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Petrol head thread!!!

Started by billy rubin, October 29, 2019, 10:41:33 PM

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billy rubin

loring air force base

https://www.facebook.com/loringtiming/

the longest ztraight line on pavement you can race on anywhere in the worlz


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

Icarus

I am out of the loop BR. I did not know about that facility. Looks like there are all sorts of machinery and lunatics there to do their thing.   I could get off on that kind of mentally deranged fun.

Is there a class for 50cc machines?  I used to try my damnest to promote moped racing here in Florida.  The reason was that it would be a cheap way to race and be able to attract a larger contingent of competitors.  I was usually laughed out of the bar when I tried to do that kind of promotion.

The Europeans, especially the Italians and Spanish made some god awful fast 50cc machines.. I once had, on loan from the factory, an NSU 50cc full on racer that was really fun to ride. As I recall it had a five speed tranny and a fearsome little two stroke engine..   It was pretty quick for a mini tiddler. Could blow the Cushmans out of the water in a stop light grand prix. Could embarass the Harley 165s also.  Matter of fact so could the NSU Quickly which was an ordinary looking Moped with bike pedals and all.   I sold quite a few of them when I was a NSU/BMW dealer back in the dark ages.

billy rubin

you can race anything so long az it has either 2 or 4 wheels. the safety people want to stay away from tricyclez.

the most interesting machinez to me are the ones where people do impozsible speeds with very little. ive seen 60s camaros do 256 mph, and a newer corvette do 269. but i was much more impressed with the engineer who got 64 mph out of an old puch moped.

theres a clasz for everything, and theyre divided up by engine capacjty, cam drive, faired or not, production or not etc.

at bonneville tbe current record for 50 cc iz a boosted streamliner that doez 147 mph. but the naked naturally aspirated machines are lezz intense.

the production based stuff is most  interesting to me, esecially the old britizh machinez. if i ran a newer OHC 650 with a turbo and a fairing, i tbink the record is around 160 something. but my 55 yearold 650 pushrod twin is the fastest theyve ever gone at 135.


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

hermes2015

I don't understand a word of this, but perhaps you guys will find it interesting.

"Eventually everything connects - people, ideas, objects. The quality of the connections is the key to quality per se."
― Charles Eames

Dark Lightning

That CVVD engine is a real trip! I wonder what's under the hood of my Kia Forte. I only bought it for the long warranty.  :-[

billy rubin

well, that's cooler than shit.

im fascinated that this mechanical system is showing up on . . . hyundais.

i'm reminded of the sophisticated combustion chambers that honda put into their 1970s civics that made them so clean. too often the really progressive changes only show up in high-end platforms, whether its a blower bentley or a passive solar house. the future is in using the high-zoot stuff in the lower level applications so more of it gets on the street.

i remember trying to figure out how one could generate variable valve timing by using lobes that advanced and retarded relative to the shaft that supported them. but it never occurred to me that you could mess with duration by changing the speed of the lobe relative to the shaft. that's impressive stuff.


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

billy rubin

ah well

my machinist took a look at my cylinder head nd said, looks worse than you thought. . . two bent vlves, a cracked guide and the edge of the combusiton chamber smooshed in a bit.

he said, got another head?

no. this one has a lot of expensive port work done on it.

well, we can duplicate the port work if we have this head here. if we can't fix it.

so i said, okay, i'll see what i can find.

my cylinder head is a one-year-only antique, cast in 1971 for the 72-73 model year. before 1973, they had nine bolts. after 1973, they had ten bolts. for mine, they had cast-in bosses for ten bolts, but only drilled nine of them. an intermediate in other ways as well, and very hard to find after almost 50 years, but very desirable because it can be ported for my 35 mm carbs, rather than the stock 30 mm.

so i looked at ebay just to see, and there were three of them for sale last night. unheard of luck. one had suffered the same thrown rod as mine and looked just as bad, but the other two seemed pretty good, considering. i told my wife i was buying one, an she said

if you don't buy both of them, you'll just be in this same predicament the next time you blow up the motor.

(wives like that are hard to find, and harder to keep. keeping mine is a permanent project that sometimes exceeds my skill set.)

so i bought one on the buy-it-now listing and put a bid on the other:



and we'll take it from there.


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

Icarus

BR your wife is an extraordinary individual.  Tell her that some old dude in Florida said so.  You can also suggest that the old dude is something of a veteran observer of the human assortment of character traits.

billy rubin

lol

yes she was a surprise to me and continues to be

we d bothbeen with other people for ten years wgen we met. we both got divorced and ran away together into the unknown. pushinh thirty years now.

its been a pretty wild ride


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

billy rubin

well, i went to pick up my cylinder head yesterday. it was repaired, as good as i could possibly expect it to be



this head took a a piston smack at somewhere around 7000 rpm, which works out to some 3000-plus feet per second, i think. i'd have to calculate it out. the timing slip said 131 mph through the mile, and it blew before i got the mile-point-five. that would have been close to a record run, and i was still tuning. anyway, the piston pressed the rim of the combustion in, bent two valves, and cracked one of the valve guides. the cases were toast, and the crankshaft was iffy, but we got through those hurdles already.

this head has had pretty extensive port work done on it by one of only two people in the united states who still do it. one of them is mostly retired (he's had a head of mine waiting to work on for five years now), and the other one has scaled back so far that he's not taking anynmore business for at least the foreseeable future. nobody else around with the interest or knowledge to work on 60 year old motorcycle heads anymore unless they'e harleys.

so i was really really hoping that this one could be repaired. and its beautiful.



he took a ball peen hammer to the edge of the chamber to rough th emetal back into place, and then used an  ancient pneumtaitic tool from the 30s or 40s to move the aluminum back into position so he could repair the rim where it comes close to the piston's squish band. the old air tool was designed to peen the insides of piston skirts out to take up clyinder clearance without disassembling the motor-- you just dropped the pan and reached up inside the clylinder. nver heard of such a thing.

we were thinking that he would have to put in new valves seats, which is an extremely finicky job on these heads. the seats are trapezoidal and cast in place. can't just press new ones in. but he ws able to seat thje new valves without difficulty and without sinking them

these heads are made with old aluminum metallurgy, and they bend like butter. normally that's a problem, because theyre hard to keep flat, but when youre reshapoing a combustion chamber with a hammer it turns out to be an advantage.

anyway, so now we re ready to go-- valves, guides, springs, and seats:



and i still have two spare heads of this one-year-only design to rebuild if i blow the motor up again:



hope not to do that


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

Icarus

Billy the exhaust valve is almost always the culprit. Post mortems almost always find that the damned ex did not get closed soon enough for the piston to get to TDC or a few degrees before. Cams with a lot of overlap is the underlying problem.  We need plenty of overlap if we intend to rev the engine. Tit for tat.

The trick is to make the damned EX close before the piston collision.  This happens at high revs only, unless there was some kind of galling or other problem in the ex guide, a heavy pushrod, etc.  Using a stronger spring on the EX valve is common enough but then that puts an unfavorable load on the push rod, camshaft, and other busy parts.

The drill is to find some bee hive springs that will work in your Trumpet head.  Those springs are progressive in that they get stronger as they are compressed.  Conventional coils have linear progression of counter force.  Bee hives have a curved progression in which the early lift is less resistent and the late lift is much stronger..........so as to get the damned exhaust out of the way when the piston gets there.

Because there is less work done in early lift, there is lessened coincident demand on the output of the engine.  In general, at least a measurable increase in out put is usually seen. 

Dark Lightning

I'd also comment that the piston isn't going all that fast at the top of the bore, given that it is close to changing direction, so the speed isn't so much of a factor. Late valve closing would be. Yer gonna have to start doing what the top fuel guys do and replace all kinds of parts after every run, and the valve springs would be on the list.

hermes2015

Quote from: billy rubin on April 15, 2020, 07:05:10 PM




Sorry that this is not a meaningful contribution to the technical discussions in this thread, but these are beautiful objects in themselves. I am inspired to incorporate those striations (are they cooling fins?) into a sculpture.
"Eventually everything connects - people, ideas, objects. The quality of the connections is the key to quality per se."
― Charles Eames

billy rubin

lol

im afraid my piston to head clearance problems had to do with the rod becoming detached at the bottom end and not zlowing down at all az it headed north. the issue was a failed rod bolt, down there at tge bottom.

icaruz, i actually do run beehive springs in an earlier head, and im planning on those in the futyee with this one. but on this iteration i ran with the springz the cam people reccommended, and so far theyve held up.

DL, i really hope not to have to do track rebuilds on this thing. LSR is more of an endurance event than all out drags, because the courze length is more than a mile. but we ll see where we go from here. got to break in the new pistons asap.


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

billy rubin

Quote from: hermes2015 on April 16, 2020, 05:06:20 AM
Quote from: billy rubin on April 15, 2020, 07:05:10 PM




Sorry that this is not a meaningful contribution to the technical discussions in this thread, but these are beautiful objects in themselves. I am inspired to incorporate those striations (are they cooling fins?) into a sculpture.

interesting you would fix on that, but i m understanding your viewpoint more. yes, old british castings are works of sculpture,  much more than modern piecez. the technology was personal and4 hands on, so much so that the cases for one of my machinez has the initials of some long dead foundry worker inside, in reverse, where he scratched tbem into the sand mold before pouring the metal.

tbeze all came from a technological culture not far removed from 1930s art deco, and the completely exposed motor was as much a part of the vizual prezentation as the swoopy sheet metal or the color of the paint. weve lost that form of art work, at least in motor vehicles. its one of the reasons i love these old things so much

yes they are cooling fins. let me see if i can locate some imagez of 1920s radial aircraft engines. some of them were exquisite in execution


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."