Hi all, I have a 51 Plymouth that we take drag racing a couple of times of year in LA, but primarily use for ice cream and restaurant trips..ie street use. I am always the only one there with a flathead mopar, let alone a plymouth. Thus, i would like to show better in the 1/4 mile as compared to chevy 6s and hudson flathead competitors. My car is bone stock with some neat 1950s bolt ons including an edmunds finned head, approx 7.5:1, an edmunds intake with twin stock carter carbs, some fenton repop headers, vintage dual point conversion and a huge holthouse 6 volt tractor coil. All of these add ons were for a vintage 50s stock weekend drag racer look and seem to have been pretty reliable thus far (5 years). fyi...we go to the races for fun.....not to break the car by over revving it....these vintage parts were costly. My plymouth takes off from the line and shifts to second gear fantastic...sounding good w/ open exhaust! Its even downright exiting.....however, when i shift to third its all over. The chevy 6s and hudsons blow past me at the finishline. Yes, my gearing and rearend need stratgeic improvements......but my question relates to whether an aluminum flywheel will improve my situation too. QUESTION: Thus, I am considering adding a 50s aluminum flywheel with a steel face, such as those sold way back when by schiefer and weber to my plymouth 230 flathead. What do you think about the following: 1) is this a true bolt on, other than the necessary balancing required? or is it a can of worms?? 2) is the aluminum flywheel w/ steel face practical for the street....ie a few thousand miles a year around town and on short trips?? 3) is there a noticiable difference in any acceleration or other driving circumstances or after installation would i be complaining about a no bang for buck installation of a hard to find flywheel? 4) do you have one for sale or know where i can find one and what should i expect to pay? I am not interested in paying an arm and leg for one, especially if they are not effective in improving acceleration or are not practical. Just thought i would seek some feedback from you been there done that hot rodders as i have zero experience with aluminum flywheels. Thanks for any feedback, Mike and the 51 plymouth family "racers" of Los Angeles ps - i will shortly add a post about rear end changes too.
You are really over complicating a car you are going to drive competitivly occasionally. resurface the stock on, flip the ring gear to account for any worn teeth, have it lightened a bit and blanced and call it done. If you swap to a more modern rear end your gear sets age going to go down numerically, which will kill your off the line performance. You likely have a 3.93 or some where in that neighbor hood. You want to go higher numerical for acceleration.
The Hudson has you by 78 cubic inches. Hard to make up for that with a flywheel. Looks like the jump from second to third is to great for your small motor to make up for. A very heavy flywheel might help. I don't see a light one being the right way to go. That is why a 4 or 5 speed was invented. Smaller differences between ratios and a 5th overdrive allows you a lower rear end to increase torque multiplication and keep freeway running.
And a heavy flywheel makes starting out easy on the clutch. For street driving, too. The mass of the flywheel helps get the car moving. Time for a T-5. Much more fun than a column shift, too.
Last year I saw your engine (one exactly as you described) at the Daytona Turkey Run! 50K+ blown what ever were everywhere. None had the class of your little six. I happen to be 65 yrs old and that was the first time I've ever seen a plym set up like that. Enjoy what you got and let the rest of them "eat their hearts out"!
Contact George Asche in PA for a 2d gear cluster out a 40 or 42, they were a bit lower, so a bit higher speed when they are rung out, would east the transition to third. Did you try to find shorter tires???
1) is this a true bolt on, other than the necessary balancing required? or is it a can of worms?? If the flywheel is 146 tooth and designed for a pre-62 Mopar application, then yes, and no 'balancing' should be needed. Note that aftermarket flywheels will have 8 bolts to the crank and old Plymouths may have 4 or 6 but the the pattern is the same. The one possible concern is the style of bolts used by the manufacturer. 2) is the aluminum flywheel w/ steel face practical for the street....ie a few thousand miles a year around town and on short trips?? A few thousand miles a year will be OK. The problem with any aluminum wheel is that you loose inertia and in a heavy car you will be 'slipping' the clutch more to get moving from a stop. Not so good on the insert. 3) is there a noticiable difference in any acceleration or other driving circumstances or after installation would i be complaining about a no bang for buck installation of a hard to find flywheel? A lighter wheel will allow the engine to spin up faster. But really, how many rpm do you expect from a 218??? 4) do you have one for sale or know where i can find one and what should i expect to pay? I am not interested in paying an arm and leg for one, especially if they are not effective in improving acceleration or are not practical. The 146 tooth wheel turns up occasionally on ebay, expect to pay $300-$400. New aftermarket wheels (labeled for the 392) are in the $400 ++ range. It is difficult to shave much weight from a stock flywheel but there are many different oem designs and you might find a lighter one than what you have. Weigh yours and start shopping, just don't expect huge differences. As mentioned, you would be better served with different gearing but you need to decide where you want the change to be and then decide how to make the change. A 5-speed would make a world of difference but you will loose the column shift and gain a floor shift. Remember, you only have 218 inches!!! The engine was not intended to be a powerhouse. Plymouth was the economy brand. .
Lightening the flywheel is an old hot rodders and racers trick for whippier acceleration. For the street it was customary to put the stock flywheel on a lathe and cut off a few pounds. For serious racing they made aluminum flywheels which were considered overkill for the street and made it hard to take off from a stop. Modern cars have much lighter flywheels than those of the fifties and earlier. When your car was made there were no automatics at least not in Plymouths so they made a heavy flywheel. That way Granny could always get to the grocery store even if she made every mistake in the book. Now Granny has an automatic and the sportier drivers buy the 5 speeds. So, I would suggest you lighten the stock flywheel. Weight taken off near the edge has a lot more effect than weight taken off near the middle due to leverage or centrifugal force. When you are done don't forget to reface the clutch surface and rebalance the flywheel. If you can find an old time hot rodder - engine builder - auto machine shop they will be very familiar with the process. It used to be as much a part of building an engine as boring the cylinders and shaving the heads. Incidentally the light flywheel will help acceleration in all gears and through the RPM range. In other words by the time you hit 3d you will have a couple of extra lengths on them just from the light flywheel.
Over-complicating my Plymouth project is my night time "tv"! I am reading and learning about this 51 Plymouth every day. So yes, I am guilty. Really, just checking in with other more experienced Plymouth do-gooders on my project before I complete the engine rebuild. Thx so much for your input. I have never run a vintage aluminium flywheel, know they are rare...and always wondered how the car would drive differently. At this point I am on the path you described. Again Thx for you thoughts. Mike
Yes, those damned hudsons have it easy with the cubic inch advantage. So (for fun, like i imagined those were doing in the 50s) I am narrowing the gap slightly. I figure my car has to be lighter than the hudson though I haven't verified this. What I can say is that i am changing to a 230 from 218. It's going to have 080 oversized pistons. Compression increase, valve size increase, cam regrind, dual cast iron headers, open exhaust, dual carbs,..all purchased and being installed by me, my books, these posts and I (an accountant). I have learnedd that in 1940 only there is a taller 2nd gear that more evenly splits 1st and 3rd gear.......what george asche an experience flathead mopar expert calls the "tall second" gear advantage. I have found the gears I need. I am also looking at changing to a bolt in 4.11 rear end or 4.3 if I can locate these reasonably. With these driveline changes I think hope I am narrowing gap on the hudson......but definitely improving my chances with the like sized chevys and other flathead mopars,eh? Hey Thx for comments, however basic the info maybe to you. I really appreciate it because while I have. reading about this stuff for years I haven't had the chance to live all these performance mods. But hope to , especially annually when my friends and entire family comes to the drag races with us cheering us on against those damned hudsons (...that we love to hate and secretely wished we had). Thx again. Mike and family.
Thx Just for Fun for the words of encouragement. I notice tons of genuine interest for my flat six, especially by the younger and older generations at our once a year fun for the whole family drag races. It's got to be fun "fast" and reliable! Well maybe cheap too!
Thx 73RR for comments. I really appreciate the info. Yes 218 cu inches isn't much but next next build for this car will be the 265 cubic inch model so all this info will be helpful on my current and next builds....all this for me and my kids is for fun and education. I appreciate your practical info on the aluminum flywheel mod as I just don't have any real experience with this and it seems many like you do. Since I have have amassed about 5 flywheels I will compare them as you suggest. Follow up question: The concern regarding stock flywheel bolts is interesting. Can you expand. My Plymouth 218 has 4 bolts but I am switching to a later 230 engine and it has 6 or 8 bolts...more the merrier was my thinking. Now what about bolts? Follow up question 2: my engine is apart and was sent to machine ago and returned, except for the flywheel and clutch. Your comment about the stock flywheel not needing to be balance surprises me big time. Since there are several flywheels and pressure plates to choose from, I posted a few topics on flywheels clutches etc. Regardless of which flywheel and clutch plate I ultimately pick I was going to send them to machine shop to have "balanced". What are your thoughts on this? Are you suggesting there is an argument to not have these balanced. Hey, Thx for for comments. We really appreciate it! Mike
Hi Rusty Otoole, Thx for comments. Based on your comments and others, I think lightening the flywheel is a practical mod as compared to the vintage aluminum flywheel mod. Its also in the spirit of my entire engine and drivline build. It needs to be practical and last! Especially we are going to try and take down the venerable Hudson at the drags...............or atleast make it from the driveway to the ice cream shop with the kids. Thx again for your comments however basic it may be to you (fyi I am a 43 old accountant...go figure). Your comments do help! Much apreciated. Happy motoring too. Thx Mike
FWIW: The flywheel/pressure plate assembly would/should be balanced separately from the crank assembly. & the flywheel its'-self would be a neutral-balance anyway. They weren't like the newer stuff that is batch-balanced. Marcus...
As noted, the flywheel (and pressure plate, if you desire) should be checked for balance if you are going to the trouble of checking the rotating assembly. The shape/design of most flywheels will provide a near zero balance in stock/unaltered form since they are a homogeneous material but checking 'just to be sure is always a good thing but not always a 'required' thing.' Be sure to discuss the intended rpm range with the guy doing the balance. Now the warning. The 208/218 crankshaft is just a little bit different that all the rest, ie, the flange does not project as far from the face of the block (about 0.200"). Since MotherMopar elected to not change the bellhousing they had to change the flywheel by the same amount in order to get the starter to engage the ring gear so the 208/218 flywheel can only be used (effectively) on a 208/218. As to the bolt pattern, since you are moving up to the larger engines and displacements you will have the standard 8-bolt attachment. If you end up with an aluminum wheel we can discuss the actual bolt issue depending on the flywheel design. Keep us posted! .
Back in High School I had a VW beach Buggy. Of course it only had the stock 46hp motor. We installed some great big fat tires on wheel adapters and went for a drive... It was horrible, the extra rotating mass killed the little bit of performance we had. Those came off in a hurry, Back to skinny and light wheels. Then we pulled the motor and had the flywheel lightened at a machine shop. Wow what a difference. Night and Day it woke the little buggy right up. It was still all over once third gear was selected, but it really improved up to 50mph. It required more rpm and smoother feathering of the clutch to get rolling, but it was a hell of lot more fun to drive.
If you go to 265 cu in as you say I presume that it will be a long block Chrysler, if so it is two inches longer than the 218/230 short block engines and none of your speed equipment will fit the larger engine block.
Hi James Curl, Yes you are totally correct. Unfortunately I have been amassing all this speed equipment for several years...........then I subquently learned that the big Desoto Chrysler flat 6 cylinders will fit pretty easy into my 51 Plymouth. I actually learned this from George Asche, a very experienced mopar flathead expert and through this forum. Had I known this earlier by participating in forums like this earlier I would have platformed my Flathead motor project off the big flat 6.......and I would have owned all the vintage speed parts for it by now! So for now I am building a "big" small Plymouth flat 6 and using all my speed parts. So to build the big flat six I will likely need to sell my parts and my left and right legs to buy speed parts for the big flat 6. We can all dream for now. Thx for comments. Mike
Take a good look at yer flywheel, the side that faces the block has a big thick outer ring and a smaller ring around the crank flange area, take it to the machine shop and have those cut down, don't remember inner ring but .375 came off my outer ring. Killed a ton of weight Sent from my C6725 using H.A.M.B. mobile app
If you are willing to go deeper with your gear the aluminum flywheel will help. If it is falling on its face in 3rd gear that you actually want a heavier flywheel. I know its sounds backward, think of it like trying to stop a locomotive compared to a bicycle. A lot of guys who are driving street/highway gears just don't shift into high. I used to run a 3.08 gear in an old pickup that I raced for fun once a year. I figured out that I could get better top end and ET by staying in second gear. The old truck would shit and git going down the highway. But the highway was more than 1320 feet long.
An overdrive transmission, set up with a manual switch to shift the overdrive in and out, provides second gear overdrive which makes all the difference in an old MoPar six.
The Jalopy Journal
