what to ask for when getting head work done?

[Lee in Ottawa]

Hey guys, Heres the scoop I'm finally ready to throw on a 745i kit i've had stashed away for about a year now but want to get the head redone first.
I have the head from the 745 and was wondering if it is the same as the one on my e34 right now?

Also i'm a little mechanically inclind. When i bring the head in to get done what should i ask them too do. I figure if i'm gonna get it done I imght as well try to squeeze some better flow out of it.
So what do you guys recomend?

[Skeen]

Nope, not the same head. You'll want to use the one on your car now. I think you might want the cam from the 745 though, others will be able to confirm. You can always have bigger valves added and port the head and match it to the intake manifold if you want. I don't think any of that is really necessary though.

[Velocewest]

I wouldn't bother with the cam either. Unless I'm way off base it's just a regular 262. Like Skeen says, use your b35 head as is. Oversize ports are not the best mod for a turbo install, especially a k27. You want that port velocity to stay as high as possible when the car is off boost.

[Velocewest]

PS: Here's the response I really, really wanted to write --

what to ask for when getting head work done?

"Do you wear dentures?"

[Lee in Ottawa]

haha took me sec.


So no port and polish? Leave the valves the way they are? So just get it cleaned up as leave it stock?

I always thought port and polish was beneficial and i always hear about 3 angle valve jobs.. I just wasn't sure if it was appropirate for a turbo vehicle.

[Jimmie G]

I as other's have had issues with machine shops and bmw heads.Screwing up the valve stem height seem to be very common. A few years back I had a 745i and the head gasket went out caught it when I went to crank the car and shut it off. Had the head done at a good machine shop and told them not to grind the exhaust valves just relap them hence they are sodium filled. Well they ground them and after about 25000 miles later I have to park it because one of the exhaust valve's are tuliping,meaning the valve is raising in the seat no more adjustment available on the centric.

So with that said port work on stock build, stock 745 turbo moderate horspower no, TCD kit build yes I would.

Jimbeaux

[Jimmie G]

Also wanted to post lift specs I measured on a good B35 cam today.

Lift same on intake and exhaust. 7.7mm or 303.5 thds.
Out of a 88 b35 head off of 735il

Jimbeaux

[Velocewest]

There's no downside to a 3 angle, and port matching/gasket matching is good to eliminate any unnecessary airflow obstructions. Polishing, and any oversizing of the ports is probably not worth the money, since you'll be pushing the air, not pulling it. And of course there's the ongoing debate over polishing, i.e. do rough walls flow better due to the effect creating a boundary layer that reduces resistance, and does it also enhance a/f mixing.