Author Topic: Sprite Race Engine Rebuild for Dave L  (Read 1153 times)

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #25 on: March 20, 2021, 06:41:38 PM »
So I took a break from the transmission builds and looked at these rings.....top ring looks like a normal cast chrome edged ring, but the second one.....this is a new one on me! Last time I built a Sprite race motor was in the late 60's (team name - Impecunious Racing) they had no sucha thing!


Anyway, like I said the top ring is a standard looking ring, but the second one.....there is a fairly normal looking ring, but on closer inspection there is a dado in the inner part of it, and in the package - a second ring that goes inside the first, and fits in the dado! It should be interesting trying to fit them as the gaps are supposed to go opposite each other. So I guess fit the inner ring on the piston, then the outer - rotate them and hope that when I use the ring compressor they stay together the way they're supposed to!

I've looked them over a bit, and I don't really see how they go together.....but I'll study them some more.....


Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline TDA

Re: Sprite Race Engine Rebuild
« Reply #26 on: March 21, 2021, 10:37:24 AM »
Is it a Total Seal gapless setup?  Prather uses them in his race engines.

If it is you might check the Total Seal web site for installation tips.

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #27 on: March 21, 2021, 11:08:45 AM »
Yes, that's who supplied them.....I'll look at their website and see what I can learn - thanks!

I also figured I could just call Kent....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #28 on: March 26, 2021, 05:07:33 PM »
After I cleared out a few other projects and did a bit of cleanup and organizing, today I pulled the Mini engine out of the test stand and installed the brackets for a Sprite motor.

Next up I laid out all the rings so I could custom cut the ring gaps - since this is a race motor Kent (who supplied pistons and rings) said he wanted 15thou endgap rather than the usual 8-12, so each of the top and second rings had to be filed slightly and re-measured several times till just right, and any burrs carefully cleaned off of the edges.

With that done, next up I cleaned up the crank journals and put in the new main bearings, then laid the crankshaft in. Next I installed the thrust washers, then the studs for the mains, then the center main cap got torqued down. The crank turned smoothly so I did the same with the other two mains one at a time, to make sure if there was any binding I knew where it was. The crank rolls smoothly, so all good there.

The next job was to mount up my dial indicator and check the end play - it should be around 3-5 thou and it was spot on at 3 thou.

The next job will be to install the pistons without the rings and then check all measurements, plastigauge the clearances and check the piston to deck height. When I tore it down 3 of the 4 pistons were proud of the deck by a few thousandths, given how the rods can stretch under high RPM use, you don't want them hitting the head or creating any more "crop circles". If we have that situation I may need to send the pistons off to machine shop to have a little taken off the tops. To that end, I have the old head gasket and I will put some clay on top of the pistons, install and torque the head down and roll it over a few times, then remove the head and see how much room there is - the owner found a deal on some 1.5 roller rockers that he wants to use so I need to make sure the valves and pistons won't meet up!

I also have to CC the heads and then try and compute the compression ratio, he thinks it's about 13:1, and we sure don't want it any higher!

So, still lots to do before it will make noise....his next run is the weekend after our Texas trip so I still have a lot to do.
« Last Edit: March 26, 2021, 05:20:20 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #29 on: March 27, 2021, 04:04:22 PM »
Today I did a "dry build", where you put the pistons in without rings so you can measure a bunch of things like rod bearing clearance and how far the pistons are above or below the deck surface. When I tore this engine down one piston was 3 thou below and the others were about 5 thou over the top of the deck.

Today they are all uniformly 25 thou below the deck, which will make all my other calculations much easier - I don't have to worry about the pistons hitting the head or the valves hitting the pistons.

With that done I installed the rings onto the pistons and put the pistons into the block, then bolted up the caps and torqued them down. Everything still turns nice and smoothly so I put the oil pump pickup tube in and installed the oil pan. Next I flipped the motor over so I could set up the dial indicator and set TDC, then set up for checking the cam timing.

I really need to cc these heads, as the calculations I'm coming up with indicate a pretty high compression ratio.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #30 on: March 29, 2021, 05:56:12 PM »
Today I had PT and as usual I was pretty whipped when I got home, but I did get a little work done on the engine. Last night I mocked up a few things to make sure they would work in the engine stand. For example since the oil cooler and assorted hoses stayed with the car I had to rig up a standard spin on oil filter setup so I can run it in the test stand. I wasn't sure the oil filter was going to clear the extra oil pan square.....which it does.

I also put the the head on, and found that the extra two studs must have been drilled by hand, they are a long way from square to the block surface! They will work, but I have to put the head on, then insert the studs.....

Then I moved around the the clutch end and found the pilot bearing was worn badly. The trick to getting one of these out is to fill it with grease, then inset the input shaft just started into the bushing and give it a good smack with a dead blow hammer - the hydraulic effect will force the bushing out of the hole. However, this one was so worn out that the grease would have just squirted out around the shaft sooo......I found a piece of allthread that was a little bigger, and carefully ground it down till it just fit the bushing. Then I did the grease trick and it came out - in three pieces. i think the hydraulic force broke it up.

Anyway, the new one went in without any drama, so I installed and torqued up the flywheel, then installed the clutch assembly, using an old input shaft as an alignment too.

I also called the company in California that supplied this cam and got the scoop on where to set the cam timing - where I might usually set one up at 106* ATDC, they recommended 103 for this scatter cam - glad I called.

More as it happens.....

« Last Edit: March 29, 2021, 06:00:39 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #31 on: March 30, 2021, 03:30:31 PM »
Progress. Cam timing checked. Front end all buttoned up....even made a little pointer to set the timing. Head is on and torqued down, valves are set. Dizzy is in and approximately set. Starter and alternator on, just about ready to set it into the engine stand.....a lot more to do before I can crank up oil pressure, then see if it will make some (hopefully good) noise....
« Last Edit: March 31, 2021, 05:43:18 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #32 on: March 31, 2021, 05:47:41 PM »
Got the engine loaded into the stand this afternoon - today was PT day so that's about all I could do - but I got it mostly wired and plumbed. Filled it with oil, I'm letting it run down for a bit now to see how much it will hold with the added capacity. I already filled up the oil filter. Right now it has 4.5 qts in it, looks like 5 is about all it will take.

I'm using the old header as I sent the new one off to be ceramic coated.

Clancy came up with an old transmission case that I can cut the bellhousing off of and make a cover for the clutch and flywheel, but it will have to be for the next one I build. Too many projects to finish first and this one will be long gone in a couple days or less.

Should be making smoke and noise tomorrow morning sometime.

« Last Edit: March 31, 2021, 05:50:47 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline 94touring

Re: Sprite Race Engine Rebuild
« Reply #33 on: March 31, 2021, 07:36:30 PM »
Did you decide if you're going to run it in with race fuel or not?

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #34 on: March 31, 2021, 09:03:09 PM »
Yes, he pulled a gallon out of his tank for me.....I have it already.

Tomorrow I'll crank up oil pressure then see if it will run. Still a few bits and bobs to do, but the owner is coming over tomorrow morning. I really wish I could fire it up before he comes over.....I hate having the owner watch me in case it doesn't go the first time I try it.




Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #35 on: April 01, 2021, 12:31:05 PM »
It runs!

Boy does high compression make a difference!

We cranked up oil pressure - and at first it almost wouldn't turn over - but his carbs were leaking gas into the cylinders and once it got some lube on the rings it spun over fine - BUT - you don't want to use gasoline as a lubricant. I insisted that we pull his carbs off and put mine on. I used a shop rag to soak up all the gas in the ports - and there was quite a bit - then put my HIF44 on it and it started after it cleared out all the wet gas off the plugs.

Once running it sounded great - good oil pressure, temp held right at 180 once it warmed up - I finally convinced him to put the muffler on it so we could hear ourselves think and it actually ran better with the back pressure, smoother and it returned to idle better.

We let it run for 20 min or so to break in the cam and when he left he had a big smile on his face! He still has some work to do to install it in the racecar, and he needs to get his carbs sorted out before he tries to run it on them.

Overall, I'm pretty happy with it now myself. I'll let it cool down overnight, then retorque the head and reset the valves then he can take it home. Sorry about the poor video, I was holding my phone while adjusting the carb.....I usually have the phone in a holder.

« Last Edit: April 01, 2021, 12:33:16 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline 94touring

Re: Sprite Race Engine Rebuild
« Reply #36 on: April 01, 2021, 01:20:34 PM »
So does that mean you added oil to lube?

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #37 on: April 01, 2021, 01:32:48 PM »
Nope, started it dry.....the gas in the upper cylinders burned off immediately when it started, from there on it only has whatever normal lubrication that gets on the walls of the cylinders.

We ran it for 20 min and as it ran it clearly seemed to be loosening up already....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline 94touring

Re: Sprite Race Engine Rebuild
« Reply #38 on: April 01, 2021, 01:35:25 PM »
Cool

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #39 on: April 01, 2021, 01:53:30 PM »
Did it seem like it took a long time for your engine to break in?

I've never started one with dry cylinders before, but since both Kent and Ivan think that's the way to do it - I decided to go with their experience.....

Kent thinks all that's wrong with the carbs is the wrong needles and jets. We're taking the carbs up to his shop tonight and maybe we'll try the twin carb setup tomorrow after I get the head re-torqued and the engine run again on my carb.
« Last Edit: April 01, 2021, 01:57:17 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline 94touring

Re: Sprite Race Engine Rebuild
« Reply #40 on: April 01, 2021, 01:57:11 PM »
It didn't have many miles on it before we hit the dyno.  500 maybe?  79 wheel horses and about the same torque.

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #41 on: April 01, 2021, 01:58:50 PM »
That's my point, I've never had an engine take forever to bed in the rings when I lube them before I install them, but maybe it does it quicker that way?
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline 94touring

Re: Sprite Race Engine Rebuild
« Reply #42 on: April 01, 2021, 02:04:24 PM »
I think it ensures maximum compression in a quicker time.  50 miles vs 500 kinda thing.  I know on rotaries sometimes it takes a couple thousand miles if guys baby them too much initially.

Offline PoolGuy

Re: Sprite Race Engine Rebuild
« Reply #43 on: April 02, 2021, 09:28:00 AM »
Sorry if I missed it somewhere, but what flywheel, clutch, cover is that?

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #44 on: April 02, 2021, 11:15:00 AM »
Tilton, super light flywheel - that's partly why it revs so fast. The disc has 6 metallic pucks that are about 1/16th of an inch thick, the pressure plate is a two piece unit, very odd looking. It's strictly and in-out clutch, doesn't slip a bit so there's no feathering it!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #45 on: April 02, 2021, 05:03:18 PM »
It was 37* at 8 this morning and 61* at noon, so I waited till noon to finish this job....   ;D

I re-torqued the head, reset the valve lash, then I fired it up again, which it did easily and ran sweet - made lots of really good noises too!

so it's ready to go home and get dropped into the car again. That will give him time to get all the little niggling bits sorted, plus he bought a Morroso Accusump and he can get that plumbed in too.

Next race is at Eagles Canyon just north of Dallas at the end of April.

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #46 on: June 15, 2021, 02:56:01 PM »
His second race weekend will be this weekend at Blackhawk Farms in northwest Illinois, I'll try and get some video of him on track if I can. Leaving Thursday early and home Monday afternoon.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline pbraun

Re: Sprite Race Engine Rebuild
« Reply #47 on: June 18, 2021, 09:39:00 AM »
Good luck !
Peter
65 Moke
60 Bugeye modified
66 Jaguar XK13 ( I can wish )

Offline John Gervais

Re: Sprite Race Engine Rebuild
« Reply #48 on: June 21, 2021, 08:15:38 PM »
Very interesting thread! 

Thanks Dave!
- Pave the Bay -

Offline MiniDave

Re: Sprite Race Engine Rebuild
« Reply #49 on: June 22, 2021, 11:35:50 AM »
So, he's done two race weekends with the motor I built him and so far it's done really well....no issues and makes really good power. He's run as high as 4th (out of 42 entries) and that's with a car that is a long ways from being sorted like the front runners.

This weekend he had a few issues with the car itself, he's been unhappy all along with the exhaust as it exits right where he sits on the driver's side of the car so it's noisy, plus it drags on almost every right turn as the car is so low - and this weekend all but one of the turns was a right - sure enough he spun in someone else's oil and tore the pipe off and damaged his header. So, a new exhaust is on the books now.

He also broke an axle - the bane of all Sprite racers - but thanks to the generosity of the other competitors he was able to get all the parts he needed to get back into action. New axle, new double lipped hub seal, new gasket and o-ring and he was back on track - till he tore off the exhaust.

I'm encouraged that the engine is running so well, I don't think he'll be on track again till September, that will give him time enough to fix the exhaust and install the new trick front adjustable control arms Clancy sold him so he can add a little negative camber to his front tires.

I've been contracted to build two more race motors now - one for Clancy and one for a new fellow out of Wichita.

« Last Edit: June 22, 2021, 12:29:08 PM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad