Trouble Getting Timing in Spec with BC 264 Cams

[Jonnymkiii]

I recently rebuilt my motor and I installed BC valves, springs and 264 cams with adjustable cam gears. To get the engine to idle right I advanced the exhaust +4 and the intake +2. The engine idles well, but I am unable to get the timing anywhere close to spec. With the engine at TDS, I tried adjusting the teeth of the CPS and the closest I can get the timing is BTDC 20-25(+) (Idles good) or BTDC 3(-) (Bad idle); so you can see there is a big gap in there between the two teeth on the CPS gear that I was switching between (The T+E1 ports are jumped). Is there anyway to adjust the CPS itself to get the proper timing withing the CPS' adjustment range?

I found a couple other threads talking about this issue with BC cams, but didn't really see a solution yet. I suspect my next task will be to get a dial wheel and dial in true TDC as the engine has been rebuilt and head and block shaved a a couple times in their lifetime and I have a 1mm MLS headgasket (For compression), so that probably has something to do with it.

Anyhoo, I thought I'd check to see if anyone has any experience with a situation like this or has any input. Thank you.

 

[plaaya69]

I have heard about the CPS gear ring on the exhaust cam itself being misaligned from 2 people when they bought their cams new and they had to send them back to BC to get a new replacement cam. After they replaced it it ran fine.

 

[Jonnymkiii]

I read in another post someone had to do the same thing and when he was sent a new one, timing was no longer an issue. Thanks for the input; I may have to start heading down that path.

 

[Piratetip]

Interesting, sounds like a serious manufacturing issue.
Mounting the cps gear out of alignment.

 

[hvyman]

Also you need to properly degree the cams. Not just adjust till you have good idle.

 

[Jonnymkiii]

Also you need to properly degree the cams. Not just adjust till you have good idle.

I certainly don't disagree; it just seems like the timing more off than it should be. I'll make that my project next week and if I still can't get the timing in spec, I'll look into replacing the exhaust cam.

 

[Jonnymkiii]

Ok, I finally have everything set-up to get the cams degreed in and I want to make sure I'm reading the timing card properly. The degree wheel has been calibrated at true TDC and the harmonic balancer is still spot on with the timing marks. I have a dial gauge set up to measure the distance the cam lob moves the bucket and lifting the valve (Doing Intake first). I just want to make sure I'm doing this right, so I have a couple questions before start measuring and adjusting things.

* For reference, the timing card information is below in text and attachment.

1) When the timing card says 'timing at .050" valve lift' and that the intake valve opens at 0° ATDC, does this mean that at 0° TDC, the value should be opened .050"?
2) Conversely, when the degree wheel is at 40° ABDC, should the valve be opened .050"?
3) Is the intake centerline true 110°

This is the first time I've done this and I've researched as much as I could, but I still have some basic, rookie questions about reading the timing card. I think I'm also being thrown off a little bit about what it means when the timing card says 'Timing at 0.050" valve lift'. Any assistance or pro-tips that someone with experience with this would be greatly appreciated. Thank you!


CAMS: BC 264

INTAKE:
Duration: 264°
CAM Lift: .336"/ 8.53mm
Rocker Arm Ratio: 1:01
Centerline: 110°
Lobe Separation: 114°
Duration at 0.050" CAM: 220°
Duration at 0.050" Valve: 220°
Valve Clearance: .008" / .203mm COLD

EXHAUST:
Duration: 264°
CAM Lift: .336" / 8.53mm
Rocker Arm Ratio: 1:01
Centerline: 118°
Lobe Separation : 114°
Duration at 0.050" CAM: 220°
Duration at 0.050" Valve: 220°
Valve Clearance: .010" / .254mm COLD


* Camshaft Timing at 0.050" Valve Lift


Intake Open: 0° ATDC; Close 40° ABDC
Exhaust Open: 48° BBDC; Close 8° BTDC


View attachment bc_0321 Timing Tag.pdf

 

[f00g00]

Did you have the machine shop measure the amount left on the head and block? 1mm seems a little thin compared to an oem gasket that is 1.37. It probably wouldn't affect your issue as the tensioner would take up the slack but it could cause other issues. You will get more compression of course but I would worry about interference problems if the measurements aren't known.

 

[Jonnymkiii]

Did you have the machine shop measure the amount left on the head and block?

inDEED They had the head, block and pistons and were the ones to ask me if I would be interested in increasing the compression. We talked about the pros/cons, but they felt comfortable suggesting the 1mm head gasket. They did say they wouldn't recommend the higher compression at sea level, but they felt comfortable with me doing it at 5K'+ elevation.

 

[Jonnymkiii]

I was finally able to degree the cams into spec. The Intake and Exhaust Open/Close specs from the timing card not obtainable, so I split the difference so that the valve open and close spec were within 3.5 degrees of spec. I am not sure if this is normal or an indicator there is an issue with the cams.

I restarted the car and the timing is at 5 degrees without the TE1+E1 terminals jumped and about 2-3 with the terminals jumped.

So with the cams degreed in, I'm still a good amount out of spec. I could hone out the CPS bolt pathway to give me a little more range, but I don't think I'll be able to make up that much. If I move the CPS a tooth, the timing is either very advanced or retarded. I am out of ideas and I'll call BC next week to see what they think? Has anyone seen anything like this with the BC 264 cams? Anything else I can try to troubleshoot?

 

[Jonnymkiii]

So to close the loop on this, the issue was the exhaust cam. The cam itself was in-spec, but the timing gear was either wrong or set wrong. I sent them the cam and their argument was that the cam was in spec and I provided them the picture that is attached to this post and they agreed to send me a new one. Once installed, the timing was where it was supposed to be and the car ran great.

Lessons learned, 1) If you install new cams and do not understand how to degree a cam, learn how and degree them when installing them and 2) If you're timing is way off, send the exhaust cam back. BC was very helpful and responsive to me once I contacted them; great customer service from my experience.

 

[JimboScum]

I had the same issue with my timing. Wish I would of contacted them like you did but I ended up skipping a tooth on the cam gear then dialing it in with my TMS adjustable cam gears. Worked like a charm

Sent from my HTC 10 using Tapatalk

 

[atlpd3147]

So did they send you a new exhaust camshaft that actually worked?

 

[Jonnymkiii]

So did they send you a new exhaust camshaft that actually worked?

They did indeed. The cam itself was within spec; there was just something wrong with the timing gear. Once I installed the new exhaust cam, the engine ran great.

 

[plaaya69]

If you don't mind me asking, when did you by these cam shafts? I'm wondering if the new ones are fixed or if other places are selling old inventory. I would like to buy a set of these 264's but this issue is keeping me away

 

[Jonnymkiii]

If you don't mind me asking, when did you by these cam shafts? I'm wondering if the new ones are fixed or if other places are selling old inventory. I would like to buy a set of these 264's but this issue is keeping me away

I think I bought these in the fall of 2015. I had a feeling there was an issue once I installed them and set the CPS, but at the time I wasn't sure. Knowing what I know now I would have sent them in a lot sooner, but I needed to do my due diligence before I contacted BC. They have great customer service btw.

I would go for it.. worth the effort IMO ;-)