Best camshaft settings for smallport 4age w/ bigport cams

[Mark K]

Hi,

I recently installed bigport camshafts and adjustable pulleys into my smallport and was wondering if anyone had any recommendations for timing settings?

Ive searched around and have found some conflicting information... some resources tell me that if i want bottom end power i should advance both cams, others say retard intake and advance exhaust, but then ive also read that i should advance the intake and retard the exhaust :S

At first, the car came back after installation with the intake retarded 3deg. It actually felt good to drive and there was a noticeable difference.
Over the coming few days i advanced the intake 3deg so it was basically at factory spec. Not much of a difference there.
Then a few days later advanced the intake a further 3deg and advanced the exhaust 3deg.
Now the car feels like its lost a bit of bottom end power and needs to be wound out even more to actually feel it move.
So my next plan of attack is to set both cams back to 0deg on the pulleys and try that for a little while before i try adjusting them again, but im not 100% on how i should adjust them after this...

Is there a general rule to cam timing? (i am aiming for low to low-midrange power).
Is there a specific way 4age cams like to be timed?
Also, what is the maximum i can advance/retard cam timing without breaking my engine?

Thanks in advance,

Mark

[w810sc]

If you do a search on the net about cam timing you will find a heap of information. Here is just one:
http://www.rbracing-rsr.com/camshaft.html

I recommend you degree your cams.
I would have them at 106* lobe separation angle for mid to top end. You can go bigger or smaller it's up to you. I wouldn't expect too much from a standard cam because it's duration was probably meant for emissions control.

Here is an example of a setting:
intake center line 104* (4 degrees advanced)
exhaust center line 108*
104 + 108 = 212
212 \ 2 = 106 lsa

When you degree your cams at least you can find out:
- advertised duration (in/ex)
- 0.050" duration (in/ex)
- max lift (in/ex)
- lift at TDC (in/ex)
- max lift before the valve hits the piston at TDC.

If you want bottom end go for something like 112 lsa, if you want top end go for 100 lsa. So anything in between would be for mid range. You can have the intake cam advanced or equal to the exhaust cam it just depends if your motor likes it.

cheers.

[Mark K]

Thanks for the reply, looks like ive got some reading to do.

[gixer]

Set it up on a dyno, we do quite a bit of dialling of cams at work and every engine(even same configurations) react differently, we do runs, overlay runs and check data(Mainline dyno) recently set up a small port with TRD head gasket, 264 HKS, vernier sprockes, headers and AE111 quads, the cams were intially set up as per the HKS cam card, but it was real unpleasant below 3000rpm, after adjusting cams, sweet as everywhere.

I have long given up saying "this should do this, or this should react like that" as engines don't react the same. last night I dynoed a WEST race car fitted with a ZX10R engine, tried a whole heap of tests, ram tube length etc and some results were not as expected.

Take it to dyno shop and get them to 'dial' them in on the dyno.

[ollie83]

It also depends where you want the power to be mate. you can set them to give you more top end power or more mid range power, depending on the cam you change and depending on how you you advance/ retard.
As always, Billzilla has covered this in an excellent article using dyno's to show the power increase/ decrease, it'd be pretty helpfull i imagine!
http://www.billzilla.org/engvariable.html
Check it out, hope it helps!
Ollie

[gixer]

It also depends where you want the power to be mate. you can set them to give you more top end power or more mid range power, depending on the cam you change and depending on how you you advance/ retard.
As always, Billzilla has covered this in an excellent article using dyno's to show the power increase/ decrease, it'd be pretty helpfull i imagine!
http://www.billzilla.org/engvariable.html
Check it out, hope it helps!
Ollie

Bill's is using a computer program called engine analyser. Those curves are from a computer program not a dyno.

I have some great mpegs of a 4age I dynoed recently, every cam change is a different mpeg, we 'sacrificed' 2kw at the top to get a SUBSTANTIALLY better power curve right across the range, MORE average power! You can't move it around as much as you think, there is a small window before it all goes to shit.....trust me I've done plenty of stuffing around on the dyno at work

[ollie83]

Bill's is using a computer program called engine analyser. Those curves are from a computer program not a dyno.

I have some great mpegs of a 4age I dynoed recently, every cam change is a different mpeg, we 'sacrificed' 2kw at the top to get a SUBSTANTIALLY better power curve right across the range, MORE average power! You can't move it around as much as you think, there is a small window before it all goes to shit.....trust me I've done plenty of stuffing around on the dyno at work

fair enough. what size cams where you running? and what degree of adjustment and on what cams were you making to get that nicely distributed power curve? would be nice to know!
Cheers