BMW twincam head installation part III

Finally I have the crank back from the grinder. It was worth the wait. I had it indexed - checking and correcting the rod throw and timing for each cylinder. It was BAD. Cylinders 1 and 4 were fine, but 2 and 3 were rotated .013" (in the same direction) and the throw was .017" and .019" shorter than 1 and 4, which were actually longer than they should have been. I suppose being off centerline, the extra lift was actually lost with the incorrect valve timing so compression would have been roughly the same?

The rods are shotpeened but not resized yet. The piston wrist pin bores need to be honed after the teflon coating process as well. Hopefully that will get done one day next week.

I installed the crank and set the end float at .0045" since it will be a very high revving engine.
At this point I need to calculate compression ratio, relieve the pistons with valve cutouts, and send the block and head out to be surfaced. Then finish the 3 angle valve job and assemble. My goal of a running car in February may be gone, but I'm still giving it my best shot. The big downfall is that the engine bay needs to be stripped and painted yet, and modify a Mini header to fit the Midget. I guess I could take a week off of building distributors...

Awesome to see some progress, thanks for keeping us updated.

Another week flies by with no engine progress, but the engine bay got painted today. Not sure the color match is any good though. I guess we'll have a better idea in the morning. The engine bay used to be overspray over the factory blue, and lots of silver hammertone. A serious mess!!!

Tues/Wed I resize the rods and maybe tomorrow night I'll get the valve job finished. The valve seats are ground WAY too wide, and need to be shifted outboard. A simple 3-angle job and shorten the valves to reset the lash. I already ground the valves and trimmed the OD .020" for unshrouding, as well as swirl polishing them. Every little bit helps produce airflow.

Progress, finally!!!

I finally did the valve job this weekend. Under a magnifying light, and by hand since the seats are so small and soft (yes they are steel inserts) that the seat grinding setup cuts way too fast. 6 hours later I have the proper width seats, placed properly on the valve faces. Excess material is trimmed off the valve circumference for less shrouding and more margin. Ports are cleaned up, short side radii are smoothed, and the area around the guides are smoothed.

Today the block and head get dropped off for minal surfacing. By this weekend mock assembly should be done to find piston to valve clearances. Then I can cut the piston tops and put it all together one last time!!!

I am interested in the progress of this, A friend of mine has used this set up on his mini with good results! Much cheaper than the A-Series 8 port head too!

Keep us posted :)

Yesterday I picked up the block from final decking, still waiting in the head to be resurfaced. We had a heck of a time finding the right rod hone yesterday, but today the rods will finally be done and the short block can be assembled to determine piston to valve clearances this weekend.

Yesterday I finally fitted the crank, one piston and rod, and the head so I could get to work on valve timing. I degreed in the cams per BMW factory spec, then advanced and retarded each 5 degrees AND set it up the way Specialist Components recommended, checking minimum valve clearances at each setting. A few hours spent on the details no one will care about in the end...

This afternoon I'm hoping to set the engine/tranny in the car to check bonnet clearance.

Then I get to tear the engine back apart, put clay on the pistons to see where to notch for clearance. Tonight? We'll see. Once that's done its final assembly and installation!!!

Photos to come, if I can get the glitch fixed emailing pics from my phone...

Here's a photo of the engine sitting in place. For all you nay-sayers who thought it wouldn't fit under the bonnet, well, you're 100% correct. I figure 1 1/2" extra clearance will be needed to get around the pulleys. I guess I have some thinking to do on how to work around this. It would look sort of cool to have the pulleys exposed, but I'd rather find a way to tuck it under smoothly and without drawing attention.

On a brighter note, the front plate fits perfectly, and with a little more notching, I bet I can get the engine to sit lower. There's got to be a way to do it and make it "right."

The next issue will be very little clearance at the steering rack crossmember, but it should fit. Its the crank trigger assembly that runs tight. Its so easy to pull the engine on this car, I'll tackle that after the engine is fully assembled.

I found it easiest to make a steel plate to mount to the top of the valvetrain for dialing in the cams. That's the easy way to have a good platform for a magnetic base. I had to make an extension for the dial inidcator to reach the lifters at the front, and make sure to use the leading cam lobe, as with dual cam lobes one will almost always open first to initiate airflow.

Shown are photos of reading the lifters, and the dual gauges on the back are reading the cams directly to calculate the difference between the lifter action and the actual cam due to valve lash. I could actually read the rear cam lobes instead of the lifter IF I set up the degree wheel to read BDC instead of TDC when the #1 piston is at TDC, since the #4 cylinder lobes are 180 degrees opposite.

Now its time to call in the big dog and figure out where to set the cams. A good friend in the owner of Damn Good Motors and designs cams for performance vehicles of all kinds. In fact, he's the motivation behind my roller camshaft for the MGB we're working on too. You'll see more about that after this project is up and running.

Why not a mini mgc style bonnet bulge? That might be kinda cute.

I'd love an MGC bulge, but don't have the skills to pull it off well. I fitted an MGC bonnet to my B in preparation...
I even own an english wheel and planishing hammer. I just never get to practice.

90's Misubishi Eclipse hood bulge.

All that is secondary at this point. I just spent another hour last night finding the cam centerlines, roughly 106 degrees each. My friend and mentor Guy is thinking 106 intake, 112 exhaust centerlines for best drivability. I need to spend more time mapping valve events with the cams dialed into those setting...

.............or get rid of the heater/battery shelf, move the engine back 6" like the racers in Blighty, move the battery to the trunk, and no bodywork is required. A perfect "stock" looking sleeper. >:D<

Seriously, a great project Jeff, nice work.

Moving the engine back was on my secret list of things to try. I could actually use more rack-to-pulley clearance and radiator space. Shortening the driveshaft is probably one of the easier mods if necessary, as is moving the shifter hole.

The other possible result would be a different weight distribution. Not sure it it would be better or worse. They have near 50/50 already when loaded with fuel and two people.

Much less effort to just make a hood bulge , and easier to reverse too. Since you are spending so much time getting your valve timing perfect, you should showcase it. See through timing belt cover with strobe lighting. :)

Seriously, I hope you share your notes in a "how to" of sorts. It would be fascinating to read from beginning to end once the end result is achieved.

Fiberglass hood with a buldge?

Jeff, is there any way that you can safely drop the engine a few inches by going dry sump?

Jeff, nice work. What a great report!

Anyway, you are right. The Midget board is fun! Thanks for hauling my rear end over here!

warmly,
dave

I was very surprised by a thread on the MG BBS recently in the K Series conversion forum (http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=thread&access=&subject=76&source=T&thread=2012030621221213187) - those guys run their engines with the sumps protruding 2"-2.5" below the rails (and 3"-4" sump to ground clearance) without any problems, even on cars that regularly compete on rough dirt. These guys drive their cars hard, and based on their experiences I definitely think you could lower a 1275 quite a bit in a street ride height car without causing any problems - you would of course want to lower the box as well to keep the driveline angles correct.

I have yet to bolt up the tranny and look at driveline angles to see where I can go safely with the engine. I have not yet cut the steering crossmember, but its in the works. I figured I'd do that and the motor mount mods at the same time, hit it with fresh paint, and call it good. I'm truly afraid to go too low with the engine, given the potholes we have around here. This will be a street car. I'm looking for longevity via simplicity, not dry sump $$$$$. There appears ot be plenty of room to push the motor rearward a couple inches, but if shorter motor mounts work I'll go that route. The downfall is lack or room to lower the tranny, so that means rear axle shims.

First I have to get the cams dialed in. We decided on 106/114 cam centerlines last evening after Guy Henson (Damn Good Motors) spent a boatload of time on his computer crunching numbers. I'll set that up today and relieve the piston this evening, which means tomorrow I can do final assembly and put the lump in the car. That'll allow me to put together a shopping list of all the AN fittings, lines, breathers, etc... that I'm missing.

Then if time allows I'll build extensions to move the throttle bodies outboard further, figure out how to wire in an intake air temp sensor, and reinstall the brake pedal box and get the hydraulics up and running.

Jeff, you have done a lot of hard work and it’s looking great! You have great fabrication skills. Theirs another way you could create more space if you wanted, you could do so by wedging out the oil pan. The roads are not quite as bad here but I had the same fear of smacking my sump too since my car will be about two inches lower. I decided to order Winners Circle's oil pan to help with that problem. At one time they stop making them but I heard that they are back in production. This pan would give you the extra clearance that you may need for your hood. If you would like to make your own, I would be happy to take measurements from mine to give to you!! Here's a photo of what it looks like.

Actually Alan those oil pan with the engine in stock position hand just bleow the frame rails, I know this too well, I repair a ton of them in my life, especially for Dick May :D

It's a good oil pan, but it doesn't do squat as for under car clearence.

Technically Hap, I think Jeff will have to make this determination himself whether he can use this style pan. Jeff may only need to drops the mounts 1 or 2” to gain him the clearance he needs, both pans are about 6" deep but he may like the extra capacity running twin cams. I would hope Jeff can keep the drive shaft angle close too the degrees that he needs and feel comfortable without stressing the Ujoints is another concern...

You guys need to be trying to persuade Jeff to make a proper power bulge. It is a necessary "badge of honor" among HotRod builders. ;)

Trevor, Jeff could modify his hood like Aaron Coupers car the "Frankensprite", NOW that’s a HOTROD!!!

... everyone keeps chanting, "hood bulge, hood bulge!", but didn't Jeff say that his goal is to avoid having to do that?


By the way, here is a link to the most beautiful and natural hood bulge ever done on a Midget (pretty XKE engine transplant too), it gets posted here from time to time, because it is just so loverly:

http://www.britishv8.org/Other/AaronCouper.htm


Norm

Yes, he said he didn't want one. That is the problem here... he doesn't know that he does want one. Make sense? ;)

Sprite with a hood bulge in Australia......

http://www.spriteparts.com.au/garage/fright.html

Norm, isn't that a grafted-in GT6 bulge? Kinda sexy. I'd do a bulge IF I could do it in a way that looks like it belongs there. I have pretty high standards with that stuff since I swear I've seen every bad/easy way to do it on the planet. Personally, I think a small fabricated scoop that just barely allows you to see the cam pulleys would be kinda cool, but it would have to be properly blended into the bonnet to look factory, had it been an option. Anyone can put a big MGC bulge into the hood somewhere. In fact, I have an MGC carb bulge I cut out of a destroyed bonnet I'll be grafting onto my tractor. Seriously. I want something more special, unique on this car.

Today the pistons were mounted on the rods and went in the block, hopefully for the last time. The NOS Vandervell bearings are all in place. Tomorrow the rest of the block gets finalized (I hope) and the head gets mounted for the last time. Then I get to sort out oil drain lines and an external oil pressure line, make a new spigot bush for the tranny, and get that mounted so I can spend Sunday trying to figure out how to mount it all as subtley as possible.

Thanks Hap for the crossmember reminder. I spent 2 hours this afternoon hacking and welding to clear some real estate for the crank pulley. I should have done that BEFORE I painted. Arghhh...

Looks great Jeff! I say a small bulge and some ITB's.

If you truly want to showcase the pulleys, then I'd suggest an inverted scoop prior to the pulleys then a scoop covering them. Have the fold lines follow the edges of the bonnet and blend them to the very front back. It is a bit of work, but can be done with very little metal shaping. All you need is patience and some welding and grinding.

Do you want a sketch?

Or you could go this route



Its got nice exposed pulleys

Hi Jeff,

the bulge on the Midget in that link is from a scrap XKE bonnet, and I posted it based on your concerns about making sure that what you do looks factory, that one is the most natural looking one I've ever seen on a Midget!



Norm

I DON'T want to truly showcase the pulleys. BUT, if I have to have a hoodscoop, it may as well show you why its there and that I'm not just a poser who thought it looked cool. :) The exhaust note will speak for itself, but first impressions from visual impact will either drive folks aways or draw them in...

How's the saying go: "any publicity is good publicity"? Except when the comments are "what the hell was he thinking???" Its funny how often I hear that. :)

Hap, I wish I was at that point.... Dealing with the dreaded body work, somthing that is taking forever :X

Ok, just spent another day playin with cam settings and a serious upscale version of desktop dyno. I have two base cam settings to play with on the dyno, both with phenomenal torque, but should develop different cylinder pressures. Base numbers, however inaccurate show roughly 140 ft lbs of torque and 135 hp. I know they're off, but by how much in which direction? Who knows. The torque curve sure looks like fun with 100+ ft lbs of torque from 1500-4500 rpms and more than 100 hp from 3500 to 7500.

Yes, I know the software is inaccurate and can't even properly load the BMW cam profiles no mattter how I lay them out, and I tried every possible method. We cheated until centerlines were right and guessed at cylinder head flow numbers since I couldn't find a shop who wanted to flow it without a king's ransom attached.

Now its off to glue in some gaskets and make headway toward putting it in the car tomorow.

I vote for moving the engine, either down or back. Not that my vote means anything of course, you need to decide what you want from your car! The hood modification is definitely the easier way to go, but dropping the engine an inch shouldn't be too difficult. Are you running a standard ribcase box? I think you may be able to drop the engine and box a little without doing any bodywork just by modifying the mounts. Actually, I'd have to take another look at the gearbox mounts, but if you can lower the box enough purely by modifying the mounts, leaving the crossmember alone, and lower the engine by modifying the mount towers, then that may even be easier than modifying the bonnet (at least to do a good job of the bonnet as you want and not just cut a hole!). If you try to move the engine back I believe you will have to cut into the heater tray for clearance, in addition to modifying the mounts, driveshaft, and probably the gearbox crossmember? You wouldn't be covering new territory though, the very-popular-in-the-UK K Series conversion requires them to cut back the heater tray.

I understand what you are struggling with, there was a lot of trial and error in getting my supercharger setup the way I wanted it but still able to fit under the bonnet. If I had been happy to add a small bulge it would have been much easier and quicker, but that was not an option I was willing to accept. Having said that, looking back and in light of this discussion, maybe I should have considered moving the engine and box, especially give I was fabricating a new crossmember for the gearbox anyway! Oh well, hindsight...

I'm using a Datsun tranny conversion, and since I didn't originally install it in the car, I'll have to take a closer look at how it fits and how much clearance I can gain. My big concerns are the tranny mount on being able to drop it any further without massive surgery, not that I'm afraid to go there. I just need to leave room for the header.

First I need to make a pilot bushing that actually FITS. Someone neglected to remove the factory bush when installing the Datsun bush, so it really didn't do any good...

Jeff if you need the demensions on the Datsun/Spridget pilot bush ,call me, I have one not yet installed, and you can get oil-lite stock from McMaster Carr,and then it's just a simple lathe project.

I think I have an extra bushing, but it is the one for the crank with the large hole (originally needle bearing?). IF it happens to be the one you need, just email me and I'll drop it in the mail to you.

I'm not going to trust that the Rivergate part is properly made. I'll just spec it out here. After all, I have a granite surface plate I can set the tranny up on to measure depth, and a full machine shop including round bars of really good cored and solid bronze to play with. You could say I have a little experience custom making bronze bushings... This is the easy stuff, but the hard part is motivating myself to make bushings for me after a long day of doing the same for eveyone else...

Also, there were two different designs on 1275 pilot bushing one had a thin bronze oil lite bushing the other one the crank is bored larger at the back and they took a roller bearing, these were on the very last 1275s,and somewhat rare to find, but i got a 1275 rebuild with one right now, the first one i seen in god knows how many 1275 crank that have passed thru my hands, in say 5 years.

Hap, Do you need a Rivergate 5 speed bushing for it?

Alan- A bit off-topic, but what alternator is that you have mounted? looks like a great fit!

Thanks,
Devin

Well, I made my own pilot bush after finding the original broken and seriously hogged out. I made it the maximum length for strength, since the last one broke where the OD stepped.

The engine and tranny are in the car together for the first time, and I learned a lot about positioning it. Basically I learned I can relocate it to fit under the bonnet, but not in the short amount of time I have, or without cutting a LOT of sheetmetal and spending 20-ish hours doing it properly. I just don't have 2-3 days available this time of year (building distributors is taking up 70+ hours a week.)

I also learned what I need to do to make the custom Mini header fit the Midget. A little more clearancing is necessary, and a fair amount of dissecting and rewelding to the centger pipe.

I also learned that the aluminum radiator I have WILL work, with the use of some custom hoses (lots or room to spare). The heater will be more work, but once again possible since it was removed long ago. The wiring will be pretty simple all-in-all since the whole new computer system is a 2-wire hookup to power/ground, and 6 wires to the fan relay, O2 sensor, and temp sensor. I really should have an intake air temp, but apparently they decided I can live without it? I guess we'll see.

There should be big progress in the coming couple weeks!

Jeff,

I can't tell by the pic... What did you do about clearing the crank trigger wheel? Did you modify the steering rack crossmember in the center or was there enough room for it?

There is NOT enough room. The center section is gone, braced with the same size box tube down to the lower support. The wide open window there is what will allow the radiator to fit with clearance for the lower hose, plus room for the pulley and crank trigger.

Moving the engine rearward will cause another issue I hadn't anticipated with lack of room for the exhaust which would require more major surgery.

Hap,
I think you should spin her around the block a couple times this week as well - scare off any demons that may haunt the weekend. I'm counting the days (there's an app for that.) :)
If you want, I'll ship the LM-1 down there to your shop to have for the weekend? If you're not 100% set on fuel mixture and want a 2nd opinion (via gauge)?