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Techical Discussions => Tech- - Engine => Topic started by: Robert Rottman on September 30, 2010, 05:36:35 PM

Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on September 30, 2010, 05:36:35 PM
I bought the car this way...This is what it's doing...It starts right up fine but runs rough...like it's missing a cylinder. Originally, I just thought it was a bad wire or plug on the passenger side because it sounded like it was missing from the passenger side exhaust pipe. Right away, I noticed the plug on the passenger side closest to the firewall was fouled pretty badly...so I replaced all the plugs and dist. cap but car still ran poorly...no change.  Then I checked all the wires by checking spark at the cap as I pulled the wires one by one. Some wires seemed to have stronger spark than others and the stronger sparks seemed to make a bigger difference as to how the engine ran when I pull them one by one. When I listen to the dual exhausts as the car is running the "miss" is on the passenger side when the engine is cold and moves to the driver side when it's hot. The "miss" sounds like an "extra puff" in the exhaust and the side that exhibits the "extra puff" also is much stronger in flow. Summing it all up...I replaced the plugs, dist cap, checked the wires (they look new)...sanded the points/re-gapped them...checked timing, Looks very steady...did not set it to spec yet. Just watched it for a few seconds and noticed it was very steady...it's not bouncing around at all. History: The car sat for a long time...in humid South Carolina...The guy hardly ran it at all from what he told me...especially the past several years. He bought it in 1985 from second owner in NC and restored it himself in 1995.  Odometer works and it shows 1960 miles....probably 101,960 or 201,960? Anybody got any ideas as to what I can do to it next?(http://www.moparfins.com/forum/attachments/68/S5004809.JPG).just
 
furyfever2010-10-04 09:37:45
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Guests on September 30, 2010, 05:49:48 PM
Two reasons the spark plugs would foul, being low compression (do a copmression check to compare pressure cylinder to cylinder), or something with the valve themselves (leaking umbrella oil seal or bad valve seat/guide). Even if spark plug wires look good and are flexible, carbon core or suppression core wires can go bad simply by disconnecting them too many times. Another thing to check would be the carburetor itself, ensure the float is set correctly and no junk near the jets. Not positive of what the valvetrain is, but the valves needing to be adjusted may be another option. dana442010-09-30 22:51:12
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on September 30, 2010, 06:12:28 PM
Oh...Forgot to mention...I did check the compression on 7 out of 8 cylinders when I replaced the spark plugs...forgot to do 3rd one back on driver side. All were 105-110 psi...Looked up in book, should be 140 when new.furyfever2010-10-04 09:38:13
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Guests on September 30, 2010, 06:22:12 PM
YOu do have adjustable rockers on this 301 A engine, they may be a little bit on the tight side, a couple thousandths can do the strangest things with running smooth, and compression (more than likely the head gaskets are thicker than the stock steel shims and dropped it that way). Just means you could pour a gallon of water in a low tank of gas and she will make it to the next gas station in an emergency (JUST KIDDING ON THAT ONE).
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on September 30, 2010, 06:40:53 PM
If that extra puff sounds like a ffffttt  ffffftttt  fffftttt, it could be one of two things.  As Ed mentioned, a problem in the heads or poor cylinders.  You could have a burned valve or a valve not closing all the way.
 
The clue to me is the guy hardly ran it.  Therefore I am inclined to think you may have sticky valves.  Take it out for a long ride up 81 and see if that clears it up.  Maybe put some lighter oil in it, 10/30 maybe, before you run it.  It could also be carboned up too.  You can get some decarboning agent and run it down the carb, by the instructions.  The best I ever used was the one from Mopar.
 
Another thing to look at.  With it running take the oil fill cap off and see if you have allot of puffing going on.  There's no PVC, the only thing there is the vent tube.  See if that is excessively wet or dripping.
 
Also, think about flushing the crank case.  Let's do this on the cheap first.
 
Did you listen to the exhaust with the new plugs?  I didn't see that.
 
Polaraco sounded like that right after I put this motor in.  It turned out to bad fuel injectors.  The plugs had a puffy white on them
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on September 30, 2010, 06:41:45 PM
Quote from: dana44
YOu do have adjustable rockers on this 301 A engine, they may be a little bit on the tight side, a couple thousandths can do the strangest things with running smooth, and compression (more than likely the head gaskets are thicker than the stock steel shims and dropped it that way). Just means you could pour a gallon of water in a low tank of gas and she will make it to the next gas station in an emergency (JUST KIDDING ON THAT ONE).
 
Good Point.  I forgot about that.  Tyhey are mechanical lifters on that.  They may be too tight as he said.
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on October 02, 2010, 05:59:45 PM
I did a compression check before pulling the valve covers today...found cyl # 5 (driver side) low @60 PSI...all the rest on that side were 100-105 PSI...So I adjusted the uppers rockers (intakes) to .012" and all the lowers (exhausts) to .019" on both sides for all 8 cylinders. I found Cyl. 5 (exhaust) was too tight...After adjusting them...engine smoothed right out and now cyls. 1,3,5,7 (driver side) are all 90-95 PSI. I haven't rechecked compression on passenger's side yet...But...The main thing...No more rough idle...no more puffing exhaust. I'm stoked...First time I ever did this. Thanks guys very very much...(http://www.moparfins.com/forum/smileys/smiley4.gif)
 
furyfever2010-10-04 09:38:46
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Guests on October 02, 2010, 09:41:49 PM
Good, now go put some miles on her, like at least a good hour of running. Solid cams have a habit of getting a dusting of rust on the seats of the valves if they aren't driven very much, so they need to be basically heated up really good, valves smacking the seats, and cleaned up really good that way, which may actually raise the compresssion a bit, too.
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on October 02, 2010, 09:59:18 PM
How could the compression go down Bob.  It should have gone up
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Jason Goldsack on October 03, 2010, 05:49:16 AM
I was thinking the same thing..

Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on October 03, 2010, 07:30:11 AM
Quote from: POLARACO
How could the compression go down Bob.  It should have gone up

I was talking to a good friend about that last night...and believe me, I don't understand what's going on in there...He said that I have the average now...(for that side of the motor)
 
Before the rocker adjustment...Compression of Cylinders 1,3,5,7 respectively were 105,105,60,100 = 370/4 = 92.5. Now...after the rocker adjustments (per spec) I have 90-95 on each of them...I thought I was in real trouble with that low one...you guys and one of my 57/58 Plymy buddies all encouraged me to do the rocker adjustments...Car is running so much better now...and these are just observations I have recorded along the way... Can anyone with the full understanding of what's going on in there chime in and explain? Note: I did the compression tests on that side several times before any adjustments so I'm sure of those compression readings.
_popupControl();furyfever2010-10-03 12:39:08
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on October 03, 2010, 09:09:42 AM
I did a few of those motors over the years.
 
So lets take it one step at a time.
 
How does it start now?
 
are the valves making any noise at all?
 
When you checked the compression, was it hot or cold?
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Jason Goldsack on October 03, 2010, 10:56:01 AM
Where did the 301 fit in with the engine classes?.. is it a smaller version of the  318 poly?

Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on October 03, 2010, 01:11:44 PM
Quote from: POLARACO
I did a few of those motors over the years.
 
So lets take it one step at a time.
 
How does it start now?
 
are the valves making any noise at all?
 
When you checked the compression, was it hot or cold?

Steve, initially I checked compression in 7 out of 8 cylinders all hot...the one I forgot to check i just did the other night (60) (http://www.moparfins.com/forum/smileys/smiley36.gif)...initially I did it cold so I was hoping that's why it was low...(60)...The next day I repeated a few more times this time...after heating the engine up...It was still at 60...While I was at it I checked that whole driver side again...the others were up near 100-105 like they were when I originally checked them...After I set the rocker arms to spec last night...uppers @ .012" lowers at .019" and rechecked....the whole driver side is now at 90-95...
 
furyfever2010-10-04 09:39:10
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on October 03, 2010, 02:15:22 PM
Are the lifters making any noise?  Or id the motor stone quiet?

Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: firedome on October 03, 2010, 03:01:49 PM
All those compression numbers are way low in general, oui? Shouldn't they be up around 140?





Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on October 03, 2010, 04:00:54 PM
The rockers are real quiet. They were before I adjusted them too...None were loose but some were obviously too tight. Most importantly now the motor runs very smooth. I can't believe how adjusting those valves made such a big difference. Checked the timing again...it's still very steady...not jumping around. When new, this 301 poly had 140 compression yes...but now it's 53 years old! No gray/blue smoke spewing out of the exhaust that I can see. I'm sure it could use rebuilding...but as long as she runs smooth for the 500-1000 miles a year that I'll be using it... it's good enough for me.
 
Anybody know how much % compression should be down on a well used motor?
 
furyfever2010-10-04 09:29:28
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on October 03, 2010, 04:47:21 PM
I think the valves are still too tight.  The poly always had a slight valve noise.  Check them again. 
 
Steady timing just says the timing chain is in good shape
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Tom Dawson on October 03, 2010, 04:49:20 PM
Could also have a sunk exhaust valve, these things do  not have hardened seats.


Tom


Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on October 03, 2010, 04:52:13 PM
Quote from: POLARACO
I think the valves are still too tight.  The poly always had a slight valve noise.  Check them again. 
 
  


furyfever2010-10-04 09:29:46
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Guests on October 03, 2010, 06:51:32 PM
Even if the valves are sunk, Mopars have been good about having hard enough material to prevent them from any major damage, so I don't think that is the issue. Now that you have the valves adjusted, no blue smoke and no other smoking, time to get a can of Engine Restore and add to the oil and drive it for a good hour to loosen everything up real good. I have had some pretty good luck with slightly tired engines and this improving the removal of glazing of the cylinders and seating the rings a little bit better, raising the compression back to normal when there isn't any real physical damage. It's worth it to try for less than $10.
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Jason Goldsack on October 04, 2010, 03:32:21 AM
I agree!!

Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Robert Rottman on October 04, 2010, 04:36:11 AM
Quote from: dana44
Even if the valves are sunk, Mopars have been good about having hard enough material to prevent them from any major damage, so I don't think that is the issue. Now that you have the valves adjusted, no blue smoke and no other smoking, time to get a can of Engine Restore and add to the oil and drive it for a good hour to loosen everything up real good. I have had some pretty good luck with slightly tired engines and this improving the removal of glazing of the cylinders and seating the rings a little bit better, raising the compression back to normal when there isn't any real physical damage. It's worth it to try for less than $10.
 
Engine Restore huh?...I'll give it a try Ed...and I'm going to back off (just a tiny bit) )on the tightness of the rockers as per Steve's advice too...Thanks guys. I really appreciate all your wisdom. (http://www.moparfins.com/forum/smileys/smiley4.gif)
 
Bob
 
One more question...I always buy 10w-30 oil for my old cars. Am I doing the right thing? I live in upstate NY....don't run the cars from Nov. through March except for starting them up a few times during that stretch. 
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on October 04, 2010, 07:58:41 AM
Engine Restore is made of Squid Oil.   LOL
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Guests on October 04, 2010, 08:49:08 PM
Quote from: POLARACO
Engine Restore is made of Squid Oil.   LOL

UMMM, in your opionion, does that make it good, or bad?(http://www.moparfins.com/forum/smileys/smiley17.gif)

Like I said, if there isn't anything major wrong with the engine, it seems to work in livening things up, if there is something major wrong, like broken rings or bad valves, one can of the stuff is pretty cheap way to find out if there is any more life in her and is cheaper than tearing her down to find out.dana442010-10-05 01:50:58
Title: 57 Plymouth Belvedere 301v8 w/ 4brl running poorly
Post by: Steve on October 04, 2010, 09:14:15 PM
Made you laugh. didn't I?  Squid oil is good.  It's better for the lugnuts, wingnuts, peanuts, what ever they call those fly boys. . . .
 
Bob. . .10-30 is fine.  But run something a bit heavier in the summer.  20-40 or 20-50.  The best way to know for sure is to put a mechanical oil pressure gauge on it and see where it is at idle and hot.  If it's 15 or below at idle with the 30 weight, go to the 50 in the summer.  Just make sure that cooling system is up to snuff.