HOP up flat head 6

[50 ply deluxe]

I have flat head and would like to hop it up anyone have ideas where to start

[JBNeal]

1st ya need to know which engine you have and how much $$$ ya want to spend, but don't get too disappointed when ya find out that making 200hp is pie in the sky...

Edited December 28, 2020 by JBNeal
added link

[Mark D]

Have a look in the reference section of the forum. I have scanned and posted several documents there from several 1950s magazine articles.

[Sniper]

How big is your budget?  Assuming a 218 or 230 engine here:

 

You can put a higher compression head on.  Only new ones I know about are the Edgy head http://www.moparmontana.com/store/c3/CYLINDER_HEADS.html

If that's too rich, you can mill your old head to bump the compression ratio up, but its combustion chamber design is dated.  There are also used aftermarket heads out there, you have to look though and they are not real cheap.

 

You can put on a dual intake, I have a new Thickstun that occasionally pops up on Ebay when they run another batch.  Offy sells a new one too, but it has issues of you want to water heat it.  Used, well they are out there you just have to look.

 

Cams, several options here.  Vintage Powerwagons sells one, The AoK boys will regrind yours as will the mopar montana boys linked above. 

 

Ignition, several ways to go about this.  Some keep the points, which is fine.  Other's will pop in a Pertronix setup so they don't have to set points anymore, but quality lately is suspect.  Others will merge a slant 6 distributor and the flathead's distributor to make an electronic ignition setup and finally Langdon's sells an HEI setup ready to install, http://www.langdonsstovebolt.com/store/#!/Stovebolt-Mopar-Mini-HEI/p/1222043/category=18665979  Myself?  I am running points right now and plan to do the merge setup.

 

Those are the more conventional options.  A blower or turbo has been done and I am working on a dual throttle body injection setup for myself.

 

I forgot about exhaust, Langdon's also sells a really nice looking set of split exhaust manifolds if you don't want to split your own.

 

 

Edited December 28, 2020 by Sniper

[greg g]

Increase suck, squeeze tighter, make a bigger bang and unrestrict blow.

Lots of discussion here regarding multi carb intakes, porting, milling heads,adding electronic ignition, adding dual exhaust.  But the simplest was is to pull the 218 and put in a 230.  If you select the right year 230 you can go from 97 horses to 130.  A bigger increase than machining and adding speed parts to a 218 will ever yield unless you turbo or supercharge the 218.  Graham Paige had a 217 engine with factory supercharger their engine went from 85 to 120 horse with the blower.  What ever you do to the base engines you will never break into the 18 second range at the drag strip.  What to you want to accomplish?  Is your current engine in good enough condition to accept modifications?  A worn engine won't give you much added performance, and the mods might actually shorten it's useful life especially if you get happy with your right foot.

 

You are dealing with a low compression, long stroke motor that isn't happy above 3500 rpm, so trying to make a hot rod can be an expensive and futile excersize, it you buck the basic design parameters.

 

Dual intake and carbs 600.00 or more

Dual exhaust 500.00 or more can be done at home if you are handy at welding cast iron

High compression head as much as 1200.00

Cam grind. ??? 400.00 just a guess.

 

Can it be done for less?? Sure if you are sharp at catching stuff at swap meets estate sales or eBay. 

[Andydodge]

I'm in Oz so pretty much everything had to be imported but when I had the 41 Plymouth Coupe I was collecting parts etc to build a 230 with an edgy Finned head, Offy twin carb intake, split cast iron exhaust manifolds, Stovebolt Engineering HEI dissy, Beehive Oil Filter,1/2 race Waggott Cam,fully balanced, OZ GM single barrel Holden Carbs, Holden water pump, ARP head studs, finned side plates and a S10 T5 gearbox.........sold the car & engine before getting it bored & machined but have attached a mock up of the engine & pic of the car.......as others have mentioned prices can be an issue....the Edgy Head cost me $1300, intake was $300, all the internal parts including pistons,rings,bearings,timing gears, & chain, lifters, valves, springs & guides & oil pump came to about $800...........split exhaust cost $200, HEI was about $300, Beehive Filter was about $350, ARP head studs $180.......S10 T5 gearbox imported from California was $800........even the finned side plates were $120........these are all Oz dollar figures but from around 2009-2012..........probably add 20% to get todays figures..........so how fast do you want to go.......lol...........a cheaper alternative would be to install a stock cast iron head with 50 thou milled off it, twin throat carby on a carby adaptor, and full dual exhaust........andyd    

[hkestes41]

When I did this one I was lucky in finding a 230 from a 57 Dodge that had been recently rebuilt with only about a thousand miles on it. The owner decided he wanted to go V8 so pulled the engine and sold it and the transmission to me for $150 just to get it out of the way. Was bored 60 over with all new bearings, rings etc. 

 

Jumping from the stock 218 to the 230 boosted it about 45HP. Then I added an Offenhauser intake, Mini-HEI, Cast Iron Headers, Carter-Webber carbs, all from Langdon's. That was around $1500. Ran 2.25 dual exhaust with a crossover pipe and small 14 inch turbo style mufflers. Then added the Edgy finned aluminum head which at the time was $700 shipped to my door. Prices have gone up a bit since, but the head has also had some updates to improve the combustion chamber and bump the compression a tad. Not sure how much HP was added by these parts but assume they bumped it around 20-30 HP which put it in the 150 to 160 range. 

 

I can say that from seat of the pants experience it was a huge increase in performance from the original stock 218. Was not going to win any drag races but it ran well and would keep up with interstate traffic running through the 53 model R10 overdrive cruising at 70 to 75 all day on some 800 plus mile round trips. 

 

They can be fun engines as long as you have the right mindset going in. They also will draw attention at shows/cruise nights in the sea of small black Chevys because you don't see that many.