Sprite Motor

Started by MiniDave, November 27, 2019, 05:37:13 PM

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MiniDave

A while back one of the Lawrence guys who buys and sells a lot of LBC's asked me to put a motor he had back together, he thought he was going to overhaul it himself but decided it was just too much for him.

Fast forward and a guy calls me and tells me he bought that motor and one of the Sprite transmissions I overhauled for the Lawrence guy. He said he's been running the trans in his Bugeye and that it works great and that he'd like me to build the 1275 he bought into a nice street motor.

I gave him a list of parts to get and after a few weeks he brought the engine to me, it's supposed to be an all winter project for him but I decided to get into it and tore it down and sent the parts off to the various machine shops to get them started while I did the work on Dan's 66 Cooper S.

Everything finally came back early this week so I started putting it back together today.

First up I started on the head, but after getting four of the valves in I realized I only had 4 stem seals. No matter, a quick trip up to Vicky Brits and I had them.....back to the head. Got all the valves in and started sorting out the rockers. On my recommendation he bought the Cooper S forged rockers, and I had them reamed at the crankshop when they did the crank. Got all the rockers sorted and realized he didn't have the spring washers for the ends of the shaft - back to VB again.

So, head assembled, I started on the block. First up I put all the lifters in their holes, then slid the cam into place. I put the rings on the pistons and with the bearing caps off pushed all 4 pistons in their respective cylinders. Then I laid the crank in and brought the rods up and put the caps on. I haven't torqued anything up at this point, just snugged for now. Tomorrow I'll get out the dial indicator and torque wrench and if everything checks, torque the rods and mains. Then I'll go ahead and put the oil pump pick up in and put the pan one. Once that's done I'll flip it over and set the cam timing.

More as it happens.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

A couple more pics....

I have just found out that Kent Prather has retired from engine building and race support, and since both Clancy's and Scott's Sprite motors are broken I may be building their new ones too.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Willie_B

Quote from: MiniDave on November 27, 2019, 06:23:37 PM
A couple more pics....

I have just found out that Kent Prather has retired from engine building and race support, and since both Clancy's and Scott's Sprite motors are broken I may be building their new ones too.

I see a rolling lift table in your future.

MiniDave

I have the engine hoist, I just have to take a car out of the garage to use it.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#4
Torqueing up the crank assembly today....couple of interesting things happened. I put the new thrust washers in and could not get any crank float at all. Dug out the old ones, cleaned them thoroughly and micc'd them - they were about 2 thou thinner than the new ones, put them in and saw 7 thou float. Put the new ones on one side, old on the other - 5 thou, Took the old ones out and put the other new ones in - 3 thou - right on spec! Weird.....

Next, I dug out the instructions that came with the ARP rod bolt kit. Normal torque on rod bolts is 35-40, but the ARP kit wanted them torqued to 55ft lbs! Mains were only 65....

Tonight after dinner I'll set the cam timing....on the Inno engine it took a 2 thou offset keyway to get 106.5* so I went ahead and bought one to start with, we'll see how it lines up. I also have a std, 1 thou and 3 thou if needed.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#5
Moving right along, till I came to a screeching halt......he bought a nice high end aluminum flywheel and clutch assy (Fidanza) and I went to put it on tonight, bolt holes line up, dowel pins are correct and fit but it won't go over the end of the crankshaft. Ruh-roh.

Got out my micrometer and found the boss on the crank measures an even 72mm, the hole in the flywheel - 71.7......well that's never gonna work!

He's going to call Moss in the morning and see what gives. He double checked his part number and it says he got the right one so we'll see what they say.

I got the bottom end all buttoned up, sump in and oil pan on. Also got the timing chain and front cover on and the front and rear mounting plates.

I may get the head on yet tonight.

Once the flywheel situation is sorted out I can get it into the engine stand and make some noise....still have lots of bits to bolt on before I can start it up - and I need to get a hose made up to the oil filter housing.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MPlayle

That oil filter housing looks at an odd angle compared to the ones on a Mini.


MiniDave

#7
Yes, they do the Bugeyes this way, there is a round hole in the sheet metal pan under the engine and this allows you to get your hand up from underneath to remove the filter thru that hole. The frame rails sit pretty close so there's not much room to get at it from the side. The aluminum part of the housing is the same as most Minis, but there is an extra piece that the aluminum part bolts to, that changes the orientation. We talked about just  bolting the aluminum part straight to the block but he says that would make it too hard to get the filter off, so we went back to OEM.

The head is just sitting on there, I haven't put the studs in yet.

Plus too and also, I just found the oil slinger sitting on the bench, so I get to take the front cover back off...... ::) :-[
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

All buttoned up, head installed and torqued up, valves adjusted and all the odds and ends I have are done.

Waiting for the flywheel, and a few other bits and bobs....he ordered the wrong plug wires so I'll need to make yet another trip up to Vicky Brits to get the right ones. I went up this morning and picked up the right flywheel to crank bolts and a pilot bearing and while I was there I measured a new crank boss to compare with ours and it matched perfectly, so the problem is with the flywheel.

He called Moss this morning about the flywheel and they said they'll get back to him, but that due to "Black Friday" sales they're really backed up and it might be a few days before he hears from them.

I also need to get the oil line made that goes from the block to the oil filter housing.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

Today was chase parts day.....

First to Vicky Brits to return some bits I didn't need and to try and pick up some spark plug leads - the ones he got were for an MGB and about a foot too long but they did not have any that would actually work. Weird, all I needed was a shorter version of what he bought but they didn't have any like that.

I also picked up a water pump for Don's Midget, his looks to be leaking. It's a pretty easy swap on these later cars with the Triumph Spitfire engines in them.

Next it was out to my favorite hydraulic hose maker in Olathe to have them make up a line for the Sprite motor from the block to the oil filter housing. $70 later that's done.

Lastly I had dropped off my 16 blade fan to the powder coaters when I picked up the tanks for the '66 and had completely forgotten about it, they called today to remind me it was there so I made the long trek up to Tonganoxie to get it.

I don't know when he'll hear about the flywheel so I'll mount the motor in the stand to get it off the bench and it will hang out there till the flywheel shows up.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#10
Engine is mounted up in the test stand and ready to run, I'm going to have to re-engineer the rear mount as the flywheel will hit the cross bar. I'm checking around to see if anyone has a bell housing from a junk transmission case that I can have....

I did re-engineer the rear mount and now it clears.

Waiting on the flywheel, so now that it's off the bench I can clean up and get back on the 66 Mini tomorrow.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#11
Borrowed a flywheel from my friend Clancy for the Sprite motor, bolted it on and filled the sump with oil. The starter motor the  motor's owner gave me is questionable and it didn't help that my battery was a little low on charge, so I cleaned the bendix drive while the battery was charging.

Once everything was up to snuff I pulled the plugs and cranked it over till I got oil pressure - once pressure came up the starter really dragged, so it may not have enough oomph to crank this motor under compression. None of my spare starters will work as the Mini has a different number of teeth on the ring gear and the starter pinion and the spacing on the bolts holes is different. The starter on his Bugeye is fine so he can just use that one.

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

Well, I got the aluminum flywheel on.....Clancy gave me the name of a guy in S. Carolina who has installed 50 or so of these, so I called and asked him what I was doing wrong and whether I had to heat it up first. He said he'd never had to and just to go ahead and use the dead blow hammer on it and bump it into place.

So that's what I did.

Once I was sure it was started on properly I put the bolts in and drew it up evenly, then torqued it up. Then I installed the clutch assy and did the same. The owner is picking up a new starter at Vicky Brits in the morning then we're gonna see if it will make some noise!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

The owner brought over a new starter from VickyBrits and once it stalled we fired it right up!

Ran sweet too. I'll have a vid tomorrow....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#14
Some video of the Sprite motor running in the test stand, it's just running to break in the cam and make sure there are no leaks and that it doesn't run hot etc.

I set up a pointer over the flywheel, there is a small hole in the flywheel that I used as a TDC indicator so I could set the timing, the regular timing marks are on the front pulley and timing cover at the bottom, really difficult to run the RPM's up and try and watch the timing marks from under the stand, so this was much easier!

The owner was there for the test run (grey sweatshirt) and was asking me how to take a video on his phone

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MPlayle

Is it just me or does anyone else see some "off-axis" movement of the center wheel of the clutch assembly?

It is more pronounced while at the idle speed, and clears when revved, then returns as the speed drops back to idle.


MiniDave

#16
It was "idling" at just over 2,000 rpm, I think it was just an artifact of the camera.....but it did look weird!

This morning I re-torqued the head - it def pulled down a bit more - then I reset the valve clearances and ran compression - it was a nice even 160 across the board. I pointed out that these were not high compression pistons like we put in Dan's engine, I think they'll be more like the 9:1 ratio, which is still better than the 8:1 it had originally. It still should make plenty of power compared to the tired 948 in there now.

At any rate, the motor goes home tomorrow.

He still has a few challenges ahead, the car now is a positive ground car and he's changing over to negative ground. I made him a hydraulic line to replace the metal one from the block to the oil filter - at his request - but as we were looking at it in the engine stand we're not sure it will clear. He wants to use his generator - unlike the alternator I use in the engine stand - because the drive for his tacho is on the back of it. Looking at it tonight, I think it might work because the genset is slimmer than an alternator and sits up closer to the block.....he'll just have to try it and see.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#17
The Sprite motor went home today. he wasn't planning to put it in the car till late spring, but he's excited about it now, so he thinks he may get it in over Xmas break.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

BruceK

Quote from: MiniDave on December 09, 2019, 06:00:43 PM

He still has a few challenges ahead, the car now is a positive ground car and he's changing over to negative ground.

That should take all of 2 minutes.  I converted my first Mini to negative ground in freezing temps in my dorm parking lot when I was back in college.  A cold winter day made me work faster!
1988 Austin Mini
2002 MINI Cooper S
1992 Toyota LiteAce (JDM)
1997 Jeep Wrangler Sahara

MiniDave

#19
Yes, just a matter of re-flashing the field on the generator, I gave him pretty explicit instructions on how to do this, and how to hook up his new electronic distributor correctly, hope he follows them.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#20
A follow up on Kent's engine build, I ran into him at the races in Texas and again at Blackhawk last month, he was crewing for Dave L. in the Sprite.

His build was drug out quite a bit as he decided to make some changes - first he completely redid the interior, and while it was out he made the decision to buy one of the 5 speed transmission kits.

He got that installed, put the engine in but couldn't figure out the wiring for the distributor. Finally he called me and I walked him thru it (only two wires but there was some difficulty with a "third baseman" offering a different opinion), but he decided to listen to me at last, and while I was on the phone with him he turned the key and it fired right up!

Once he got it out of the garage for the first drive he was massively disappointed, the diff someone had sold him screamed, even tho he had put in new bearings - the gears were either not set right or simply badly worn. So he spent some time acquiring another diff and now the car runs sweet. He still hasn't done the 500 miles so I can get it back for one more head retorque and adjustment but I expect to see him sometime this summer - I'll get some pics then.

He's still not happy with the tune on his Weber carb, he took it to a guy he knew who was supposed to know Webers inside and out, but he said when that guy was done with it it was worse, so they put it back like it was.....I don't know who he's going to have tune it now but I suggested Kent and Jesse Prather, but that's a bit of a drive as he's an hour or more east of me and Kent/Jesse is more than an hour west.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

Several of us went up to Jesse Prather's shop a few weeks ago to run cars on the dyno, including Kent - this was the first time I'd seen the  Bugeye and it's a sweetheart! He's done a great job with it.....

It has a Weber carb and he hadn't been able to get it tuned so they put it on the dyno and changed jets and such several times till it finally came into tune. While we were there we retorqued the head and reset the valve lash.

He called me a few days ago to tell me how happy he is with the car now - the engine runs like it never has before and with the 5 speed it's really comfortable to drive on the highway - although he's mostly scared to take it over 65 or so.

At any rate, it was nice to get the feedback!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

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