Mini Rebuild


Step 72 - Close But Not Quite


I currently have a lot of unanswered questions, all of which can be answered by just putting the engine into the car. I need to know the following:


-Will the clutch hydraulic line's bulkhead fitting clear the engine and its various components?

-I need to know the length of the custom clutch line to order.

-What kind of clearance will I have between the exhaust headers and the firewall?

-Will my old coolant overflow tank and its mounting location still work?

-Where can I mount the engine breather overflow tank?

-How will the radiator fit?

-Where should I route the coolant lines and thermostat housing?

-Where to mount the fuel pressure regulator?

-Location of fuel lines?

-Engine steady clearance?

-Where should I drill thru the lower firewall to run the transmission shifter shaft?

-Throttle cable routing?

-Speedo cable routing?

-Will my existing exhaust system mount up with the new headers?

-Will I be able to close the bonnet?



Mini Rebuild Step 72

Down the engine goes. This was far easier than the R1 engine.


Mini Rebuild Step 72

It's still a close fit though.


Mini Rebuild Step 72

The intake plenum just clears the slam panel, depending on where I position the engine. Although it is fixed at the bottom by the motor mounts, the top of the engine can swing thru an arc and then be locked into place with the engine steady. You will notice I removed the bonnet latching mechanism from the slam panel to ease installation of the engine. With the latch back in place, the temptation is to swing the engine backwards to give plenty of clearance. The problem with that is...


Mini Rebuild Step 72

....that the exhaust headers are *right* up against the firewall. I will be installing some heat barrier material on the firewall prior to final install. That will help but there is a limit to how far back the engine can tilt.


Mini Rebuild Step 72

Thankfully the radiator fits just fine. Tight, but that's normal in a Mini engine bay.


So in going thru my list, I'm not running into any real issues until it came to the last item - bonnet clearance. A quick test fit reveals that the bonnet almost closes but won't. Right before the bonnet closes, it contacts the forward cam gear + belt:



This is a problem. Everything else on the list should be relatively easy to address in one way or another, but if the engine is too tall then there is no easy way out. I cannot easily change the height of the engine. My only real options are to push the bonnet up or drop the engine down in the car. Both of those choices come with a cost. For other Mini owners installing the same or similar engines, it is common to install an aftermarket bonnet with a bulge in it or an entire raised section or both to allow the needed clearance. There's nothing wrong with that but I prefer the look of the standard bonnet. I also already have a perfectly good one that was painted along with the rest of the car.


By the way, the reason this is an issue for twin cam / double overhead cam heads is that they tend to be significantly taller than a head using a cam-in-block/pushrod arrangement. The photo below is an excellent illustration of this difference. The blocks aren't terribly different in size but compare the heads bolted onto either side of the V:



The second option is to lower the engine in the chassis. The Mini, like nearly all unibody cars, has a front subframe that carries the engine, transmission, and suspension. This steel subframe can be cut out where the motor mounts bolt up. The cut sections can be relocated downward then welded back up to the car. Sounds easy in theory, but what about in practice? I'm about to find out.


Mini Rebuild Step 72

The area inside the taped lines shows where the motor mounts bolt up to the subframe. By my calculations I will have to lower these mounting points anywhere from 1/2" to 1". That will lower the engine by an equal amount, allowing the bonnet to fully close. I've spent the last week crawling all around the front of the car to and thinking thru the process. I think the best way to proceed is to cut out the entire angled section of steel out, test fit the engine, install the bonnet and slowly lower the engine from beneath until I have the necessary clearance. I will then tack weld the sections back in, remove the engine and subframe, fully weld everything back up, and it should be good to go.


Mini Rebuild Step 72

With my cut lines marked and a new mini-sawzall in hand, the cutting begins.


Mini Rebuild Step 72

No going back now. The righthand plate is free.


Mini Rebuild Step 72

And now the lefthand.


Mini Rebuild Step 72

Was this a good idea or a very bad one? More updates soon...


Continue to Rebuild Step 73

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