It has been suggested to me to use straight cut gears in my 1776. I have Berg HD valve springs, a very mild cam (Wade 149) and 1.25 ratio rockers.
Noise aside, are straight cuts worthwhile with the above specs?
Cheers............Wayne
If u go straight cut ensure u use double thrust cam bearings.
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hulbyw wrote:Noise aside, are straight cuts worthwhile with the above specs?
no - but they do sound cool
Futue te ipsum!!!
I thought you would have less need for double thrust bearings on straight cuts as you don't have the crank gear trying to drive the cam backwards /forwards? saying that if you have the case split regardless of what style cam gears you are running double thrust bearings can only be the better way to go. They aren't that noisy either, definitely nothing like a Holden red 6😁
Are you running double valve springs, straight cut gears are only needed if you have high spring pressure, apart from the noise there is no gain as the cam you will be running is quite mild, be aware of the lack of quality some of the cam gear sets have, standard cam bearings will do the job as there is no load on the thrust bearing any more. if you are running double valve springs it is a good idea to break the cam in using only the outer springs and fit the inner after the cam has been broken in.
No doubles, only HD Berg singles
hulbyw wrote:No doubles, only HD Berg singles
I'd recommend no straight cuts, just double thrust cam bearings which I use in every engine and modify them slightly for improved oiling.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Straight cut gears give you absolutely no power gain
HOWEVER they do give you a headache listen to the extra noise
if there was a power gain every engine manufacturer in the world would have used them they didn't spend millions on research and design for nothing
the cam and rockers will give you more power which when added will need the heaver springs you will need extra carburation and a decent exhaust system as well
what have you planned for that
My biggest concern with straight cuts is getting the cam gear lash right. The stock set up allows a range of gear sizes to choose, gears range from +9 to -9 so 19 different sizes including a zero gear.
You don't get that with straight cuts, one size fits all, or not.
I have seen single thrust bearings very worn on some high mile engines, so I believe paying careful attention to fit, end float and oiling is important here.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Exhaust will be VS and 40dcn ( yes I know I would be better with twins but using that single weber to start with).
The CB straight cuts are actually not too bad noise wise, but given the above advice I will save my money and forget the straight cuts
Thanks all for your comments and help. Much appreciated
I'm no engine builder but I like straight cuts mostly because quality of aftermarket helical gear sux, do you need them in your engine? Not really but it's up to you to decide. As posted above, dual thrust proper clearance bearings and right combination of size and pitch in gears will work for you.
bitten by the bug..........several times
vw54 wrote:Straight cut gears give you absolutely no power gain
On a Holden six in a 15 sec Torana the straight cuts with no other change at all, nothing, is worth a solid tenth and a half, tested before and after then back again.
And yes, on a 192 crap they're loud!
😂
Your experience of doing the same testing was obviously different..........
