Has anyone direct experience of swapping a 649 for an SW23, I'm told that they are a bit torquier and have a wider power band. Please note this is for a different engine than my other questions about cams. For a 1380 with a very good cylinder head st cut box etc. Possible sprint / hill climb/ Blyton use.
God why is burning petrol such an expensive habit lol!
649 vs. SW23
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wantafaster1
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rich@minispares.com
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wantafaster1
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Re: 649 vs. SW23
Thanks Rich. Does it waken up any sooner? To throw another spanner in the works an STR930 is supposed to be better as well.
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LarryLebel
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Re: 649 vs. SW23
A long duration cam will always be a "dog" until the air/fuel mixture gets moving ... at higher rpm. If you want something that "wakes up sooner" a long duration cam is not what you want. I would say about the longest duration for poking around town is about 270.
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wantafaster1
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Re: 649 vs. SW23
Yes Larry I totally understand, I want the power I have now, It's maybe what you could call "modern equivalent" syndrome. Why and how is it better?
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Earwax
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Re: 649 vs. SW23
saw reputed (not reported .. as i cannot confirm this) that the sw23 is the same profile as 649 but LSA different... i think closer, 100 instead of 103 so the mid range torque is more...
i thought STR930 was a clone of 648/649 so again a good cam
if the 649 was a good cam ( and all reports it is) then slightly wider torque band offered by a newer version would be a good thing....
thinking about it some more.... when did 1.5 or 1.6 rockers make their way onto racecars? .. i am wondering of the development timeline of this and the cam designs
... again from hearsay .... from a racer in the states who has run both the SW23 and the 649... both good , couldn't really say if one was better ... but runs high CR ( near 14)
i thought STR930 was a clone of 648/649 so again a good cam
if the 649 was a good cam ( and all reports it is) then slightly wider torque band offered by a newer version would be a good thing....
thinking about it some more.... when did 1.5 or 1.6 rockers make their way onto racecars? .. i am wondering of the development timeline of this and the cam designs
... again from hearsay .... from a racer in the states who has run both the SW23 and the 649... both good , couldn't really say if one was better ... but runs high CR ( near 14)
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In the shed
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Re: 649 vs. SW23
Good point about the silly rockers.
I have a 1430 with 37/31 head with MASSIVE PORTS. Sleeved pushrods...it is extreme. It does run normal rockers though. Old race engine. The cam is totally unknown and is stamped "319". I assume it's something to do with a 319 duration somewhere....perhaps 319/319....
I was wondering if it was going to be a dog and wondered about fitting something a bit more tame. I have decided that I am going to stick with it and see how it goes.
If I change the cam/rockers, it's going to be a totally different engine.
I don't think anyone has answered the question re:- rocker ratios.
I suppose you could look at it differently and consider "curtain area" of a valve, this would give you a A/t graph which would then exclude rocker ratios. After all, ignoring the size of the ports and how good your head is, the A/t graph is the crux of the matter.
I have a 1430 with 37/31 head with MASSIVE PORTS. Sleeved pushrods...it is extreme. It does run normal rockers though. Old race engine. The cam is totally unknown and is stamped "319". I assume it's something to do with a 319 duration somewhere....perhaps 319/319....
I was wondering if it was going to be a dog and wondered about fitting something a bit more tame. I have decided that I am going to stick with it and see how it goes.
If I change the cam/rockers, it's going to be a totally different engine.
I don't think anyone has answered the question re:- rocker ratios.
I suppose you could look at it differently and consider "curtain area" of a valve, this would give you a A/t graph which would then exclude rocker ratios. After all, ignoring the size of the ports and how good your head is, the A/t graph is the crux of the matter.