martin67 Posted February 23, 2012 Report Share Posted February 23, 2012 Hi, I am new to the forum and live in Australia. I do a bit of historic car racing, circuit and hillclimbs. Recently I have purchased a 39 Plymouth that has been made into a race special, the car weighs about 800 kg and has a 218 engine that is a bit underpowered for what I want. It already has tripple Carter carbies and that is about all. I think I have got on to a 250 for a transplant and I was hoping that some of you people that are much more experienced than me could tell me the best way to extract as much power and torque out of these engines as possible (I have a pet aversion about crossing the finish line too far down the list) Thankyou, Peter. Quote Link to comment Share on other sites More sharing options...
greg g Posted February 23, 2012 Report Share Posted February 23, 2012 Recently on another website, a light green early 30's Dodge race car was posted, also from OZ. It was still running the flathead 6, not sure of the cubes, but it was a pretty neat car. Keep in mind you are flogging a long stroke (nearly 5 inches) engine and plan accordingly. More compression via milling the head, and free flowing exhaust are probably the most cost effective modifications. Match the ports to the gakets, take some weight out of the fly wheel, and go with your dual or triple carbs. and keep the revs under 4K. Torque is what these engine like to make. HP maybe 160 max at the flywheel. Like to see spme pictures of the car. Quote Link to comment Share on other sites More sharing options...
martin67 Posted February 23, 2012 Author Report Share Posted February 23, 2012 I hope that this works! 2 Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 23, 2012 Report Share Posted February 23, 2012 I like your race car. If you can find a long block flathead Desoto or Chrysler 265 cubic inch engine to install in your car you will gain a lot more horse power. Most stuff inported to OZ was made in Canada and you may already have a long block flathead if your head measures 25 1/2 inches long. As Greg mentioned you can mill the head and deck the block for a big HP gain. Is htere a good cam grinder in OZ who can do a regrind for you? As you have a true race car I would think you could go with a pretty radical cam. It is possible to cross drill the crankshaft for better oiling and spin your engine as high as 5000 RPM's. Is there an internet sight where the races you enter can be seen? 1 Quote Link to comment Share on other sites More sharing options...
Andydodge Posted February 23, 2012 Report Share Posted February 23, 2012 Peter, as Don & Greg have mentioned, measure the head length to check whether you have a short or long engine...23" or 25'..........the 25" engine is known here in Oz as a "Kew" engine and used either a 3&3/8th or 3&7/16th bore with 218/228 or 250 capacity. The 265 engine I have never heard of being used in Oz but its possible I suppose, maybe in some mid 50's Oz trucks?........as far as hipo goes, as mentioned mill the head, multple carbies...usually Holden Stromberg or the stock style Carters carbies work best here in Oz, years ago I saw a set of TRIPLE WEBERS(!!!!) hanging off the side of a Kew 6 in a speedboat, dunno how it went but looked the bees knees......lol.........extractors or headers, update the dissy...I have a Stovebolt Engineering HEI on the still stock 201 as pictured, also get a good balance job,lighten the flywheel, I have had the cam for my 230 reground by Waggott Engineering in Alstonville near Lismore NSW 02 6628 3795. Also have you heard of Stewart Campbell from Maitland NSW.he is a hotrodder who has a 29 Dodge Roadster running a very hot 250, triple carbs etc......I can get his phone number if need be.......if allowed in your class a finned head from Earl Edgerton in California is expensive but a nice way to up the ante..........anyway if you want I can be contacted via phone on 02 6642 5963 a/hrs or at my shop 02 6643 5260 m-friday & sat morning......regards, andyd 1 Quote Link to comment Share on other sites More sharing options...
Rusty O'Toole Posted February 23, 2012 Report Share Posted February 23, 2012 Would only add, most Australian Chrysler products used Canadian sourced engines which were all the "long" DeSoto/Chrysler block, 25", vs the US Plymouth/Dodge 23". The Canadian blocks when used in Plymouth and Dodge came with an undersize 3 3/8 cylinder bore. These can be rebored just as far as the 3 7/16 bore block. In those days, several rebores were common during the working life of an engine and the cylinders were made accordingly. Any Canadian block can be safely bored to 3 9/16 or 1/8 over the stock 3 7/16. Possibly bigger. As always, sonic testing is recommended before really big bores as your block might have core shift or corrosion. Common sizes of the Canadian engine were 218 ( 3 3/8X 4 1/16) 228 (3 3/8X 4 1/4) 236 (3 7/16X 4 1/4) 251 (3 7/16X 4 1/2) and 265 (3 7/16X 4 3/4). In other words, if your car has the Canadian engine you could bore the block you have and install the longer stroke crankshaft and rods, and get up to 283 cu in (3 9/16X 4 3/4). What compression ratio did the last Australian flatheads have? If it was a 228 with 8:1 then that head on a 283 would give 10:1 compression. Quote Link to comment Share on other sites More sharing options...
martin67 Posted February 23, 2012 Author Report Share Posted February 23, 2012 Thankyou for your input. The car has a 23inch block and is log booked as a 3300cc 79.4 x 111 bore and stroke At the moment it is far from home at my son in laws place, I have driven it on the circut for a practice once and it handled pretty well but did not have much go and competition is fierce these days hence the need for more speed. I am still on the hunt for a25inch block and one will turn up somewhere. Most others who are competing are using long motors with a reground cam shaved head and tripple carbs,but whatever we must only use period external bits, ie carbies etc. Quote Link to comment Share on other sites More sharing options...
greg g Posted February 23, 2012 Report Share Posted February 23, 2012 The green dodge looked quit similar to your special. A flat head specialist here, says you can go .090 total milling on the head and deck and still run regular gas. Have seen SU side draft carbs used to good effect. What transmission and rear end are you using? What is the gear ratio of the rear? Quote Link to comment Share on other sites More sharing options...
Rusty O'Toole Posted February 23, 2012 Report Share Posted February 23, 2012 The 250 or 251 cu in (actually 250.6) that you mentioned is the largest of the passenger car engines except for the 265, the difference being 1/4" longer stroke. It is probably the largest you will find in Australia. The 265 was used in Canadian and US made Chrysler Windsor 1952,53, and 54 and in Canadian made DeSotos the same years. Also in heavy Dodge trucks 1 1/2 ton and larger to 1962, and as a Crown Marine and industrial engine. Massey used a lot of Chrysler industrial engines so it is possible that old Massey Harris combine had one. If you can find the crankshaft and connecting rods they will fit any 25" long block. The pistons are all the same for a given bore, regardless of stroke. I will bet your local competitors have worked out the "winning formula". If you can find out their speed secrets, or who builds their engines, they can give you the specific information. One good thing, by picking a Chrysler product you have a sound base to work from. They are a well made engine, strong and with state of the art tech for the time like full pressure lubrication and insert bearings. There are not many weak points. One has already been mentioned, the long stroke which means keeping the revs down to 4000 or 4500 tops. Another is that the cooling system was only meant to deal with 120HP or so. One guy who used the Plymouth engine for tractor pulling said he was competitive with the newer OHV 6s on power but noticed at the end of a pull, his engine was smoking hot and his radiator was cool while his competitors' radiators were hot and their engines were cool. Excess heat will affect the exhaust valves and seats first so a free flowing set of headers would be a must. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 23, 2012 Report Share Posted February 23, 2012 One guy who used the Plymouth engine for tractor pulling Who is this guy? Quote Link to comment Share on other sites More sharing options...
Frank Elder Posted February 23, 2012 Report Share Posted February 23, 2012 Who is this guy? Doesn't Hudsonater have pulling tractors? Quote Link to comment Share on other sites More sharing options...
Andydodge Posted February 23, 2012 Report Share Posted February 23, 2012 Peter, the long engine is generally more common here in Oz, being used in the Chrysler Royal up to the last one in 1962.........they used to be fairly common but the scrappies have a lot to answer for....... Rusty, the Chrysler Royal 250 flathead had a 7.25 compression ratio, at least thats what my workshop manual has listed............andyd Quote Link to comment Share on other sites More sharing options...
Rusty O'Toole Posted February 23, 2012 Report Share Posted February 23, 2012 Doesn't Hudsonater have pulling tractors? That's right, we had several long discussions on the subject of hopping up flathead motors on another bulletin board 2 or 3 years ago. There were at least 2 makes of tractor that use Chrysler engines, Massey and someone else. He had one of the other ones. He said when he started he did not expect too much out of the old flathead in performance but was impressed with the way it held its own against more modern engines. Since then he seems to have gone on to Hudson Hornets. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 24, 2012 Report Share Posted February 24, 2012 That's right' date=' we had several long discussions on the subject of hopping up flathead motors on another bulletin board 2 or 3 years ago.There were at least 2 makes of tractor that use Chrysler engines, Massey and someone else. [/quote'] The other was a Custom Tractor and most likely Innliners was the forum where you spoke with him. Mark Hudson and his dad are both very good friends. I have seen and touched this Custom tractor. They did cross drill the crankshift in this engine for better lubrication and they have spun this engine to five grand or better more than once. Mark is stuffing his face next to my car in this photo. I am parked next to both of his Hudsons in this picture. Quote Link to comment Share on other sites More sharing options...
martin67 Posted February 24, 2012 Author Report Share Posted February 24, 2012 Thank you all for your input, it has been most helpful. Peter Quote Link to comment Share on other sites More sharing options...
greg g Posted February 24, 2012 Report Share Posted February 24, 2012 Would like to see some more pics of the car if you can post them. Used to do some hill climbs and autocrossing in a AH Sprite MK I. Quote Link to comment Share on other sites More sharing options...
martin67 Posted February 25, 2012 Author Report Share Posted February 25, 2012 Sorry I do not have any other photos of the Plymouth, but if this works one of my other cars a 39 Riley special - pretty and quick! Quote Link to comment Share on other sites More sharing options...
martin67 Posted February 25, 2012 Author Report Share Posted February 25, 2012 (edited) And then there is the Ford. Ugly, very fast - handling? brakes?? The concept behind purchasing the Plymouth was to replace the Ford as it handles much better and is more comfortable. But first it has to go much faster! Regards Peter Edited February 25, 2012 by martin67 Quote Link to comment Share on other sites More sharing options...
Tim Keith Posted June 3, 2012 Report Share Posted June 3, 2012 In recent an email I asked Earl Edgerton about the compression ratio for his alloy 25 inch head. He said the CR is about the same as the stock iron head. I want to use the iron head. Can the CR be increased with custom pistons ? Are the stock piston below deck more than .040 inch? I have a DeSoto 236 with the 8 inch connecting rods. I'd like to use the rods with a 265 crank. I think custom pistons would cost about the same as the alloy head. Durability is more important to me than the custom looks. If there is no boost in compression I would rather spend money on lighter and stronger modern pistons with 3 rings. I figure that I can mill the stock iron head to up the CR. Here is a interesting thread on a 265. I just don't have the money for the fancy stuff - if its mostly for show, but I might swing for custom pistons. Its what is inside that counts for me. Also, some say these motors have a reputation for breaking the top ring land. If so, what is the cause? I am told that Dodge trucks with the 265 had pistons with steel supports for the top land. There is a 265 build at http://olskoolrodz.com/ "Chrysler 265 flathead performance build" Quote Link to comment Share on other sites More sharing options...
greg g Posted June 3, 2012 Report Share Posted June 3, 2012 If you go back over this thread you will see the limits for milling and decking the head. I believe the pistons on the 265 come pretty close to the dexk at TDC, so doomed pieces are likely out of the equation. Can you post a direct link for the refereneced article? Hard to fid listenig to the music opening the glove box shifting the leaver and turning on the lights...... Quote Link to comment Share on other sites More sharing options...
Rusty O'Toole Posted June 3, 2012 Report Share Posted June 3, 2012 RE: breaking the top ring land or breaking pistons. This is fairly common on old Chrysler flatheads that have a lot of miles on them. They develop a ridge above the top ring from wear. If the rod bearing and wrist pin also wear, eventually this allows the top ring to hit against the ridge especially if you rev the motor higher than it is used to. At least, this is my theory of what breaks pistons. I suspect if you use modern low tension rings the ridge will not develop, and if you use synthetic oil wear will be kept to a minimum and this will not happen. 1 Quote Link to comment Share on other sites More sharing options...
Tim Keith Posted June 3, 2012 Report Share Posted June 3, 2012 (edited) Can you post a direct link for the refereneced article? Hard to fid listenig to the music opening the glove box shifting the leaver and turning on the lights...... Here is the 265 thread http://olskoolrodz.com/forum/showthread.php?t=52197&highlight=Chrysler+265+flathead+performance+build Too much money for me but I would like a 265 crank in mine. I think a traditional split exhaust, milled iron head might be good for 150 HP or so. I would probably put some money in custom pistons and slip the shiny stuff on the outside. Edited June 3, 2012 by Tim Keith Quote Link to comment Share on other sites More sharing options...
james curl Posted June 4, 2012 Report Share Posted June 4, 2012 I broke two top rings on a rebuilt engine with new +040 pistons and a fresh bore during a 4800 trip to Bonneville for speed week. I contributed it to the fact that I set the advance at an initial 10 degrees advance to start with not realizing that I would still be pulling 14-15 inches of vacuum at 3200 RPM which I ran for most of the trip. With the centrifugal and the vacuum advance plus the initial 10 degrees advance works out to too much advance. I subscribe to the theory that in a little is good more will always be better. Sure ran good with all of that advance, I am sure it pinged but I am almost deaf so I never heard anything plus we ran with all of the windows down. Quote Link to comment Share on other sites More sharing options...
Tim Keith Posted June 5, 2012 Report Share Posted June 5, 2012 The explanation of broken rings makes sense. I would like to build a 25 inch motor similar to Don Coatney's but with custom pistons using the 8 inch rods. I doubt that I will find a 265 crank. I do know of a 251 motor in an older Windsor. I would keep my 236 block as its original to the car, the full flow oil filter is not a biggie. I think with modern oil and careful maintenance these motors would last longer than they used to, but I'd never drive it that much to know for sure. Quote Link to comment Share on other sites More sharing options...
michael.warshaw Posted June 5, 2012 Report Share Posted June 5, 2012 not really a technical one, but wouldnt a small block chevrolet be the easiest and cheapest way to go? Quote Link to comment Share on other sites More sharing options...
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