Bimmerheads reground cams?

[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

[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

[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]

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]

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]

0.012" for exh

[digger]

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

[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...

[zaq123]

I set it to 0 and plot full profile ,

isn't most cams spec'd (dur, lift etc) at recommended lash? just wondering

[So Live]

Duration kind of is. The advertised duration can be at whatever lift the manufacturer wants. Some durations are specified at .006” some are .050” some are at the recommended lash. I think mapping a cam at zero degrees probably isn’t necessary other than to see what it looks like. You can time your cam without mapping it fully but that wasn’t the intent here. My intent was to see what the cam was because there wasn’t really any info about it anywhere (including from bimmerheads). So now that the cam is fully mapped out at zero lash, I can plot accelerations and figure out what lash to use, see durations at different points and see where valves will open and close regardless of what lash I use.

Also, in this case bimmerheads’ advertised lift is at the valve, not the cam, which makes sense.

[zaq123]

Duration kind of is. The advertised duration can be at whatever lift the manufacturer wants. Some durations are specified at .006” some are .050” some are at the recommended lash. I think mapping a cam at zero degrees probably isn’t necessary other than to see what it looks like. You can time your cam without mapping it fully but that wasn’t the intent here. My intent was to see what the cam was because there wasn’t really any info about it anywhere (including from bimmerheads). So now that the cam is fully mapped out at zero lash, I can plot accelerations and figure out what lash to use, see durations at different points and see where valves will open and close regardless of what lash I use.

Also, in this case bimmerheads’ advertised lift is at the valve, not the cam, which makes sense.

I've done some cam mapping myself, just to verify manuf. cam specs. In my case, dbilas 274 cam... which was off. https://www.r3vlimited.com/board/sho...d.php?t=409476
Advertised lift is obviously at the valve, which will obviously change with different lash numbers or different rockers (different rocker ratios to cheat the lift)
I was just under the impression that the lash needs to be set to the spec in order to really check the cam vs. the manuf. adv. values or find what the cam specs are.

[ForcedFirebird]

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...

What did you end up using for a jig? Just realized my PM's were full. :/

[digger]

isn't most cams spec'd (dur, lift etc) at recommended lash? just wondering

If you notice the 3 black horizontal lines these allow you to get the duration at lash (0.25mm normally) then duration at 1mm (I.e. 1.25mm on the graph) and 0.050"(I.e 1.52mm on graph)

If you put 0.25 lash in before measuring the 0 to 0 will be same duration as 0.25 to 0.25 on graph that had zero lash

It's worth noting that with pushrod stuff they use duration at0.050" tapped lift not valve lift as you do with ohc stuff. So if they have 0,050" tapper lift then valve lift is multiplied by rocker ratio so for the same duration at 0.050 a pushrod cam is bigger.

[So Live]

What did you end up using for a jig? Just realized my PM's were full. :/

Yeah haha found that out too, not a big deal though dude! Ended up fabbing two little jugs that get secured by the head studs. One for each valve as there had to be two different size cutting tools (based on the valve diameters). And I didn’t feel like trying to figure out if the valve center lines had the same spacing relative to the studs. I’ll post pictures later tonight or tomorrow. Should be done cutting the pockets tonight, I hope.

Definitely appreciate you finding a head for me though.

Cheers,

[digger]

A cracked head cut up also works well, then make a cutting tool from a o/s valve. There is a thread on e30 tech