Brian Crower 7M cams and ignition timing issue

[amichie]

There are a bunch of variables that will affect the Cam's true 0 point such as ANY machine work done on the block or head, Belt stretch, Pully wear, Head Gasket thickness and so on.

This is why they give you the "220@50 thou" Spec so you can degree them in and when your degree wheel says 220@50 thou you look at the Cam pully and this will be YOUR motor's true 0.

From memory 1mm difference is around 2>3 degrees.

Thanks Ian

My motor has had atleast 2 head shaves and one decking of the block when I rebuilt it earlier this year. These were all absolute minimum though at my request. Shaving head or block or gasket thickness does give cam retard.

It also has just an oem style ACL head gasket with ARP studs for a bit of piece of mind.

Just a little update. I tried retarding the inlet cam this morning about 5 degrees to reduce valve overlap since my adjustable wheel is on the inlet cam. And it started and idled no problems. Looks like this weekend will be spent accurately degreeing the cams.

BTW Ian the front crank pulley on the cressida 7mge appears to be solid and not have any rubber damper. So as long as the drive key is healthy my TDC timing marks should be OK don't you think.

Andrew.

 

[IJ.]

Andrew: The Cressida damper is still a damper it just has a big weight pressed into it so it's worth check for true TDC before you start on the Cams.

You'll also need to verify ignition timing once the Cam timing is done.

 

[amichie]

OK will do.

Unfortunately I must now go to work ARGGGGHHH.

I will try and accuratley degree the cam over the weekend.

BTW did you have a look at the little timing chart?? Does it give you any feeling for the cam timing. It seems to be pretty mild to me.

 

[IJ.]

Andrew: They're going to be a nice punchy midrange type of Cam

 

[AJ'S 88NA]

It looks like the BC's are close to the hard weld regrinds I have, 322 and 218. I don't have Adj. cam gears though, and was told that they wouldn't have to be degreed in. Was I misled? I just lined up the cam gears and it started right up.
I agree with IJ as far as the "punchy midrange". They really made a difference 3k to 7k which is were I wanted the power.

 

[amichie]

Just thinking out load here but I should be able to check the intake opening and exhaust closing events without a fancy degree wheel since they both occur so close to top dead centre on the non firing cycle. Atleast according to the little timing chart anyway.

I have accurately set all the clearances and I have decent digital vernier caliper that I could use to determine the 50 thou lift points.

 

[IJ.]

Measure the circumference of the Damper divide by 360 then multiply this by 220.

Take a tape measure using TDC as 0 then mark where 220 degrees is on the damper this needs to coincide with 50 thou lift

 

[AJ'S 88NA]

I was checking the BC website and the Stage 2 are suppose to be "plug and play"? Should you have to degree them in?

 

[amichie]

I was checking the BC website and the Stage 2 are suppose to be "plug and play"? Should you have to degree them in?

Update

I have checked my TDC mark on the front crank pulley and it appears to be correct. I have made a simple check of the valve timing events and they are also as per the little timing card.

I have compared the BC exhaust cam with both a stock NA cam and a stock Turbo cam and the distributor drive gear is retarded on the BC cam by about 10-20 crank degrees.

I am borrowing a mate's cam degreeing set up on the weekend to set the cams up properly. I will also put the cressida intake plenum back on since it makes access to the cams easier than the supra style Y pipe ACIS intake that I have been using for the last 6 months.

I emailed Brian Crower with a few issues and asked if they have had any other feedback on these cams. Short version of the answer is they have sold around 400 pairs and not heard anything about ignition timing problems. They also reported a customer who fitted these cams to an NA engine and gained 20 hp.

I will keep you posted.

 

[IJ.]

I was checking the BC website and the Stage 2 are suppose to be "plug and play"? Should you have to degree them in?

Degreeing is only really making sure you have a known 0 point to start tuning due to the variables I listed a few posts back.

In this case it will help verify that the Helical gear has been indexed incorrectly to the Pin holes in the Camshaft.

 

[upgradedsupra]

AJ: Very welcome I learned all about it when I made my own billet cam for my old 3.4L Toyota V8 way back when

No idea why Duane moved it but it's back where it's meant to be now

After I moved it I remembered that it was a GE but didn't move it again. This is more of a Tech section discussion not general. It can work here too I guess.

Duane

 

[IJ.]

Duane: Cool was wondering why it had been moved is all
(Didn't know it was posted in General the first time)

 

[AJ'S 88NA]

Degreeing is only really making sure you have a known 0 point to start tuning due to the variables I listed a few posts back.

In this case it will help verify that the Helical gear has been indexed incorrectly to the Pin holes in the Camshaft.

As always IJ you are a wealth of info.

So basically all cams should be degreed to ckeck everything as far as lining up?
Is the Helical moveable on the end of the distributor?
How is Amichie going to correct? If the cams gears have to be moved and don't line up with the "hash marks" on the rear timing cover? Just reference the new marks?

 

[IJ.]

AJ: It's more subtle than just lining up hash marks, because the Gear on the Cam isn't where it's meant to be the Reluctor teeth are out of phase so you end up not being able to get the Ign timing set within it's correct range.

He has the option I outlined earlier of pressing the Reluctors off and then back on in the correct position or if indeed it's the Cam gear in the wrong place I'd be returning it for replacement.

 

[cuel]

Most definitely hope that this is a one time manufacturing defect. I ordered a set Sat., and should be getting them any time now...

 

[AJ'S 88NA]

Most definitely hope that this is a one time manufacturing defect. I ordered a set Sat., and should be getting them any time now...

I thought you posted that somewere and I was thinking about you when I read this thread.

IJ: Yeah I understood about the cams gears being off and having to change the dis. gear, I guess what I was getting at was to correct the cam gear being off the the "hash marks" would be off still from the stock location. Would you just have to mark the timing cover for future reference?
PITA to have to change the cam out again, but I agree with sending them back.

 

[amichie]

Progress update

I have refiited the cresssida intake to allow easier access to cams etc.

I removed the exhaust cam drive wheel and advanced it by 3 cam degrees.
Started off with the inlet cam set at zero. Checked static ignition advance and I had about 13 deg BTDC at 700rpm with the te1 to e1 shorted.

Started OK but pretty dissappointing performance. Nothing down low at all, seemed OK when the revs built up.

Advanced the inlet cam by about 3 cam degrees. Low down pick up improved and power above 4000rpm was good.

Advanced the inlet cam to about 5 cam degrees advance and low end and top end both improved dramatically.

Wife came home from work and now the fun is over.


Tomorrow I will try a little more tweaking. I can now get upto about 18 degrees static ignition advance so this should be enough.

I really need two adjustable cam wheels but I will have to make do with one at this point.

 

[7M-fanatic]

----

Anybody else tried these cams out and had similar issues??

Well, I never got as far as putting the things in.
My set looked like crap,
and the intake cam's front bearing journal had an oil grove from hell !!
Where the stock cams, and all my other aftermarket cams (HKS, TODA)
have a 3.5mm wide oil grove, the BC intake had an 8mm wide grove.
This left very little actual bearing surface on the cam that has the most downward force on it.
The exhaust cam was fine (except for the over-all finish).
I called BC, and he said all their cams were the same,
and if I didn't like it, send them back.
(I guess the exhaust cam,
that had the normal grove width was a mistake then??)
Anyway, he didn't want to admit that there was a problem,
and made no offer to just replace just the intake cam.
So they were re-packed, and sent back.
I now have a set of good used TODAs going in the head.

You might try an Apex S-ITC, with one of those you can dial the timing up to +/- 15 degrees.

 

[IJ.]

^ NOT a good sign

 

[amichie]

IJ. Any thoughts on why it seems I need to run heaps of advance on both intake and exhaust to get these things running well?? 3 cam degrees on the exhaust and 4.5 cam degrees on the intake.

I'm going to do a full cam degreeing over the next week as I have borrowed the necessary gear off a mate. I will also be able to take pics of anything of interest. I will try and get a pic of the dizzy drive gear on the BC cam and also a stock cam.