Hypothetically, If you had a 1950 mercury, and you want to run the flathead motor as a daily driver, would you use the factory 8CM heads or replace them with aluminum heads? I am putting on a very small 4 bbl carb since I will be driving on the highway most days. I figure the flathead has a reputation of running hot, so seems like the aluminum heads would help with that. I don't have the motor in the car yet, so I can easily do the switch. Edlebrock or Offenhauser heads? Thoughts? Opinions? Best service/price to order from?
Aluminum heads are cool looking. Other than that I've never seen any real facts regarding better performance. Lots of opinions, not many facts. They won't cure a cooling problem and they won't give you a 10 second quarter mile time. The bottom line is that if you have an extra $500-600 lying around, aluminum heads are cool looking. If you don't, then drive, drive, drive with the cast iron heads.
My theory is they carry more water and they are finned aluminum. I would think between the water, design and material they would radiate more heat = run cooler? That's my theory.
Complicated...aluminum removes heat from combustion chamber faster, allowing more compression for more power without pinging. Aluminum removes heat from combustion chamber faster, resulting in less power being generated because more heat is going into the cooling system and less driving the piston... On those points, they almost certainly add more than they lose but iron has potential superiority here, you notice. Flow...better flow means fuller chambers at any particular condition, resulting in more actual compression pressure regardless of ratio. Note that comp ratio can only translate into actual compression as long as chamber is filling well. Here, MANY aluminum aftermarket heads generate compression by filling in transfer area. There flow generally improves if transfer area roof is deepened more like stock '37-53 heads... Displacement...with small flatheads, it's difficult to get lots of compression without compromising chamber. As flatheads grow into 255 Mercs and then bore and stroke to bigger, compression becomes a freeby and stock type transfer area is not a problem or compromise area. You presumably have something close to 255-265 here...modern gas is higher octane than 1950 gas. I would start by swapping the 8CM for 1952-3 EAB, somewhat higher comp at pretty much scrap prices. Try for 050 or so clearance over dome, much more increases knock sensitivity and hurts everything. Try it, very little money involved for good basic heads with decent flow. If problems...you have spent very little, and it's easy to change heads in the car. A good distributor with a quick centrifugal curve and some vac advance will give you more felt response than any of the shiny things on top...
I put a Pertronix electronic ignition in the distributor. I have an MSD coil as well. i am hoping to get significantly more spark out of this set up.
Speaking of advance, we used to run our flathead Indians and Harleys at full advance (mechanical) all the time. Anyone do that with a street Ford?
Well If I keep the factory heads, is it worth the cost and effort to upgrade to a 390 cfm Holly carb? I figure some extra air and fuel should help when driving down the highway.
Aluminum heads will give a little more compression which means more power and mileage. Use new heads and the correct coolant (antifreeze) and you will have no problems. The bigger carb will work no matter what heads you use. A mild cam and dual exhausts or headers will help release the power.
In a video I was watching, Kenny Makuch was flowing a flathead he had been working on. In the interview, he said that a stock Merc head flowed better than the nostalgic heads out there today. So is there a trade off???? Would a stock head actually perform better?
I have been running stock heads and a 390 carb on my pickup for about 50,000 miles with no problems, not much in the gofast department but sure do like the sound.. Heat really doesn't kill a flathead but excessive revs will.
And you couldn't hear the detonation over the exhaust, is my bet. Yet, the stock Ford Load-A-Matic distributor does not have a centrifugal advance, and the vacuum advance operates via ported vacuum, so the higher the revs, the more advance (IIRC). THIS, is THE part that needs to change for best performance with any engine combination. Those that stated that combustion chamber fill is more important are quite correct. Back to flatheaded Harleys, the fastest (Sifton) KRs that raced back in the 60's were running about 4 or 5:1 compression, with quite radical cam timing to make sure the chambers were filling properly without the shrouding effect of a typical high-comp head, which would usually shroud the valves. Cosmo
On the carb...flatheads in general, even stock 221's, respond to a bit more carb capacity. A good distributor swap is mandatory on the '49-53's, as the ported/venturi vac combo works poorly at best on a stocker and is pretty much worthless modified. Also think about where you are going to tap venturi signal on a carb not designed for that thing! Here's an old post in which I try to describe an old Car Craft/HRM dyno and drag test of a 239 stocker, using only bolt-on parts. Note that a good distributor (which came stock on the earlier flatheads) will be absolutely first priority on a '49-53. http://www.jalopyjournal.com/forum/showthread.php?p=1220519&highlight=merc+dyno+drag#post1220519
The stock distributor will NOT work with anything but the stock carb. If you hook it to a "normal" ported carb, the advance works backwards!
Before you plunk down the bucks to go four barrell you might want to give this a read:http://www.hotrod.com/techarticles/hrdp_1301_flathead_ford_intake_manifold_smackdown/viewall.html
Bruce. Any idea what gears were in that Merc. that you referenced in the Car Craft article? 16 flat with no port/valve/cam work is pretty impressive.
There are few details in the article...it should have had 3.54 standard, but could have had a number of other sets. Ford had published performance standards for dealer tests on MPG, accel, and top end...these were MINIMUM standards to show if car was not up to snuff, not advertising best numbers, and the acceleration was entirely tested in 3rd gear, so was of course a lot slower than any sort of spirited driving usin lower gears. 3.54 239 '40 Merc had to be able to go 10-60 in high gear within 23 seconds, top end of 88 minimum, at least 18 MPG at 60. A serious 0-60 test would of course have not even used high gear, so who knows what a stocker was capable of.
This thread has some good discussion about the distributor vacuum advance (or lack thereof. I'm going to install a Holley 390 on a stock 8ba. Any advice? I've seen the dizzy set to full advance, but it's been a long time. Any input on that procedure? Thanks! Sent from my iPhone using The H.A.M.B. mobile app
According to Joe Abbin,flathead wizard from Albuquerque, the best flowing aluminum head is only 2-3-5 h.p. over a stock cast iron head that has been modified. His 34 sedan makes 335 h.p. with a small blower and he runs modified cast iron heads. He is an engineer; has a flow bench and a dyno and knows how to use them! His 34 sedan runs mid 12's and is regularly seen on the street at car shows and rod runs.
if you have the money and the small gain in power doesn't bother you ,go aluminum . myself , stay with good set of cast iron.
I'm concerned about this post about the distributor Not so much about the heads. Sent from my iPhone using The H.A.M.B. mobile app
OK...on stocker, vac line goes into a double passage in carb. One branch is fed by ported vac, one by venturi depression, vac. At part throttle you have lots of vac coming form ported hookup...so you have good part throttle power and response. At full throttle the ported vac drops off to close to nothing and the rather weak venturi vac takes over and is supposed to provide the smaller amount of advance needed at full throttle...it usually does very badly at this. Some early tests showed better 0-60 times at 3/4 throttle than at full because of this! Note that any chance at proper performance requires a Ford/Merc carb with the proper port! A fully centrifugal distributor will give (assuming proper curve) will give good full throttle response but serious power loss at part throttle or cruise, a BIG handicap in the real world. Best would be a centrifugal distributor with a vac can to keep proper performance at part throttle. Heads...stockers generally flow better, so question is whether you can attain a decent CR with milled EAB's or something like that. More than stock '49 compression would be a significant improvement, again one that is most important at part throttle.
Read the first 2 sentences in post 4... If you can get the same compression with iron, engine will make more power...unless you get pinging, in which case the cooling is a benefit.
The Jalopy Journal
