Cams n stuff

[crow]

Hello gents, looking for some advice/opinions/abuse on the valvetrain for my 1109 motor. 
I've got a set of Kent camshafts with 6.5mm lift (9.9mm at the valve). Will I be OK with standard rockers & springs as opposed to hard welded & heavy duty?
Is there any performance benefit to the heavy duty springs or is the idea just to prevent valve float with big cam lifts?
 

[canamant]

What was the standard lift at the valve ?

 

Check several things.

First, will the springs go coilbound with the additional lift ?

Second, is there sufficient clearance between the valve collets/upper spring retainer and the valve guide ?

What will the valve to piston clearance be at the valve timing you want to use?  You might not be able to use the timing you want unless you pocket the pistons.

 

Valve springs need to be strong enough to keep the valve in contact with the cam when closing.  It depends on the cam profile as well as the lift and how hard you are revving it.  Sorry I can't be of more help.

 

[jonny1bump]

That's a lot of lift on a standard head you certainly need to  check everything stated above I'm sure the spring with go coil bind and that lift on stock as a start. On 1127 head which is last head I've worked on this is deffiatly the case.

[Oilyspanner]

Stiffer springs will be required with a cam giving .396 lift (9.9mm) standard is .346 (8.8mm), else you'll get valve float at high revs - Yes, stiffer springs will lose you power - in tuning you use the softest springs that still control the valves at high revs - plus you need to check all the things already said above .... A good flow job, raising the compression and good carbs is a sure way to get good solid power gains. Big cams don't always give you good power - best done as a part of whole top-end project to make them work well.

1109cc isn't very big for these motors, GSXR1100 cams or GSXR750 K/J cams give good power for the 5 speed box.

Depends what you want to achieve ? there's a lot of experience on this board to help you.

[manden]

I remember it like the Yoshi stg 1 is 9.8mm lift and it's for standard springs. But I'm not sure. Ape has decent springs for the gsxr but somewhat pricey. Your rpm is going up at least 1000 rpm, so maybe better safe than sorry. Ported head gives great gains even on STD engine me with STD cams so do that as well.

[jonny1bump]

Stay away from Ape unless drag racing only. I have broken quite a few really think quality for prolonged rpm is just not there.

 

[manden]

I didn't know that about ape springs. But I got an recommendation on other valve springs. I'll find it tomorrow when I get home

[markfoggy]

I'm interested in what you can get away with and keep the valve seals.

GSX loses them on the inlet on stage 2 .

What's the collective wisdom on Boilers and into Blandit world?

[george 1100]

That's a big cam with big duration. You will likely encounter coil bind, valve to piston issues, valve retainer to valve guide clearance issues. Apart from dealing with those issues you will need hardweld rockers with extended pads, port work, bigger valves(big power here) and higher compression. In other words I'd be building the engine around that cam. On one hand if it's not installed correctly using the correct parts it's highly like it will self destruct and on the other hand if you don't build the engine using the appropriate parts to get the most out of that cam, it's likely you won't see a significant power increase. Lastly, that cam won't like traffic. Good cam, will make a lot of power

[manden]

I agree with loads of power in porting the head and larger, lighter valves. I have some half race cams that's going in mine owner the winter. I don't know what valve springs I'll be using but I'll be looking at 0.397" lift on the valve.

[clivegto]

20 hours ago, jonny1bump said:

Stay away from Ape unless drag racing only. I have broken quite a few really think quality for prolonged rpm is just not there.

 

What other cam springs are avalable ?

[nopokewithoutsmoke]

Just a thought, but I wonder how 30 year old standard Suzuki valve springs would measure up against a new set of the same springs?

[nopokewithoutsmoke]

12 minutes ago, clivegto said:

What other cam springs are avalable ?

Kibblewhite?

[jonny1bump]

Clive I'm using stock springs with shim to get base pressure I want.

[jonny1bump]

1 hour ago, nopokewithoutsmoke said:

Just a thought, but I wonder how 30 year old standard Suzuki valve springs would measure up against a new set of the same springs?

I have found four pound drop on base pressure with old springs. Not 30 year old mind you.

Edited October 1, 2018 by jonny1bump

[jonny1bump]

20 minutes ago, jonny1bump said:

Clive I'm using stock springs with shim to get base pressure I want.

Just check for coil bind once you shim if using high lift cam.

[dupersunc]

42 minutes ago, jonny1bump said:

Clive I'm using stock springs with shim to get base pressure I want.

What seat pressure are you aiming for?

[crow]

Thanks for the input chaps! It turned over fine (by hand) before I tore it down, so I don't think the springs were going coil bound and there must be at least a silver rizla's worth of clearance between valve & piston. Will check it all properly once it's back together and timed appropriately.

In the meantime, anyone got experience of using a similar cam, what other parts did you use it with/did it eat your rockers etc?!

Jonny1bump... How do you go about determining the appropriate pressure for a given valve lift?

[jonny1bump]

I Aim for 38 to 40 lbs at your install height.

Need to check you got enough clearance on  your valve guides too. 

[jonny1bump]

Using valve spring pressure gauge and vernier to get your install height.

Edited October 1, 2018 by jonny1bump

[Oilyspanner]

Have you fitted /will fit fresh valve springs Crow ? 

[crow]

The old ones check out OK for free length but I haven't checked the reaction force yet. Sounds like it might be a good idea to replace them even if with stock ones