Sunday, September 21, 2014

Vintage Dual Carbs, Part 1

Undoubtedly one of the most popular topics on this blog is that of dual carbs.  As I have mentioned before, I tend to be a sucker for exotic carburation myself.  Judging by feedback, both via email and in the comments section, I am not alone. 

Most of us are at least somewhat familiar with the fact that the Factory (as in Harley Davidson Factory) dipped their foot in the waters of land speed racing, placing legendary racer Joe Petrali on board a specially modified dual carb Knucklehead, during the spring of 1937 at Daytona Beach.  The result was a new one mile speed record of 136.183 mph; a record which would stand for 11 years.  The heads on that bike were modified in the conventional manor of one carb on each head.

This is a pic I snapped at the 2008 Cincinnati Dealer Expo.  I assume that it is a replica of Petrali's mount since the original color is normally portrayed as blue.

Less common are Panheads modified in like manor.  Though it seems that George Smith modified a number of them in days long gone by.

This is a shot of the George Smith dual carb Pan heads on a bike Teach did a few years back.

Though modifying the heads for dual carbs was a popular performance trick of the day, it was not the only way to achieve dual carbs.  One of the alternatives that I suspect to be a very early example of a dual carb manifold is shown below.  It was a mass produced aluminum casting made to fit the early "small port" Knuckle heads and featured a 3-bolt Linkert pattern.  IMHO it suffers from a couple of design flaws, but certainly was nicely done and the (unknown to me) originator was on the right track.

Vintage dual carb manifold for early, small port Knuckle heads.
My critique of this manifold stems from a couple points.  One is that the aluminum material of the manifold would be unlikely to hold up well to the sealing system of the day, that is "plumber nuts" with brass seals.  If you have perused a well worn OEM steel manifold, you have no doubt noticed how badly deformed the surface that the brass seal rides on becomes from use.  I suspect the relatively softer cast aluminum would fare much worse. 
My other issue has to do with airflow (not surprising since I deal with airflow for a good bit of my livelihood).  The mere fact that this manifold is an aluminum casting limits the airflow in this particular case.  Since the "spigots" of the manifold need to be the same O.D. as an OEM steel manifold in order for the  plumber nuts and seals to fit, it follows that the I.D. must be smaller that stock in order to provide some strength.  My educated guess is that an aluminum manifold nipple that shares the steel manifold's .075" wall thickness would probably not hold up to even the first tightening of the plumber nut.  On a similar note, and of even more concern on this particular manifold, is the runner diameter.  Ideally, the cross sectional area of the manifold runners would remain constant.  In the case of this particular manifold, the entrance of the port is nearly round at the carb mounting surface, as it is at the exit where it feeds into the head.  In between these two points, the runner takes an elliptical shape, maintaining a constant height, but  suffering from a severe narrowing in width.  The third picture above shows this, and yes...  it is as bad as it looks. The major reason for this was to keep individual runners, in other words keeping each cylinder's intake tract isolated from the other.  More on this later.
Now, given the tortuous path that a Knuckle or Pan present to the air/fuel mixture as it finds its way from the carburetor to the combustion chamber, it would not surprise me to learn that this manifold provided a performance increase despite it's inherent flaws.  Recently it appears that someone has undertaken the task of reproducing these vintage performance manifolds, since I often see un-finished versions for sale on eBay.  One notable change on these new ones is a flange the shape of the 4 bolt Linkert.  Few details are given and one cannot tell from the pictures whether any other improvements have been made.  If anyone has real world experience with this style manifold, either the original or new, I would be happy to hear about it.

Another early example of the quest for dual carbs is the "Seeley" manifold, something which I have written about previously here.

 The Seeley manifold was basically a re-imagining of the stock Linkert manifold, putting one carb on each side of the engine.  An obvious minor drawback to this type of dual carb manifold is leg clearance on the spark plug side, particularly if the relatively "long" Linkert is used.  In fairness though, the customary modification to Knuck heads for dual carbs suffers from the same issue.  As a side note, I am certainly no historian of the Seeley manifolds, but I have seen pictures of an aluminum version very similar to the steel one pictured above.  And that brings up a question; was the steel one an early prototype or was it possibly a home made copy?  The aluminum version is stamped with the Seeley name, the steel is seemingly unmarked.  One thing I would note is that the aluminum version suffers from the same drawback as the dual 3 bolt manifold mentioned earlier with its thicker walls on the spigots.

Over the years there have surely been many variations on these three basic dual carb designs, and probably a few that I missed as well.  The fact is, I have built a number of variations myself.  During the 1980's and '90s I modified a number of Knuckle heads for dual carbs as part of my quest for drag strip performance.   The fact that even then I was three generations removed from the latest technology in Harley head design would seem to reveal something about "where my head was at" (as they used to say). I wanted performance, but was not willing to entirely give up the "cool factor" (as they also used to say) to get it.  I would venture a guess that the same could be said for many today who  are drawn to the concept of dual carbs on vintage motors.

Of course motivations will vary from one man to the next, and where you fall in the spectrum of desire for "the look" verses "performance" will have a lot to do with how you approach a dual carb conversion.  If the look is more important to you than the performance, then any of the designs listed above will fit the bill nicely and I say go for it.  If, on the other hand, you lean more toward the performance end, then there are a few other things to consider.  One of the biggest of these is air flow.  Face it, even in the vintage world, today's motors tend to be larger than yesterday's, and a larger motor wants more air.  In the early days an 80" Knuckle was a big motor, and possibly the most common size used for drag racing.  In the years since, 84 ad 86 inch engines have become common for street builds.  What I am suggesting is that what may have been a performance upgrade on a 61 inch motor could very well be a restriction on a 96 incher.

Airflow and how it relates to these vintage style dual carb modifications will be the subject of a soon (hopefully) upcoming post.


Monday, September 8, 2014


As is so often the case, I have been trying to find time to write fresh post for this blog.  I have the topic and the desire, but always so many other "projects" that steal away my time.  Sooooo, ...rather than taking the time that I would like to right now, I am going to post a link to a cool little video about someone I am proud to call a friend; Kevin Baas, or "Teach" as he is oft called.

Teach stopped by last week so we could discuss an idea for a really cool engine modification I have in mind for the current Kennedy High School Chopper Class vintage dragbike project.   While here Teach mentioned that he had a link to this new video on his blog, Vintage Bike Addiction.  The video does a pretty fair job of helping you to get to know the man and his priorities. So, without further introduction, here is

Friday, August 15, 2014

The Power of a Song, part 2

continued from here...

Psalms and hymns and spiritual songs can be a great blessing, but have you ever heard of using singing to win a battle?

Back during the reign of Jehoshaphat, king of Judah approximately 900 years before the birth of Christ, that exact thing happened. And here is the story as we find in 2nd Chronicles chapter 20. The nations of Ammon and Moab along with the people of Mt. Seir decided to invade Judah. When Jehoshaphat learned of the impending attack, we read his reaction in verse 3.

And Jehoshaphat feared, and set himself to seek the Lord, and proclaimed a fast throughout all Judah.

That was the right reaction. The Bible goes on to tell us this in verses 4-9:

And Judah gathered themselves together, to ask help of the Lord: even out of all the cities of Judah they came to seek the Lord. And Jehoshaphat stood in the congregation of Judah and Jerusalem, in the house of the Lord, before the new court, And said, O Lord God of our fathers, art not thou God in heaven? and rulest not thou over all the kingdoms of the heathen? and in thine hand is there not power and might, so that none is able to withstand thee? Art not thou our God, who didst drive out the inhabitants of this land before thy people Israel, and gavest it to the seed of Abraham thy friend for ever? And they dwelt therein, and have built thee a sanctuary therein for thy name, saying, If, when evil cometh upon us, as the sword, judgment, or pestilence, or famine, we stand before this house, and in thy presence, (for thy name is in this house,) and cry unto thee in our affliction, then thou wilt hear and help.

The people went on to ask this in verse 12:

O our God, wilt thou not judge them? for we have no might against this great company that cometh against us; neither know we what to do: but our eyes are upon thee.

This seems to be one of the few times that we find the children of Israel trusting in Jehovah to protect them from enemies, as they ought, rather than seeking help from other nations. And of course they were rewarded for putting their faith in God to deliver them..

We find this in verses 20-24:

And they rose early in the morning, and went forth into the wilderness of Tekoa: and as they went forth, Jehoshaphat stood and said, Hear me, O Judah, and ye inhabitants of Jerusalem; Believe in the Lord your God, so shall ye be established; believe his prophets, so shall ye prosper. And when he had consulted with the people, he appointed singers unto the Lord, and that should praise the beauty of holiness, as they went out before the army, and to say, Praise the Lord; for his mercy endureth for ever. And when they began to sing and to praise, the Lord set ambushments against the children of Ammon, Moab, and mount Seir, which were come against Judah; and they were smitten. For the children of Ammon and Moab stood up against the inhabitants of mount Seir, utterly to slay and destroy them: and when they had made an end of the inhabitants of Seir, every one helped to destroy another. And when Judah came toward the watch tower in the wilderness, they looked unto the multitude, and, behold, they were dead bodies fallen to the earth, and none escaped.

Did you catch what they were singing? "Praise the Lord; for his mercy endureth for ever." I can’t help but wonder if they were not singing Psalm 136 which ends every one of its 26 verses with that same phrase: for his mercy endureth for ever.

So, what should we take away from this little bit of history?   ...Keep a song in your heart and everything will be all right? ... Singing can deliver us from our enemies?

I believe the real lesson to be learned here is found back in verse 12. The people said to God "we have no might against this great company that cometh against us; neither know we what to do: but our eyes are upon thee."

That should be how we approach Jehovah when we consider our greatest enemy; and our greatest enemy is our own sinful nature. Each one of us has been racking up a mountain of sin debt since we were little children. We have no might against this sinfulness, any more than Israel had any might against those invading armies. Israel did not know what to do and neither do we know what we can do to pay this sin debt and make things right between us and a holy God.   But like the Israelites, our eyes need to be on the Lord. He is the only one who can deliver us from this formidable enemy; this great mountain of sin. Just as Jehoshaphat and his people went forth to battle singing Praise the Lord; for his mercy endureth for ever, we too should put our trust in the great mercy God has shown us in sending his own Son to suffer and die on the cross in payment of our sins.



Thursday, August 7, 2014

The Power of a Song

Singing is one of the ways that we worship God, but it is even more than that. The book of Ephesians tells us that singing is one of the ways to be Spirit filled, or at least evidence that we are.

And be not drunk with wine, wherein is excess; but be filled with the Spirit; Speaking to yourselves in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord   Ephesians 5: 18-19

But the practice of singing psalms and hymns and spiritual songs is even more than evidence of being Spirit filled. It is also a teaching tool. Colossians 3 tells us this:

 Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord.  Colossians. 3:16

How often do we stop to consider that? Singing psalms and hymns and spiritual songs are a way of letting Christ’s word dwell in us. But when we sing to the Lord, we are also teaching each other and admonishing one another (admonishing: to advise, warn, to caution). That should make us consider what we are singing to be sure that the right things are being taught.

to be continued...

Tuesday, July 29, 2014

Jane and Lee's Big Adventure

Recently the wife and I took a weekend off to go to a drag race. The drag race in question (The Meltdown Drags) is an annual event which seeks to take the spectators and participants back to a mid '60s drag strip experience. Now, attending was kind of a "spur of the moment" thing.  When I brought it up a scant week in advance, I received absolutely zero resistance to the idea from Jane.  In fact, as I have mentioned to more than one person, Jane's sense of adventure is certainly alive and well - more so than my own in fact.  Since The Knuckledragger was built to be period correct for 1955, it would fit right in at the Meltdown Drags.  But in the spirit of the event, Jane insisted that we go the extra mile (or 385 miles to be precise) and put the bike on our open trailer and tow it behind our '46 Studebaker pickup.   I must admit I had reservations about taking such an antique rig from our home in Minnesota all the way to Illinois, but as is so often the case my wife was right and all went well.  So, a 770 mile round trip in a 1946 Studebaker (powered by a Studebaker flathead six I might add) towing a 1947 Knucklehead drag bike on a trailer built out of a 1941 Studebaker Champion frame, and somehow neither Jane nor I managed to snap a picture of it... go figure?
[EDIT- After mentioning here that we did not take a picture of the rig, Jay and Irish teamed up to get one to me.  Thanks guys.]
And here it is.
Wheelstands by straight axle gassers was the order of the day.  Very fun to watch.

The crew from the A/h Garage was on hand and made us feel welcome from the get go.

First start up of the Knuckledragger in over 2 years
This invention by Demaar of the A/h Garage, a dolly for the front wheel & towed by a three wheeler, was ingenious and very handy.  Since we were pitted all the way down by the time slip booth, the guys were kind enough to tow the Knuckledragger to tech and to the staging lanes
Jay from "Fear No Evo Drag Racing" along with Dash (?) and Motorman from "A/h Garage" in the staging lanes.  Big inch Pan versus even bigger inch Harmon. 
Another shot taken in the staging lanes.
Chris, also of the A/h Garage, on an Iron Head Sportster
Roller starting at the head of the staging lanes.  The Byron Dragway staff was very gracious in letting us set up the electric rollers near the front of the staging lanes so bikes would not have to idle excessively.
Jay and Deemar pushing me from the rollers to the burn out area - saves on the clutch don't ya know.

A little action shot.  In fact very little action.

Just a very small portion of the spectators.  Word was they had record crowds.

Did I mention that wheelstands were the order of the day?

Before anyone asks, I will come clean and admit I made a far less than spectacular pass on the Knuckledragger.  Shifting problems continue to haunt me.  I may have sorted them out in time for a last pass, but to my chagrin the batteries for the roller starter were too weak to fire the motor.  I should have paid attention to the CCA rating of the second battery (which was on loan to me).  Turns out it was only half of what normally supplies the second 12 volts for the 24 volt system.  Oh well...

A big thanks both to Jay and to all the guys from the A/h Garage who made us feel at home and helped us out at every turn.  Also a big thanks to the Meltdown Drags Association and to Byron Dragways for making this awesome event happen.


Thursday, July 17, 2014

If Yer Gonna Melt Down, Here's the Place

The weather prognosticators say it will be a perfect weekend. There are over 500 entries, a few of which are vintage bikes.  Billed as the World's Largest Vintage Drag Meet, this looks to be the closest thing to a step back into the '60s as a gear head is likely to find!

Thursday, July 3, 2014

A Better Country

The 4th of July
The fourth of July. It is the day that most of us, as American citizens, celebrate the founding of this nation called the United States.  Many Christians celebrate it in part because of the Christian roots of this country.  In fact, if I may be so bold, I would suggest that some Christians take patriotism a bit too far.  They read scripture, particularly prophetic passages, and find the United States front and center.  

You know, during the 15 years that I have been Christian, I have read at least a small portion of scripture nearly every day. In doing that I have read the Bible through from cover to cover enough times that I have lost count.   In all that reading, I cannot recall a single instance where the Bible talks specifically about the United States of America.  Now, that is not to say that we can’t find anything in the Bible which applies to our nation. In fact 2 Timothy 3:16 says "All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:"

If there is anything that this nation is in need of right now, I think we could argue that it is reproof, correction and instruction in righteousness! That is not to say that there ever was a time when our nation did not have this need, only that taken as a whole it seems that the United States is in the midst of abandoning all pretense of reliance upon the teaching of the Bible.

Many of our forefathers came to the new world seeking the freedom to worship God according to their understanding of the dictates of the Bible, rather than the dictates of the unholy alliances of churches and states. Later, when in the course of human events it became necessary for this people to dissolve the political bands which had connected them with England, they were careful to seek the guidance of Jehovah, the one true God. In making that declaration, they prefaced it with these words:

We hold these truths to be self-evident, that all men are created equal, that they are endowed, by their Creator, with certain unalienable Rights, that among these are Life, Liberty, and the pursuit of Happiness.

Noble ideas, and possibly the first government which was not a theocracy to ever acknowledge that rights come from the creator rather than from kings or governments. In fact, one of the battle cries from the Revolutionary War is said to have been: No king but King Jesus!

Today however, there are many in our country who would like to say that this nation was never a Christian nation, but if one takes the time to look at the writings of those we call the founding fathers of the United States, one would be hard pressed to deny that the majority of them believed they were founding a nation based on Christian principles and reliant upon God. For many people, this is one of the reasons for their sense of patriotism. The phrase "for God and Country" resonates because of their love for God, and out of that love for God flows a love for the country which holds freedom of religion as one of its pillars. The very first amendment in the Bill of Rights of the constitution begins like this:

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof;

Today, over 200 years later, this nation arguably still enjoys more religious freedom than any other country on earth.

All of this is good reason to celebrate the founding of this nation and to feel a sense of patriotism. On the other side of this coin, however, things don’t look so rosy. If you spend any time reading the Old Testament, particularly the books of Chronicles and Kings, one thing that becomes crystal clear is how God’s chosen people, the nation of Israel, were constantly in a cycle of backsliding, apostasy, and then finally a short lived revival. It played out over and over with the people falling into idolatry, often worshipping Jehovah alongside their false idols, and sometimes abandoning Jehovah altogether. If that happened in the nation which God chose for himself, why would we be surprised when it happens in our nation, no matter how good the intentions at its founding?

In fact, because of what they see taking place in our country today, many Christians have adopted this passage from 2 Chronicles 7:14 as God’s promise to them:

"If my people, which are called by my name, shall humble themselves, and pray, and seek my face, and turn from their wicked ways; then will I hear from heaven, and will forgive their sin, and will heal their land."

While I applaud the sentiment and highly recommend that we all do exactly those things: humble ourselves, pray, seek Jehovah’s face, and turn from our wicked ways, I am not sure of the long term results. That promise was made to Solomon when he was king of Israel but after the many repetitions of backsliding, apostasy and then revival, there finally came a time when no revival came. Judgment came upon the nation of Israel and it was scattered and remained that way for nearly 2000 years.

But we have a better promise than the one given to Solomon. We can find it in Philippians 3:20  "For our citizenship is in heaven; whence also we wait for a Saviour, the Lord Jesus Christ:"

You might say we hold a dual citizenship, like the apostle Paul who was not only a Jew, but also a citizen of Rome. As Christians, we may be thankful to be American citizens and for all the blessings God has blessed us with here in the United States, but our far more important eternal citizenship is found in heaven and our far more important allegiance is to Jehovah.

So let’s just quickly look at a couple of our fellow citizens of heaven:

"By faith Abraham, when he was called to go out into a place which he should after receive for an inheritance, obeyed; and he went out, not knowing whither he went. By faith he sojourned in the land of promise, as in a strange country, dwelling in tabernacles with Isaac and Jacob, the heirs with him of the same promise:  For he looked for a city which hath foundations, whose builder and maker is God. Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised. Therefore sprang there even of one, and him as good as dead, so many as the stars of the sky in multitude, and as the sand which is by the sea shore innumerable. These all died in faith, not having received the promises, but having seen them afar off, and were persuaded of them, and embraced them, and confessed that they were strangers and pilgrims on the earth.  For they that say such things declare plainly that they seek a country.  And truly, if they had been mindful of that country from whence they came out, they might have had opportunity to have returned.  But now they desire a better country, that is, an heavenly: wherefore God is not ashamed to be called their God: for he hath prepared for them a city."  Hebrews 11: 8-16

In this section of scripture we not only have our nation put into perspective as merely a place of pilgrimage until we go to that better heavenly city, we also see how to obtain citizenship there. Unlike American citizenship, you are not born with it.  You can't receive it by passing a test and swearing and oath.  It is a citizenship which comes by faith. And this faith is not a insignificant thing for only citizens of the heavenly Jerusalem will be allowed in. If you have not already done so, won’t you put your faith in Jesus Christ, trusting that he has paid the penalty for your sins on the cross of Calvary? Won’t you turn from your sins and to Jesus? Won’t you make sure of your citizenship in heaven?