Mopar, Sounds and looks great. Hud, Thanks for the info on flathead ignition timing. I've never had one on the dyno. Ron
Peeking in, hoping for some news. I was tossing Ron and Mopar's numbers around at the Rumble this weekend - folks were impressed with what you fellas are doing. The more I think about Ron's Jimmy, the more impressed I get. The hit count on these dyno threads should tell us something, people are interested. Hud
I'm stuck! this thing starts missing at 4750rpm, and I don't know what to try next to get it to quit. The engine is built capable, and acts like it wants to go, MAN does it catch R's quick from 2000 rpm to 4750. Then it picks up a miss. Today they pulled the Magspark and red wires, replaced 'em with a bone stock distributor and cheapo wires. Same Crane coil, but with a ballast resistor. Total advance at 38*. No change. Added an MSD 6 box, no change in the miss, but it picked up a horse and a half!! At this point we're all thinking the miss is not ignition related, but what are we looking for? anybody got any ideas, hints, ANYTHING? here is the link to the post I started on the main board http://www.jalopyjournal.com/forum/showthread.php?t=298125&highlight=mopar+dyno tomorrow they're going to open the plug gap back up, recheck the dyno setup, and then????
Chitty coil? Bum ballast? It would be hard to believe bad wires, with two sets, but weirder Chit has happened. Do your AFR #s do anything weird during the 'miss' (weird as in not what's expected, which would be unburned fuel and air in the exuast)? Have you checked the coil has a good primary ground, ground strap between the engine and whatever the coil's grounded to? +12V to the ballast, +6V-8V (ish) coming out of the ballast? Reversed polarity at the coil? All these are reaching I know, but you've already tried the obvious stuff.
You wouldn't happen to know your manifold pressure right before the missing starts? How's your A/F ratio just before it starts to miss. It may be time to bring in that pesky step-up jet. You also might want to check your tappet clearances, flatheads have a tendency to close up your gap after break-in. On the positive side, that rev-rate is kinda shocking huh? They'll get there in a jiffy.
Just from running my Plymouth four flatmotor, I would back down the timing some more and see what happens
Is it possible to hook it up to a oscilloscope that would at least eliminate the electrical problem. what about point bounce maybe one weak valve spring?
Couple very amaturish thoughts. Step up jets in the carbs. These are designed so that the high vacuum signal from the manifold holds them closed against the spring. The vacuum drop during acceleration allows the spring to open the jet. If the springs are removed, I would think the needles would stay seated in the jets thereby not providing any enrichment. make sure the slots in the carb to manifold gaskets allow the vacuum port to be open to the port in the base of the carbs. Second, are you getting point bounce at the higher rpm? maybe stiffer springs for the points would help. Another thought on ignition; A slant 6 distributer can be modified to work in a flathead by switching the drive tang, and doing a bit of machining on the body to fit the hole in the block. Then you can run MOPAR early electronic ignition eliminating the points. You might also consider some one inch or 1 1/2 inch spacers beween the carbs and the intake. And as a personal observation 6K for and engine with nearly a 5 inch stroke might be expecting just a little more than is mechanically possible.
That engine is too cool! I have a long block 237 with Spitfire head and I am envious! I have a question for you. I have been trying to figure if dual carbs are worth putting on the engine. Everyone seems to have a different opinion aout how much difference a dual carb/intake setup would make. I have never seen one of these Dynoed with single carb then dual carb.......wanna humor me? I doubt it but good luck with your setup. Can't wait to see your progress.
Mark; I really enjoyed conversing with you at the Rumble. Thanks for pointing me towards this thread. Did you pull that black Hudson onto the dyno rack after I left? Moparsled; I am running a dual point conversion in my long block Mopar flathead. I am not pushing for high RPM's but I have been up to 4500 a time or two. Just a tought on your misfire. For the dyno test get rid of the ballast resistor and run a full 12 volts through the coil.. This will shorten point life but for a dyno pull who cares. I also agree with Hudsonator that too much spark advance is not good. You mentioned that you added spacers under the spark plugs. During assembly of my engine I measured valve lift with a dial indicator to insure I had ample room for the spark plugs. My cam is 270 duration @410 lift for both intake and exhaust. Hudsonator mentioned that valve clearance can and will close up with heat and mileage. What was your initial valve lash setting? I think I set my valves at .014" cold. Have you indexed your plugs? What is the depth of the spark plug threads in your head? I have heard of some aluminum heads with non standard plug thread lenghts. I am also running dual B&B carburetors that I got from George Asche. I have a pair of Langdons Carter Webbers sitting on my bench but the longer I run the B&B's the better I like them. Your engine and header setup really looks good. I hope to soon hear of a 200 HP pull.
I've been looking in my engine design textbook, and I think the long stroke is making your problem. Seems the average piston speed is the real limit on the high end rpm. "We will find that a fundamental limitation on the maximum gas flow is the occurrence of sonic flow at the valve aperture, and we will be able to relate this to the average piston speed" Later on he notes that the upper limit for average piston speed(APS) is around 4000 feet per minute. This APS is V = 2NS where N is RPM and S is stroke If you're running a 230(?) then the stroke is 4-5/8" Changed to feet this is 0.3854. At an RPM of 6000, this would put your APS at 4625. If you solve for N and use 4000 as the constraint it gives you a max RPM of almost 5200. Since you're stuck at around 4750, it may be that you have an issue with a spring(point or valve) or that the valve size in this engine is too small. Smaller aperture-higher gas flow-quicker sonic flow conditions. I'm into these motors but I've never looked into changing valves. It is possible. The larger Chrysler engines had larger diameter valves with the same stem dia. and length. Another option is going with a 218 crank 4-3/8" (0.3646 ft) stroke gives a max RPM of almost 5500. Though you may still run into the restriction you are seeing at 4750. Take what you will from this, I'm not trying to rain on your parade. I want to hear your motor do it!
I emailed Earl Edgerton, he backed up what many of you have said- max rpm in his experiences is about 5200. Hudsonator- what's the max you saw on your tractor? He also echoed the "too much timing" comments, which I wholeheartedly agree with. what gets me about this, is that the engine isn't running out of steam at 4750- there's more left in it. We are getting out of the throttle at that rpm because there is an audible misfire, miss, stutter, stumble, whatever, at that rpm. Also, and I have forgotten to mention this previously, it is in exactly the same spot whether under load or free-spinning. I made an adapter hat tonight to fit a 4 barrell onto the 2x1 intake, if the 4bbl doesn't change anything, and the ignition doesn't change anything, then it must be mechanical.
The maximum rpm on the pulling tractor was 6000 rpm when it was fresh. It would get there fast too. Even though it would turn 6000, I quit running it that high because it was way over the cam anyway. Off the line at 2700-3000, buzz it up to 5000-5500 on the track, and hold it there until the load pulled it back down to 4700-4500. No telling how many runs were made with this recipe. Now, since the engine has aged, it won't turn over 5500 without the exact "bobbling" you are talking about when revved under no load. I passed it off to weakening valve springs. I never fixed it because it was a nice rev limiter that effected nothing below its "bobble" rpm. The piston speed at that rpm is rather high, and will start to limit your ability to make power, but its not going to limit an engine's ability to attain a certain rpm. Its just that if you hold it at that rpm and the piston material can't handle it - you are pumping 6 pieces of shrapnel at critical velocity. That's the reason I quit whacking the tach at 6K. Somewhere between 5200-5500 is more reasonable, but still way high. I would check the tappet gap, just in case. I still suspect that your valves have "settled" a bit and maybe cut your gap a little shy. Hey Coatney! Ain't this interesting stuff? Good to see you here keeping up with developments. You'll catch this bug and have a HA/GR towed behind your pilgrim, I can see it now. Hud
GOOD NEWS!!! Replaced the Autolite 295's with Autolite AR73's gapped at .035" Replaced plug wires (3rd set) fabbed a carb adapter using a flat plate bolted directly to the Edmunds dual intake, and bolted a single 4bbl top (just a lid basically) for a Weiand Team G tunnel ram to it. Edelbrock 1405 carb. 5100rpm!!!! the air/fuel #'s were terrible, the horsepower was terrible, the "intake" was terrible, but we got some R's. Turns out bad plug wires SUCK ASS!!!! Pulled the four barrel junk off, put the B&B's back on, changed the #69 idle emulsion tubes for #71's, and ran it. Too lean, but NO MISS, and it HELD 4990 rpm. On the low end, it peters out a little soon, between 1200-1400 rpm. I have a pair of #70 Idle emulsion tubes, I might stick them in, and I'm going to put the step up springs back in. FINALLY we get to try to tune this thing!!!
BINGO!! I'm glad it was a simple thing. Lots o' headache nonetheless, but at least it was found. I have a feeling we'll be asking you for discourses on the venerable B&B by the time this is over. You're going in good directions now. Have you taken any manifold pressure readings yet? Hud
whole mess of dyno pulls today, and I would say progress has been made, however, I'm kinda two steps back at this point. Tried to get the B&B's "in", and got to a place that wasn't perfect, but was satisfactory enough for me to leave. Fat, but not terrible, not as consistent as I'd like. Played with the timing some- it likes 34 to 36 degrees. Pretty close to earlier peak #'s Pulled the exhaust pipe off--- HOLY CRAP IS IT RICH NOW!!!!!---screwed me up all over again. This thing is just dying for more air. My jet selection is limited, but I put in the smallest idle emulsion tubes and step up jets I had, and cut two coils off each step up spring. This is where it was "satisfactory" with the tail pipe, and WAY rich without. guess we'll try it Monday with no step up springs again.
Some other Dyno numbers. I went to a cruie in at the college I used to work for. they have as part of their automotive technology facility a Mustang Dyno lab. This is a chassis deal with the rollers and eddy current braking resistance. engine is a 230 56 plymouth, dual Carters on a Fenton intake, Single ezhaust, stock cam, .040 off the head, .010 of the block. I limited the pulls to 70 mph. got this at the wheels. HP 74.2 @ 3328 RPM / 66.7 mph Torque 157.6 @ 2430 / 48.9 mph add 20% for drive train losses = 89.2 HP and 189 lb ft torque engine was rated at 120 HP and 200 lb ft at the flywheel by the factory. Has about 7k on it since a rebuild.
Autolite and Champion have made "racing plugs" for a LOOOOONG time. And the reason was that the normal plugs were not made for the temperatures in the combustion chambers in high performance engines. Plugs too hot will preignite like a glow plug does a diesel engine! Spark plug wire is seldom a problem, as the voltage on the plugs wires is the same regardless of the revolutions of the engine as to the voltage carrying ability of the wire. barring , of course, resistor wires. The problem with wires is not the core, but is the insulation on the wire which allows the current to jump to another wire or to the metal blocks. and that happens at both low and high revolutions of the engine. If the coil and distributor are in good condition there should be no problem for an ignition system delivering all of the spark you need at those revolution, as long as the wires are not shorting , or jumping from wire to wire. At 5,000 rpm the coils delivering sparkt at about 500 times a second, and the usual coils will handlie that quite easily. Ergo, problems in ignition at upper revolutions are usually in the spark in the combustion chamber You could put a scope on the ignition system and see if the system is functioning properly at those revolutions. But, that is the joy of internal combustion engines, triying to find out exactly what is happening. I could be in error, but I think not, for I am an old man! tradrjack
two more runs tonight- open header. without step up spring, went lean. Next run put bigger main jet in, good A/F, no power. tomorrow it goes back to Saturday's best setup, and maybe we try to choke down the exhaust some. This lends credence to the header being too big as mentioned previously. once it's off the dyno I can get the chassis started. After all this with the engine, I'm a bit worn, I might take a break.
I know how you feel, been there with your exact carb setup. You've heard me say that you'll need those step up jets, and that's where you are. They are entirely too big stock, you'll have to plug them and re-drill them to suit. We used a numbered drill and a brazing rod. Find a numbered drill that is close to the diameter of a good brass brazing rod, and drill that jet out to that diameter, press in a plug made from the brazing rod, then drill that out to .025" to start. I still haven't measured the step-up springs in the B&B, but I have measured the springs in other Carter carbs such as the WGD/WDO/WCD etc. They are common to the power valve springs in the Edelbrock/Carter AFB. Which is nice for us dualing oldies, they come in pairs. Something you might want to consider when dialing that baby in, some variability in the vacuum point. Have you taken any manifold pressure readings? It gets frustrating. Hang in there. Hud
at this point, there are some obvious issues with my overall engine plan. I'm ready to take the thing off the dyno for now, work on the chassis for awhile, and STUDY. The bottom end is clearly capable of withstanding my horsepower and rpm goals, but, IMO, the top end was poorly planned. Throwing parts at it arbitrarily doesn't cut it, and that's what I've been doing. I need to learn how to pick, or make, the RIGHT parts to achieve my goals.
DONE!!!! the engine is off the dyno! another goof led to the last SNAFU. The points were burnt in the stock distributor. As I switched back to the Mallory I discovered loose wires leading from the coil to the points. Made sure everything was tight this time (duh) 171.5 hp. http://www.youtube.com/watch?v=mDzgnn1se6I http://www.youtube.com/watch?v=WQhLpWkaThI videos of the last two pulls, one with tail pipe, one without. Both are to 5000rpm. this winter's project, besides building the car, is to figure out where that other 30hp is hiding. It's in there, I just have to find it. Home made flowbench...here we come
haven't been working on the chassis lately, but I got an opportunity to (learn how to )blueprint my engine, so I took it! I finished the teardown a couple days ago, and BOY AM I GLAD I decided to do this. ALL the main and rod bearings are SHOT! Fortunately, I caught it in time, nothing else is hurt. Autopsy time! gotta figure out what went wrong and fix it. This also gives me time to "fix" my intake a bit, finish the new carb linkage, and redo some bellhousing/starter stuff I'm unhappy with. seems counter productive to backtrack this far on my build, but, hopefully it will result in a more enjoyable racing season later on. (no breakage)
Sled, I hope I'm wrong, but I think you will find the bearing problem is related to the RPMs you are turning that long stroke 230. In stock form they were seldom turned much over 3500 and you just may be approaching the limits of the stone age technology, what with the offset rods and such. We're not planning on turning our 218 much over 4000, probably 4500 at the max and I doubt our set up is going to be putting anywhere near the load on the bearings that you are. Good luck and keep us posted on your findings.
Nice catch Mopar!!! I was not so lucky this week. One of my guys blew both sides out of a cat 3306 in a wheel loader. This is the first time I've seen cam shaft parts laying on the ground. I have a 10 pound box of block chunks sitting on my desk... Off subject but glad to see ya dodge major trouble.. Later Dusty P.S. The cat dealer said they could put in a good "used engine" for $18,000. No thanks
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