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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
I have finally gotten my valve train noise issues sorted and have started to ride my newly built engine a bit more to its full capacity. The recipie is as follows.
- 2002 Dyna Superglide with Twin Cam engine
- Bored to 95" with Wiseco pistons, 4.6 cc dome - S&S super stock heads with 79 cc chambers, 1.94" intake and 1.575" exhaust - Mikuni HSR42 carb with S&S intake, size matched to 45 mm ports in heads - S&S Grand National Exhaust, looks like a 2-2 but with a connecting chamber between the headers - Dynatek TC88 ignition with a custom curve - Andrews TW55 gear drive cams
Static compression should be at 10.5:1 according to big boyz calculator. I have installed electric ACR:s so starting is a breeze.
The only part of this that I'm maybe not fully happy with are the cams, I actually choose them because they were really cheap, $65 for a brand new set on Ebay, and having bought them I then chose pistons to arrive at a good CCP of around 195 psi, once again according to big boyz.
I was fully aware that these are mid to top range power cams, and that low range torque might lack a bit, and to some extent that is true, running at 2000 rpm it is a bit rough and not super strong, but as son as it reaches 3000 rpm things get really fun and acceleration is really nice.
I had some idea that I might want to change to cams with a bit more low range torque, I can not really go to super torque cams like S&S583 since static compression is too high, but I thought going for cams with shorter overlap like Feuling Reaper or Andrews TW32 would improve low end a bit.
But having used the bike a bit I actually think the low end is fine and I would rather have even more of the kick from 3000 rpm and upwards. The valve springs in my heads can handle up to .650" lift so there is room for more agressive cams in that sense.
So here comes the question, finally.. Would it make sense to go to an even "bigger" cam than the TW55, with this configuration of parts? I don't want to lose any more low end power, but I not really expect to gain any either, I'm looking for maximum power between 3000 and 6000 rpms.
Or are there even cams that would improve the whole power band? I seem to have read that the TW55 is quite an old design, classic long duration long overlap cams, and that there might be more "modern" grinds that are plain better overall.
I was fully aware that these are mid to top range power cams, and that low range torque might lack a bit, and to some extent that is true, running at 2000 rpm it is a bit rough and not super strong
define running rough at 2000rpm...
surely you're not trying to cruise at 2000rpm, are you?
surely you're not trying to cruise at 2000rpm, are you?
No for sure I don't, I know very well these engines should not be lugged at too low rpms.
I rather mean that compared to the previous state, stock 88 with 509 cams the idle is more uneven and the throttle response is a bit slow, I actually have to give a bit more throttle when starting from standstill now than before.
I think this is mainly down to more overlap and a big intake port, so the gas velocity is a bit low.
But then of course from maybe 2500 rpms it's a completely different beast, its way faster than before.
That sounds like a nice cam, but it seems only be available for 2007 and newer bikes, and only chain drive. But regardless it seems I should look for a cam with more lift and less overlap than the TW55?
Yes. Not a cam expert but dropping from 42* overlap to 18* seems like a lot but 42* to 37* not so much. Funny about the availability for the CR595 because I am running it in an '05 model with gears. The cams were purchased almost five years ago so something migh have changed but I would call Wes Brown to verify availability. Contact info is at the CR website. Wes is easy to talk to.
I ran S&S 575G cams (gear drive) in my 2000 Electra Glide and they were really nice, good torque down low ,a little flat spot about 2500 rpm but I think that was because of the Rinehart true duals.
At 3000 rpm they really kicked in and kept pulling through 6500 rpms and above.
It was a 95" build with Baisley ported heads,10.25 pistons with Cometic (if memory serves) .030 head gaskets static was 9.7.
I had a Mikuni 42 but it didn't like high altitudes above 10,000 ft ( I tour a lot in the west) having been tuned at just 300 ft so I swapped it for an SE CV 44 jetted out and it was a lot happier in the mountains.
The Dave Mackie 590 has a little earlier intake closing, also it has 7 degrees of advance ground into the cams, and less overlap, so they should add more get up and go sooner in the RPM's.
It has more intake TDC lift than the Andrews 55's have. So I'd check the head setup, and as well insure your springs will accept .590 lift.
The Dave Mackie 590 has a little earlier intake closing, also it has 7 degrees of advance ground into the cams, and less overlap, so they should add more get up and go sooner in the RPM's.
It has more intake TDC lift than the Andrews 55's have. So I'd check the head setup, and as well insure your springs will accept .590 lift.
Valve springs can handle up to .650" lift, do I need to worry about TDC valve to piston clearance? Pistons are Wiseco with quite big cutouts for valves. I know the proper way is to check clearance with clay, but that's a lot of extra work removing the heads.
Also a related question, at what lift do I need to go to roller rockers?
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Cam suggestion for 95" TC
