Preyupy

Yes, many years ago I had a number of heads repaired by installing "cam bearings". People that did not change their oil often enough and a few that had oiling issues had damaged the cam journals and cylinder head bores so badly that we had to replace the camshafts. The fix for the cylinder heads were to have them bored and have bearings installed and bored back to the original size. Anyone that is capable of line boring the head to install the larger camshafts should be able to install bearings and size them correctly. Finding someone with the proper line boring equipment to do it properly is the hard part. The 3 shops in the Seattle area that had Toben-arp TA14 line boring machines (and people that knew how to correctly use them) have all closed down. In 1976 it cost $75 to have the cylinder head cam bearing journals repaired.

Tom, This was mid 80’s. Improved Touring was an idea that started in San Francisco region SCCA. It is what most of the spec car classes are roughly based on, extremely limited preparation. The trick was figuring out which car was the right one in IT. Spec is much easier.

In the early days of improved touring racing the 2002 was the car to have in ITB. There were a bunch of us all trying to figure out how to make the most power inside the rules ( and maybe even a bit outside). We were allowed flat top pistons, max 90mm. Stock cam and rocker arms,32/36 Weber or factory 2bbl Solex (legally we could run the single bbl carb but that would have been stupid). The head and intake manifold could be ported within 1” of the gasket surface just to match the ports. Stock rods, flywheel and clutch. Headers and exhaust were free. We all found the additional compression of the 121 head was worth not just more peak HP but a significant increase in average torque over the entire rpm range. I don’t remember any of the top cars that were running the E12 heads. With the cam, carburetor and porting restrictions they were all done making power by 6500 rpm. Lots of people spun them to 7000 just because of the gap between the gears ( we had to run the stock 4 speeds) but any more than that you were just breaking rocker arms and making noise.

If you are planning on running the flat top pistons and a 292 cam or less don’t worry about the “assumed” decreased flow of the 121 head. As long as it has the 46mm intake and 38mm exhaust valves the 121 is a better choice. The compression increase is worth a tone more than the small increase in flow. What carburetor(s) are you running?

There are a number of special tools that make the process much easier. A puller that removes the input shaft bearing and another one for the output shaft bearing. There is another tool that presses the input shaft bearing back into the case while pulling the input shaft OUT so you don't drive the input shaft down over the 5th gear synchro and have trouble putting the snap ring back on the shaft.

It won't take much, it just depends on what kind of RPM you are planning on running as well. Valve float (even just a little bit) will break rocker arms right away.

Depending on the amount of boost you are planning on running some increase in valve spring pressure is probably advised. A 46mm intake valve is roughly 2.57 square inches of surface area at 15psi of boost that is 38.6lbs of force trying to open the valves that is about 1/3 of the pressure a stock valve spring is putting on the valve when it's seated.

You would not want to use the factory turbo exhaust valves in a high RPM engine. They weigh a TON. If I remember correctly about half again more than a 46mm intake valve. Titanium valves are cheaper as well.

They are quite accommodating and IF you have an original BMW ZF S5 transmission with a good housing they can fit their new internals and you have a proper box for your BMW. They will need to make a custom main/output shaft as the new boxes are designed around the sliding yoke used in the Ford applications. If you do not have an original BMW ZF gearbox they can't make you one as they don't have the cases. I even tried to send them a front section from a ZF 4 speed that uses the same front housing as the 5 speed but it will not match up with their new castings. As I said the modifications to a bell housing is not all that difficult with some proper welding and machining skills. The sliding yoke output gets rid of the Guibo as well. Just remember it is designed to be a racing gearbox. It's strong, you can get repair parts easily BUT it is noisy and you won't like it in a street car unless you are a deaf as me or wear ear plugs.

I have 2 of the Elite ZF S5 18/3 gearboxes we use on a Gp2 CSL and I can highly recommend them. The output is not the same as the BMW based gearboxes (this car came with a BMW version of the close ratio ZF 5 speed that did use an output flange and the larger 6 cylinder Guibo coupler) it uses a sliding Yoke style output shaft that I adapted to a custom drive shaft that uses U-joints. The biggest problem you wil have it they are built to bolt to a Ford Cosworth bell housing not the standard BMW pattern. I had to modify a bell housing to fit as well as have them build the gearbox with an imput shaft with the correct length, spline and pilot size. They are a racing box including the synchro boxes, the gears are not straight cut teeth but they are not a full helical cut either and as such would be a bit noisy in a street car.

The only problem with using MSD's 15 degree timing is that your BMW has timing marks at 0 and 25 degrees. If you use one of them it makes life a lot easier. Most of the domestic stuff MSD sells to have fully degreed pulleys on the front of the engine and it is easy to pick 15 degrees.

You have to set the distributor at 0 degrees if you want the advance you put into the map to be correct. The distributor has no idea where it is set in relation to the engine. If you set the advance in the distributor to 25 degrees and then check it with a timing light you need to rotate the distributor until it is actually at 25 degrees. From that point on you can do everything on the computer. You can set the distributor anywhere you want but you need to add or subtract the initial timing offset to your map to know what you realy are running.

I don't know what the inside of the MSD distributor looks like but I would think that figuring out how to lock the advance should be simple enough. You might look and see if you can drill and pin the advance weights so they can't move (reversable if you decide to go back) If you have access to a lathe you might machine a different stop that does not allow it to advance at all (like the ones that come with the distributor but large enough to stop the weights from moving instead of only allowing 10-15-20 deg) I would use 25 deg just because you have a good 25 deg mark on the flywheel (the ball) and you don't need an adjustable timing light to set the base timing. You can always use your 7 degree base timing you just need to remember it when you are looking at the timing curve in the computer. Whatever you do have an idle advance that is stable from about 800-1400 rpm so you don't have an issue with trying to set a stable idle when you have the timing changing with every 100 rpm of speed change.

How did you decide on 28deg of total advance, especially at 5000+ feet of elevation? And I am assuming you have checked the timing with a light. I usually lock the curve at 25 degrees and check it at multiple RPM and make sure it is dead on. Then you have a proper reference to 0 degrees and you can do everything with the laptop from there.

Or you could log onto your 123 app on your phone remove 2 degrees of advance between 5000 and 6000 rpm as you are driving down the street.

Getting all fancy with ignition timing is not going to find you a lot of performance advantage (unless you are WAY OFF BASE to begin with) It will have more to do with drivability than anyting. Stumbles and surging are the most common problem if you are to far off the ideal advance. You can spend a ton of money and time and when it is all said and done you might find 1-3% at any RPM point. The trick is getting it set and having it be reliable.

The programable units like the MSD 6AL-2 or the 123 make it really easy. Install the distributor, put the car on a dyno and lock the curve at 5 degree increments and make runs then compare all of them and figure out how much advance is optimum at each rpm then program THAT curve into the system. Start at 15 deg and keep going up until you see the TQ/HP fall off then back up a couple of degrees and leave it there. You can then modify the curve using the MAP sensor based on throttle/manifold vacuum for drivability. This is a ton easier than trying springs and weights in a distributor. Some engines even like more advance around peak torque than they like at peak HP and you can't get a spring/weight advance mechanism to advance then retard.

Sit down and do the math. The real numbers you need to think about for a track car is the RPM gap between the gears. This is something you can't change between tracks, you can always change the final drive based on the longest straight or fastest section of the tack. The difference between a 245/5 (over drive box) and a 245/10 (close ratio box) if you shift at 7000 rpm the RPM in the next higher gear is: 245/5: 1st - 2nd gear 3200 rpm drop, 2nd - 3rd 2200 rpm drop, 3rd -4th 1700 rpm drop, 4th - 5th 1200 rpm drop 245/10 1st- 2nd gear 2600 rpm drop, 2nd - 3rd 2100 rpm drop, 3rd - 4th 1600 rpm drop, 4th - 5th 1300 rpm drop Then think about the top speed in each gear once you have figured out what gear you need for the top speed you will need for that track. Say you need a 130MPH gear for the straight. If you have a 7000 rpm limit you would want a 4.6:1 final drive ratio if you are running the 245/5 OD Box this would give you MPH/7000 rpm in each gear 1st/28 2nd/53 3rd/80 4th/106 5th/131 If you are running the 245/10 CR box you would need a 3.64:1 final drive and you would have MPH/7000 rpm 1st/36 2nd/58 3rd/83 4th/109 5th/134 As you can see there is not a significant difference in effective gear ratios other than 1st gear (transmission ratio X final drive ratio) between the 2 transmissions. If I was choosing a transmission for a race car I would get ratios that drop the rpms between gears of roughly the rpm drop from MAX HP to MAX TORQUE of the engine I am running. I would also have a 1st gear that is a usable ratio on track ( the slowest corner on the track should be 1st gear) as long as you are not doing standing starts. For the cost of changing the transmisson from one to the other (245/10's are really expensive these days) and then the cost of getting the correct final drive there are a ton of other things you can do to make your car faster for a lot less money. If you are starting from scratch and don't have a trans or diff then do it right the 1st time.

That is a 118 head, it is used on a 1600 or early 1800 engine. Small valves, small intake and exhaust ports.

Probably because they added the larger rear brakes. The Turbo rear drums were the same as the e21 320i but used a larger slave cylinder ( same as used on the e9 2800’s with rear drums.

They use a different ramp angle and don't rely on spring preload to initiate the locking action.

I bought three 75% Alpina limited slip units from Miller and Norburn in 1975 for use in Solo II cars. I still have all three and they work fantastic. There is no preload/break away torque, on the bench they act like an open differential, but apply a bit of power and drive around a cul-de-sac and it acts like a locker. I have them fitted in 3.45, 3.64, and 4.11 diffs now.

Or someone used them to jack up the front of the car a few times.

At some point the value of a 2002 was low enough that a bent bumber and grill might have been enough to "total" the car. Someone could have bought it back put on a new bumper and grill and all good again but the title would still have a "rebuilt" lable on it.

It is a 48 year old car that has been repainted and modified. The value is not changed by the "rebuilt title". The car is what it is and an inspection will show what condition the car is in. If someone wants to mark it down because of the "rebuilt" title just wait for someone that really knows the cars to come and look at it. In my opinion the car is worth what it is worth and the "rebuilt" title should not change anythig.