ClassicCar

flathead6

Hello everyone, this is my first post and I hope for more to come. I've always loved classic cars (50s and prior) and I'm finally ready to buy one. I've been looking at early late 40s and early 50s Mopar cars with flathead 6 cylinder engines. I've always liked them and I think that they could be a good place to start. I may have found a 1950 Chrysler Windsor with close to mint interior, straight body with extremely minimal rust (none on floors or in trunk), and a good engine and transmission. The car has 87,000 original miles. It's a second owner car and has always lived locally. It has been stored since the 60s and the owner stored it properly.

I'm curious about how long I should have until the flathead finally quits. I've read that these engines are bullet proof, but I've also read that they last from 70-90K miles. Is that accurate? I believe the car has been mechanic owned since the 60s or so. I know that old engines don't typically last as long as newer engines do. I do have experience with engines and lots of auto repair experience, so the project doesn't scare me, but I want to know how long I generally have until the car is dead. Also, just for kicks, what kind of fuel economy does an old inline flathead 6 give? Around 12ish? Thanks for all the help. I hope to have one of these cars soon and hang around longer!

Thanks everyone,
Dan

BJ__TN

[attachment=9355]GWEN 037.jpg[/attachment]
Hi Dan and welcome to the old car world. Sounds like you have found a pretty good car. My experience with the flatheads is that if properly maintained they will last quite a long time. Most of my experience has been with Hudsons and they have a very durable engine due mostly to the metals used in the blocks. I have seen many Hudson engines that have gone 100,000 miles and are still going strong. Then again Hudson blocks were extremely tough.
As for milage, again this is with a Hudson 308 ci flathead 6 cyl.with a 4sp dual range hydromatic trans. On a trip to Charlotte a couple of years ago I got 20 mpg overall. Low 18 mpg, High 21 mpg.
Bob Hickson

flathead6

Hello BJ_TN, thank you for the help. It is much appreciated. The engine runs smoothly and doesn't miss a beat. The car hadn't been started in over a month before I got there, but after a battery charger was on it for a while, it fired right up on the first try. Just a couple cranks! My fuel injected cars don't usually fire up as fast as it did! I'm just hoping I could get another 20K out of it maybe before I have to pull it out and rebuild it. I know that may be a long shot, but who knows? I was thinking about putting a paper air filter in the original oil bath canister (to keep it as stock as possible) and adding a pcv system. I want the car to be completely stock, but if they will help it out in the long run, I don't see why not. Thanks for the pictures of your flathead too. That engine is really clean!

Edit:

Here is another one I'm interested in. It's a few hours away, but it looks well worth the drive:

http://sfbay.craigslist.org/scz/cto/2153948784.html

Ok, so don't hit me if this is a really dumb question, but I've been told that what killed these engines most was sludge buildup that blocked oil passage ways. I've heard about excessive carbon buildup as well. So, although it doesn't sound like a great idea to me, what if I used some seafoam in the oil and through the carb? I'm only asking because I've used it before, but on much newer cars. It really seems to work. My old cadillac went through a treatment and it really smoothed it out, but it will totally ruin an O2 sensor (if you have one). Just an idea.

BJ__TN

Dan, I've never used the seafoam but have heard good things about it. I use Marvel Mystery Oil in my oil and in my gas tank. It doesn't take a lot, and some say it's not necessary, But it doesn't hurt either. Most of the older engines are fairly low pressure in the oiling system and there may be some sludge build up over the years, But if the oil has been changed regularly, I don't think it would be much of a problem ( I may be wrong ) Most of the problems I've seen and heard of are with the coolant passages getting stopped up due to rust flaking off the inside of the block and clogging the passages causing overheating. I would back flush the coolant system and then flush it forward then back flush again. Don't flush the block through the radiator though, as you may force rust into the radiator. Probably wouldn't hurt to have the radiator flushed and cleaned at a shop. Just cheap insurance. Then use a good 50/50 mix of antifreeze/ water. One Tip " don't use the premixed antifreeze they sell now. It costs as much as pure antifreeze but you are only getting half as much, which leaves the rest as water...cheaper overall to use pure antifreeze and mix it yourself. Also helps to use one of the Water Wetters available now, it helps the 50/50 mix cool better.
Bob

37 Terraplane#2 · 37 Terraplane#2 March 2011 Posts: 1,659Platinum Member

HI DAN , at 75 I grew up with these things all around me . Many owned by my family . They will go the 100,000 if properly maintained and it sounds like yours has . The guys have all given you some very good advice . I will add one more . No matter what the oil companys claim or the I'VE BEEN USEING SUCH AND SUCH FOR UMPTEEN YEARS tales , most of who have been using oils with ZINK not knowing it , BUT , modern oil formulas change according to invironmentall dictatates . These old flat tappet engines need ZINK in the oil . DA OIL COMPANY , Indols . IND. makes an oil speciffically for these old cars . You can buy direct from them as little as a case at a time and they will ship it. Enjoy your new old car , and the many new friends you will meet by haveing it . BUD

flathead6

Bob and Bud, thanks for the help. It is greatly appreciated. You guys have a couple of my favorite cars!

I'm sorry that I never gave you guys an update. I ended up purchasing the 1950 Chrysler. So far, I've rebuilt the carburetor, replaced the exhaust system (stock), head gasket, most of the hoses, spark plugs, distributor cap, rotor, condenser, spark plug wires, engine oil, and the transmission fluid. I haven't done much to the fluid drive yet, nor have I tuned the carburetor just right or changed the points and checked the timing. The car runs absolutely beautifully and it is as quiet as a hybrid

. I've also done some cleaning, but I'm not done with that. I should post some pictures up here!

The engine seems to be in pretty good shape. I did a compression test and I got 110 psi on all cylinders except for cylinder 3, which was around 100-102. This was before I did the head gasket, so I don't know if #3 is any better. I've been told that 120 is good, so I figure that 110 after almost 90K miles is pretty acceptable. I keep reading about people with 70K miles having only 95-100 on all cylinders, sometimes even lower. The oil pressure seems good as well. When out of gear and idling, it runs at around 45 psi, when in gear idling it goes to about 20 (seems fairly normal), and it runs at 52-55 psi when cruising at 50-55 on the freeway. That seems to be pretty decent.

The only thing I've noticed is that it smokes a bit when decelerating from around 50-55 mph, like if I'm leaving the freeway. I've been told that this is a classic example of bad valve guides and that it's kind of my choice to replace them.

Does that sound like a relatively healthy engine to you guys? I'm hoping I can hit that 100K mile mark! I know it's not perfect, but I drive it really easy and I'm doing the best I can with it! I'm proud to be the only 20 year old with a 1950 Chrysler in town, hahaha.

Also, Bob, I did end up flushing the cooling system. It seems to maintain an ok temperature easier now. The radiator has a few leak spots at the fins, so it will need to be rebuilt. I'm going to try to make it hang on until summer. Thanks again.

Bud, I will look into that oil. It sounds like a good oil and it could offer that peace of mind. Thank you.

Oh, and so far I've had a high of 14 mpg. Doesn't seem all that bad for an old car, but I think it's capable of better, even with those miles. I'm averaging 12-13, and I really baby it. Then again, I haven't tuned the carburetor properly yet or touched the points and the timing, so I'm not sure of what I could get. With fuel prices going up again, it would be nice to get the most I can out of it.

Thanks so much for the help,
Dan

Paal

Hi,

I have a question: What advantage is using flathead than OHV and newer engines?
What were used flathead, when exist OHV engines?

BJ__TN

Paal, The real question is why change from a flathead to a newer OHV engine when the Flathead is doing it's job just fine? Besides, Just the look of wonder when onlookers see that big old flathead under the hood, is priceless. My car will far exceed the allowed speed limit anywhere I can take it. Just one request though, If you ever do remove a flathead to replace it with a newer engine, Please make the Flathead engine available to those who might need it for their project..
Thanks
Bob Hickson

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