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Early 948cc Engine Restore

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BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Thanks, Bob. I actually for Mini/Spridget Mania - we've got most of the parts I need right on the shelf spinning smiley sticking its tongue out.

In reply to # 208423 by minimarc Source for engine plates and VIN plates:

http://www.retrominisltd.co.uk/index.php?main_page=index&cPath=31&sort=20a&page=2

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AN5L Ken G
Oklahoma City, OK, USA   USA
If you want it to look like an original 948 while adding a few upgrades there are a number of tricks you can use.

1) Ribcase internals can be put in the smooth case transmission housing.
2) A dynalite alternator can be used, giving the output of a modern alternator in a casing that looks like the original Lucas generator.
3) Cooper style air cleaners can be purchased for the HS2 carbs to make them look similar to the original H1’s.
4) Brass caps for the HS2 carbs can be purchased from SU to replace the black plastic caps.
5) A “tar topper” can be purchased to make a modern battery look like an original tar topped wet cell lead acid battery.
6) An upgraded wiring harness can be ordered with traditional style woven covering.
7) Use later timing chain cover with modern type oil seal, rather than felt oil seal. Paint to match original timing chain cover.

Lots more tricks, but one of the most convincing is to paint the engine as would have been painted at the factory. Painting details are available in AH concours guidelines.

Another trick to help mimic originality is to use original style electrical connectors and original style hose clamps.

BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Hi Ken,

Yes, Heathrow Transmissions do a smooth case with later internals that has me intrigued. It's something we're going to have to experiment with here at some point as it's an option I'd like to offer in the future for those wanting an original look.

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BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
We put the block and some other components through the "dishwasher" which is a new addition to the shop. Makes life a lot easier - and parts much cleaner for inspection and prior to bead blasting (if necessary).

We're going to go with 998cc .020 over pistons for this build. The 998 pistons have the same pin height and 3.0" stroke as the 948's are a .0645" larger bore in standard size. So, effectively, this engine will be a total of .0845" over standard. That will give us just over a 1 liter engine that will still look completely stock.


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grey1 Avatar
grey1 Mike H
Delta, BC, Canada   CAN
Hey Brendan, Really appreciate you posting this detail here. I am sure there are others who have done all of this in the past, but I am new to my project, and the photos of your steps are very helpful. Sure wish I had a dishwasher like that! Good luck with the project. Mike

BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Thanks, Mike.

Yeah, since this isn't a common rebuild for us I thought I'd share diary of this one. We have engine and gearbox builds going on every day but most are 1275cc and for Minis. I'm excited to see the results of the 998 pistons as they're more readily available than most older style 948 types. If everything works out well it'll be another option for breathing life into these smaller power units.

AN5L Ken G
Oklahoma City, OK, USA   USA
Hi,

Of course the biggest reason/advantage to changing the internals on the smoothcase gear box is the change from the cone type syncro’s to the baulkring type syncro’s, due to serviceability of the later.

A fortunate byproduct of the change is the 1st gear ratio goes from 3.68 to 3.2, which was the close ratio gearing for the 58-60 competition cars.

Input shaft (first motion shaft) is different length, and spline length through the clutch is slightly different, both of which can be dealt with. Later input shaft is slightly longer, and was used with thicker engine backplate.

Different front cover, with modern seal arrangement, is available for the smooth case, but be sure to sort clutch arrangement first, as front cover clutch pivot point changed for clutch types.

Dimadee Tim Lennon
Melbourne, Victoria, Australia   AUS
In reply to # 208398 by AN5L8016 Mike- I turned an aluminum flywheel for my last 948- complete with a steel insert it weighed in a 11 Lbs- WAYY TOO LIGHT for a road car. The flywheel that I just redrilled for my Datsun Clutch is turned to the Stage 1 specs and it came in at 23-25 Lbs IIRC, about 5 lbs lighter than original. Here are the dimensions if you don't have the Special Tuning spec for it. I think I've posted them previously as well..

This is a great thread.

FWIW, I went a little more conservative with my flywheel. I changed the dimensions (see attached, dims. in mm) to leave a little more material on the flywheel (i really like my feet).

Call me a chicken. :-)



Yours Spritely

Tim


Check out my Bugeye blog here: https://59bugeyesprite.wordpress.com/



Edited 1 time(s). Last edit at 2019-01-19 04:25 PM by Dimadee.


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Dimadee Tim Lennon
Melbourne, Victoria, Australia   AUS
Not wanting to hijack the thread, but can anyone tell me why they painted the internal surfaces of the engine from the factory?

The head I have just reworked had a lovely green paint all over the internal surfaces.



Yours Spritely

Tim


Check out my Bugeye blog here: https://59bugeyesprite.wordpress.com/

AN5L Ken G
Oklahoma City, OK, USA   USA
Hi Brendan,

The 998 +.020” will allow you to use an Omega or RE forged piston, as neither are making a 998 std. piston, but offer the +.020”. The 998 stds are available in cast. Putting the 998 std cast flat-top pistons on 1098 rods will bring you close to zero deck height with a virgin block.

BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Hi Ken,

Yes, we’re aware of the differences, in fact, I’ve got a video on youtube explaining the differences in the gearboxes. One additional difference is the length of the selecting rods. Like the input shaft, they’re also longer in the ribcase with selecting detents in different spots.

At some point during a slow period in the shop, we’re going to experiment with fitting a 22G1100 synchromesh gear set to a smoothcase.



In reply to # 208486 by AN5L Hi,

Of course the biggest reason/advantage to changing the internals on the smoothcase gear box is the change from the cone type syncro’s to the baulkring type syncro’s, due to serviceability of the later.

A fortunate byproduct of the change is the 1st gear ratio goes from 3.68 to 3.2, which was the close ratio gearing for the 58-60 competition cars.

Input shaft (first motion shaft) is different length, and spline length through the clutch is slightly different, both of which can be dealt with. Later input shaft is slightly longer, and was used with thicker engine backplate.

Different front cover, with modern seal arrangement, is available for the smooth case, but be sure to sort clutch arrangement first, as front cover clutch pivot point changed for clutch types.

BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
We considered the flat tops for higher compression but opted for a set of dished pistons instead. We also didn’t consider making it a stroker with the 1098 rods as this is a more mild build. The customer isn’t going for pinnacle performance but an engine that’s upgraded but not all-out hot rodded.

In reply to # 208493 by AN5L Hi Brendan,

The 998 +.020” will allow you to use an Omega or RE forged piston, as neither are making a 998 std. piston, but offer the +.020”. The 998 stds are available in cast. Putting the 998 std cast flat-top pistons on 1098 rods will bring you close to zero deck height with a virgin block.

AN5L Ken G
Oklahoma City, OK, USA   USA
Hi Brendan,

Let me know when you’re getting ready to do the smoothcase project, I’d like to “watch”, whether in person or via pictures. I’ve got a couple of the converted smoothcase gearboxes that Gerard built for me and I’am working on getting a SCCR gearset to put in a third smoothcase. For FIA Appendix K with the Bugeye/Frogeye use of the smoothcase housing is required. We’ve just gotten another of the FIA period E GTS3 engines about ready to bolt to the gearbox and put into an early frog. This one is patterned after the BMC works rally car XOH 276.

BlueMax1 Avatar
BlueMax1 A G
?, ?, USA   USA
Removed pressed in oil galley plugs front and rear of engine block?

BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Yes, our machine shop does this as a matter of course. They tap the channel ends and locktite in threaded plugs.

In reply to # 208503 by BlueMax1 Removed pressed in oil galley plugs front and rear of engine block?

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