Camshaft Questions

[Ol_Girl_58]

Hi all,

I need some advice regarding cams. I've decided that I want a lumpier, tougher cam in my FC.

It's a 192 red motor, with extractors, 2 1/2 inch exhaust and (soon to be fitted) triple webers. I'm not sure what the head is (i.e. Yella Terra) or if it has been modified. I intend to compete in off-street drags once the motor has been upgraded.

I've been looking at various sites - most notably Crow Cams - to get an idea of what I need, but I've got no idea.

Firstly, what's the difference between a hydraulic lifter cam and a solid cam? Which would I choose over the other? 

I understand that Webers can be setup to work effectively at low revs, or at high. Obviously I'll need a cam that does the same - works well down low or up high? 

A mate of mine recommended that I get a Bathurst XU-1 spec cam. I want something pretty lumpy and on the extreme side of a streetable cam - the car doesn't come out too often, so it doesn't matter if the car doesn't have good road manners and isn't particularly streetable. I don't do short drives or city stop/starts in it. Any advice?

Also, are there any cam companies that are recommended or that I should stay away from - and an expected price? Any recommendations in Tassie would be appreciated too. 

Kind regards,

Josh.

Ol_Girl_58

[FB_MAD]

This is one of the questions that gets asked very frequently in various media where you will get so many varied answers on do's and don'ts and contradictions and disagreements between the answers given that you will probably end up confused after reading it all.

Best bet is to talk to a performance engine centre and tell them what you have on the motor now and on the drivetrain at present with all specs including diff and gearbox ratios and what you want your new dream engine to do and take their advice, it's what they do for a living.

Knowing how much you want to spend also helps.

DON'T just pick a cam and whack it into an engine.Unless its specs suit the engine components you want to use you will most likely be disappointed with it.Same goes with other performance parts.And bigger isn't always better.Betterment has a limit.

Every performance part works in conjunction with other performance parts as a team so to speak and if one of the team isn't playing it's part, the whole team suffers.

Choose an engine upgrade package from those that do it all the time.

[CraigA]

Good advice Terry. Its a sum of matching parts, not one thing or another.

Josh, read this thread from the Torana forum.

This guy has built up a 202 at home using very little investment and has obtained quite amazing results - a 13.1 second 1/4 mile @ 103 MPH with a single spinner diff centre and M20. An LJ sedan weighs 1070kgs, your FC with the red fitted would weigh about the same.

Here's a list of his specs:

Engine
202 Black motor rebuilt with new pistons, bearings and rings. Stock rods
Yella Terra 12-port
Pro Comp roller rockers (IMHO yella terra would be better as I've heard horror stories about the pro-comp ones)
186 pushrods
Kelford cam (Local to Christchurch)
Solid Lifters
Stock Lightened flywheel
Stock Electronic Ignition with a trick twin coil ignition set up
Stock M20
Stock 3.55:1 Open diff
Knife edged factory crank (he did this at home in his garage with a hand grinder  )

Cam specs



Carbies
He also uses Weber's with 38mm chokes and these settings:

Pumps = 50
Idle = 55F9 (These were 45 F9)
AC = 200
Emul = F2
Main = 145

And a link to his Youtube channel so you can see/hear this thing for yourself.

Cheers,

Craig.

[Ol_Girl_58]

Thanks for the insight Terry and Craig.

I gather it will be better to get the gearbox I want first before getting the cam.

Admittedly, I did think that I could just plug a cam in without thinking about the other variables.

By the way, what is the difference between a hydraulic and a solid cam?

Cheers,

Ol_Girl_58

[CraigA]

Basic Craig understanding - Hydraulic lifters use oil pressure within the lifter to maintain correct valve clearance. Solid lifters require a preset lash as they do not use the oil pressure to control clearance as per hydraulic.

Solid has an advantage over hydraulic in high RPM/high lift applications as the hydraulic version tends to lose its ability to control valve lash.

Hydraulic are 'self adjusting' whereas the solids need to be adjusted regularly. Solids are typically noisier as they run wide clearances whereas the hydraulics are set with a pre-load. You can see in the cam sheet above (its a solid cam/lifters) the clearance needs to be set at 14 thou inlet/16 thou exhaust - I run mine at 20 thou inlet/exhaust but it is dependent on your camshaft profile.

Your requirement for hydraulic or solid will depend upon cam specs and ultimately how hard you are going to rev the thing.

A roller cam is the ultimate - the lifters (where they contact the cam lobes) use a roller similar to that used by roller rockers which reduces mechanical loads.

I'm sure other guys will know more than me and add to this but if you are going to select a cam just call a camshaft manufacturer like Crane Cams and talk to one of their tech guys. Tell him what you are trying to achieve and he'll recommend a cam profile and advise on valve train components.

There's some good reading here

http://cranecams.com/?show=mechanicalLifters

http://cranecams.com/?show=hydraulicLifters

[era58]

hi, im new to this site but hope to offer some advise - ive been racing - building red motors for around 25 years or more so i have a fair idea what works & what dont , in my latest 192 that i just fitted in my fc sedan i have gone to a very large wade solid cam - i did try a  crow cam but i find them no good - for my use anyway - am running counterwieght knife edge crank , good rods ,acl flat top pistons, very modified high compression yella terra 9 port head - to me these are the best heads to start with ,triple 2 inch su,s , large primary extractors ,straight cut timing gears ,lightened flywheel, 3.9 diff gears ,ect ect , cams usually cost around the $250 mark  , alot more if u want a roller cam package . get yourself a solid grind cam & some good top end gear - hope this helps u out in the cost of cams at least .