Bimmerheads reground cams?

[So Live]

That’s awesome! Thanks Digger! Cool to see next to two well known cams. Also nice to see ivc differences between all three side by side.

Pulled the head last night and put together a pair of tools to cut the valve reliefs so I can adjust the cam and also rest at night. Just need to turn a beefier drill stop so I can accurately cut the reliefs to the depths I want. Should be a fun night...

[digger]

here is a plot of the BH cam regrind, schrick 288 and stock b25K

[digger]

0.012" for exh

[So Live]

Hmm interesting, straight up is about as close as I’m willing to get with my set up. Maybe could advance 2 degrees and still stay over .030” p2v. Even then I’m under .060” regardless of position which makes me a little nervous with a well used bottom end.

I think I have to pull the head and cut the reliefs cause I know I’m going to want to optimize it.

Would you suggest over a .010” lash on the exhaust?

[digger]

So your saying should run fine as is with the stock gear? If you were going to adjust it which way would you go?

Shoot me a pm with your email and I’ll send it out on Monday.

Thanks again for the help!

yes, as long as their is clearance. it is as expected 2.1mm/1.5mm lift at tdc

i would run as is, then advance 4* run it again and retard 4* run it again but make sure there is enough clearance first. if you do it on the dyno you will see a trend and driving on the street you will feel the difference particularly throttle response and make up your mind from there

people who have done this with the 284/272 schrick favoured slightly retarding it

[So Live]

So your saying should run fine as is with the stock gear? If you were going to adjust it which way would you go?

Shoot me a pm with your email and I’ll send it out on Monday.

Thanks again for the help!

[digger]

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).

0.050" net (1.27+0.25cl = ~1.5mm on graph) i got eyeballing it

224/215 105/108 should run fine like that . sounds like the aftermarket cam gear is a dud

i would set the exh lash looser has really long ramps

if you email me the data i can add to my chart

[SLEEPYDUB]

I use this cam and set it like factory. I barely had anything skimmed off of my head, and used an oem thickness elring gasket. I did have a bit of low vacuum that I just associated to the cam profiles, but it wasn't severe. Looking at this thread, I hope I installed it correctly. Im not really sure how I could have installed it any other way tbh...I used the oem cam gear so I cant see how it could have been done any other way

[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).

[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

[zaq123]

Best method is to set lash to zero, correct?

set it to spec

[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?

[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]

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]

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.