Bimmerheads reground cams?

[So Live]

Hey guys,

Anybody have any experience with the reground cams from bimmerheads, specifically the 280/274? I bought one and there is no cam card and no instruction on how to degree the cam. Bimmerheads support assured me that setting it to tdc will be fine. When asked again for numbers I got the same response.

Problem is that my head has been decked and my p2v clearances are way too tight on the intake side with everything at “zero”.

Kinda wish I bought a new cam.

Any input or other ideas on who to contact?

[digger]

If you know how to degree it set the ICL to 108 or 110*

[digger]

You aren't supposed to degree cam to fix lack of p to v.

Unless it is massively advanced off the bat then degreeing it may not solve your p to v and a new cam doesn't solve your issue unless it has less lift at tdc

What Pistons ? What gasket ? How much was removed off head or block ?

[ForcedFirebird]

I would also like to know more info. Purchasing a new cam would put you in the same situation, as it's lift that will cause more issues than CL.

[So Live]

Digger, that’s what I ended up doing and that ended up being about 1 tooth more retarded than “zero”. P2v looks much better. Also dropped the lash to .010” from .008” based on schrick recommendations for their cams. It’s just aggravating that the suppliers response is “set it to tdc” and “we don’t have any problems on our m20’s”. The lack of information and knowledgeable support is why I’m a little nervous, not to fix the p2v.

Not sure how much was taken off the head but I may be able to measure height tonight, for reference.

Stock bottom end b25. Stock goetze gasket going in but used the old oem style gasket to measure clearances.

[digger]

at tdc what is the lift of each valve off the seat with it installed as you have and wfstcwas it before ? 1 tooth is a lot, retarding a cam too much kills lowend and midrange.

[apostate]

^ What he asked is crucial to timing. Especially for asymmetrical camshafts.
Get it at the marks and measure valve lift.

[So Live]

Absolutely agree. I need to check it again where it will be. In trying to figure out extents of useable travel on the cam I found that P2v was close to perfect with intake valve open about .065”, exhaust valve about .058”. I say about because I didn’t have clamps to get the indicators clamped to the head but those are within a few thou and the relative magnitude between measurements should be closer than a few thou.

Schrick calls out 2.2 and 1.7mm (.087 and .067”) for their “284/272” and cat cams 2.3/.9mm (.091” and .035”) for their 294/273 so I figure I am headed in the right direction. One thing that isn’t clear to me is the lift numbers and how to compare schrick to cat cams, to what I have (supposedly 10.5mm). Digger, I think I remember seeing you mapped out some cams for one of your motors, do you have any of those plots available (photobucket sucks).

I guess the right way to move forward would be to map out the cam to figure out what this thing actually is and go from there, right? I think I’m too much of an engineer to just say good enough without knowing the whole story.

I should be able to get better numbers sometime this week. Thanks for the input here guys, I definitely appreciate it.

[digger]

for a backsplit duration cam (ex duration lower than intake duration)
1.65mm in and 1.47mm ex @ tdc doesnt seem at first glance like its off by a tooth, more like 4-6* kind of magnitude. if the gear is retarded a tooth to achieve those numbers then the dowel could be in the wrong spot (unlikely given its a regrind thats limited by the where the metal is on the original, of course if welded then all bets off) or the gear is wrong or cam grind to

first thing id do is map it out with stock gear to see how it installs. probably don't need to fully map it out just need key points to see the open and close points and values at tdc to get a feel.

you can tell alot by rotating cam to tdc on the head and looking at number 6 valve lifts by eye noting the respective lifts. e.g. a stock cam should have both valves about the same and its a small slit as its only open about 1mm.

[So Live]

Thanks for the maps!

I reread what I wrote about the 1 tooth and I was mistaken, the cam was retarded 1 tooth. No measurements were taken here.

I had to advance it 1 tooth to get the .065/.060 numbers and an acceptable p2v. To get the BEST p2v, I did have to advance the cam 2 degrees from this .065/.060 State but I didn’t record lifts at this point. I will be able to roughly map the cam tonight and determine ICL as you suggested. Will post again after work.

Thanks again for the help! Really thankful to have a place like this to get some knowledgeable input.

[digger]

I'm curious to know what the measurements were with the oe fixed gear I always trust the oe gear.

You will want to find the ICL and ECL

[So Live]

Sounds good. Will check tonight after I check where it is with the adjustable gear.

Had a hard time setting up the dials on Tuesday and then ran out of time. My China indicator stands we’re giving me some issues so I broke down and ordered some Nogas based on experience with them at work. Should be able to record numbers tonight...

Best method is to set lash to zero, correct?

[zaq123]

Best method is to set lash to zero, correct?

set it to spec

[digger]

I set it to 0 and plot full profile , then if I want true seat to seat duration i look at open 0.25mm angle and close 0.25mm angle or if I want duration at 1mm net lift i look at 1.25mm on opening to 1.25 mm as the valve is closing.

For dialing a cam by centreline method it doesn't matter as long as you use a consistent check point. The centreline if you measure at 0.5mm or 1mm is going to be the same even with a asymmetrical cam you will struggle with detecting a difference. On an asymmetrical cam the centreline at say 1mm will be different to the peak lift angle

[So Live]

Looks like ICL is about 115...

Duration at .050” is about 231 intake and 222 exhaust.

Keep in mind this was done by hand, recording valve lift at every 10 degrees of crank rotation. It’s definitely not perfect.

This was done with zero lash (using the bmw spring tool to set the eccentrics).