Sprite Race Motor for Clancy

Started by MiniDave, June 22, 2021, 11:02:13 AM

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MiniDave

Clancy brought me a Sprite race motor to rebuild, maybe refresh is a better word. The engine originally came from MiniMania and I doubt it has all that many hours of run time on it. The motor is to be used in a race car, but I'm not sure exactly which car or even series or class it will run in.

The cylinder head seems to be the biggest issue right now, as we found cracks in three of the valve seats.

I took the head down to the cylinder head shop to see if it was savable and he thinks it may be....the cracks are not into the water jacket so it may be possible to just put in new seats and save it.

The valve sizes on this head are as big as they can fit, so they were surprised it didn't make more power on the dyno. It ran one race weekend and the driver wanted more motor, so he gave it back to Clancy and is getting one from another source.

In the first pic you can see where they marked where the cracks are.....after I took a wire brush to the area I could not see the cracks, even with a magnifying glass so when I took it to the cylinder head shop first thing we did was magnaflux it. Sure enough the cracks showed up clear as day.

The trickiest one will be the one between the valves, as you can see the seats are almost touching each other, when he installs one seat the edge will overlap the other and have to be machined back to allow the other seat to go in too.
Like I said, tricky....... but maybe do-able.

As for the rest, we're going with new rings and bearings, probably a new timing chain.....same cam, same lifters but the head had 1.5 roller rockers and Clancy wants to go back to good springs and 1.3 rockers.

The pistons appear to be dished 10.3-1 compression, so not the super high compression flat tops like I used in the other motor. I'm trying to work out a deal with Kent where once it's built we take it up to his shop and start it on his dyno and tune it there. I don't know right now what carbs Clancy has slated for it, or what exhaust and ignition - plenty to work out yet......

I think if he can get around 125-130 HP at the crank, that will be a good reliable motor for a student or occasional racer.

The reason it's so rusty in the combustion chambers is that it supposedly blew the head gasket and then sat a good long time before it came back to Clancy. They also tore it down and I had to wait for the valves, springs etc to come back too. However, when I pulled the head off the gasket did not appear blown to me, so I hope we don't spend time and money on this head only to find out it's a boat anchor.

I found the markings in the last pic, 37 and 30 are the intake and exhaust valve sizes, I'm guessing 10.13 is when it was built?
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

The cylinder head came back today and they were able to save it - I'm surprised but pleased. If you look at the before pics and compare to these pics you can see what they had to do to make it work.

Really impressed with the quality of their work - cost - $200 including magnaflux, seats, 3 angle valve job and skim.

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

TDA

Did you use Noland's Cylinder Head Service down on Charlotte?

Are those "Rim Flow" intake and exhaust valves?


MiniDave

Yes and Yes!

Nolands has done all my head work for probably 50 years or more. They do a great job and they have the absolute latest equipment now.

Note the precision of the angle cuts on the seats.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#4
I mounted this engine into my engine stand since my hydraulic table is occupied by the 998 automatic for now, and pulled the oil pan off - it's clear this engine has had a blown head gasket, but it didn't run for long that way - the oil was starting to be a milkshake but not badly infused with water yet. The green in the bottom pic to the right of the distributor drive gear is the underside of the #3 piston - full of this oil/water milkshake.

That's as far as I've gotten with it, today I'll pull the pistons and rods out and get bearings and thrust washers ordered, along with a new chain and oil pump. The pistons to me look like 10.3-1 Nurals, compared to the flat top pistons we put in the other Sprite race motor I did. We're not going to change them at this point.

I also haven't cc'd the combustion chambers so I can get a compression ratio figured out.

Other than that this is just a quick refresh, when the head comes back to me I'll put it all together and put it in the engine test bed and fire it up.

In the last pic, there is what looks like a piece of plastic pipe - not sure what that is but I think it was in the pan and fell in there when I rolled the engine over in the stand.

Edit: it's the bottom half of the dipstick tube, broken off.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

OK so after discussing it at length, a plan is coming together.....

I'm going to take the block over to the machine shop for a very light hone just to clean things up, they'll also check the block to be sure it's flat, if not they'll skim it just enough to clean it up.

New rings, bearings and thrust washers, new timing chain (this one looks fine to me but OK) new oil pump (same) and I'll put it all back together.

The head is already done so it's just a matter of assembly there. Once it's all together I'll start it up in my engine stand and run it for a while, make sure things don't leak and that it doesn't overheat or put water into the oil. I'll use my carb, distributor, exhaust and oil filter like I did with the last Sprite race motor I built but I'm hoping that we can take it up to Kent's and run it on his engine dyno and see what it really makes.

These pistons look pretty low compression for race pistons but he's not really interested in replacing them at this point. I'll cc the combustion chambers and see if I can figure out the compression ratio so we'll have that bit of info to help with the sale. The bearings and all were in great shape, I think what ultimately happened is it blew the head gasket.

This crank gear is interesting, first one I've ever seen like this. I don't know but it looks like the grooves are such that you can set the cam timing with it, otherwise why have all these different grooves for the key? so I marked it to make sure I put it back exactly where it came from. The cam and lifters were good too. I bought some V blocks and I'm going to see if I can learn the lift and duration on this cam, just for the experience.

The rods appear to have been shot peened and are really nicely done, the crank and all have been balanced too.

The first pic is why I'm having it honed, that's just a stain from water sitting in the cylinder, but I want to clean it up plus we need a good cross hatch pattern if we want the new rings to seat in.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#6
Following up on this post, after running it in on the engine stand Clancy and his partner on this build, Skip came down from Lawrence to see it run. After we ran it on the stand there were smiles all around. We pulled the motor out of the stand and they loaded it into the truck.

Later I found out the motor has been sold to another Bugeye racer (a rank beginner) to replace his very tired, leaky 1098. I expect to see it run in about two weeks at Eagles Canyon. Haven't decided if I'm going yet, but it would be nice to see some of these cars I've worked or running the track. It's always good to make the connections too. Both this owner and a guy I built a transmission for want me to build really hot race motors for them, with all the good stuff like forged billet cranks, custom rods and pistons and completely modified and flowed heads.

We'll see if that happens but if so it will have to be next spring as I still have a LOT to get done this fall first.



Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

This motor is now in this blue Bugeye.....

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

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