I've got a 230 Flathead in a '53 Meadowbrook. I was wondering how much can safely be milled off of the head to bump compression, and how much of a bump I can expect? I did try searching, came up with 0.040-0.060" to jump from 7:1 to 8:1...has anybody done this that can post some real world numbers? 0.040-0.060" seems like a big range for one point of compression (is 0.060 the limit). I constantly fall victim to More's Law, so any help would be appreciated. I am also planning on running an Offy 2x1 intake with two of the stock carburetors (looking for a second if anybody has one) and a split manifold or set of headers. I just swapped in an 8.8 ford with a 3.3:1 posi, so I am going to need some extra grunt to pull the car now. Any other pointers would be appreciated. Thanks, Casey
According to the 1959 complete book of hot rodding stock is 7.25 and removing .070 will give you 8.1.
i know a place that has a 265ºdur 107º lobecenter with huge lift cam patern they can do a grind for $89 if your lookin for a regrind on your cam
<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" width="100%" UNSELECTABLE="on"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off"> Check out www.50plymouth.com. Also, I suggest you call Tom Langdon (586-739-9601), he has speed stuff for these engines and can probably answer any/all questions you might have. He was a big help when I was putting the 230 Dodge engine into my '39 Plymouth. The engine was bad and I wanted to go for more cubes. In the process I ended up having to re-drill the Ply flywheel to be able to bolt it up to the Dodge crankshaft (early Ply's have 4 bolts and the Dodge has 8 bolt pattern). Anyway, Tom is a wealth of info and is more than willing to share his knowledge. Dave ------------------------------------------------------------------------------------ '46 Plymouth Coupe - Dodge powered '39 Plymouth Coupe - same </TD></TR><TR UNSELECTABLE="on" hb_tag="1"><TD style="FONT-SIZE: 1pt" height=1 UNSELECTABLE="on"> </TD></TR></TBODY></TABLE>
Does the 1959 Complete Book of Hot Rodding say what years of flathead six that applies to? Mine is a 1953, but consequently, I have read that in 1959 they switched to a different head that yielded an 8:1 compression ratio. Does anybody know if by removing that much meat from the head (0.070") I will be significantly weaking it? Thanks for the info!
Milling the the head .070 won't weaken it enough to worry about. My 50 Wayfarer has a stock head, Offy intake with two '48 Plymouth Carters, and a split original exhaust. It woke it up a bunch. The engine for my rail has a shaved Edgy head for around 9.5 to 10 to 1, a Schneider cam, and to start with it will have the same Carters as above, on an Edmunds intake, with custom tube headers. I'll post the results after the dyno pulls, but suffice it to say, it's no street engine.
Look down toward the bottom of this string of posts and there is a chart showing info for head milling and compression increases. http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=668&highlight=head+milling+chart
Casey, Start with a head from a '57-'59 Dodge (car) or Plymouth as they had 8.0:1 CR from the factory. Then mill 0.050" and you should have a CR od about 8.75:1. If you are looking for an aluminum head track down Earl Edgerton. His head has about 9:1 on a 230" motor. N B R
Is there anyway to tell (i.e. casting numbers, physical traits, etc) a '57-'59 head from the early ones?
Earl's in Santa Rosa, Ca. Reach him thru email at: [email protected] Last I checked his head was around $750ish. You can also call George Asche 814-354-2621. He's an OLDtimer Mopar inliner that knows all there is to know and can help you with parts or questions.
You can mill that '53 head up to .070 but that is a lot of meat. (make sure that is a '53 head) Instead take .005 to .010 off of the block to get it straignt and take .060 off of the head. This should give you about 7.7:1 compression. The '58 and '59 heads were at the maximum compression ratings. Yes these heads will have a casting number on them but I don't have access to that data. I've actually found one in a closed junk yard in Pittsburg, KS but I never could get the old timer who owned the place motivated enough to give me time to get in there and pull it. If you are going to push this thing you will want the aluminum head. The aluminum dissipates the heat better and that is going to be one of the limiting factors. The other is oiling. Some have cross drilled their cranks to increase the effectiveness of the oiling. You probably have the fluid drive between the engine and the clutch. If that is the case you are not going to throw any tire burning power to that rearend. The 3.3 might be a little too high if you live in an area with a lot of hills. something in the 3.5 to 3.7 will give you the ratio you need to make highway speeds and leave a little left over for climbing the hills. Remember these are long stroke high torque motors and even though they have a good reputation for strength they are not high rpm engines. Instead of going with 2 single barrel carbs and the linkage/tuning problems that causes there are 2 other options. The '56 dodge had a 4 bolt 2 barrel intake manifold. If you could find on of these that would be an easy fix. The other option is like I did and built an adaptor to mount a holley 94 (from a '56 Ford) to my single intake. http://s262.photobucket.com/albums/ii86/jacobsheir/?action=view¤t=Holley94.jpg To make it work all I had to adjust was the length of one rod. I also put a second outlet on my exhaust manifold. I did not split the manifold (a lot of guys like the bumble bee sound from split) I also wanted to keep my heat riser working, I did lessen the tension on the spring by 180 degrees.
Check on inliners.org, there is a guy there "Hud1" That has a pulling tractor powered by a flathead 6 mopar that he spins to 6500RPM, and it holds together. There is quite a bit of info on that site..
"I am also planning on running an Offy 2x1 intake"... Casey, for much better performance and drivability you can also go with two Carter/Weber 2bbl "progressive" carbs. They have electric chokes. Langdon sells them along with the adapters (cheap) and linkage/air cleaners. They should work right out of the box but the jets are changable.
I did .060 on a stock head, in a 217 I had as a daily driver for a couple of years. Had no problems with it. Langden as someone mentioned above has a wealth of knowledge on these motors, there is a good book out there which the last chapter focused on souping these motors, (can't remember if it was Langden's or not) The author said he took a stock head to .080 or .090 and was having re-occuring head gasket failure. I spent some time porting my block and knife edging my guides, along with a performance valve job. Whenever I took the time to remove my inner fender well, and re-adjust my valves I had very satisfying results. These are fun motors to play with, my buddy "moose" who is on this site has spent years playing with custom intakes on these mills, maybe he'll speak up. -Torr
Neat post with lots of good information. I am going to build a twin carb manifold for the 230 in my wife's 55 Plymouth. I have a spare single barrel Carter carb which I am going to use. Is the stock jetting suitable for this? I have a couple of spare exhaust manifolds so I also want to do a split manifold. I also read somewhere that Chevy HEI distributor will also fit. Anyone know about this? Not looking to make a speed machine just something different when the hood is open.
Does anyone here know what the casting numbers mean on these flatheads ? I have a Chrysler flathead on a welder with the casting # P23 then a star I49675 then another star . It has a 6 volt starter and generator on it also . The head casting is 1616323-18 . Should I put this in a new thread? Thanks
I have just gone through the same problems with a Mopar flathead 6. Have a look here and you should find the answers. http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=10368
What makes you believe its a Chrysler motor? "P23" is the model designation of a 51/52 Plymouth Cambridge or Cranbrook. I don't have a casting # guide on the flathead motors but you might have a 51/52 218 ci ply motor. My book sez on a 51/52 the motor serial number is located near front upper left side of block between 1st/2nd clys. Sometimes theres a letter or two designating overbore (A orB) or a diamond shape indicating tappet size. Serial #'s for the 51/52 P23 motors started with P23-1001. The number you gave is within the production runs on these cars. The head may not be original to the motor as no doubt the motor has been rebuilt before (head changed?) The Chry cars had the big block motors whereas Plys had small blocks. If your head is 21" long its a small block 218. Heres info on the 51 motor: http://www.secondchancegarage.com/public/431.cfm
Another worthwhile job while you've got the head off, is to pull the water distribution tube and check it. It wont give you any extra power, but it'll save you the possibility of overheating. If the tube is corroded and blocked up with crud, it prevents coolant circulating around cylinders 5 & 6. A new tube is around $40 from memory. When you put the milled head on, use a good sealant (plumber's black graphite grease or similar) on the head bolt threads, because some of them go straight into the water jacket. Same with the water pump bolts. For a street engine, be very careful not to over cam it. Anything more than a mild grind is going to mess with the 230's best feature..... its low rev torque. Similarly, porting and relieving is questionable on a street motor because these blocks do not suffer the valve angle problems that a flathead V8 does. An earlier poster suggested crossdrilling the crank. This is also questionable on a mild street job, the benefits are not going to be realised unless you envisage doing a lot of running at 4000+ revs. Remember that these motors were used a lot in jalopy racing in the 50s, and my understanding is that very few, if any, had crossdrilled cranks.
Langdon's Stovebolt Engine Company makes a drop in GM HEI for your engine. You would have to convert to 12 volt neg. ground. Otherwise it is a drop in. I have one in my 265 Chrysler IND engine and it works great. http://www.stoveboltengineco.com/acartpro/category.asp?catcode=19 He also makes a nice cast iron set of dual exhaust headers and aluminum side covers.
i ran a edge head. it was milled .060 and had no problems. I ran a fenton intake with two one barrel carbs. porting the block makes a lot of hp. getting rid of the gear oil pump and putting on a g-rotor oil pump is a good upgrade. pertronix makes a good drop in unit. the oil filter can be replaced with a moon bee hive. vintage speed makes aluminum finned valve covers. stovebolt offers headers and a adaptor to run a s-10 five speed trans. works great. also look up vintage power wagon in iowa. lots of parts offered including a hp cam and springs. I agree on changing the water tube. buy the removal tool at the same time.
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