I have a buddy with a '07 Road king. He is running Reinhart True Duals, SE breather, and SERT. He wants to change JUST cams and wants to go to gear driven cams.

He is trying to pick-up cruising power to be able to run with the bigger bikes in the club. Someone has convinced him the Andrews 21hg cams are the way to go. I'm thinking the 37hg... I'm also thinking there is little if any advantage to switching to gears with just a mild cam... Looking for advice from those that have "dun it"....

(I tried to insist he should just go 103" but he is wants cams only)

 

We just installed a set of mufflers, breather kit, and a set of Bob Wood TW-6-6 cams, 4*advance gear, 2007 RK.
We do not tune EFI here on our 150 Dynojet. Only can test.
It showed 100.8 ft/lbs, and 81.8 hp. UNTUNED.
We would expect a 10% gain once tuining is complete.

 

Either the 26g or 37g will be a good choice. The 21's are better suited for the smaller 88" builds with the 4" crank from a few years back. I would have to agree myself though on the 37's. That would be my recommendation to him for his 96" build.

 

Looks like I've been able to talk him into the Woods TW 6-6s. Scott, is the 4 degree advance a seperate part? Oh yea, he has his Reinharts sold and is going with 2-1 Thunderheader.

 

What exactly would he gain on the woods 6-6 and a 4 degree advance gear that he wouldnt get from just a 37 cam? Other than lightening his wallet an extra $2-300? Tossing in an advance key on a short duration cam can actually hurt performance and tuning, and make running a bike off low octane fuel a b!tch. An advance cam gear should only be added of cold cranking compression is LOW(like with long duration cams). If someone is looking to get more performance and punch OFF IDLE, he should get a cam designed with an earlier clsoing intake point, shorter duration and less overlap.

 

For those of us reading and learning, what is the advance key?

thanks

 

gunnert,
Yes it is a seperate part #.
Scott

 

The 37 won't stand a snowballs chance in hell, stacked up against a Wood 6/4* advance, for a cam only set-up, or many other applications for that matter.
The 4* key/gear kicks up the ccp about 10 psi, and that bike will crank at about 190.
Perfect for that cam.
Also, you can juggle the torque curve around to suit the particular riding wants/needs with the key/gear.
It has been done in the automotive industry, since the steam locomotive.
Don't believe me??
Give 'ol Bob Wood a call at 1-205-525-4949, or www.woodcarbs.com.
Cheers,
Scott

 

Hmmmm.... some specs:

37G 18/38 236 dur. .510 32 degrees overlap (intake opening and exhaust close spec combined ='s overlap)
......46/14 240 dur. .510 (less overlap tends to bring the powerband down low and exhaust plays less of a role in power potential, more raises the powerband up high and exhaust pipes can either HELP OR HURT PERFORMANCE MORE)

Wds 6-6 20/40 240 dur. .510 38 degrees overlap
............42/18 240 dur. .510

Wds with 4 degree advance key: 24/36 240 38 degrees overlap(still)
.............................................46/14 240

How you can say the woods will "kick the crap" outta the 37g is beyond me. The cams are very close in design to begin with, but the 37g ON ITS OWN, closes its intake off 2 degrees quicker and has 6 degress of LESS overlap between the intake and exhaust ports being open together.

Now with the 4 degree advance key you can make the woods close 2 degrees sooner(and you will increase cylinder compression by about 5psi, not 10psi as you claim), but you can never change the overlap between the intake and exhaust valves. More overlap decreases low end power.

The 37g is already a strong punchy cam off idle(stronger than the woods cam)with very broad midrange power and its hundreds of dollars cheaper than the woods setup.

Cams straight up the 37g will have slightly more compression on its own by roughly 2-3psi(which is negligible really). Regardless it will outperform the woods cam down low and keep up with it through the midrange. Even with the woods cam WITH a 4 degree(gaining about 2psi in ccp over the 37g, which is really negligible)advance gear installed the 37g will pull just as strong down low(due to less overlap) and it will now have a slight advantage up towards the top of the powerband too since your choking off the woods timing specs adding the advance gear to get more boost down low.

To put it simple, youll spend twice as much for the Woods 6-6 and an advance key to get typically the same performance and power curve just buying the Andrews 37, LOL.

And I'll garentee that any independant dyno testing done on the above cam combinations will prove this. Better yet, call up a few places like Deweys head porting ( http://deweysheads.com/ ) or Johnson Engine Technology ( http://www.johnsonenginetechnology.com/ ). These guys are ripping out 90/90 SAE plus hp/tq numbers on 95"/96" cam only setups and 110/110 SAE hp/tq #'s using the modest 37g cam on very mild 95"/96" builds with minimal headwork done. http://www.rrcycles.com is another place that holds the 37g cam in high regards for good street performance. Call any of them and ask for their .02. Its a great cam on its own and with the money saved you can use towards a mild basic port job which in itself will gain you some good power.

The only thing a Woods cam will kick the cr@p out of is your wallet. I bet Hillside and other Woods dealers' makes more just in profit out of a Woods cam/advance gear combo than what you would pay for retail for an Andrews cam.

Really want to d!ck around with a cam advance gear for cams that really dont need it? You could use it just as easily on the Andrews as well and still save a boatload of money. But its still really a waste. The V-twin street range powerband is really narrow enough where you can find a cam that will give you the powerband you need, WITHOUT having to add a cam timing gear. Advancing or retarding cam timing is normally done for long duration/overlap agressive cams that many times will have relatively low ccp. Not mild street cam setups.

 

Holy Molly BatMan!

Really for just a cam change, the Woods 6 -6. I would use regular chain drive cams. Only thing, I would also use Woods behive valve springs for this cam. But thats just me.

There are more that just opening and closing numbers with cams. Ramps opening and closing rates and seperation angles for a couple. Woods cams are different.