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what its the highest compression ratio a 230 can take ? im picking a edgy head this weekend and it says that it raises the compression ratio 10 to 1 . can the block handle it? is there anything i will have to do to the block to make it run good?thank you

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Wouldn't Eddgy be a good place to start asking?? Biggest concern is valve to head clearences.  Did they specify a certain gasket.  Torque specs. Recommended fuel. What kind of shape is your engine in?  Do you have numbers from a recent compression check?  Did they specify a spark plugs, or hint at an initial timing setting?

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I don;t know where you got 10:1 from but the source says

 

" These 74cc heads raise the compression ratio of your engine to approximately 9.0:1 and provide an instant, noticeable horsepower increase. "

 

http://www.moparmontana.com/store/p5/23"_DODGE_PLYMOUTH_218_230_GEN_II_EDGY_HEAD_-_FREE_DOMESTIC_SHIPPING.html

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i just heard it was 10 to 1 but was not sure . i knew that the are not made in santa rosa anymore so i was not sure if they are still made.

 Greg my engine was rebuild with low miles i compression tested each cylinder held 150 psi

 

 Thank Sniper and Greg

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Much above 9:1 they quit breathing.

So you can bore valve pockets into the head all day for clearance but then the motor can't breathe and you've added somewhat back to chamber volume. You might be able to relieve the block like they do on Ford flat 8s but that relief adds back to chamber volume and lowers the ratio again.  So you've got a losing battle trying to raise it a whole lot.

 

Recent rings and a good bore are in order.

Edited by 50mech
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First there's no way you'll get 10 to 1 compression. I won't bother to enumerate the reasons.

 

The question was how to make a higher compression head reliable. (if I may restate it)

First, the head must be flat. You may assume a new head is flat.

Second, the block must be flat. In nearly 70 years an engine can be brutalized a great deal by over torquing the head. The area around the threads might be raised or there might be corrosion working its way from the water jackets or the combustion chamber.

Third, bolts and studs should be changed. They get fatigued just like everything else. ARP studs are the gold standard for quality.

Forth, use a thread sealer on the studs and only screw them in enough to protrude into the water jacket less than one thread. Of course the threads should have had a tap run down them to clean things up.

Fifth, A sealant can be applied to the gasket. The FIAT guys used to put spray Permatex High Tack on their gaskets and said that was the only way to get them to seal. I never saw a "comeback" so it must have worked or at least did no harm.

Sixth, Torque the head to the proper torque, then once started let the engine warm up, then re-torque again. Don't wait a month or two, re-torque on the first start. When I say re-torque that just means run the torque wrench over the studs (you don't need to loosen them first as some modern cars require). If you used a thread lube on initial assembly it will make this re-torquing a lot more accurate.

I happen to have read this just last night on a tech tip section of a major engine rebuilder's site (Ferrel's).

They also talk about the gaskets available (in this case for Continental Red Seal engines). The gaskets I've seen lately (Best Gasket brand comes to mind) are acceptable.

 

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I use copper spray a gasket on my metal head gaskets, if it's a composite head gasket I use nothing.

 

You can run a draw file across the deck (valves out) and see the high spots.  If you are real cheap and have steady hands you can continue to draw file till the high spots are knocked down but a trip to the machine shop for a decking is better, same with the manifold and tappet cover area, the factory sometimes got real sloppy machining there.

 

ARP might be the gold standard but an ARP part number that works for our application would be useful.  I am running Milodon studs simple because I could figure out what I needed with Milodonn's catalog, ARP not so much.  With as low performing as our engines are fancy studs aren't really needed.

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Thanks guys for all the info and help . I’m dyslexic so some times it’s hard to word what I’m trying to say and also hard to read millions of post . I have a good amount of info here and can’t wait to use it. I ended up buying the head, intake and exhaust manifold for the car and can’t wait to put it on. I figured 10 to 1 compression was way to much and I would start braking thing but I don’t think that is the cause with this head .

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  • 1 month later...
23 minutes ago, Mopar-Boy said:

will the edgy head fit a '33 201 engine?

33 Plymouth was a 190, not a 201. On the Plymouth side, the 33 190 and the 34 201 had a more narrow block than the 35 and up engines. So, no a head designed for the later engines won’t fit. I believe that is also true on the Dodge side.

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Thanks TodFitch.  Is there a link or resource that shows years/displacement/specs for these engines?  I have a 65 Coronet but I'm brand new to flathead world.  Would like to know what options I have, get another motor, put mine in storage; or modify my 201 (nothing dramatic).  I definitely don't want to go w a modern motor.  I love the flathead with this car.  For instance, would a D30 fit or is it a 25 inch block?  If there was a book/website or anything that covers the specs and history of mopar flathead inline 6s, it would be a FANTASTIC find for me personally. 

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Go to carnut.com check out the car specs section.  Click on Plymouth 40s. Not the horsepower ratings and the related compression ratios.  Then check the 50s list.  I believe stock cr topped out at 8.1 to one giving 125 to 130 up.   When I did my engine the machinist calculated the with modifications at 8.5 to one.  Engine runs good on 87 octane.  50000 miles since rebuild with zero issues.  I did locate and am running a one piece solid copper head gasket which is thinner than the composite from the regular suppliers.  Just thinking about this GS, the sparkplugs that went in when the build was done are the ones still in there.  I pulled them two years ago before a trip to Detroit and they appeared brand new.  Miles at that check was 39 or 40k.

 

Some where on this site is a page which shows beginning cr and expected yield based on .020 to.040 milling.  Look in the downloads or resources area.

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Kind of hijacking the original thread. Might want to start a new one on this. But a quick summary:

  • 1933 is the first year for the L-6 in Plymouth. A number of running changes in 1933, mostly involving the oil pump and oil pressure relief.
  • It was stroked to 201 in 1934, same bearings, block, pistons, etc. as the later 1933 engines. Only real difference being the crank throw and thus the rod length. Deluxe models started using a bypass type thermostat.
  • In 1935 the block was widened to provide full length water jacket and they started using a water distribution tube to direct coolant to the valve seats. To accommodate this, the starter location on the bell housing had to be changed.
  • The revised location for the starter is the one thing that makes fitting a 1935 or later engine into a 1933 or 34 car difficult.
  • And the wider block starting in 1935 means that things like aftermarket performance heads won’t fit on a 1933 or 34 engine.
  • As I understand it the basic block dimensions and mounting points are the same from 1935 through the end of production. There are, I think, changes in things like number of teeth on starter ring gear, etc. But many things are bolt for bolt compatible (most gaskets, oil pump, distributor, manifolds, etc.)
  • The DeSoto, Chrysler and post about 1938 Canadian built cars have a block that is about 2 inches longer (25 inches vs 23 inches). There is very little room between the firewall and the engine or the engine and the radiator in a 1933. It would take major surgery to fit one of those longer engines into a 1933.

 

p.s. Follow the link in my signature to my “vanity” website. There are specifications for the first 10 years of Plymouths there.

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  • 2 weeks later...
On 8/30/2020 at 12:13 PM, Loren said:

First there's no way you'll get 10 to 1 compression. I won't bother to enumerate the reasons.

 

The question was how to make a higher compression head reliable. (if I may restate it)

First, the head must be flat. You may assume a new head is flat.

Second, the block must be flat. In nearly 70 years an engine can be brutalized a great deal by over torquing the head. The area around the threads might be raised or there might be corrosion working its way from the water jackets or the combustion chamber.

Third, bolts and studs should be changed. They get fatigued just like everything else. ARP studs are the gold standard for quality.

Forth, use a thread sealer on the studs and only screw them in enough to protrude into the water jacket less than one thread. Of course the threads should have had a tap run down them to clean things up.

Fifth, A sealant can be applied to the gasket. The FIAT guys used to put spray Permatex High Tack on their gaskets and said that was the only way to get them to seal. I never saw a "comeback" so it must have worked or at least did no harm.

Sixth, Torque the head to the proper torque, then once started let the engine warm up, then re-torque again. Don't wait a month or two, re-torque on the first start. When I say re-torque that just means run the torque wrench over the studs (you don't need to loosen them first as some modern cars require). If you used a thread lube on initial assembly it will make this re-torquing a lot more accurate.

I happen to have read this just last night on a tech tip section of a major engine rebuilder's site (Ferrel's).

They also talk about the gaskets available (in this case for Continental Red Seal engines). The gaskets I've seen lately (Best Gasket brand comes to mind) are acceptable.

 

 

Even when you do all that it is no guarantee. In my case on the '47 Desoto Suburban, the head was NOS and lightly milled to make sure it was flat.  The deck was decked. I used ARP studs. Torque was done by the ARP book.

 

After about 50K miles of San Francisco city hill driving plus running back and forth to Winters California on the I-80, it ate a head gasket.

 

This engine was set up at 8 to 1 compression. The gasket was one of the better than "Best" MOPAR NOS gaskets with the extra copper around the sealant holes that Best does not do.

 

I used copper coat spray on the gaskets and let it hang for 20 minutes before I place it.

 

For my 265 engine. I am going to have a solid copper gasket cut, at a fair cost.

 

James

 

 

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