I rebuilt a 225 , I followed all the recommendations as far as break in procedures, I had some carb problems, but solved those over a short period of time. I followed recommendations from this site and the cam manufacturer, and set valves as required. I drove the car and had what I considered bugs that just needed to be found as I drove the car, as the car is a forty year old Duster.

Eventually the car started to run rough again and then would not tune up at all. All this and I have not met the 500 mile break in for an oil change. I pulled the valve cover and found that the exhaust valve adjusting screw on cyl six had been worn down, severly. I called and talked with my machinist and we discussed the issue and I came back to this site and ordered a set of screws from Mancini.

I went back through the valve train, as I had before. The motor ran great, but upon checking acceleration, with the car in park, found that I had a knock in the motor. I re checked the valve area again, pulled the plugs, checked for material on top of the cylinders, which I had done to begin with, I put it all back together and still have the knock.

I am hoping that I have not spun a bearing, but that I may have dropped a valve, I was told if that metal were to drop, it would have gone through the oil return and hit the pan.

If anyone here can shoot me some suggestions as to what I could check next I would very much appreciate it. My vacuum is good, oil pressure is good, just in case, I bolted the balancer.

Lastly, could I have lost a wrist pin, piston skirt? The motor ran fine up until the adj screw took a crap. Look forward to the replies.

Thanks John

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1971 Plymouth Duster

check the cylinder compression.. if there is a valve not closing, the compression will be low on that cylinder,,
back to the knock that you are hearing, can you better describe it?
is it RPM sensitive, hot or cold motor,,,
folks have found loose torque converters, and that sounded like an engine knock

The torque converter is fine had to hold it in place to tighten the balancer bolt, engine is at running temp, it is not a hard knock but its a knock, did get lucky and may have some help locally within the next day, but I dont want to tear into the motor til I know if it is the top or the bottom of the motor

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1971 Plymouth Duster

the knock itself cant be heard until you bring up the rpms while in park, if I dropped a valve, the guy that did my machine work may cover the cost of getting it fixed, as long as it wasnt caused by the loss of the valve adjusting screw. other than all of that the motor sounds fine at idle

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1971 Plymouth Duster

Check the torque converter bolts.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

I will re check the bolts on the converter, though its been done once before, as I said earlier, will not attempt repair til I know which end of motor needs yanked. Thanks

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1971 Plymouth Duster

Since I have had so many views, and so few replies, I shall give an update, through a friend I was led to a decent mechanic and his father John. We started the motor and within less than a minute John said I had a bad rod. I explained to him that the car has been sitting since the knock was discovered and only started maybe three times since. He told me that, I probably saved myself alot of grief and that since I used the old connecting rod bolts, it was probable that one had stressed or streched and could no longer hold the new build .

So, I am going to pull the pan, find the bad rod , do an inspection, and replace all the connecting rod bolts along with a new bearing ,....providing that the crank has not suffered. Only an inspection will tell and I will let you guys know once I have all my parts and have pulled my pan.

For a point of interest, I was told that using the old c-rod bolts was fine and that they should not be mixed, as in, do not try mix and match, keep bolts with the rod. So, there it is .

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1971 Plymouth Duster

Used connecting rods need to be reconditioned or carefully inspected for roundness & size, before being re-used.

By far, the most common problem I see is either a con rod cap gets put-on "backwards" (they must go back together, the same way they were, when finished honed) or the caps get switched onto other rods.

Pay careful attention to the numbers stamped into the the sides of the rod & cap, prior to dis-assembly.
The numbers should be the same and both numbers on the same side of the rod assembly.
Look for this as part of your dis-assembly inspection work.
DD

Thanks Doc,

I knew this and only expect to pull one bolt at a time per rod, to avoid confusion, I know for sure the rods and caps are correct, just didnt forsee issue with the bolts, pulling the steering drag link, pan, are the other issues since I will be working flat on my back in the Texas heat in the next few days, I plan on doing all my heavy drinking after the work is done. Hoping this will be the only time I will have to break into the bottom end for a good long time. Have rod bolts on the way, will buy into bearing/////bearings, after I get pan off, the good grace is this was caught way early and the crank may not have to be pulled,,,ie the motor, will keep the board posted...J

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1971 Plymouth Duster

Are you trying to pull the pan with the engine in the car? Not sure you can get it out that way. Honestly it is a nightmare working under a car and trying to do careful inspections and get stuff cleaned up.

You can have it out in an hour or two . Just my 2 cents.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Yes , its the hard way, but you have to pull the link between the idler and pittman then it will come out , have an original Chiltons from the day, describes it in fair detail, may drop the pan to four corners , then see , if it has, to come out at all, I am only looking for one bad rod, not multiples. One step at a time , Praise the Lord, I have the time right now, Those close to the north side of Houston, please feel free to stop in and hand tools to me , project starts asap, this friday I am thinking

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1971 Plymouth Duster

Well,

for those of you dying to hear the latest, the best I got is that all the parts are on the way, and we, or shall I say me will give it a go come friday or saturday, still looking for volunteers

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1971 Plymouth Duster

Good luck brother. I recently rebuilt my 225 as well. Had carb issues and a few "bugs" along the way as well. Now shes on the side of the road with no fuel through the pump.. Im guessing its a worn cam

Good luck and wish I could lend a hand. Keep us posted

225 Brothers,

Listen up, it is thoroughly possible to pull the pan with the motor still in place, some fanagling but it is done and I have found my bad rod bearing, from what I can see and tell, it went bad from improper seating which could have been from a bad torque to whatnot, Plastigage is next, should have the whole thing put together within the next 24 hours. Any who wish to know the details of how I worked through this, I will be glad to let you know what I did and how I did it, in 95+degree heat, in the dirt, in the side yard , with two simple jacks and some decent determination. Oh, and I might add, with the addition of some 150 plus dollars in tools to do the job right, not including what may be a front end alignment do to the fact that the guy who had done it previously did not tighten all of the tie rod ends from what I can tell.

Last but not least, what may have been my mistake on the build would have been to trust a bearing, that did not come from where it should have, as in I can almost see a difference in the thickness of the bearings, no visible damage to crank, only to the bearing itself. Wish me luck as I have , as all of the work , or 95% , done all of this work on my own with little or no help from anyone, would still accept a volunteer , cept, I will be done before one could arrive.

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1971 Plymouth Duster

Just for now,


The Duster is back up and running, finshed the pan, while the front end linkage was still apart I started the motor and my knock is now gone. The linkage was re set and my buddy and I drove around for a good two hours and had no troubles. This morning first off I checked for any signs of leakage from underneath and so far from overnight I have none.

Will be driving the car again today and waiting for the 500 mile motor break in mark, and change oil, and re set valves for the next time around. The Mancini adj screws are currently doing their job as well. I did find a small chunk of metal from the bad adj. screw, and one bad bearing that did not spin. The bearing did not seat, from the pictures I had from my manual.

Will keep the forum posted as to my progress with the car. Hope to finish the last of my body work, and get a final prime within the next week or so. Thanks to all who replied and lent their advice....J

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1971 Plymouth Duster