That just might be your motor's sweet spot
As I said earlier this is why degreeing is so important to establish a 0 point
As I said earlier this is why degreeing is so important to establish a 0 point
Brian Crower 7M cams and ignition timing issue
- Thread starter amichie
- Start date
The idea of the 50 thou is to get the cams off the base circle and to remove the ramps so you get a consistant reading without having to add/subtract anything 
(cams can have very different ramps and this will affect the reading and this is how/why you can have 2 "272" cams that are quite different as the "272" is measured from the base circle and is the "advertised duration"
Quite often a big stupid number so they sell...
(cams can have very different ramps and this will affect the reading and this is how/why you can have 2 "272" cams that are quite different as the "272" is measured from the base circle and is the "advertised duration"Quite often a big stupid number so they sell...
On this video they are degreeing a set of Cr0wer cams in a supra 2jz.
In this case they set the timing up at 50 thou valve lift and not 50 thou lobe lift. I emailed crower and they said use lobe lift. I guess its a case of suck it and see.
Video is very informative except the repeated use of "trick" is a bit annoying, I must be getting old.
http://www.youtube.com/watch?v=_MsqA-C3vGI
In this case they set the timing up at 50 thou valve lift and not 50 thou lobe lift. I emailed crower and they said use lobe lift. I guess its a case of suck it and see.
Video is very informative except the repeated use of "trick" is a bit annoying, I must be getting old.
http://www.youtube.com/watch?v=_MsqA-C3vGI
I indicate off the back of the bucket so 50 thou valve but I can't see that there's any difference as we don't have a rocker arm or anything that changes the ratio from Cam to Valve..
Well I think using the term valve lift is a bit confusing as the 7M engines use overhead cams so the valves actually fall not rise when they come of the seat.
There isnt a lot of room to place the dial gauge on the bucket or shim but the way I see it you would have to preload the gauge to something like 60 thou & turn the crank until the valve opens & the gauge reading falls down to 10 thou.
There isnt a lot of room to place the dial gauge on the bucket or shim but the way I see it you would have to preload the gauge to something like 60 thou & turn the crank until the valve opens & the gauge reading falls down to 10 thou.
There's enough room to get a direct reading off the bucket but you need an extended probe on the indicator to do it.
I use a magnetic base and a piece of 3mmx50mm flat that bolts onto the Cam Cover bolt holes.
"Valve Lift" is generic in nature and refers to the Valve coming off the seat irrespective of the valves orientation in the motor
(last motor I can think of that actually had "valve life" was an old side valve from the 40's/50's)
I use a magnetic base and a piece of 3mmx50mm flat that bolts onto the Cam Cover bolt holes.
"Valve Lift" is generic in nature and refers to the Valve coming off the seat irrespective of the valves orientation in the motor
(last motor I can think of that actually had "valve life" was an old side valve from the 40's/50's)
amichie said:
are the threads on the bolt long enough to reach the crank? when rotating the motor, wouldn't it just tighten the degree wheel more, causing it to bend?
TS: Yep just machined a step on the back of the Bolt so the wheel centres perfectly bolt it down then line the pointer up to true TDC 0 and it's good to go
The bigger diameter the wheel the easier it is to read accurately.
The bigger diameter the wheel the easier it is to read accurately.
IJ. said:TS: Yep just machined a step on the back of the Bolt so the wheel centres perfectly bolt it down then line the pointer up to true TDC 0 and it's good to go
The bigger diameter the wheel the easier it is to read accurately.
understood, thanks. looks like you can get degree wheels fairly cheaply on ebay. I assume the step is very shallow, less than the thickness of the wheel, so it is held tightly?
IJ. said:
I hope I kept that old crank pulley bolt. I'll have my machine shop machine a step for me when I get closer to assembly time. Thanks again IJ, you are very helpful.
Here is a very short update.
I now have the gauge etc set up for degreeing the cams.
So far I have checked the exhaust cam only.
With the cams set up on the centre drive pin and lined straight up then the timing events occur as per the timing card at 40 thou valve lift with 10 thou valve clearance. This should correspond with the 50 thou lobe lift on the timing card.
I haven't done the inlet cam yet. That is a job for Saturday.
I now have the gauge etc set up for degreeing the cams.
So far I have checked the exhaust cam only.
With the cams set up on the centre drive pin and lined straight up then the timing events occur as per the timing card at 40 thou valve lift with 10 thou valve clearance. This should correspond with the 50 thou lobe lift on the timing card.
I haven't done the inlet cam yet. That is a job for Saturday.