| Hadrian |
Posted
Thursday, Apr 12th 5:27pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 25
Australia, Melbourne
E21 323i |
I've heard/read numerous times about the use of E30 325i valves in an E30/E21 323i head, but I've never known of anyone who has actually done it.
Can someone clarify if it's do-able or not? |
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| Greg323i |
Posted
Thursday, Apr 12th 5:58pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 322
Melbourne, Australia
1982 Hennaröt 323i |
I don't have experience with this but I'm sure it's possible. But by the time you get all the work done for the bigger valves it would probably be cheaper to just get the 885 head. |
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| imaradiostar |
Posted
Thursday, Apr 12th 6:29pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1039
Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i |
possible. Have a head at the machine shop now for this.
jamie |
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| Madhatter |
Posted
Friday, Apr 13th 1:16pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 163
Australia - QLD
E21, E24, E30 |
| Greg323i wrote: | | I don't have experience with this but I'm sure it's possible. But by the time you get all the work done for the bigger valves it would probably be cheaper to just get the 885 head. |
If you can find 885 heads you are talking upwards of $1200. Thats a hell of a lot of machine work, for $1200 you would want him to supply the head, the valves and do a lot of port work.
Larger valves arent as hard as people think, generally they simply fit larger (matching) valve seats and take the others out. Then you need new guides and facing, but it isnt seriously difficult or stupidly expensive. |
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| Hadrian |
Posted
Friday, Apr 13th 3:33pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 26
Australia, Melbourne
E21 323i |
mmmm good. Now need to find a machinist who knows what they're doing with M20 heads... |
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| Greg323i |
Posted
Friday, Apr 13th 5:27pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 323
Melbourne, Australia
1982 Hennaröt 323i |
I thought they might have to cut the hole larger for the seat. If that's all that's involved I'll have to look into doing this for my stroker.
I took my head to a place off Rooks Rd in Nunawading to get it checked for cracks and warpage, but I don't remember the name. They could probably do it, but you might want to check with BM Tech on Canterbury Rd to see who they use. |
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| Madhatter |
Posted
Saturday, Apr 14th 9:09am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 166
Australia - QLD
E21, E24, E30 |
They dont really have to know anything about m20's at all, its still only a basical SOHC design.
better to deal with people who specialise in cylinder head reconditioning. Some machine shops dont and are either half arsed about it, or send it off to someone else who does, then charge you more for it.
Simply tell them what you want done, if they refuse go and find a second opinion. |
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| Hadrian |
Posted
Saturday, Apr 14th 12:22pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 27
Australia, Melbourne
E21 323i |
Yah but I mean for the porting. Isn't it better to get porting done by someone who knows the engine?
I basically want to build the best 731 ever built in the whole world  |
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| Madhatter |
Posted
Saturday, Apr 14th 12:54pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 167
Australia - QLD
E21, E24, E30 |
No.
Flow dynamics dont really change just because of an engine. Its better to take it to someone who knows cylinder heads and porting in general. Having the work flow tested along the way is a good indication of potential horsepower increases. I dont think there would be any specific bmw machinists in the country. |
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| Marquis_Rex |
Posted
Wednesday, Apr 18th 8:47am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 524
UK
BMW 323i 2.7-as featured in Total BMW Nov 2002,Porsche 911/993TT |
Always better to give it to some one who knows the specifics of that cylinder head.
Someone who knows alot about the intricacies of An A series cylinder head or the Rover V8 will be of little help on an M20.
It's even better to get porting work done with someone who has a flow rig and has completed flow rig work.
The science we're talking about is fluid dynamics- so even someone with an engineering degree that covers this is only covering the basics. Someone with flow rig experience, degree or not, who questions and understands- particularly our era BMW engines would be better placed.
Most wannabe performance folks, especially on many internet forums haven't the faintest idea.
For instance- I've been testing post 1999 BMW 328 and 330i cylinder heads- why do they have a flat base design at the bottom of the port? Someone "who knows cylinder heads and/or "flow dynamics"' will probably have no idea. The E30 325i "885 heads have a flat upper design in the port and this works well with the guide shroud and emphasizing in cylinder motion with the "Drei Kugel Wirbel" design. Mucking about with this could easily lose performance.
Oh, and using a flow rig alone without understanding could easily make you end up with huge huge ports with minimal restriction that actually lose you power.
Good luck!
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| Hadrian |
Posted
Friday, Apr 20th 10:54am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 29
Australia, Melbourne
E21 323i |
Okay then riddle me this - can I use even bigger valves than the 885 in my 731? |
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| Marquis_Rex |
Posted
Monday, Apr 23rd 12:21am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 525
UK
BMW 323i 2.7-as featured in Total BMW Nov 2002,Porsche 911/993TT |
| Hadrian wrote: | | Okay then riddle me this - can I use even bigger valves than the 885 in my 731? |
I'm currently trying to accomodate 45mm inlet valves and 37mm exhaust valves on an 885. It would require new valve seat inserts. I've taken many measurements and made a moulding of the chamber itself and visually it looks like it can take it. The biggest problem is that if you have a wilder camshaft that lifts the inlet valve more than about 2mm at TDC there is likely to be inlet and exhaust valve clash. I'm looking into this right now. This would be easier for me as I'm being adventurous in the bore seize department also.
As for the 731, in terms of the valve guide, seat and spark plug boss positioning as well as the water cores- there isn't alot of difference between the 885 and 731 casting- so it should be possible. |
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| Hadrian |
Posted
Monday, Apr 23rd 8:23am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 30
Australia, Melbourne
E21 323i |
Okay thanks |
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