to the top." Thanks for all the great help man.
Any chiming in is appreciated!

 

[jenkins71]

YO.
Back in the garage today. I was able to borrow a little "donut" air compressor. Figure I'd dig a little deeper looking for clues. I didn't really feel like buying a leak-down tester for this one job, and didn't really need a "percentage" number. I all needed was to find out WHERE the compression was leaking from. I just needed to blast the #6 and #4 cylinders full of compressed air. So i just welded a little air chuck coupling to a shell of an old spark plug and made my "adapter," so to speak. I spent $0.00 since I had these things laying around and was able to borrow a mini compressor.
Soon I had the #6 cylinder hooked up to air:

I did it with the #6 cylinder at TDC of the compression stroke. I heard the air coming out of the tailpipe ... hmmm... bad exhaust valve? Then I figured I'd make sure that valve was totally closed, and removed the whole rocker arm assembly, which meant all valves were closed. This is key. After doing that and re-testeing #6, it was leaking all right, but not our the tailpipe.... AIR WAS BLASTING OUT OF THE #4 SPARK PLUG HOLE!!!

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Then I'm thinking, shoot, I'm going to pull this head and see whats going on here. I never thought it would be so easy. Having a cordless impact made it simplicity itself.

the intake came off in about 5 minutes:

Then its just a matter of jacking the engine up out of its mounts, dropping the headers:

and yanking the head! I figured it would be "sticky" but it just lifted right up. Boo-yah!

 

[Hemi Rebel]

What do the heads look like? I take it the gasket was bad causing the leak between cylinders

 

[jenkins71]

BOOM!

That would be correct, sir.

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I'm can't tell you how happy I was to discover it was a blow head gasket, and not rings.