I have a simple question. What suspension are you A guys running. Is it stock or later 30s/40s. I want to build a banger ,26/27 T roadster on a Model A chassis 16" Ford wires , reversed eyed springs. I read that some guys are going 60/65 mph with hopped up bangers and the right trans. So will the stock suspension hold up to that? My thought was just to pick up a decent complete chassis and go from there. it makes sense if you can use all of it, but if you cant. Then I would have to rethink this. Anyway would like to hear some input.
Wow, this thread with all the combustion chamber info needs to go in the Tech-o-matic. This is the best banger meet in months! -Dave
Thanks so much for you coments and input which is what these flathead guys are looking for. I am just presenting information I have to help them understand what is going on in their engines. Most of what I am submitting is passenger car info and may not apply to racing and visa versa. I am not an expert at this but am trying to show them what is happening in these particular instances presented in the engineering books. Racing and high performance is different matter and we all want look at that also and hope you will show us all you know and what everyone else has found. Most of these bangers that are on this thread have a mild compression increase and this passenger car info is applicable to them. The movie I mentioned I looked at in the sixties when I was a kid at an old car club meeting. It was a simulation by MIT students? of a V-8 Ford flathead and the model head had the same CR 6:1 ? or whatever a 59AB has. The head on the simulation side was an exact copy that was clear. The engine ran on the other four cylinders and they were able to vary the speed from an idle to full throttle. They used some form of smoke to simulate the flow so you could see it. It was close to real conditions except that there was no explosion. They also were able to show it by also using a high speed movie camera? They could also show it in slow motion. You could clearly see the valve flowing all around, not just to the side even in the tight Ford V-8 chamber. They mentioned that in their engineering studies along with TRW? what we were looking at was not that much different than what other researchers had been able to capture w/high speed photography on actual running test engines. Ricaro also was able to see these events by photographing them on his running test engines which is incredibly interesting if you really look into it. I once looked at a video that actually showed a running engine combustion chamber an it was fascinating. You could see the intake as a fog and also watch the flame travel.
SCHOOL me master... I can't do much about the intake length in the engine. I could be wrong. The A-Bs look to me like the intakes are about the same. Not like most OHV engines. If you can make the time I will save all and any info you got about any thing. many thanks Bill
some where on here is a great write up on how to tune intake runner length (how to calc sine waves and all that jazz). either post it, good stuff to know. next we can learn about exhaust extraction. thanks for all the great stuff T-Head.
Quote:Originally Posted by 88daryl88 Breathing sideways, under the valve head might not be as disasterous as it first appears. Consider the high performance Two-Stroke engine which does all it breathing sideways through rounded rectangular ports,yet manages to produce the most HP/cc of any naturally aspirated engine. Many Flat head engines have very large valves on relation to their bore diam. You are right if these valves ACTUALLY ONLY breath sideways it is not disastrous. But for them to ONLY breath sideways and make power the valves have to be huge and that has always been one of the limiting factors in a flathead. I don't know a thing about two strokes but I am guessing that it flows sideways out of the port and they size it to what is needed. Thanks for showing us the photos of the other heads. Is there anyway we can see actually where the valves are in relation to the side of these combustion chambers and also find out how much room there is over the top of the valve at full lift?
I like how you think. I looked for that post last year I never did find it. Sorry T-HEAD I hope you like to post. I will go buy more ink some I can print all this info
Thanks.... And I appreciate you getting back to me on the Rajo manifold. What I am looking for is one like this without the heat riser.
70 HP..... The Jobs OK but not easy, you have to make most of everything you need..... Just ask Herb he does the same thing as I.
TH, I'm starting to think you might have a problem. It's called hoarding. BTW, is that Thomas engine the same one that was sitting under your computer table at one time?
I wish one of you guys would do a banger building seminar. I would definitely buy a ticket. I bet a few other people on here would also. Not only would it be informative it would be a blast! TK
Well. There you have it gentlemen. Anyone else have a better footrest? TH, i've been meaning to ask you what series steel are these cranks made from? 4100 i'm guessing.
2 strokes have the advantage of a pressurized charge that forces the air / fuel mixture into the cylinder. Once the charge is in the cylinder, the tuned pipe draws even more air fuel in and then packs it back into the chamber much like forced induction. All without the HP robing requirements of a cam and valve train. But your Sideways flow comments are valid. The valve size and port shape is the key to this. That doesn't say that it is ok to have the combustion chamber wall right next to the valve. If the head is too close to the valve, there will be an "Eddie" flow effect in the area around the valve closest to the chamber wall. This has a negative effect on air flow. In our case @ 25% of the valve face is restricting flow. Dennis Piranio has done many dyno tests on the banger with many different modifications and the highest HP results for a flat head was with a 7.25:1 head and 1.700" intake valve. I have seen a picture of the modification he does to the Yapp Lion's head and what he basically does is open up the combustion chamber around the intake valve to improve flow in that area of the valve. Here is a link to some of his dyno sheets: http://www.modelaparts.net/dynosheets.htm/dynosheets.html Keep in mind that it takes more then a head change to attain these performance gains. Discussing theory is fun lets keep this stuff going. I will add this discussion to the Banger info list. .
Thanks TH. I'm somewhat amazed that this alloy was chosen. I would think the cheaper 4100 is just as suitable for a low RPM application as this.
4340 is much more resistant to twisting as fours w/long journals do (A & B Ford center and rear mains do this also which leads to breakage). In the total cost it really is not that much more % wise. If you look close you will notice this is five mains which ends a lot of problems. The original crank in this engine was cracked all the way around both sides of #4 rod journal and also both ends of the rear main. Both of these areas are where most fours break. This is a big 525 CI four so it needs to be a very good alloy to live.
Chris..... Nice truck...... heres a nice 30-32...... the photo is so dark its hard to tell which...... Can't tell if its a B though....sure looks nice. The plate is Oregon from 1947.
I see in the dyno sheets they call out a Crane f 220/320-12 camshaft last mouth I looked up that cam on the Crane web sit and found no info I dont think they make it any more any one have a spec sheet on this cam <table x:str="" style="border-collapse: collapse; table-layout: fixed; width: 528pt;" width="704" border="0" cellpadding="0" cellspacing="0"><tbody><tr style="height: 12.75pt;" height="17"><td class="xl2322751" colspan="2" style="height: 12.75pt;" height="17">DESCRIPTION:</td> <td class="xl1522751" colspan="8">BURNS MANIFOLD, STROMBERG CARBS DONOVAN 7.3-1 HEAD, 26 DEGREES</td> <td class="xl1522751"> </td> </tr> <tr style="height: 12.75pt;" height="17"> <td class="xl1522751" style="height: 12.75pt;" height="17"> </td> <td class="xl1522751"> </td> <td class="xl1522751" colspan="5">HEADER, 1.700" INTAKE VALVES, PORTED BLOCK</td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> </tr> <tr style="height: 12.75pt;" height="17"> <td class="xl1522751" style="height: 12.75pt;" height="17"> </td> <td class="xl1522751"> </td> <td class="xl1522751" colspan="4">CRANE F 220/320-12 CAMSHAFT</td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> </tr> <tr style="height: 12.75pt;" height="17"> <td class="xl1522751" style="height: 12.75pt;" height="17"> </td> <td class="xl1522751"> </td> <td class="xl1522751" colspan="2">OPEN HEADER</td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> </tr> <tr style="height: 12.75pt;" height="17"> <td class="xl1522751" style="height: 12.75pt;" height="17"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td> <td class="xl1522751"> </td></tr></tbody></table> <table x:str="" style="border-collapse: collapse; table-layout: fixed; width: 528pt;" width="704" border="0" cellpadding="0" cellspacing="0"><tbody><tr style="height: 12.75pt;" height="17"><tr style="height: 12.75pt;" height="17"><td class="xl1522751"> </td> <td class="xl1522751" colspan="4"> </td></tr></tr></tbody></table>
Before the second world war, motorcycle racing in this country was controlled by the American Motorcycle Assn.,and since the majority of members of the board wher associated with either Harley, or Indian. The rules for class C racing (which covered nearly everything except hillclimbs) were set up so that the domestic sidevalve products were allowed 45 CID, and OHV (primarily English) were limited to 30 1/2 CID, the argument being that the sidevalve engines were less efficient and were given this displacement handicap. Indian stopped supporting racing after the 1948 season, but several riders were still competitive on dirt tracks with their Indian Scouts for a few years. Harley found it harder and harder to stay ahead of the OHV (and OHC) bikes, and in 1952 came out with a all new 45 inch flathead, called the Model K. The stock bikes were slugs, but fitted with a factory kit of cylinders with larger polished ports, larger carb, higher compression heads and a set of cams that woke up about 3000 RPM, They became a fun bike to ride (my second motorcycle). With even more tuning Harley engineers were able to keep this antiquated engine design competitive for far longer than it deserved to be. The factory poured many dollars into developing a specific set of cams for each race course, and many other special parts. Harley is credited with the most highly developed sidevalve combustion chamber- and while it may not be the very ultimate, studying what they came up with and going from there might prevent a lot of "re-inventing the wheel" SOOOO, Here you are-- pictures of a factory KR (K racing) head Chew on this a while kiddies!!! Not sure what the limit is per post so continued--
Herb and I both are trying to educate you kids and he just came up with a textbook example that I mentioned the other day. The KR heads were and still are excellent. Good going Herb. I am posting more chamber info from a book that was state of the art in 1967 by Phillip Smith who is very well regarded engineer. Read what he has to tell us about flatheads back then. He also mentions that even at that date Ricardo designs were still valid.
The "pressurised" transfer is sometimes over emphasised. The 'pressurisation' is caused by the displacement of the piston into the crankcase. A pressure increase is possible if the case volume is minimised by packing the crankwebs, under piston etc. This was done to aid scavenging in the early days, but transfer timing needed to be dramatically reduced to prevent loss of charge, resulting in extremely peaky power bands. Not a priority in modern engines. In any case, the total volume transferred is one cyl displacement volume. This is basically equivalent to the cylinder charge in a 4-stroke produced by the vacuum created by a decending piston. The effects of a tuned expansion chamber exhaust, that's a whole other thing...
Nice photos of the KR heads, thanks Herb. What year are they from? My observations: Huge valves in relation to bore diam. Intake flow designed for "over the valve" with increased chamber volume and clearance needed for plug on top of valve. Exhaust flow predominately "under the valve" If any-one has a copy of "Tuning for Speed" by P.E. (Phil) Irving he has an excellent chapter on "side-valve" motorcycle engines.
88daryl88 wrote Nice photos of the KR heads, thanks Herb. What year are they from? Not sure, but will check with the owner. Will also ask if he has a loose cylinder that I can get a shot of. The head came to our shop to get a couple broken fins replaced. Herb
The Jalopy Journal
