Porting the 45 Inch Flathead, part 2

In part one of this series, I published the results of a flow test on a stock cylinder from a '48 WL. In order to get an idea of what effect different modifications had on the process, I resigned myself to spending a lot of extra time with multiple flow tests. My first step in the process was to do a basic porting job. The cylinders were in need of new valve guides anyway, so I removed the old ones before working on the ports. In almost all cases, more flow can be obtained by doing the port work with the guides removed. Much of the "work" involved opening the intake port to a nominal I.D. of 1.250 inches. This is a modest increase in size, and I would consider it to be the minimum that one would want to invest effort into.

Once the ports were cleaned up and shaped, new guides were installed and sized. Next the seats were cut for new stock size Rowe valves. The exhaust seats received a radius seat, which in actual practice on a motor such as this, does very little. The "choke" or "venturi" just below the 45 degree seat is too large relative to the valve size for the radius to enhance the flow much more than a conventional three angle valve job would. If you lack the equipment to do a radius seat, just do a 3 angle and blend it into the port. The intake seat (only one since I would be installing larger valves next) got a multi angle seat, although this too suffered from similar size issues as the exhaust.

The results of a flow test in this state are as follows:

Intake .100" lift - stock 48.2cfm / ported 42.5cfm
Intake .200" lift - stock 83.8cfm / ported 81.7cfm
Intake .300" lift - stock 98.7 cfm / ported 107.1cfm
Intake .350" lift - stock 102.6cfm / ported 114.2cfm
Intake .375" lift - stock 103.8cfm / ported 117.3cfm
Intake .400" lift - stock 104.3cfm / ported 118.6cfm
Intake .450" lift - stock 104.4cfm / ported 121.0cfm
***
Exhaust .100" lift - stock 41.9cfm / ported 52.0cfm
Exhaust .200" lift - stock 82.4cfm / ported 92.8cfm
Exhaust .300" lift - stock 104.4cfm / ported 112.4cfm
Exhaust .350" lift - stock 110.6cfm / ported 117.2cfm
Exhaust .375" lift - stock 113.3cfm / ported 120.8cfm
Exhaust .400" lift - stock 115.7cfm / ported 121.2cfm
Exhaust .450" lift - stock 119.3cfm / ported 124.6cfm

You will note that there was actually a loss of flow under .300" lift on the intake side. This is due to the shape of the Rowe valves. Basically what they do is manufacture an exhaust valve and offer it for use in both intake and exhaust. Nothing wrong or deceitful about that. It is not sold as a performance valve, and in the long run, by reducing their manufacturing costs, Rowe is saving the owner of a stock motor money at rebuild time.

But back to the valve in question; on the back side, just below the 45 degree face, is a lip (shown in picture above) which inhibits flow. Which leads to the next logical modification: a 30 degree back cut on the valves. It is well established that air will "follow" a 15 degree change in direction with minimal flow loss (if you have never heard that before, then just now a light bulb should have come on in your head explaining why a three angle valve job consists of angles of 30, 45, and 60 degrees). With a 30 degree back cut on both valves, the next flow test looks like this:

Intake .100" lift - ported 42.5cfm / add back cut 48.7cfm
Intake .200" lift - ported 81.7cfm / add back cut 88.4cfm
Intake .300" lift - ported 107.1 cfm / add back cut 109.5cfm
Intake .350" lift - ported 114.2cfm / add back cut 115.7cfm
Intake .375" lift - ported 117.3cfm / add back cut 118.1cfm
Intake .400" lift - ported 118.6cfm / add back cut 119.2cfm
Intake .450" lift - ported 121.04cfm / add cut 121.8cfm
***
Exhaust .100" lift - ported 52.0cfm / add backcut 58.1cfm
Exhaust .200" lift - ported 92.8cfm / add backcut 99.2cfm
Exhaust .300" lift - ported 112.4cfm / add backcut 114.0cfm
Exhaust .350" lift - ported 117.2cfm / add backcut 118.4cfm
Exhaust .375" lift - ported 120.8cfm / add backcut 121.3cfm
Exhaust .400" lift - ported 121.2cfm / add backcut 122.5cfm
Exhaust .450" lift - ported 124.6cfm / add backcut 126.2cfm

As can be seen above, adding the 30 degree back cut on the valves adds flow at all lifts, and more than makes up for the loss of flow in the previous test. At this point, for this application, the exhaust ports are done. They still outflow the intake by a substantial amount, just as they did when stock.

Before moving on to installation of a larger intake valve, there is one more modification that I felt was worth a try. Due to the long length of the valve guides in a Flathead 45, I felt that it would not significantly shorten longevity to remove the short portion that protrudes into the intake port. I have never been a fan of this modification, and though I have seen it done before (I believe it is more prevalent with auto engines) I have never done it myself. The 45 however, seemed a promising candidate. The results are thus:

Intake .100" lift - prev. test 48.7cfm / add guide mod 48.5cfm
Intake .200" lift - prev. test 88.4cfm / add guide mod 87.3cfm
Intake .300" lift - prev. test 109.5cfm / add guide mod 109.7cfm
Intake .350" lift - prev. test 115.7cfm / add guide mod 116.4cfm
Intake .375" lift - prev. test 118.1cfm / add guide mod 118.9cfm
Intake .400" lift - prev. test 119.2cfm / add guide mod 121.8cfm
Intake .450" lift - prev. test 121.8cfm / add guide mod 124.9cfm

This would seem to be the first modification that did not really pan out. The flow differences at .375 lift and below are inconsequential and would rule out shortening the guide at this level of modification. Better flow at .450 lift does nothing if your cam only lifts the valve .360" (as the regrind that this motor is getting does). I have to admit that I kind of dropped the ball on this one though, in that I did not test the other cylinder with the bigger valve before and after modifying the guide. That would have told us whether it was more viable at the higher level of modification. The increased flow at higher lifts would seem to suggest that this mod could be more beneficial with say, for instance, a larger port diameter.

So, what have we learned so far? Porting work; Do it! With the little done so far we show a 13% increase on the intake at .350" lift. Just be sure that you put a back cut on those Rowe valves. As to the shortening of the valve guide. At this point I would say no. Definitely not if you are not going beyond stock valve size. Further testing using a larger valve is in order though.

Up next: a larger intake valve with step by step testing. Stay tuned.

Knoxville Vintage Flat Track Nationals

I got a call from Bill Hofmeister yesterday to report on Friday night's Knoxville Vintage National Flat Track race. If you follow my blog, you know that I am really a drag racer, not a flat tracker, so some of the details may be a little muddled, but the main points should be correct.

As I have mentioned before, I did a little top end work on Billy's old iron head Sportster engined XR. Porting, some pistons, and some modern coatings in the combustion chambers. Nothing super trick, but the things I did turned out pretty well. Bill raced the bike a time or two last summer with good results, but this spring we put a modern wet clutch in the bike, and that seems to have been a game changer. It always helps if the power from the engine gets all the way to the rear wheel!



So it was off to the vintage flat track races at Davenport, Iowa as part of the AMCA national meet. After sorting out some issues with the rear chain, Bill took his XL engined XR to the "Dash for Cash," which he reportedly was leading by half the length of a straightaway when he ran out of gas. He got beat by a wheel length, dropping from the first place $750 prize money to the second place $0. No, that's not a typo. Second paid zero/ zip/ nada.

But all that is just lead in for the real story. Billy brought the XR back to me last Monday morning so that I could work out a few bugs (such as aligning the rear wheel to prevent further chain problems). Since the bike showed such promise in Davenport, Billy decided to put a young gun on it for Knoxville. Since he also uses the old iron head to help promote his venture in producing street going XR replicas, he wanted all the press he could get.

The young man Billy decided to put on the bike for Knoxville is National #68 Josh Koch from Cedar Minnesota. If you are not familiar with flat track racing, earning a National number plate is a really big deal. In fact, I believe there have only been about a dozen Minnesotans to win the right to a National number in the history of Grand National racing. Now, Billy is one of those riders, having held several National numbers, as well as a Canadian National Championship, however Josh not only has earned a National number; he has another advantage. He is nearly 40 years younger than Billy!

It seems that Josh is presently looking for a team with an XR750 that is in need of a rider. It sounds as though Billy didn't have too much trouble talking Josh into riding for him with the lure that if he were to beat bunch of vintage XR750s while mounted on an old iron head, it should really get some attention. And that is just what he did!

I took a long time to get to the punchline, but here it is. Josh Koch won the main event in the Open Class at the Knoxville Vintage Nationals on the Grand National Replica/Lee's Speed Shop sponsored lowly old iron head XR by about the length of the straightaway. How 'bout that!

Porting the 45 Inch Flathead

I have to admit, its not something I'd have given much thought a few years back. What got me onto the subject, was having a customer bring in a 45" WR (racing) motor last spring. Being somewhat unfamiliar with the nuances of such an engine, I decided I would read up on 45 engines in general on the Flathead Power Bulletin Board .

Now, I have frequented the board for some time, but had always skipped the 45 section of the forum because, well, there just aren't enough hours in the day to read everything on the Internet. But now, with a new found reason, I tackled the job of reading the backlog of posts on the Flathead 45 ....well at least those with titles which indicated they were engine related. A huge task, and it has taken me some time, but I am nearly through.

I was SHOCKED. Who would have expected a forum on 45 Flatheads to be such a hotbed of performance talk? That stirred my interest.

Then, soon after the WR motor came in, another long time customer brought in a 45" trike motor. While the WR is here for a rebuild/restore, the trike is in need of a little more power. Well, 45 or not, that is still right up my alley. In the past I have had to slap myself to keep from doing performance modifications on an old cast iron Briggs and Stratton that I had apart for no other reason than to clean and paint it for display; sure markings of a gear head bordering on lunacy.

There are two ways to modify a motor. One is to do all of the things that you think should help and then test the results. On an engine type that you are not likely to get a lot of repeat business, that is the sane way to do it. The other way is to test each modification before going on to the next. That way you find out how much each step helps, or in fact if it helped at all, or even in some case if it hurt. Its a lot more work, and you are seldom paid for it, unless you consider increasing your knowledge base as "pay."

So, as if I needed to prove my insanity to anyonen else, here are the results of my first step in "porting the 45 Flathead"; a flow test of the stock ports.

Intake .100" lift - 48.2cfm

Intake .200" lift - 83.8cfm

Intake .300" lift - 98.7 cfm

Intake .350" lift - 102.6cfm

Intake .375" lift - 103.8cfm

Intake .400" lift - 104.3cfm

Intake .450"lift - 104.4cfm

***

Exhaust .100" lift - 41.9cfm

Exhaust .200" lift - 82.4cfm

Exhaust .300" lift - 104.4cfm

Exhaust .350" lift - 110.6cfm

Exhaust .375" lift - 113.3cfm

Exhaust .400" lift - 115.7cfm

Exhaust .450" lift - 119.3cfm

Tests were done on a Superflow SF600 @ 28 inch test pressure with a radius entry directly on the spigot (no manifold)

The next test will be with conventional porting work performed. Stay tuned.

Noah's Ark

(Here we are, up for our turn to do the service at Friendship Manor again. Continuing to follow my wife's advice, I will go with another familiar story from the Bible. Short and sweet.)

Gen. 6:5-8 "And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually. And it repented the LORD that he had made man on the earth, and it grieved him at his heart. And the LORD said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for it repenteth me that I have made them. But Noah found grace in the eyes of the LORD."

NOTE: Noah found grace in the eyes of the LORD. What wonderful words those are! Doesn't that make you long to have those words written of you? Lee found grace in the eyes of the LORD. "Your name here" found grace in the eyes of the LORD!


Gen. 6:12-14 " And God looked upon the earth, and, behold, it was corrupt; for all flesh had corrupted his way upon the earth. And God said unto Noah, The end of all flesh is come before me; for the earth is filled with violence through them; and, behold, I will destroy them with the earth. Make thee an ark of gopher wood; rooms shalt thou make in the ark, and shalt pitch it within and without with pitch."

God goes on to give specific instructions to Noah for the construction of the ark. I have heard it said that in modern times a scale model of the ark has been built, using the dimensions from the Bible, and found to be one of the absolutely most stable, and unsinkable shapes ever constructed.

Gen. 6:17-22 "And, behold, I, even I, do bring a flood of waters upon the earth, to destroy all flesh, wherein is the breath of life, from under heaven; and every thing that is in the earth shall die. But with thee will I establish my covenant; and thou shalt come into the ark, thou, and thy sons, and thy wife, and thy sons' wives with thee. And of every living thing of all flesh, two of every sort shalt thou bring into the ark, to keep them alive with thee; they shall be male and female. Of fowls after their kind, and of cattle after their kind, of every creeping thing of the earth after his kind, two of every sort shall come unto thee, to keep them alive. And take thou unto thee of all food that is eaten, and thou shalt gather it to thee; and it shall be for food for thee, and for them. Thus did Noah; according to all that God commanded him, so did he."

Did you catch that? It says that Noah did ALL that God commanded him. How important was Noah's obedience? It would seem that the fate of the whole human race depended on it. And not only the human race, but also the animal kingdom. How good a job do we do of being obedient to God?

So Noah did as the Lord has commanded him, and the Lord did as he said he would. It rained for 40 days and 40 nights. The flood rose to a point approximately 20 feet higher than the tallest mountain. Every creature that lived upon the land perished, except for those in the ark. After the prescribed amount of time, the flood waters went down, and the ark came to rest upon Mt. Ararat.

The story of Noah and the ark, though it is a true story, also serves as a pretty good picture of salvation. We already mentioned some things about Noah that line up with salvation. The Bible says "But Noah found grace in the eyes of the LORD." All around him was great wickedness, but Noah found grace. There is great wickedness all around us, but if you are truly a Christian, then you have found grace in the eyes of the LORD.

The Bible says that "Noah walked with God." It is not possible for a person to be truly saved unless he walks with God, and walking with God involves going the same direction, and with a common goal.

Noah did all that God commanded him. Salvation involves doing as God commands. In the New Testament Jesus says: if you love me, keep my commandments. I think it is safe to say that most of us fail miserably at this. But the difference is that a true Christian will try to follow God's commands and it will be grievous to them when they fail.

Another parallel between salvation and the story of Noah is the protection from God's judgment. While all the earth was being punished for its wickedness, Noah and his family were shut up safely in the only vessel capable of withstanding the judgment. In fact, in Genesis 7:16, the Bible says that "the LORD shut him in." The same is true for the Christian. Once Jesus Christ is your Lord and Savior, then you are safe from the judgment to come. Jesus said "And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand." (John 10:28)

Hebrews 11:7 "By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark to the saving of his house; by the which he condemned the world, and became heir of the righteousness which is by faith."

Just as Noah was saved from physical death by his faith in what God told him, and his putting that faith into action, he was also saved spiritually and declared righteous before God because of that faith. The same is true today. Through faith in the death, burial and resurrection of Jesus Christ, we can also become an heir to righteousness.

Jesus Christ died in our place paying the penalty for our sins, and what he gives us in place of our sins, is a share in his righteousness. And just as Noah's faith in what God told him resulted in his work of building an Ark, our faith in Christ's sacrifice on the cross, if it is real, will result in turning from our sin, and to building his Church.

Remember what it says here in Hebrews. It was Noah's faith that caused him to build the ark, and it was his faith that allowed him to inherit righteousness. The work of building the ark was simply the result of that faith. The exact same thing is true for you and me. It is our faith that will cause us to turn from sin and our faith that will allow us to inherit righteousness. The repentance and good works are simply a result of that faith.

If you have never done so, won't you put your faith in Jesus Christ? Won't you believe that he died in your place, and paid your penalty so that you might live? Won't you have faith like Noah?