These pages discuss flatheads for the Model T. Head design discusses compression ratio and head design and their effects on engine performance. Dyno tests presents the horsepower and torque for various heads. Head photos contains a photo gallery of accessory Model T heads. Dyno test photos shows photos from our field trip to the dyno shop in Oklahoma City. The graph below summarizes our best estimates of head performance. It is a combination of dyno tests and calculations with an engine simulator. All results are relative to a stock unmilled high head. Blue indicates peak torque and red indicates peak horsepower. The solid lines are from the engine simulator and the symbols are from our tests on a chassis dynamometer. Both the Waukesha-Ricardo head and the Z head perform better than the engine simulator predicts. We believe this is due to the improved squish style combustion chamber. The dashed lines estimate the performance of a squish style head with various compression ratios. As you can see, we would predict that a squish style head with 6.2:1 compression ratio would produce 50% more power (30hp) and 34% more torque (111 ft-lb) than a stock head. If you want to understand how this will effect the performance of your car, look at the Power and Torque page.
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><!--msnavigation--><TD vAlign=top><!--mstheme-->[FONT=Arial, Arial, Helvetica][Technical Page] [Head Page] Due to the poor quality of gasoline during the Model T era, the compression ratio of the Model T engine was intentionally held at about 4:1. Since good quality gasoline is now available, an easy way to improve the performance of your engine is to increase its compression ratio. Compression can be increased by milling a stock head, installing pop up pistons, or by installing a high compression head. The increased compression will not only improve the power of your car, but also increase its fuel economy. <!--mstheme-->Theoretical Effects of Compression Ratio<!--mstheme--> Compression ratio is strictly a ratio of volumes, i.e. the volume in the cylinder and head when the piston is at the bottom of its stroke divided by the volume when the piston is at the top of its stroke. Many factors effect engine performance, however, if air flow, volumetric efficiency and other factors are equal, a theoretical relationship (see Huntington*, p. 67) can be used to estimate the effect of compression ratio on engine power. For the Model T engine, this relationship is plotted on the following graph. An engine simulator can also be used to estimate the power from increased compression (see Cams/Simulation). The results of two computer simulations are plotted below to show the effect of compression ratio on the horsepower and torque curves. A nice feature of this modification is that unlike other modification (cams, carbs, etc.) it increases power and torque for all engine speeds. <!--mstheme-->Combustion Chamber Design<!--mstheme--> A key phrase in the preceding discussion is the one, "if air flow, volumetric efficiency and other factors are equal". Generally, these factors are not equal. Huntington* states that increased compression is usually accompanied by poorer air flow, so that one generally does not achieve the theoretical power increase. However, the Model T combustion chamber is antiquated even compared to other flathead engines, e.g. Model A or flathead V-8. These later engines employed squish style combustion chambers patterned after the work of Harry Ricardo. The Waukesha-Ricardo head produces a significant power increase with only a small increase in compression. The photo and sketch below show a stock high head and a Waukesha-Ricardo head. The crossection sketch of the combustion chambers compares the shape of a stock head (dashed lines) and Ricardo head. The Ricardo design employs a small clearance over the piston and a larger cavern around the valves for good air flow. For best results, the clearance above the piston should be 0.050 to 0.080 inches (Huntington, p. 70). We have started a photo gallery of Model T heads (see Photos). Most of the aftermarket heads have a squish style combustion chamber. The Reeder head is a notable exception. The combustion chambers for the Haibe, Giant and Simmons heads appear to be identical. The combustion chamber for the Z head is quite similar. Unlike the Ricardo head, all of these heads have a "valley" in the combustion chamber. <!--mstheme-->Compression Ratios for Model T Heads<!--mstheme--> The photo at left (click to enlarge) shows the method we use to determine head volume. A Plexiglas plate with a small hole is clamped onto the head with a little silicon sealer. The head is filled with water using a 100cc syringe. The compression ratios can be determined from the measured volume. A stock high head has a volume of about 294 cc or 17.9 cu in. The volume is reduced by 2.8 cu in because the piston rises 5/16 inch above the deck. The volume is increased about 0.8 cu in due to the head gasket. For a stock head, the combustion chamber volume is 17.9 - 2.8 + 0.8 = 15.9 cu in. An engine with stock bore and stroke has 44.2 cu in displacement per cylinder, so the total volume when the piston is at the bottom of its stroke is 44.2 + 15.9, and the compression ratio is (44.2 + 15.9)/15.9 = 3.8. The values determined for other heads are shown in the table below. The volumes for milled heads were calculated using the open area of 18.3 sq in and the thickness of material removed. This works out to about 3 cc for each 0.010 in milled. For example, milling a head 1/8 inch reduces the volume by 18.3(0.125) = 2.3 cu in or 37.5 cc. The compression ratio calculations can be modified for other cases. The table shows compression ratios for a engine with stock bore and stroke and values for one modified with an 0.060 overbore and a Model A crank (48.5 cu in per cylinder). The rare antique heads (Green and Riley) could have been modified at some time in their past, so the head volumes may differ from their original values. <!--mstheme--><CENTER><!--mstheme--> <!--mstheme-->[/FONT]<TABLE cellSpacing=2 borderColorDark=#006600 cellPadding=7 width=683 borderColorLight=#66cc33 border=1><TBODY><TR><TD vAlign=center width=298 bgColor=#c0c0c0 height=42><!--mstheme-->[FONT=Arial, Arial, Helvetica]Head<!--mstheme-->[/FONT]</TD><TD vAlign=top width=98 bgColor=#c0c0c0 colSpan=2 height=42><!--mstheme-->[FONT=Arial, Arial, Helvetica]Head Vol. (cc) (cu in)<!--mstheme-->[/FONT]</TD><TD vAlign=top width=95 bgColor=#c0c0c0 height=42><!--mstheme-->[FONT=Arial, Arial, Helvetica]Corrected Vol. (cu in)<!--mstheme-->[/FONT]</TD><TD vAlign=top width=201 bgColor=#c0c0c0 colSpan=2 height=42><!--mstheme-->[FONT=Arial, Arial, Helvetica]Compression Ratio Stock Modified<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Stock Low, 1909-10<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]262<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]16.0<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]14.0<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.2<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.5<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Stock Low<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]278<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]17.0<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]15.0<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.0<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.2<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Stock High<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]294<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]17.9<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]15.9<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]3.8<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.0<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Waukesha-Ricardo<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]272<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]16.6<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]14.6<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.0<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.3<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Haibe<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]255<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]15.6<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]13.6<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.3<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.6<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Green Engineering<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]218<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]13.3<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]11.3<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.9<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.3<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Riley Multi-Ford<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]183<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]11.2<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]9.2<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.8<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]6.3<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Z Head<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]203<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]12.4<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]10.4<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.3<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.7<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Reeder<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]200<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]12.2<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]10.2<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.3<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.8<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Stock, milled 0.125<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]257<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]15.7<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]13.6<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.2<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.6<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Waukesha-Ricardo, milled 0.050<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]257<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]15.7<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]13.6<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.2<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]4.6<!--mstheme-->[/FONT]</TD></TR><TR><TD vAlign=top width=298><!--mstheme-->[FONT=Arial, Arial, Helvetica]Z, milled 0.050<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=30><!--mstheme-->[FONT=Arial, Arial, Helvetica]188<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=68><!--mstheme-->[FONT=Arial, Arial, Helvetica]11.5<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=95><!--mstheme-->[FONT=Arial, Arial, Helvetica]9.4<!--mstheme-->[/FONT]</TD><TD vAlign=top align=middle width=98><!--mstheme-->[FONT=Arial, Arial, Helvetica]5.7<!--mstheme-->[/FONT] </TD><TD vAlign=top align=middle width=103><!--mstheme-->[FONT=Arial, Arial, Helvetica]6.1<!--mstheme-->[/FONT]</TD></TR></TBODY></TABLE><!--mstheme-->[FONT=Arial, Arial, Helvetica]</CENTER><!--mstheme--> <!--mstheme--> <!--mstheme-->References:<!--mstheme--> *Huntington, Roger , Souping the Stock Engine, Fisher Books, 1950[/FONT]</TD></TR></TBODY></TABLE>
Did a 1,200 mile round trip to the Big Easy this weekend to pick up a few spare roadster parts! This cowl came from a Mail Truck. Has the cowl band that allows you to not run stock roadster windshield stanchions. You can choose a custom style windshield.
I agree 100% with this. You have a poor running SBC and lose 50hp you're not really going to notice it. You have a poor running Banger and lose 50hp and the thing is barely going to run. Sometimes I wonder if this is why early engines (Bangers, Flattys, stovebolts) get reputations for being underpowered. Great links on the T heads, Biscuit.
They came in all shapes and sizes! Here's my 1-1/4" downdraft mocked up on a manifold from a B engined generator.... I may just try it out. It's a smidgen bigger than the Tillitson! But if I really wanted to go much faster I could always start by throwing away the body... Apart from that, little else has changed except a little altitude adjustment to the front. Finally worked out all the pieces! Brakes seem improved with the B cast drums, although the handbrake support ring collapsed tonight bringing everything to a shuddering halt. Reversed all the way home! Reverse eye spring for the rear is lurking in the garage as the next plan.
I might add here for those who have never CC'd heads etc and may be contemplating doing it. ,don't use water .it has surface tension which affects the reading .Use ATF. it's also important to incorperate a used head gasket to include the volume of the gasket open space in readings. Most,if not all of Roger Huntingtons work is still relevent today and a pretty good driver considering he was wheelchair bound.
Monkeybiker, looks flippin sweet! I plan on upgradinf my roadster to a 32 axle and brakes as well! What a bitchin ol car!
The front has come down quite nicely. Like it. Be interesting to see how you check the dashpot oil, Phil...
Use red color and you can dish the remainder up at dinner ...would you like a dash of fine red my dear?
I'm saying tara for now. No, I didn't turn into Cilla Black but I have sold my 103E so apart from the broken engine in the garage and some go faster goodies I am bangerless at the moment. I've had a lot of fun with these little engines
The old guy that showed me how to do it used coffee. He drank coffee all day long and allways had it around. Thanks to another hobby of mine, I like to use discarded model engine fuel. I have also used WD-40 and Marvel oil too. Although ATF is the cheapest of the above. .
Just received a well needed part in the mail today. NOS 6v Autopulse fuel pump, too bad it wasn't $12.36. Any idea how old this is? I hope it is old enough to have the brass bellows.I guess I'll find out after a few tanks of 10% alcohol fuel. Can I wire a 6v relay to the ignition circuit so the key switch controls the pump? I was told tapping into the switched B- could affect the ignition. Tad
I am finishing up a cam driven distributor drive for a customer's bonneville effort, just got my first side drive mag assemblys back form the foundry, and of course the stock A timing covers in aluminum are keeping me busy. I seem to enjoy the manufacturing side of hot rodding much more these days. A good pal told me about a killer deal on a coupe. I gotta set up a time to go see it.
Well I finally did it! After driving my almost stock A bone several thousand miles last summer, I put one of those Weber carburators on it for a little more umph and sun of a gun my rods now sound like my garbage disposal. Had a to make a decision about what to do this summer and decided to put a fresh motor that was scheduled for my roadster build and has been sitting on a stand for several years into my stocker. If all goes well, it will be back in motion in a week or so and I'll be thinking about a replacement for the hi boy roadster.
WOW thats RED against the black and body colour! What jet size would you run on a twin 94/97 manifold like that? I ask b/c I am running a single 94 and its a little rich, but have a twin carb and want to run that, but i am a little gun shy of running it rich all the time.
You must run a relay and just connect the relay coil to the igniton 'hot' connection and the other end to earth on the body.. Turn on the ignition,pump starts. If you know anyone handy who has a 1970 or earlier mercedes wreck laying about ,ask if you can have one of the relays( and the bakelite plug,just unsolder the wires from the pins and use them again). They are absolutely bullet proof and the look will suit a banger powered rod ,rather than the plastic cube ones. Wiring is the same, old or new.
Need some help. Trying to get the banger running. I know it runs because the guy that rebuilt it for me had it running very nicely. The only thing I have changed is the carburetors to a Burns manifold with 2 97s. I have a stock model distributor on a Winfield head running 6V. The starter hooked up directly to the Battery as well as the black Amp wire to the same starter post. I then have a lead wire to a junction panel from the starter to the panel. On another post, but connected to the same circuit, the generator is fastened. A red wire lead from the ignition switch is hooked up to the (-) negative side of the coil. The (+) positive side is to the distributor where the pop out ignition would be connected. I am not running a pop out ignition, just a simple key ignition (off/on). Following all instruction to place the rotor on the number #1 firing post. I believe I have the points set correctly for a 1243 firing order. My problem is that I cannot get the brand new coil to fire out to the rotor/spark plugs. My connections are hot at the starter, panel, both sides of the coil with ignition on and at the points. Any help would be appreciated. Thanks, Chris
Is the coil a 6 volt? if so it may be in the distributer shorting out. check it with ohm meter to see if it is grounding out with points open. also check to see if coil wire to top of cap into rotor is good. sounds like you have it hooked up right . hope this helps
Hey Phil the ol' ceedan is looking good,Heres a pic of mine now a bit lower. Not very happy with the Vicky low at the moment it is too low and the caster angle has gone way off giving me the death wobble and not much spring to axle clearance.(front is down 3")the reverse eye spring has also been de-arched which although the car looks good it really needs to come up 1.5" so I have ordered a new replacement spring to be sent to the hotel in Vegas(cant wait!!) this is a standard reverse eye spring so it should bring the ol girl up a little. Anyone else on the banger meet going to VLV Rockabilly weekend ?
You have any shots from the front? You around this weekend? Pop by if you have a mo - or I'm heading through maybe Sunday afternoon. I'd like to see the unwanted spring as I may have a plan for it...!
Chris do the basics first. check the coil between (+) and (-) for continuity.( I run a hairdryer over them to get them up to working temp,the results can surprise sometimes) check you have voltage to the coil with the ignition switch on Check the continuity of the high tension lead from the coil to the distributor. Check the cap and rotor for ANY track marks or cracks. Check the rotor is right home and the disrtibutor is in fact turning. ensure points are not shorting to ground through the low tension circuit . swap the condensor for as known good one. If all check OK, check timing against number one. Check for a good spark,not a weak yellow spark. If that is OK and still not firing check for compression. If you have compression ,check fuel by simply splashing a little fuel down the intake .
Clark, Darren... the letters are right next to each other on the keyboard! Sorry. Seriously though... we should talk via PM. Might be a fun experience for all of us! Right now we're on schedule to have the car done by 2010. We have a motor program, but realistically, it's not going to be ready until the following year.... unless the money fairy visits us! Sam
The Jalopy Journal
