cam timing . adjustable pulleys :O)

[evo arm's m7960]

hi guys

now just have a couple of questions that i think i kinder know the answers to but you can never have to much advise :O)


now i have some bc 272 cams in my e4 and a pair of tru lock adj pulleys fitted

the cams are dialed straight up as per the instructions that came with them and they also came with a timing data tag/ sheet for fine tunning them

1 / what i was wondering is is it worth the hastle tweeking the cams to match the data tag as a starting point or just tunning them to maximise the engine turque curve ect

and
2/ as im not after any more top end power at this stage and would like to try and improve the low end torque as much as possible is it advisable to widen the lsa , lobe seporation angle , as i believe this should move the power band to help lower down the rev range ??

3 / now would you move both cams to do this or one at a time checking the results per adjust ment ..




im am just getting a idea as im about to fit my new s90 throttle body and will be popping the car back up to dynotech to have it checked on the roller so might make the most of it buy dialing the cams at the same time


cheers

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[evo arm's m7960]

now i made up a tool for finding tru top dead center out of a spark plug and a bolt but to check the cam lift will i need to make a soild lifter or are the hydrolic ones stiff enough to take a propper dial reading :O)

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[sponners]

yeah deffo find the true centreline to start with as zero on the pulleys could be way out.

have you got access to a dyno so you can then mess with the timing/overlap to find the best power curve your after?

 

[evo arm's m7960]

yeah deffo find the true centreline to start with as zero on the pulleys could be way out.

have you got access to a dyno so you can then mess with the timing/overlap to find the best power curve your after?

hi
i will be going to dynotech in the near future to tweek the map " as im also fitting a s90 throttle body "

just wanted to save dyno time and sort this out befor i go . will have a chat with bob and lee5 befor i go to make the best of the day .

cheers


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[evo arm's m7960]

i read some where that its better to just set the cams for equal lift on overlap at tdc @ the cam check hight " 0.050" and then work from there ,

i can understand the logic but
can anyone tell me if its viable ?????



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[evo arm's m7960]

:sad:

 

[And@fcm]

theres a few things to note when dialing in cams

to find top dead centre does your bolt move freely in the spark plug end? and do you have a dial gauge to measure the lift and calculate the dwell time to find the actual TDC?

its recommended to start with the maunfactures settings as go from there, this dyno graph shows the difference when a set of kelford 272's were set at standard and then the recommended settings

 

[sponners]

as mentioned, make sure you set them up properly usind a dti to the specs that came with them then adjust from there.

to increase power lower down then you want to be advancing, and idealy have cams to suit like 264's

you will need to fine tune the settings and overlap on a dyno though to get the best results.

 

[sponners]

why are you fitting a larger TB if your not after any more topend power?

 

[evo arm's m7960]

thanks for that And@fcm great info :O)

i cut a thread in the spark plug to allow the bolt to wind up and down and has a lock nut .

i have a dial gauge and a timming disc ,

i think the idea is to move the piston to around 10 - 20deg atdc then wind in the bolt till it touches . take a reading

then rotate the engine clock wise slowly till its stops on the bolt again , take a reading , and half way between the 2 is tdc

check twice and mark once , ect

do i need to make a solid lifter to accuratly measure the cam lift ???


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[And@fcm]

ideally the bolt would slide up and down the spark plug freely then you put a dial gauge on that and you'll get as accurate as you can be, this is what i use

your technique is write though

 

[evo arm's m7960]

why are you fitting a larger TB if your not after any more topend power?

good question :O)

i am getting parts together for more power but fitting them as i go rather than leave them in the shed till im ready as so many people do then end up selling parts they never use .

the idea is to fit the throttle body and mod the manifold now to save having a big job / build later on .

so hoping to be able to turn the boost down and tweek the cams and fit the throttle body and end up with the same if not a better car to drive till i sort the bottom end eg forge :O)

if that makes any sence

as for the cams i got the 272's with out really knowing what i was buying i probably should have got the 264's but they where the same price so me being me i got the bigger ones ,

but they work well slight lop on idle and work well with this turbo

cheers


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[sponners]

I've found a small socket extension bar works well as its quite a tight fit in the plug hole.

 

[evo arm's m7960]

ideally the bolt would slide up and down the spark plug freely then you put a dial gauge on that and you'll get as accurate as you can be, this is what i use

your technique is write though

oh i see like in the old days using a screwdrive down the plug hole but a propper tool .

i like it :O)

great advice


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[evo arm's m7960]

so for the cams . once tdc is found

dial the cams back till no lift then dial forward untill 0.050" ect recomended lift

again checking twice / three times to be sure . you would know if you where miles out by the marks on the pulleys being miles out and if in doubt put them back ect

in the past i have set cams by max lift after tdc on 8 v engines but not much on 16v twins

or is there more to it than that eg, 0.050 @ -- deg

as i believe the engine is only seeing equal lift @ tdc being that there is only one cam check hight , eg 0.050" in and ex ???:O)


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[Steve220]

Get a professional to time in cams, its a precise art and needs verniers to get it accurate. I wouldn't touch it unless i had the full set of verniers on the inlet, exhaust cams and piston in no.1 cylinder.

 

[evo arm's m7960]

Get a professional to time in cams, its a precise art and needs verniers to get it accurate. I wouldn't touch it unless i had the full set of verniers on the inlet, exhaust cams and piston in no.1 cylinder.

good advise steve :O) thank you


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