Author Topic: 103 cams - again  (Read 1888 times)

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Offline Finn

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Re: 103 cams - again
« Reply #25 on: February 20, 2020, 10:16:08 PM »
 :beer:

The decision making process is always so agonizing as you wish and hope that you have managed to gather enough information and advise to be able to make a decision.

And then you realize that there is a product you haven't considered at all. And the 'circus' starts over again.  :teeth:

Luckily I'm having this problem now only with:
- cams
- exhaust
- tyres

 :cry:
« Last Edit: February 20, 2020, 10:20:52 PM by Finn »

Offline Hossamania

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Re: 103 cams - again
« Reply #26 on: February 21, 2020, 07:38:06 AM »
Tyres - nothing wrong with OEM.
Cams - do you need to beat your friends off the line to the next stoplight, or beat them at the 1/4 mile and top speed?
Exhaust - pick one based on the looks and sounds you like, within reason.
See? Easy!
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Offline Finn

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Re: 103 cams - again
« Reply #27 on: February 23, 2020, 10:30:58 AM »
There are cams such as Andrews 57 and Cycle-Rama CR575 for which manufacturers/forums tend to recommend slight bump in compression ratio from stock when.

If I were to advance either cam with 4 degree sprocket is it so that it
- would move hp/tq to the left slightly?
- would remove the need of extra compression?

Online Ohio HD

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Re: 103 cams - again
« Reply #28 on: February 23, 2020, 11:33:02 AM »
Just my opinion, I would stay within a 25 to 30 degree intake closing with a stock motor to insure decent compression.

Why not do something different? How about an Andrews 48 with 1.725 rockers?


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Offline Finn

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Re: 103 cams - again
« Reply #29 on: February 23, 2020, 11:53:23 AM »
Yes, around 30 degrees is my layman's goal. CR575 with 4 degree sprocket would have 31 intake closing and leave room for further modifications such as 110 kit.

I fear a set of rocker arms would unfortunately break my budget and I would prefer not to pull the heads for thin head gaskets.

This probably would be easy to solve by ordering a set of Andrews 48s but one tends to think too much...  :embarrassed:

Online Ohio HD

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Re: 103 cams - again
« Reply #30 on: February 23, 2020, 12:01:18 PM »
Buy what works now. You can always sell them when you want to go bigger in motor. I would do that before buying cams that may be a comprise on one or both side of pre and post performance upgrades.   
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Offline rigidthumper

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Re: 103 cams - again
« Reply #31 on: February 23, 2020, 12:07:09 PM »
There are cams such as Andrews 57 and Cycle-Rama CR575 for which manufacturers/forums tend to recommend slight bump in compression ratio from stock when.

If I were to advance either cam with 4 degree sprocket is it so that it
- would move hp/tq to the left slightly?
- would remove the need of extra compression?
4 sprockets shift peaks 300-400 RPM from straight up.  + (advance) moves it to the left, - (retard) moves it to the right.  Remember, any advance/retard sprocket will change all the cam events; advances/retards the intake and also advances/retards the exhaust events. Opening and closing the intake valve sooner can increase the CCP, but it means the exhaust valve is opening/closing sooner, so blowdown pressure is increased, which means some of the pressure designed to push on the piston ( and help make horsepower) is now flowing out the pipe instead.
Sometimes (depending on the pipes) nullifying the expected changes
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Offline Finn

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Re: 103 cams - again
« Reply #32 on: February 23, 2020, 12:58:32 PM »
Thanks guys for good pieces of advise, much appreciate it.  :beer:

Offline Finn

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Re: 103 cams - again
« Reply #33 on: March 25, 2020, 12:38:31 PM »
Cycle-Rama CR570-2 it is.

Cams were on back order for a while but they got them early this week and just took my order. Which is nice.  :smile:

Offline 838

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Re: 103 cams - again
« Reply #34 on: March 27, 2020, 08:00:54 AM »
Cycle-Rama CR570-2 it is.

Cams were on back order for a while but they got them early this week and just took my order. Which is nice.  :smile:

There are a few 110s with that cam too... for when you just cant resist!!!!

Offline Finn

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Re: 103 cams - again
« Reply #35 on: March 27, 2020, 12:52:09 PM »
Will keep that in mind. Just in case.  :teeth:

Offline Tail Ridr

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Re: 103 cams - again
« Reply #36 on: March 28, 2020, 08:13:57 AM »
I took all of the dyno sheets from the Fuel Moto study, used a plot digitizer on the sheets to extract data, put them in excel, and analyzed them. (Yes I spent way too much time on it)
Being that FM did their test on a 2012, IIRC, It'd be curious as to how the H.O. cam interpolates in with these.
Eliminate the Imperfections of mass production!

Offline Finn

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Re: 103 cams - again
« Reply #37 on: March 28, 2020, 09:00:35 AM »
As far as I can tell the 103HO cam specs are as follows:



For my layman's eyes that looks fairly decent but I decided to change cams nevertheless.