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Hot BTSV cams

Moderators: Curt!, Pa

Post Thu Oct 20, 2005 12:58 am

Posts: 33
Location: Borne, The Netherlands
My 5” stroker engine is progressing rapidly and I am now working on the cams.
Is there anyone on this board who has put hotter cams in a BTSV, preferably a 5” stroker, and is willing to share is experience?
Or even better, does anyone have dyno charts for hot BTSV cam grinds?

The only suggestions I got so far is to put in KRTT grinds, but I do not want to rev. higher than 5500 rpm, so I doubt if these cams will work in my engine.

Short post, difficult questions………….


Post Thu Oct 20, 2005 6:14 am

Posts: 693
Location: somerset, oh usa
No experience here but here's a link to a guy that can help you.

Post Thu Oct 20, 2005 9:16 am

IMHO you're not going to get what you want from the original lobes - not enough metal.
The ideal would be as much lift as poss with about 300 degrees intake duration (no more), intake closing no later than 70. Exhaust milder, center positioned to give as much overlap as you think you can stand.
Be prepared for a lot of work and big springs.

Post Fri Oct 21, 2005 7:17 am

Posts: 197
Location: Bucktown, PA
If Reid Greer is still around, he's the man.
Some folks think he's crazy, but he makes horsepower!

Post Fri Oct 21, 2005 8:11 am

Posts: 233
Location: Richmond Va
I did a Google for grins, Greer showed up as a registered racer in '46

Post Sat Oct 22, 2005 6:18 am

Posts: 13
Location: norway
Joy cams in uk is doing good work on btsv cams. More metal all over the lobe. Steve on VL HEAVEN may have more info. :?: 8)

Post Sat Oct 22, 2005 6:19 am

Posts: 13
Location: norway
Joy cams in uk is doing good work on btsv cams. More metal all over the lobe. Steve on VL HEAVEN may have more info. :?: 8)

Post Sat Oct 22, 2005 6:25 am
Yes I am running a set of Joy cams in my '34 VL racer, which puts out 36 bhp at the rear wheel and revs over 5000 rpm. The specification for these is in the flathead archive on this bulletin board, but they basically have more lift and overlap than the stock cams. There is an article in the Antique Motorcycle describing this bike. I also have plans to reproduce the 'hook cams' put on the inlet valves only on Harley racers and hillclimbers up to 1939. These have no more lift than stock cams but serious extra overlap.

Post Sat Oct 22, 2005 11:01 am

More lift is (in general) good, remember that you may need to blend in some metal at the radius of the valve pocket, and/or plunge cut the relief deeper. The compression loss will be very minor.
More overlap is another story. All the original SV cams (except WR etc.) have very little, so adding some is safe, but a change in lift with the same lobe centers and duration (as in Joy, quoting from Steve's archived post: intake 24-54 degrees, exhaust 54-24, overlap 48, lift .460".) will increase the effective overlap (i.e., area of both valves open).
Things to be avoided, in order of priority:
1. late intake closing (not as important with large motors, strokers, short rods, high compression)
2. late exhaust closing
3. early exhaust opening
Extending the duration significantly on the original lobe centers will cause all 3. For best effect, a big change in intake duration should also be advanced (early opening), but this requires either a new lobe or re-timing the cam.
If you're going to use more OL (and tuned exhaust is useless without it) on a Linkert you need to learn how to mod it. Anyone who advises "increase the main jet size" hasn't a clue.
Mikuni is easier but still needs some work. S&S, Kei'Hin, Bendix, SU, CV: good luck.

Post Mon Oct 24, 2005 1:50 pm

Posts: 919
Location: RENO,NV. U.S.A.
I agree with Panic,advancing the intakes will definitely help,the KR grinds are also a step in the right direction. BREWSKI

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