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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 1014423 times)

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Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1020 on: January 21, 2013, 04:27:35 PM »
The engine timing cover looks like the one on the Triumph you are showing.  The oil tank looks BSA to me.  In those days the BSA chassis was better than the Triumph and the opposite for the engines.  Maybe is is a Beezumph or a Tribsa.  There were a few of those around here.

The next posts will be about building the big motor.  Most of this is nothing new for an experienced racer.  Some of this might help someone who is starting their first build.

The last step before the engine is put together is to get the measurements for the build sheet.  I call it a clearance sheet and it is attached.  The pistons and gudgeon pins are measured by our local machinist at River City Machine.  He made the measurements on the 2010 clearance sheet.  I always want the same person to do the measuring.  This helps make the measurements more consistent and I have more confidence when I look at it to spot trends.  Everything else I measured.

The last engine had a big problem with piston and cylinder wear.  I looked on the 2010 clearance sheet and it said it was built with 0.004 inch skirt clearances.  That was slightly more than ideal.  It was not enough to cause the problems I was seeing.  This told me that I needed to do more investigating to figure out the cause of the trouble.  This is an example of how the clearance sheet helps.         

Offline Koncretekid

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1021 on: January 21, 2013, 04:57:05 PM »
Interesting that he could read your cylinder dimensions to .0005", but all the other measurements, presumably made with micrometers, only to the nearest .001".  I would have expected measurements to the .0001, using a micrometer.  Crank end play measurement is wacky, or probably he put the decimal in the wrong place.  I don't like to see a machinist make those kind of sloppy measurements.  I would be suspicious.
Tom

P.S.  Your brochure photo looks like custom to me.  I see only a single downtube in front of the motor, like Triumph, and a Triumph like emblem on the gas tank.  Most BSA tanks were chrome.  Front fender is custom, with no front stay, but sort of looks chrome, like BSA.  Rear brake looks like cable with the brake actuating arm upward (BSA was below the axle, I believe), and no doubt has a jackshaft thru the swingarm as the pedal would be on the left. I don't know my pre-units well enough to confirm.
« Last Edit: January 21, 2013, 05:04:16 PM by Koncretekid »
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Offline Koncretekid

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1022 on: January 21, 2013, 05:38:41 PM »
Bo,
I forgot to respond to your post about making a sleeve gear for your Matchless.  I thought you might enjoy this photo of my first bike - - a Matchless G80TCS.  If you know your Matchless models, you will know that this was the 600cc version of the G80.  I paid $60 for it in 1966 while at University, and learned to ride on it.  I used to do burn outs on campus until I broke the crank.  My brother (a machinist) and I bored out the cases and made a sleeve to hold the main crankshaft drive side bearing which had spun.  I rebuild it as you see it here, and sold it for $350. Last I checked, the 600TCS models were selling for about $10,000.  That's life!
Tom
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Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1023 on: January 22, 2013, 09:43:31 PM »
All measurements from the rings to the bottom of the page are mine.  The bearing clearances are from some official Triumph plastigage I have and it gives readings in metric.  The conversion to american is sorta hard.  The accuracy of the stuff does not warrant a conversion to the nearest 0.0001 inches.  I round it off to the nearest 0.001 when I write it down on the sheet.  Maybe I should record the metric measurements?  The crank end play is 0.0035 inches.  I wrote it down wrong. 

That is a nice Matchless in the style of the way we did things back then.  Occasionally I see one for sale.  They are worn out beyond belief and my kick start knee is, too.

The red line on these Triumphs 7,400 rpm as built in Hinckley.  I was regularly running the motor higher than that at B'ville.  There were dark stains from oxidized oil around the big ends of the rods at the first teardown.  It was getting hot there.  The Triumph bearing shells are color coded and I had "red" shells.  I put in the larger diameter "white" coded shells and this increased the crank to rod clearance a bit to 0.050mm.  This cooled things down by reducing the shear in the oil and giving better circulation.  The oil holes were sharp edged in all journals, booth main and rod.  Another thing I did was to champer them as shown.  The wear patterns look good during this teardown and there is no sign of overheating.  Problem solved.

A popular modification is to also install white coded shells in the main bearings.  I bought a set, put them in, and then plastigaged them.  The clearances were real close to the 0.080 mm wear limit.  This made me worry.  Looser main bearings allow more oil to pass through them and the rod bearings will not get as much oil as they did before.  I put in new "blue" bearings to set the clearance on the main journals at 0.050mm.  This works very good.  The wear pattern on the shells are good, there is no sign of overheating, and I am not worried about starving the rod big ends.

         

Offline Freud

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1024 on: January 22, 2013, 09:48:55 PM »
It's easier to see now.

FREUD
Since '63

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1025 on: January 23, 2013, 08:57:04 PM »
The first time I put the engine together was very difficult.  I did it the usual way.  The cases were assembled, the pistons were installed on the connecting rods, and the cylinder was lowered down onto the case over the pistons.  There is not much chamfer on the bottom of the cylinders and the big pistons like to rock.  It was hard to get the pistons and rings up into the cylinder bores.

This time I do it different.  The pistons are installed on the rods.  It is easy to see that the pin circlips were installed correctly.  The ring end gaps are spaced where they should be on the piston and the pistons are put into the bores.  Automatic tranny fluid is used as a bore lubricant.  It is easy to install the pistons in the bores this way.  The base gasket and the five o-rings are installed on the cylinder block.

This picture shows the grooves on the Carrillo rods that direct oil to the rod small end bushing.  This feature, and the phosphor bronze pin bushings are why I use the Carrillo rods  The standard rods are plenty strong.  They do not have this oiling feature and their small ends are not bushed.  The steel on steel contact between the pin and the small end of the stock rod tends to gall when used for racing.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1026 on: January 23, 2013, 09:01:13 PM »
The upper case is turned upside down and it is lowered down onto the cylinders.  The rods stick up through the case.  A couple of spacers are put on some of the cylinder studs in place of the cylinder head and they are held tight with nuts.  This keeps the cylinder block up tight against the upper case. 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1027 on: January 23, 2013, 09:12:01 PM »
The cam chain is put on crank and it is lowered down into the case.  The rod caps are put on and the rod bolts torqued up tight.

This is a street roadster style engine that will rarely see 8,000 rpm.  Genuine race versions of this motor are revved up to 9,500 or even 10,000 rpm.  I would use the thinner piston ring option to prevent ring flutter and have the crank webs knife edged if I was building a real race motor.  I did not do these things.

A fellow racer asked me about removing the balancers for racing.  I looked at this idea when the engine was apart.  I do not see any reason why it could not be done.  This is a street motor so they are left in place.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1028 on: January 23, 2013, 09:15:08 PM »
The bottom case is put on and everything is tightened up.  This is a much easier method and there is a lot less chance to screw things up like bending a piston ring or not having the gudgeon clips installed correctly.

Offline Koncretekid

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1029 on: January 24, 2013, 07:44:58 AM »
If you ever want to just check the bottom end bearings, I think you can use the same method, without ever having to take off the head.  Just turn the motor upside down and remove the bottom half of the case.  Only works on a horizontally split motor.  I once rebuilt the bottom end of an old snowmobile motor this way.
Tom
We get too soon oldt, and too late schmart!
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Offline saltwheels262

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1030 on: January 24, 2013, 05:09:29 PM »
I'm sure that those pistons will not give you any problems.

bf
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Offline 4-barrel Mike

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1031 on: January 24, 2013, 05:17:44 PM »
Bo:  are you going to the auto show and buy a chance on the Triumph?



https://www.facebook.com/pages/TIP-of-PortlandVancouver/145347135479871

Mike
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1032 on: January 24, 2013, 10:56:03 PM »
It is tempting, Mike.  I am sort of low on money right now.  This is the year when the motor is being built.  The Greeks had problems with Pandora and her box.  They would have written about race motors instead, if they had them.   

Thanks for the help with the photo, Freud.  It was hard to see it the way I did it.

The last engine wore out really fast.  About 10,000 miles and only seven runs down the salt.  Some work with PipeMax is helping me figure out what happened, I think.  The first step is to look at my last good motor as a reference.  Triumph in Hinckley built it, not me.  It was in pretty good shape after 20,000 miles and ten runs down the salt from a wear standpoint.  This first page is the engine data.  The second page is the valve and cam calculations.  First I look at minimum valve lift to prevent choke at 7,400 rpm.  It is .315 and .293 for the intake and exhaust, respectively.  The actual lifts are .374 and .370 for intake and exhaust.  The 790 cams have plenty of lift for he 790cc motor.

The "Operating RPM Ranges of Various Components" vary, but the bracket the 7,400 rpm target I have for maximum horsepower.  It looks like the cams and valves match the displacement, compression ratio, and the target RPM.   

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1033 on: January 24, 2013, 11:13:23 PM »
The next page gives the port areas.  The minimum intake area on my motor is 1.55 square inches.  It is in the "Largest Intake Port Entry CSA" range according to PipeMax.  The minimum exhaust port area is 1.53 square inches.  This is in the "Torque Loss + Reversion" range on the printout.  It seems like I had big ports for a 790cc engine.

This little motor ran good.  It went 127 mph with the rudimentary streamlining I had at the time.  Most important, it did not have much reversion and the mixture was on the lean side of stochiometric at normal road rpm and throttle openings.  The bores were almost like new when I pulled the engine apart.  The pistons were worn and it was from abrasion.  I ran open stacks on the salt and oiled gauze pod filters on the street.  Neither filter out the dirt very well.

Tomorrow I will post the PipeMax output for the problem engine.   

Offline fordboy628

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1034 on: January 25, 2013, 06:49:10 AM »
Walrus,

If you list some of the other engine design parameters I'll look them over to see if I can give you some help with the math for your engine build.

Need to know:

Race/street/ or both
fuel octane to be used
power band desired
peak hp rpm desired
frequency of maintenance / miles between rebuilds, etc, etc....

If I'm reading your #'s correctly 74.7bhp (crank) @ 7400 rpm from 790cc's.  That's 94.6bhp/litre on pump gas.  Bmep of 183.8psi from PipeMax.  That's pretty tame for a 4 valve, BUT, reliable because of the 9.2/1 static C/R.    (9.94/1 effective C/R @ 108% V/E)   Are you willing to bump C/R to try to get Bmep to 195psi?    Substitute a higher C/R into PipeMax and see what that does to your output & octane requirement.....

How far do you want to push output?   What are you willing to trade away for more bhp?
 :cheers:
Fordboy

Edit:  I have not read your whole build diary yet, so please point me to any pages that may have more details on the engine.
« Last Edit: January 25, 2013, 06:55:28 AM by fordboy628 »
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