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218 To 230 Flathead How Much Real Difference?


drillmastertommy

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Hi all, I finally got to drive my 39 Plymouth pick up legally on Saturday and far further than just up and down my little road and I loved it! My engine has a number of extras like high compression head, dual carbs and headers etc and after recently finishing a ring and valve job it was smoke free and ran like a champ!! Got some looks too.

 

Throughout the last 3 and a half years of rebuilding the old girl I've also been on the lookout for a good useable 230 engine as mine is currently a 218 and the concesus seems to be 230 everytime.

 

Now I know the gearing on my old truck is very tall with a rear end somewhere up in the 4's but one thing I didn't appear to lack was power! As it stands I'm more than happy with the 218 and other than to have a spare I could happily stop unsuccessfully searching for a 230.

 

My question really being, if I swap in a lower ratio rear being somewhere in the 3's would it still be worth me looking for a 230 to build? Would I really notice a significant power increase or am I only gonna lose a second or so from my 1/4 mile time?

 

The current engine sounds awesome by the way!!!!

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Drill, from what I have read the best 230 put out 140 neddies with 8:1 compression and I think a twin barrel WW Stromberg carby, it wouldn't surprise me if the stock cam had slightly different specs over the yrs but not by much.

My thoughts with the 230 I had before I sold it was that with the Edgy 9:1 finned head, twin Offy intake and Oz Holden carbys, reground cam, HEI dissy,split headers & a decent balance job that 170-180 or so, maybe a few more throbbing neddies might have been possible.........but as for the difference between a 218 and 230 with the same specs, I doubt if you'd notice the diffence, maybe 2 tenths on the 1/4, if that........have you any place that has a dyno handy?...........lol...........regards, andyd    

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I'm sure the 230 would probably help some but I think the rear gear is going to help more. I've got my 46 swapped down to a 3.9 and between that and some fairly tall 16s it cruises along nicely.

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I have the same thoughts as Ed. It may help but the gears would be higher on my list. A 230 would be more of a consideration IF you hadn't already put as much work into your existing engine. From my perspective you have already made that decision and and things seems to working well. So what gears are you thinking about?  Something in the 3.54 area if there are not al lot of hills and your running 16 inch tires would be a good guess I think. I am sure others will add there thoughts if asked.

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From my experience driving a hopped up 218 was like driving a stock 230.  Driving a hopped up 230 is at least as notable a difference.  Your truck should be well suited for a differential with a bit higher gears.  3.55 or 3.7 to 1 would be good for more relaxed cruising and the occasional use it like a truck. 

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If you want to win the race with the next guy running a 218 then go with a 230. If you want to drive all over with out caring about beating the next guy then stick with the 218. It has plenty of power to get you where you want to go and as long as your engine runs great then why spend the money to upgrade.

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If you want to win the race with the next guy running a 218 then go with a 230. If you want to drive all over with out caring about beating the next guy then stick with the 218. It has plenty of power to get you where you want to go and as long as your engine runs great then why spend the money to upgrade.

 

Totally agree.

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Well, I am going to agree with Gregg. My .060 bored 218 had the dual Offy intake, cast iron headers, HEI dist and I though it ran pretty good. Bought a .030 bored 230 from a guy on the HAMB who pulled it from a 57 model to put in a 318. Broke a valve in the 218 so I Swapped over all the "speed parts" to the 230 with the addition of an Edgy head.

 

I have not timed it in the 1/4 or put it on a dyno, but I can tell you from seat of the pants that there was a VERY definate, noticible difference with the 230. I did not have the Edgy head on the 218 so how much difference it would have made to the performance of the 218 I do not know. I just know that were I in your shoes and I could swing it financialy, I would swap out the rear for something more drivable then swap to a 230 in a heartbeat.

Edited by hkestes41
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From a 218 to a 230, is only 12 cubic inch. How much HP will you gain from 12 CI.

What made my 38 Coupe more of a pleasure to drive, was when I installed the 5 speed trans.

When I went from a 3.9 rear, to a 3.7 rear, it was a more pleasure to drive.

My 38 Coupe has a 218 about 80 HP that is fun to drive now. With more power, maybe

more fun to drive.

I have a spare engine, 1956 230, rated at 130 HP. Maybe next winter...

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the improved highways of today compared to the time these cars were built is remarkable..the old ratios are a thing of history..yeah they work and such but limiting you to what highways you can travel safely..going 55 on an interstate though legal is a risk to yourself and those around you..I assure you if these cars were built given the roads of today..the ratios would not be anywhere near the same...one of the better improvement is the T5 or equivalent trannies...and a wide ratio  tranny can be your best friend...giving you the best of both worlds...

Edited by Plymouthy Adams
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From a 218 to a 230, is only 12 cubic inch. How much HP will you gain from 12 CI.

What made my 38 Coupe more of a pleasure to drive, was when I installed the 5 speed trans.

When I went from a 3.9 rear, to a 3.7 rear, it was a more pleasure to drive.

My 38 Coupe has a 218 about 80 HP that is fun to drive now. With more power, maybe

more fun to drive.

I have a spare engine, 1956 230, rated at 130 HP. Maybe next winter...

 

There is actually a decent amount of difference.

 

1938: 201ci / 82hp @ 3600 rpm / 145ft lb torque @ 1200 rpm

1948: 218ci / 95hp @ 3600 rpm / 172ft lb torque @ 1600 rpm - a 15.85% increase in hp and 18.62% increase in torque

1957: 230ci / 132hp @ 3600 rpm / 205ft lb torque @ 1600 rpm - a 38.95% increase in hp and 19.19% increase in torque

 

If you compare the 1938 to a 1957 in your situation, you get a 60.98% increase in hp and 41.38% increase in torque

 

Now I agree that the change in rear gear and/or OD would be the first change that I would make but the jump to a 230 would be beneficial to Drillmaster. He would just have to determine if it was enough to justify the expenditure.

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Tommy, I'm seriously still looking to make that jump to the 230 combined with a s10 t5.  If you don't do it think of what will happen when you and I pull up to the lights somewhere near Chichester... tears my friend, tears.

 

Listen to Kirk though, those facts speak for themselves! 39% increase in HP!

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What did they do to get more power out of the later 230s? Just bump the compression and a different cam? 

 

The compression ratio continued to climb throughout production from 5.1 for the 1933 190ci version, to 6.6 for the 281 in 1948, to 7.1 for the 218 in 1953 then to 8.1 with the 230 in 1957.

 

Not to sure about any changes to the cam specs, but they may well have made changes to take advantage of the increased CR and CIs.

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The compression ratio continued to climb throughout production from 5.1 for the 1933 190ci version, to 6.6 for the 281 in 1948, to 7.1 for the 218 in 1953 then to 8.1 with the 230 in 1957.

 

Not to sure about any changes to the cam specs, but they may well have made changes to take advantage of the increased CR and CIs.

 

Correct so just comparing those stats may not exactly be apples to apples. A shaved head on a 218 bringing the compression up to that of the 230 may get you some or a lot of the difference between the two engines back without swapping motors.

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 interchange say 46-56 all flathead HEADS interchange Dodge/Plymouth but we know the CR was the difference between the years due to head chamber volume to take full advantage of the fuel as it increased in octane rating.. this being true as the bolt pattern did not change..the car would run but you would have to CC the head to know your compression ratio for who knows if it had ever been milled before you got your hands on it.

 

camshaft for the Plymouth/Dodge 41-59 also all carry the same interchange number...now as to if there is a duration/lift change it is not stated one manner or another..no sepcial note on this subject

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Thanks all for the info, the next step is definitely going to be to find better rear gears, which being this side of the water is going to be dictated more by available width than just picking a ratio although I will hope to find something around the 3.5-3.7s.

To clarify a couple of details, my current engine is a 53' 218 with an Edgy head, Edgy intake with 2x94's, Langdons cast headers and Pertronix ignition. Unless I come across a too good to pass up 218 in the meantime I will still keep searching for a useable 230 to build up whilst wearing out my existing unit but I have been searching now for nearly 3 years! Any of you guys got one you can put in a holiday suitcase?

Duds! There'll be more tears when your mrs finds out how much you want to spend on speed parts in your desperate attempt to leave me at the lights!!

Edited by drillmastertommy
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You can do a lot of modifications to a flathead 6 to boost horsepower. But in the end you still have a flathead 6. The most HP gain I have heard of from a flathead 6 is close to 200. But pushing the upper limit reduces reliability. In stock form a flathead 6 is very reliable. With a few bolt on modifications it is still reliable. If you want gobs of horespower install a V-8. If you want reliability with a "cool" factor dress up the flathead with dual carburetors and other bling. This will give you a car that can be driven at todays road speed. When you open the hood at a car show you will have more lookers than the guy next to you with the SBC.

 

Dont expect V-8 power with a flathead 6.

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Are there Jeeps in your neck of the woods???  If so the rear ends from the original small cherokee, (maybe the grand cherokee) or the wrangler should be a place to look for a 3 something ratio.  I had a 2wd late 80's Cherokee that had a 3.55 limited slip.  I believe that the 4wd drive versions did not commonly have the Limited slip.  Same bolt pattern for wheels also.

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Greg They have Jeeps over there. So that may work I used a Jeep grand Cherokee on my 50 Plymouth 4 door. Allot of trucks using them as well.

 

http://mopar.pairserver.com/p15d24ph_forum/index.php?/topic/31502-rear-axle-swap/?hl=jeep

 

http://mopar.pairserver.com/p15d24ph_forum/index.php?/topic/28976-rear-axle-97-wrangler-to-52-12-t-part-ii-perches/

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i have a 49 dodge 230 i want to hop up .what is a good grind on cam to do? i found a video on youtube that a guy did to his flatty and had compression up to almost 10;1 sounded great.i want to do 2 carb setup and split manifold ,but not sure on motor work. also saw some one talking about chevy lifters being put in,but i could be wrong.im just getting into these great inlines. so information and opinions would be appreciated.

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i have a 49 dodge 230 i want to hop up .what is a good grind on cam to do? i found a video on youtube that a guy did to his flatty and had compression up to almost 10;1 sounded great.i want to do 2 carb setup and split manifold ,but not sure on motor work. also saw some one talking about chevy lifters being put in,but i could be wrong.im just getting into these great inlines. so information and opinions would be appreciated.

I think you mean Chevy valves.

 

That info is discussed here. http://mopar.pairserver.com/p15d24ph_forum/index.php?/topic/29665-stainless-steel-exhaust-valves/?hl=%2Bchevy+%2Bvalve#entry296413

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