Hey Guys, Im working on the 217 1951 Plymouth flat 6. All this is new to me, and I am thinking about taking on my first rebuild job. Bear with my lack of knowledge, but I have got to start somewhere, right.... A few questions about whats going on before I pull engine. The car has sat for a good many years. But suprising, after running a gas line in a gas can and dumping some gas in top of the carb, it cranked up rather quick. There was a knock as soon as it ran, so I shut it down, only to try a few times to see where the noice was coming from. Sounded like it was right on the top, very high. (dont worry,only run it 10-15 seconds,..one or two times). It ran real well and was suppose to have been a running car. Oil looked good, water looked fresh,plugs looked good. I took off the head and aside from some carbon, it appeared cleaner than I thought. Funny thing is that the front piston was very clean, even silver looking on top with little carbon. The other 5 looked dark, with more carbon build up. I looked at the valves hoping one was stuck making that be the sorce of my noice, but all where moving. I have never build an engine and I know very little about flatheads. But I want to learn this, and dont want to send it to someone else.I really would like to stay with the original motor..... What can I look for that would make that noice? Is it a for sure rebuild, or is there something that can be done before a pull ? Please dont tell me to just take it to a shop, I do want to learn and start somewhere...Thanks guys!!!
The piston was clean most likely due to a head gasket leak.The knock may be from low oil pressure or worn out bearings.I would drop the pan and take a look at the bearings.
Is this a difficult engine to start on? Are they pretty basic or are they tough, even for an experienced guy?....I was hoping with it running as good as it did, this would be quick and painless I have not found one person yet, in my area, who knows anything about flatheads...especialy the Plymouth Flathead 6.....
The flathead 6 is not that difficult to rebuild. It just takes some attention to detail in that the main bearing caps must stay in the original locations. You must be sure that the oil hole in the bearings and rods are pointed to the side of the block with the cam. The water distribution tube can be a real pain to get out of the block. You need to pay attention to the location of the bolts holding the timing chain cover on as some of them are different than the rest and go into water jackets, these need to have sealer added when putting them back in. Off the top of my head that is all I can come up with that is not just standard rebuild type stuff. Just take your time, get a good shop manual and you should be fine. Chrysler built this engine up until very earyl 70's for industrial applications so engine parts are not all that difficult to come by, NAPA has most of what you would need. Before you start I would strongly suggest you register at the P15-D24 site and ask your questions there. There is a ton of knowledge over there on the flathead Mopars. Here is a link to the site. http://www430.pair.com/p15d24/mopar_forum/index.php?referrerid=1152 If you want there are "speed" parts available out there too. Here is the flathead in my 48 Plymouth.
Thanks so much man, I just registered at that site last night and will use them for sure. Very nice flathead you have, I wish I could snap my fingers and see that in place....Thank for the help!
I turned over the engine without the head on top , and there was no sound or visual, showing the knock or bump.....?
my old six sounded great at idle but you put any load on it and it sounded like a diesel when i tore it down it had 60 thousand clearance on the rods and every top compression ring broken except for one piston that had been replaced i had mine rebuilt balanced and blue printed it runs like a top and pulls like an ox mine is a 230 truck engine but its the same block as the 218 different rods and crank
The number one piston is hitting the head thats the knock i think pistons i this engines i known to crack in the ring groves all the way around or you have a wery lose bearing
I was thinking the same thing "piston slap".usually due to exessive bearing clearance,shattered a piston in a 53 ford that way once.
doesn't look to me from the pictures that any pistons are hitting the head, but...holy **** would that take a TON of wear to do! The pistons in these are usually .010 to .020 down in the block, and the head gasket compressed is .040 or more. These engines are easy and fun, but as a "first engine" they have a learning curve for sure. Oil technology, and filtering technology ****ED back then, so the insides of original engines from the day are usually a mess, and quite worn out. As mentioned, the Mopar flathead sixes always seem to have broken rings and ring lands. Valve stem-to-guide clearances are trashed, and pay particular attention to the main bearing oil clearances, and the #2 and #5 rod journals my advice? try it....you'll like it!!! Get some reading material on blueprinting an engine, buy some precision measuring tools, and educate yourself. You'll be glad you did.
I would rebuild it. I have a 230 in my 50 Dodge. Its basically the same engine but bigger. Those are good engines tough as hell. They look lite but there heavy as hell. I snaped the bolt on the cherry picker pulling one out. My friend and I had to work quick before the cherry picker gave up and droped the engine. The bolt bent and then snaped a few minutes after. By then We had the motor siting on the create.
These engines had two chronic problems. The first was a marginal lubrication system with a by-p*** (partial flow) oil filter and road draft system. This means that dirty air (complete with dirt and grit) gets into the oiling system and accelerates wear. The relatively low-performance lubrication system can't keep up, so these engines tend to eat rod bearings. The second is poor alloy used in the pistons. The upper ring land gets wider and wider and then the top ring breaks. Then, pieces of the ring land break off and things start getting very exciting. That said, these are not bad engines. They are quiet and do what they do. They don't produce a lot of power but with those long chicken bone connecting rods they have tons of torque. Rebuilding one is easy and can even be done with the engine in the car. Remove and regrind the crank. Cut the ridge and if the taper is not too bad simply hone the cylinders. ****on her up and done. I would recommend modern synthetic oil. The biggest improvement you can make - this one should be on the top of anyone's list - is the addition of a modern PCV system so that only clean, filtered air is drawn into the crankcase. A PCV and modern oil do wonders for the longevity of these motors.
Man guys, Thanks for the ton of info!....I do believe I am going to give this rebuild a shot. Thanks for all the info and any new info to come.....Which there always is here.....
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