A cams question..

[--Redwork--]

ok guys... got some cams for my pig today.

Staggered sizing 272 and assumed 288 (me thinks posibly bigger)

My question is which way sould I install them...

Traditionall thinking is to use the Bigger cam on the intake.
This would be my guess.

I have seen quite a few turbo guys go the other way around...
Obviouly to try and get as my exhaust flow driving the turbo as possable...

What do you guys think...??

[Dish]

Well how I would think about it, not necesarily right is that. If you're getting more air into the intake but not getting as much out of the ehxaust, then your compromising the whole point of cams etc.. But if you can flow more out of the exhaust is that not better???

I'm not sure, I want to know this too.

But then again, the volume of the cylinder doesn't change... I dunno.

[--Redwork--]

An old school engine build told me that what ever your intake flows your exhaust only needs to flow 75% of that...

Which is why your intake vavle is bigger than your exhaust...

But on an NA car air is sucked into the engine at atmopheric preasure and then forced out my the piston travalling upwards. Which I guess would also explain why they used this theory...

Any engine builder here.???

Goin to ask another engine guru friend tomorow... see what he suggests...

Can't wait for the lumpyness again

[3s-86]

Hey mate

Putting the bigger cam on the exhaust side would yield more top end HP
and less low & midrange torque and high revs 8k to 9.5k.
Then putting the big cam on the intake you would yield more low to midrange
torque and HP with less revs about 7 to 8.5 roughly.
So it all depends on how and what your using it for which head aswell
Bigport or Smallport.

[--Redwork--]

Thanks 3s-86..


I'm Running a ported bigport engine with around 10.6:1 comp...

Deff don't want to spin standard bottome end to 9.5k...... dissaster!!!!

So biggy on the intake it is...

[adam]

What lifts are these cams? And I'm assuming they both have the dizzy gear drive?

There was a pretty good thread about this topic over on Toymods, I'll try to find the link.

Here we go..

[3s-86]

Hey dude

Make sure you have the cam specs if not get them.
As you will need to set up/dial in full lift (lobe centres)
for inlet & exhaust cams, run in the engine then you should go to the
dyno and tune & adjust cam timing according to where you want your power etc.

Let me know how you go when it's tuned & dynoed.
GL mate

[--Redwork--]

yeah I know I need the specs to dial them in...

Need to find them...

Anyone know where they can be found...

I was under the assumption that most cams of 272 and larger should be dialed in around 100/100..

[3s-86]

Nah mate

They vary anywhere between 102 to 110
and it depends on the cam lobe design & shape.
272 cams would be about 106 > 108
280 cams be about 100 > 106
Do you know or is there any grind numbers stamped
on the back face of the cams?
What brand are they?
If you have trouble trying to get specs
then you'll have to do it the old fashion way.
Set them up on std markings and measure valve timing
opening & closing figures @ zero lash and write them down.

[--Redwork--]

There both HKS cams.

1 is stamped 272x 8.3
The other is a mistery...

But as I already stated.. would be 288 posibly larger.. Has no markings..

Gunna have to do it proper way.
Degree wheel dial indicator...
Guess I'll just try somewhere in the middle... say 105. And then dyno from there...