M20 camshafts

[OP6 27]

! - Are all 320 323 and 325 M20 camshfts the same and interchangeable?

2 - I had heard that the early 323 camshafts allowed the valves to stay open a little longer, is this correct?

3 - Is the South African built 325 F/L engine the same as the Japanese and European F/L engines?

I have searched for the answers on this forum but found nothing conclusive, so anything anybody can tell me would be great.

I have a 325 engine which is about to go into my 323 ( E21) and I am trying to find out if there would be an advantage in using my 323 cam in the 325.

Cheers

[*Glenn* 854]

There are alot of variations dependant on which country, year and with cat or without cat

ETK does not give the differences...just the different part numbers. Some BMW's have different camshafts for manual & auto as well... more overlap on manuals. If you use the manual camshaft in an auto they tend to stall at idle in gear. Got caught with this years ago.

[*Glenn* 854]

If your car is manual...have you thought about getting a mild street grind ???

[OP6 27]

Glenn, thankyou for your reply, in otherwords there is no specific rule as there are too many variables therefore the only way is to have the camshafts measured and go from there.

I have an E21 323 manual with a camshaft that I believe has been ground and then hardened, and I am now replacing that engine with an auto 1990 South African 325 engine, for 2 reasons - piston slap and continual problems with the K Jetronic - and I thought that I could put the 323 cam into the 325. I shall get the 323 cam checked and go from there, the mild street regrind would probably go well with the ACS headers that I intend putting in there.

Again thanks

[*Glenn* 854]

Watch out with camshaft grinds on Autos... you might get stalling issues because of camshaft overlap.

Manual conversion would make what your doing alot better

[Deano 1]

Watch out with camshaft grinds on Autos... you might get stalling issues because of camshaft overlap.

Manual conversion would make what your doing alot better

Hi..I have measured E21 320/6, E30 325 F/L, E30 320i pre F/L cams and are identical. Never measured a South African M20B25 cam though.

I can't imagine cams for auto's and manual's to be different. P/N are the same. You would have to have very aggressive cam with say 288 duration to have stall issue's??

[*Glenn* 854]

Hi..I have measured E21 320/6, E30 325 F/L, E30 320i pre F/L cams and are identical. Never measured a South African M20B25 cam though.

I can't imagine cams for auto's and manual's to be different. P/N are the same. You would have to have very aggressive cam with say 288 duration to have stall issue's??

If you check ETK.... they give various part numbers for different M20's.... what are you measuring ... diameters, ramp heights or overlap ?

E30 320 Pre Cat 11 31 9 058 572

E30 320 With Cat 11 31 1 716 139

E30 323 with Cat 11 31 9 058 577

E30 325 Pre Cat 11 31 1 706 655

E30 325 With Cat 11 31 1 716 138

Please tell me what I'm missing ??

Edited May 6, 2009 by *Glenn*

[Yamahoo 6]

My reading has led me to believe that an E21 323 camshaft is the one to go for if you can find a good one, and don't want to spend several hundred bucks on a regrind or a Schrick / Piper / whatever. The early 323's (E21 only) have a 260 degree duration, as opposed to the 252 of the standard E30 325. If you can find a Total BMW magazine from March '07 it's all in there, written by the guy who wrote the "BMW E30 series Restoration Bible"

[kerrynzl 3]

You'll find that Cams, Compression and 'Gear Ratios' are all good "bed partners".

The short duration cams [ or less overlap ] hold more cylinder pressure so they generally need less static compression.

Unfortunately short duration cams run out of "lungs" at higher RPM's [ unless it has variable advance ]

A higher revving [ lower diff ratio ] engine usually has a 'fatter' cam, so the manufacturers usually 'up' the compression ratio.

They also used higher compression and 'fatter' cams to overcome poor breathing of the engine [ helped with high octane fuel ]

I would guess that the early E21 would also have a higher static compression etc [as well as a fatter cam]

Many street "wannabe's" usually put the fattest cam they can buy into their engine [ so it can go "rump rump" ] and discover the engine has no low down torque because all the cylinder pressure has bled off

[ "she couldn't pull the skin off a rice pudding" was the description I once heard ]

Up the compression as well

[OP6 27]

You'll find that Cams, Compression and 'Gear Ratios' are all good "bed partners".

The short duration cams [ or less overlap ] hold more cylinder pressure so they generally need less static compression.

Unfortunately short duration cams run out of "lungs" at higher RPM's [ unless it has variable advance ]

A higher revving [ lower diff ratio ] engine usually has a 'fatter' cam, so the manufacturers usually 'up' the compression ratio.

They also used higher compression and 'fatter' cams to overcome poor breathing of the engine [ helped with high octane fuel ]

I would guess that the early E21 would also have a higher static compression etc [as well as a fatter cam]

Many street "wannabe's" usually put the fattest cam they can buy into their engine [ so it can go "rump rump" ] and discover the engine has no low down torque because all the cylinder pressure has bled off

[ "she couldn't pull the skin off a rice pudding" was the description I once heard ]

Up the compression as well

Thanks to all, re the camshafts. Looks like an area worthy of further investigation some time in the future. For the present I shall check the condition of the 323 cam and if all good install it in the 325 head. As for upping the compression, that too makes sense as the I believe the later 325's have a 8.8 compression ratio and not being a daily driver it is something I could live with.

I shall try to find a copy of Total BMW magazine - sounds like a worthy read

Cheers guys

[topcat 11]

8.8 compression isnt all that exciting,up will run cheap gas without

prolems.

if you want to do a grind or along those lines, have a m20 cam from

an 525 e34.$80

[Deano 1]

If you check ETK.... they give various part numbers for different M20's.... what are you measuring ... diameters, ramp heights or overlap ?

E30 320 Pre Cat 11 31 9 058 572

E30 320 With Cat 11 31 1 716 139

E30 323 with Cat 11 31 9 058 577

E30 325 Pre Cat 11 31 1 706 655

E30 325 With Cat 11 31 1 716 138

Please tell me what I'm missing ??

The 4 cams I have had measured were done by Kelford cams here in Chch. The cam cards read the same and the owner of the place reckons he has done a few and are all the same. Its a standard cam check..lift, duration etc and they do it a 50 thou lift.

I was looking for the 264 duration cam apparently in the E21 baby 6's or 323i E30s to go in the 2.7 build currently under way. The subject has been discussed indepth on E30tech.com and one member "madhatter" who is now making his own cams from billets in Oz, reckons he has measured many and are the same(quote: "Ive also checked the E21 323i, E28 520i and E30 323i cams myself, given the fact ive started making billet camshafts, I figured id better know exactly what the standard cam was before I started").

So to satisfy my own curiosity I am measuring the different cams myself so I know exactly where I am. We have a 89 SAF 325i to check and an early 78 323i E21 also.

I have trawled over the net for M20 cam specs but there is nothing solid..so really the only way to know for sure regarding M20 cam specs is to measure it.

Anyone measured an M20 cam recently?

[euroitalian 62]

The 4 cams I have had measured were done by Kelford cams here in Chch. The cam cards read the same and the owner of the place reckons he has done a few and are all the same. Its a standard cam check..lift, duration etc and they do it a 50 thou lift.

I was looking for the 264 duration cam apparently in the E21 baby 6's or 323i E30s to go in the 2.7 build currently under way. The subject has been discussed indepth on E30tech.com and one member "madhatter" who is now making his own cams from billets in Oz, reckons he has measured many and are the same(quote: "Ive also checked the E21 323i, E28 520i and E30 323i cams myself, given the fact ive started making billet camshafts, I figured id better know exactly what the standard cam was before I started").

So to satisfy my own curiosity I am measuring the different cams myself so I know exactly where I am. We have a 89 SAF 325i to check and an early 78 323i E21 also.

I have trawled over the net for M20 cam specs but there is nothing solid..so really the only way to know for sure regarding M20 cam specs is to measure it.

Anyone measured an M20 cam recently?

According to Febi Bilstein, 11 31 9 058 572 is 252^₀

11 31 1 716 139 is 260^₀

11 31 1 706 655 is 260^₀

11 31 1 716 138 is 260^₀

11 31 1 276 441 is 228^₀ (525E)

All the 260^₀ camshafts have a different Febi part number.

[Madhatter 0]

Problem with the part numbers is bmw (along with other euro marques) are notorious for using new part numbers for updated/revisions of (car) models, yet the part is actually physically the same. What you end up with is a part that might have been used in both early and late E21's, then used again in say, series 1 E30's, but has 3-4 different part numbers for exactly the same part. Thats where the superceeding comes from, when you open their epc you can scroll back through the revised part numbers to the original.

All the smaller capacity (2.0-2.3L) m20 cams ive measured ive measured have been the same. Only one I cant say for sure of is the later series 2 320i's which run motronic, so im expecting they went the way of the 325i and reduced the duration, the ramp angles and lsa of the camshafts.

As I said in a pm, I know the south africans did "hot up" the 325is they sold over there, they also gave it m3 bits too, but the few normal south african models Ive seen in aus have used euro motors, so id expect the motor (and cam) to be basically a euro 325i motor.

I want to buy an optical pickup and plug mine straight into the computer to make some profiles, but the electronic cam doctor type setups cost upwards of $2000, so there are simply other things to spend money on at the moment.

Ive got a stand I made by cutting a couple camshaft bearings out of a spare (cracked) head, then bolted them to a frame to locate and support the cam. With a little oil on the bearings, you can turn the cam without a problem. A timing wheel on the front coupled with a point welded to the front of the stand (so its fixed in position) gives you cam timing to the degree, then a magnetic stand and a good quality dial indicator can be positioned over the lobes to take cam measurements at any given timing event. Works well and is just the same as old school cam indexing, I just didnt like the idea of paying $700 for a universal stand to place the cam in for measuring when something could be made for cheaper. Only thing ill probably buy is a good cam package that allows you to plot points and generate both a master profile and a electronic graph from the data. That wa you can send the electronic data away to a company and have master profiles cut for the grinding machines without actually taking measurements from a physical camshaft (so essentially you can create any profile you wish).

heres a couple prepared earlier

Edited May 15, 2009 by Madhatter

[*Glenn* 854]

Madhatter..... How are you measuring these cams ? are measuring lift height or duration/overlap configurations ?

[kerrynzl 3]

Madhatter..... How are you measuring these cams ? are measuring lift height or duration/overlap configurations ?

Glenn,

Hotrodders used "Madhatters" methods years ago [ a degree wheel and a dial-test indicator ]

I think they called it "fingerprinting cams" or something

They would graph the valve lift [ not lobe lift ] with a degree wheel on the crankshaft

[Deano 1]

All the smaller capacity (2.0-2.3L) m20 cams ive measured ive measured have been the same. Only one I cant say for sure of is the later series 2 320i's which run motronic, so im expecting they went the way of the 325i and reduced the duration, the ramp angles and lsa of the camshafts.

I had a 84 L-jet 320i cam measured and was virtually identical to a 89 UK import 325i

[actletpone 43]

This is a significant thread bump, but on topic so..

The febi site list

11 31 1 706 655 as '260^₀  (F) Degree' for vehicles without catalytic converter

11 31 1 716 138 as 260^₀ Degree for vehicles with catalytic converter 

 

What is the difference? can they be interchanged?