Greetings, i was wondering what you flathead guys are running for compression? any mods done to the bottom end? from the sound of the video, the flathead seems to be buzzing a bit over 5k rpm? also, regarding an in-out transmission... does the car have to be pushstarted? im not very knowledgable when it comes to manual transmissions, so any wisdom anyone can provide will be appreciated. we have a '54 passenger car 3spd, it was bolted behind a Ford Inline 6. we are going to use a side shift tranny because of the setup, (rear engine). thanks!
I am pretty sure an in/out box has to be push started- think sprint car. Don't think they normally have a clutch.
You need gears to get these things off the line. If by "in-out", you mean using only high gear, it aint gonna work. You're thinkin' nitro.
thanks guys, i kinda shy'd away on my engine spec question in case no one wanted to reveal what they were doing, (some people are weird that way). Mac - 6000 rpm through the lights? thats pretty cool... have you guys torn into the motor to have a look at the bearings yet? do you think the inclusion of a center main strap would be helpful in keeping things together longer? for the most part i jumped the gun on the in-out question.... it was braught up by av8 in a very early rail post, so based on the self start rule its out of the question.
Doc parsons built the engine, he isn"t worried. We cut the filter open and check it every oil change. And like I said I hold my breath.
Whitey McDonald says he runs a stock bottom end with nitro. We ran a stock bottom end on our race flatty, but it was a shorter stroke engine on gasoline.
i have read about both sides of the coin regarding stock bottom ends and reinforcements and it seems as if the need to use reinforcements is 50/50... its recommended but not absolutely necessary. correct me if im wrong here, but there are plenty of checks a person can do to make sure the block & rotating assembly are in the best condition they can possibly be in. ie. pressure check, magnaflux with a large amount of scrutiny in the Main area and balancing of the crank/rods will field a pretty stout and reliable motor, (i guess the same could be said about any engine). cylinder pressures with nitro must be really high? ...even with a small dose of nitro... im curious to hear what some of the build specs are, ie. stroke, piston, comb. chamber CC, bearing clearance.. Jim, what do you think the compression is in that particular motor? and do you know what the redline is?
Whitey tends to build 3/8x3/8 type motors with a little variation thrown in so he can get the rings he wants. If I recall correctly, his biggest are a tiny skosh over 300ci. He runs a dry block and to keep the copper-clad gaskets in place, he pecks the deck with a punch around gasket sealing surface. This helps lock the gaskets in place. He told me once he wouldn't recommend that for a wet block. He builds his strokers old style with lightly polished 21A rods and full floating bearings. He has used some hand made rods welded up by a fellow that worked for Jerry Livingston (early drag racer and now Bonneville racer). These had Chevy 327 bearings and tube beams. Whitey said he didn't think they were any better than Ford rods. His cranks are what he calls forged Merc cranks that are seriously lightened. I took a bunch of pictures of one he was tossing because it didn't ring any more, but the pictures were slides and my scanner is such a pain to use any more, I haven't converted them to an electronic version. I have seen Offy 400 heads on his cars and, I think, 375s. He says he does a little work on them. He has also made a set of very high compression heads that he uses most successfully at the Flathead/Inline Nationals in Denver. I have no idea what the chamber volume is on any of these once he has worked on them. No idea about his bearing clearances or any other clearances. I'm not sure how well it would translate anyhow. That nitro gets kind of hot. I've never seen a tachometer on Whitey's car. Unnecessary weight, I suppose. No oil filter or dip stick either. Back when manual four speeds were the transmission of choice in blown gassers, Vern Holzman used to pilot the Nail and Holzman BB/G car. Vern once told me that Larry Nail kept asking him what rpm he was shifting. Vern said he told him he didn't know. He was busy driving the car. I think Whitey has the same idea. If I had to guess, I would say it doesn't see much over 6,000 rpm, but that would strictly be a guess. Rick Schnell told me his flathead dragster was turning 7,000 in the traps on a seven second run, but he thought that was way too high. He was looking for a taller gear to go in his non-quickchange Halibrand rear end, but he sold the car, so I don't know if he ever found anything. He had a full girdle and all the best rods and crank. I think you need all that with blown nitro. What was the question?
hey jim, thanks for the info... i like detailed answers for more random info, i was emailing back and forth with Brian King who with his father holds a 200mph record in an XXF streamliner as well as campaigned an 8sec Ardun FED with the same motor, it was blown/unblown and ran nitro. this is what he told me: "We always use the 8BA, and so does everybody else. Our preferred bore is 3 5/16" for blown and unblown applications. Blown we use a 3 3/4" stroke, whereas unblown we have gone as high as 4 1/4". When we retired the dragster last October after the NHRA Reunion in Bakersfield, we retired its motor which was a blown 3 5/16" X 3 3/4" motor. That motor was probably the best we have ever built in that we ran it for FIVE years between rebuilds! After each meet we would look at the bearings and do a leakdown on it, and it just ran and ran. That motor had set the blown fuel record at the salt at 219, the blown fuel record at the lakes at 210, and made over 20 passes at the drags in the mid 8's and over 160mph. The C4 tranny we use was wearing out before the motor did." perhaps the same bore/stroke specs will work for the flathead... although, he doesnt go into fine details about what sort of modifications were done throughout the bottom end, i can always find out.
Mr. Mac, that fuel stuff will just make you spend more money. Not to minimize the King's accomplishments, but I wouldn't think a blown nitro mini hemi was working all that hard only turning mid 8s. I saw Whitey go 8.77 a few weeks ago injected and with flat heads. Still, 20 runs on nitro without touching it is not bad. Not bad at all. I do think it would be interesting to see just how much difference the stroke would make in power output of a flatty. Back in the day there were a number of AHRA classes for "stock" flatheads. Our short stroke Ford crank car was quicker and faster than the 4" Merc crank record holder in the class above us, and his was in a lighter '40 coupe body. I'm not sure it was apples to apples because our car was very seriously built to the limit of the rules and I don't know what he had inside. I often thought about cheating and telling them our engine was bigger than it was. But I digress. I suspect Doug King used a Doug King main cap and girdle on the bottom end. Since he made (makes?) and sold them, I can't imagine him not using one.
a blown Ardun is a REALLY cool motor, but by the time it's all screwed together it's about as closely related to a flathead as Rosie O'Donnell is to Heather Locklear. As I go thru design iterations, the thing I keep getting stuck on is the relationship between engine torque and the contact patch. Between the two tires, there's less than 100 sq. in. of tire contact. Using some old rules-of-thumb, the upper limit of launch HP is between 100 and 120 HP...any more and you cook the tires. Therefore, you gotta either be able to modulate the hell outta the launch - which is where an auto trans is magical - or the motor has to breathe like a Sherpa on the big end. I was planning on a 400+ ft/lb motor, but all that's gonna do is cook the tires. A shorter stroke and good breathing characteristics would favor an HA/GR, IMHO.
I think this illustrates the genius of both the tire rule and the transmission rule. Essentially the more money spent on a killer motor the more driving skill will be required to get it cleanly off the line. Chuckspeed is likely right that the torque limit will be somewhere south of 400lb.ft. This increases the variety of powerplants that people will feel free to use and will help avoid the seemingly inevitable belly-button nature of heads-up racing.
jim, awhile back i looked at the El Mirage and Bville records for the classes i wanted to run in, the flathead and Ardun records are very close in MPH. 20 passes on a nitro motor is very impressive and im sure a lot of good and bad experiences have gone into its success. when you say short stroke, what crank would you use for that? or is it a shorter rod in a later flathead? perhaps with the 3spd and tire rules a high rpm short stroke FH would be better... slower off the line, but quicker by half track... im just speculatin' i think Ardun's and flathead are 50% alike... both have weak ass bottom ends and are subject to the same process's to make them more stable. i enjoy both equally.
I was thinking of just a straight Ford crank - 3 3/4 inch stroke. Rod lengths are all the same at 7" except for at least some of the French flatheads. I'm trying to remember a discussion or pontification about flathead rod lengths. Whoever it was thought the rod angle with a 7" rod was better with a longer stroke if I recall correctly. However, the odds are not overwhelming that I remember it correctly or that whoever said it was right. Flatheads are such enigmatic beasts.
The Jalopy Journal
