i've got a 74mm crank with 90.5's which gives 1955, lovely.
Minimal minimal clearancing, but you will have to alter some of your parts.
If you dont want to alter anything use your stock crank, or if you plan to rev it a bit higher, a counterweighted stock crank would be advisable- £179 for a welded or £210 for a forged CB item (speedshop). Even the slightly longer stoke makes a nice difference to the drive
I have the same as doobyscoo and can confirm that it runs real nice, and I think it is a great combo as the bore/stroke ratio is kept somewhere standard and the engine does not get wildly over square as just increasing bore. As the $ is in the toilet at the moment this is the time to get a new crank. The $ WILL increase in 6 months.
I think when you say 'do not want a stroker' I guess you mean you do not want a large increase in crank throw, because as everyone else has pointed out, a crank throw greater than 69 is a stroker crank. It is generally accepted that a 74mm crank will go in without any or very minimal clearancing or change to pistons rods etc.
76mm might also be possible, but as each case is ifferent you might nee dto get working. After that you will need case work and different rods and probably pistons to keep angular acceleration and clearance at the BDC.
74mm crank is a good choice for a easy win on displacement gain (pm me if you need one ) stock rod length is 5.398 IIRC not 5.5 but either way as metric says it makes for a nice combo, suits the flat4 well and makes good power without the need to go BIG!!
hey, i have a 1955cc - thats a 76mm crank with 90.5 none stroker style pistons... iv used cb unitec rods which are stock length... 5.4
you guys with a 74mm crank and 90.5 pistons have a 1905cc not 1955cc.
i love my engine, it used 2 be running on 40 dells with 8.8:1 cr and it was pretty quick.. ran 16.3 down the strip with 36mm dells and tiny venturis - this stopped it revving over 5k. i changed to 40 dells and bigger vents and i could rev way higher which i needed as i had a bigger cam (web110 - engle 120ish) and scat D port heads with 40x37.5 valves... this woke the engine up a load, i reckon id hav been mid to low 15s easy.... it made just over 100bhp with 40 dells and small vents and again, stopped makin power much over 5k... thats when i put the bigger vents in, but i didnt get it dynod again.
iv now added efi and turbo, and will get it dynod soon...
my 1955cc is a load nicer to drive than my 1776cc was
My 1955 gave 110bhp at the crank on first couple of runs It gives 78bhp at the wheels on the RaceShack dyno after a 1000 miles
Very modest mods - 110 cam, 8.5 CR, matched inlets, fully balanced, 40 x 35.5.
But a torque curve that climbs almost vertically up to about 700 ish rpm and then is flat through out. Power curve is not at all peaky.
Exactly what I was aiming for.
Would putting a 74mm crank in a tuned 1600 be a waste of time?
would you suggest getting the parts to make a 1776 on a stock crank and then fit a 74mm instead as it sound like you all have/had 1776 motors before fitting the new crank to make 1905cc?
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