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I've heard stories about the flathead six racers doing well on dirt tracks.  On the street the hopped up flathead six cars probably looked like most other Dodges and Plymouths.  The stripped down fenderless Fords were cheap, plentiful and light and looked like the hot rod. 

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  • 7 months later...

Hello, I am new here , and have read some interesting things about the flathead Chrysler 265. Me, being an old drag racer always want to know , What will it do in the 1/4 mile? I have read every page of this thread and no one is mentioning weights, gear ratios, including rear end gear ratios, actual readings from a tach, or even oil pressure. I myself have been racing super stock Hemis and max wedge cars since 1972 and I am thinking on building a Chrysler Flathead 6 in a Willys body. I will be using all the same parts suppliers as I have used in the Hemis and max wedges. My machine shop is on red alert about this project. This will be my second Chrysler 6 in a Willys  that I own. The first one is still together and ran a best of 14.50 @ 91 miles per hour. It weighed 2860 with me in it, had a 4.78 gear in the 52 Plymouth housing, a 38 Dodge 3 speed tranny, went through the finish line at 5200 rpm. It was wound out long before the finish line. The motor was 60 over with 3 ford 94's for carbs, on a stock manifold,( reworked ), 100 thou off the head, a reground cam which I have the blanks so that I can grind more, headers. Absolutely no off the shelf speed equipment was used on this motor. This combo gave us 60 class wins, I still have the trophies, and many cash awards. This car has been retired since 1968, and sits about 15 feet from this keyboard. The car was driven to the track until 1966 and then we used a tow bar. So my question is , how fast are the big boys going with their new style "Speed Parts", on their flatties?

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Way back in my misspent youth in 1960 my friend had a 1947 Plymouth 2 door sedan and put a new Sears rebuilt Chrysler 6 cylinder  that came bored 1/16 over.. It had a stromberg carb and split manifold.  Sounded good.. Dragging on the old University ave in St.Paul where there were about 30 consecutive stop lites and three lanes   we got alongside a 1960 Bonniville and a 1959 Buick.  We beat them every time for the whole course.  The Pontiac second and the Buick last.  The guy driving the Pontiac stopped us to look under the hood.  My friend told him it was a stock Plymouth because unless you sit them along side one another they look the same.  So anyway using the Chrysler six with slight modification was pretty darn good.  I think to install the Chrysler the frame under the balancer had to be notched and something with the radiator.  Great days back then.  At 73 now Im nearly done restoring my 1946 Plymouth convert.  I put in a Chevy 350 with a 350 turbo in but in retro I would have found a Chrysler six and bored it out some and added a couple carbs.

Edited by dale
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hey all, now here is a thought! Been watching old "Hotrod" movies lately, and have made some observations.

Most of these "jalopy"s are A and T Model Furds, with souped up L head V8s.

Now was this the public norm in the late 40s through the 50s, just Furds and L head V8s until the Hemis, Buick Nailheads and Olds Rockets came onto the scene.

So where are the Chrysler Flathead 6 cylinder hotrod engines and cars? How well did the smaller souped up Dodge and Plym engines stack up against the Furd flathead V8s, and how well did the big block Mopar 6s do against them too.

I am still looking for old movies that had Hotrod mopar 6s, racing against Furd L head V8s and also against those GM Stovebolt 6s......

 

 

Old "Hotrod" movies were like the "Hotrod" magazines are now, with most of the content being about 1932 Fords or a car that looked similar to a 32 Ford.

 

I stopped getting Street Rodder mags after 20 years, because of very little info in the mags about Mopars.

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It would be a good thing if anyone with a head off could accurately mike it and post the dimension say from the same spot so we could come up with the stock thickness of a stock 218/230 early late head ect and same for the 236/251 and 265 engines.

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It would be a good thing if anyone with a head off could accurately mike it and post the dimension say from the same spot so we could come up with the stock thickness of a stock 218/230 early late head ect and same for the 236/251 and 265 engines.

Been there done that. 251 head that I believe to be unmolested. Lower left head bolt near the thermostat in the photo.

 

spithead.jpg

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Well I measured a 265 I've got...1.912".

Figures the guy was a machinist/mechanic who was the previous owner and I think he always shaved every head including his own!. Bummer . 

I prefer not shave em if i don't have too.

I'll have to check a 265 in my truck. I'd like to know have at least one 1.930" 25" head.

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I just measured 3 Spitfire heads I have here.

I had the gray one milled .050 and it measures 1.902

The rusty one measured 1.850

The blue one measured 1.865

The gray one was powder coated so maybe that coating measures something.

post-32-0-88388200-1443364087_thumb.jpg

post-32-0-10077600-1443364134_thumb.jpg

 

 

 

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Generally I am not looking to get better performance by modifications. 

 

I have always bored my blocks at a max of .o30" and if the heads were flat left them at that.

 

Thicker cylinder walls and heads help control engine temps to slow down cylinder combustion heat transfer too.

 

I just leave the drive trains as stock.. To me they are just fine and trouble free.

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  • 1 month later...

It could be really hard to even verify a head has never been shaved. Even at the factory, I'd think they'd make a couple more passes to get it flat and usable than set a specific depth or toss it plus, differences in casting plugs. As many times as these engines could have changed hands and memories of work done in the past on them, swaps from one vehicle to another, etc., how would you REALLY know it had been untouched since the factory.

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Dave72dt, on 05 Nov 2015 - 07:45 AM, said:

It could be really hard to even verify a head has never been shaved. Even at the factory, I'd think they'd make a couple more passes to get it flat and usable than set a specific depth or toss it plus, differences in casting plugs. As many times as these engines could have changed hands and memories of work done in the past on them, swaps from one vehicle to another, etc., how would you REALLY know it had been untouched since the factory.

you cc the head......do the math...then you know for certain if stock

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  • 1 year later...
On 1/20/2015 at 6:25 PM, Tim Keith said:

These flathead motors are capable of producing good power.  On the street they're more limited in compression than an OHV motor, L-heads are not thermally efficient and will blow head gaskets when you push the limits of compression.  Respect their limits and they do better than most would expect of them.  In a lighter vehicle the low-mid range torque gives good seat of the pants response.   If they only had the displacement of the Hudson 308....

Wonder if anyone here has swaped that Hudson six into a P-15...

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1.93 inches would seem to be the way they left the factory.  The best way to raise compression is to use a head from a smaller displacement head on the larger engine.  Say a 51 Plymouth 217 head  on a 230 .   If both  engines started out with   7 to 1 compression and you compute and compare  the volume of the cylinders  ( pi x radius squared x height)  then you can arrive at a compression ratio  ,    

In my  50  , i have an American 230 with .040 overbore and a 52 Plymouth head, resurfaced only.  Cranking pressure is 145 lbs.  Runs strong.

In my 51, I have a 57 Canadian 251 bored .060  with a 51Plymouth  218 (Canadian) head.    The compression ratio is 8.5 to 1.  It has run 50 000 miles on unleaded gas without any problems.  

Putting a 230 head on a 217   or a Spitfire (251) head on a Canadian 218  would lower compression  as some people have learned the hard way.

In any event, these engines can be made to perform, but  are used to best advantage when low end torque  can be utilized.  The 265 is gutsy but not a high revver.  A local circle track racer around here was competitive against small block V8 s  .  His B Modified class racer would pull the left front wheel off the track coming out of turns.  One season... in the late 60s he finished 2nd overall.   Did those Zoomie headers ever sound GOOD.

I never had to nerve to get out on a track  but  I enjoyed the reliability at low cost of these engines.   And still do.  

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