Advice on head redo and related dizziness...(lots of details

[Guest Anonymous]

Hi folks-(and thanks for taking the time to actually read this!)

Gettin' ready to redo the head of my stock '72 with all kinds of nifty goodies. I'm more than a little excited because I haven't had a chance to do any of this stuff to a 2002 yet (zoom zoom). My current cyl. head needs valve guides, orig 1bbl solex is bogging, and I think the vac. dizzy is getting on too (makes lots of dust and some noise). It's time to kill a bunch of problems at once and make this thing quicker!

I have a nice clean '76 E12 head that's off the car and going to the machine shop for valve guides, a cam regrind to 292, and any involved springs or rocker mods. While the head is bare, a racer friend is going to do a quick little port-match to the peanut-style-bored intake mani and to a used Tii exhaust mani I picked up. Going on top is a used Weber 40/40 downdraft (orig from and jetted by Metric Mechanic supposedly for a 2002) with a fresh rebuild. All of this is happening on a stock '76 bottom end (no idea of mileage) that's showing great compression but will also get a leakdown when the head work gets started. Whew, that was long-winded.

Okay, the dizzying question is this: I have a mech advance distributor in addition to the worn vac one that is on the car... which one do I use with the new setup? I'll do a pertronix either way, I think. This is all in a daily-driven '72 car that should have whichever pistons were in that stock '76 bottom end. Also, any other advice in this whole process would be VERY welcome.

Thanks all!

>Davin

[Guest Anonymous]

URL: http://www.zeebuck.com/02bc/index.htm

(nt)

[Guest Anonymous]

(nt)

[Guest Anonymous]

...there's an '83-casting E12 head on the car now. The head that I'm having reworked is a '76-casting E12. I didn't want to use the older one but it means I can drive the car while the work is being done to the other head (and it was really clean anyway). Where is the date mark on the block? The prev owner said the bottom end was a '76 (car is a '72). I haven't checked on this yet. Thanks for the help!

[Guest Anonymous]

...and apparently it's working fine with the E12 that's on there. Does this make any sense? Thanks!

[Guest Anonymous]

I am looking in Mike McCartney's book and it says that flat top pistons should work with an e12 head. If the bottom end of your engine is 76 then it should have flat tops. Your compression with this match up should be about 8:1

[Guest Anonymous]

BTW, if you're interested in getting rid of one of your e12 heads, let me know. I'm gathering parts to rebuild my '73 engine and would like to do a head ahead(so to speak) of time.

Mike

[Guest Anonymous]

The late model motors used the E12 head and very few had the E21. The pistons are a slight piano top w/ compression rated at 9.0:1, and I'd use the mechanical advance distributor set at about 35 degrees BTDC.

I have just about the same set up in my '76, except for 284 cam, 38/38 and Stahl header. It's got some poop (scares my wife), so I think you'll be pleased w/ the gains in HP and top end with the 292 cam.

[Guest Anonymous]

Early 76s had the E12 heads. -J

[Guest Anonymous]

But it could ruin a stock motor's drivability.

[Guest Anonymous]

Probably going to be way too rich for your application.

Heck, it was even too rich for one of their own motors.

My guess is that it is at 180 main/185 air. May need to try something smaller. I have 170 main/175 air, but I still have air leaks that I will be taking care of over the winter. I should end up with something like 160 or 165 main with a 170 or 175 air.

Still have not dealt with emulsion tubes yet either.

-Justin

'76 02

'97 m3

http://www.bmw2002.net

[Guest Anonymous]

(nt)

[Guest Anonymous]

(nt)

[Guest Anonymous]

I'll have to check that bottom end to see.

[Guest Anonymous]

I guess I'll find out when it's all together. Thanks!