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 Post subject: 68mm 1098 Engine Build
PostPosted: Wed Jan 05, 2022 1:05 pm 
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With the TwinCam engine build all but done only needing power runs on a dyno, I've been looking for the next project to donate my hard earned to. I recently sold a Morris Mini K sedan and I did so to fund the purchase of a similar, but more functional car for my lifestyle with my better half and pup. This 1969 Morris van fit that bill pretty well, and having just completed a pretty involved exotic A series engine build, I was keen to get back to the basics of the A series motor without the complexities of a twin cam conversion. While this thread will be more about the engine build for the van, the van itself is relatively solid only with a few spots of rust and some cool accessories including some Australian made roof racks that I've never seen before. This'll be a full up resto - not quite to show standard but will be pretty cool once it's done! The car is currently stored elsewhere and I'd like to get it to my garage about 3/4 of the way through 2022. The goal is to get the engine build all done for it before then!

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I plan on using the 998 block that came out of my clubman, fitting a1098 crank, boring to 68mm to suit some 68mm GR Flat top pistons to bring total capacity to ~1220cc, GR 266SS Camshaft, 12G295 head, single 1.5" SU Carb on a minisport manifold with some maniflow 3-1 extractors I have lying around. My goal for this is for it to be relatively cheap in comparison to the twincam build and torquey from low in the rev range. The van engine won't have it's nuts revved off on the track or through the hills - that's what the clubman is for. Ideally, I'd like to drive this most days once it's done. Here it is as it stands;

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The block cleaned up really well at home after being in a CLR bath for 2 weeks followed by high pressure hose/wire wheel and repeat.

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The 12G295 head is standard, all I have done so far is clean up the combustion chambers which now measure 29cc. After reading GR's blog of knowledge and chatting with him, I plan on leaving the ports of the head alone as they're probably a bit too big if the goal was to optimise low down torque. A worked 202 head would probably be better for this but I've already got this head so I'll just stick with it. I plan on fitting slightly bigger valves with an inlet of 1.26" and exhaust of 1.06" (i think that's the next step up anyway - any gurus please step in). Other than plugging and re-drilling some water holes to accommodate the 68mm bore, I don't plan on doing anything else to the head.

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The crank will stay as is - no wedging or anything like that. It has been crack tested and ground to .010/.010"

As for compression ratio, 11:1 to 11.5:1 is the aim. Ignition system will likely be a 123 Distributor which I plan on running all curves on a dyno as a bit of R&D which can be recorded here for all to use and learn from. As for rockers, I am not quite sure what is best here. I currently just have the pressed steel type, although would consider (and most likely will) fit the 1.5" forged or roller type. Are there any benefits over the 1.5" forged vs 1.5" roller type rockers?

Next up for this build will be to get the head crack tested, the block bored and the necessary water holes plugged and re-drilled along with new cam bearings fitted.

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PostPosted: Wed Jan 05, 2022 2:39 pm 
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Good to see you’re keeping busy Joe!

In regards to forged vs rollers - I’ve seen a lot more broken roller arms than forged. I kept the standard rockers on mine, but I think the 1.4 or 1.5 forged would have been my choice if I had a bigger budget

I’m not sure on the limit of the 1.5” SU, but seeing as you’re going a bit higher spec than mine, you might want to think about a single 1.75”

Any ideas on what you’ll do for the gearbox?

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PostPosted: Sun Jan 09, 2022 2:13 pm 
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timmy201 wrote:
Good to see you’re keeping busy Joe!

In regards to forged vs rollers - I’ve seen a lot more broken roller arms than forged. I kept the standard rockers on mine, but I think the 1.4 or 1.5 forged would have been my choice if I had a bigger budget

I’m not sure on the limit of the 1.5” SU, but seeing as you’re going a bit higher spec than mine, you might want to think about a single 1.75”

Any ideas on what you’ll do for the gearbox?


Thanks for the gouge re rockers, timmy. I reckon in that case I'll go with some 1.5 forged rockers! As for the 1.5" v 1.75" SU, so far I've done the mods to the carb that Vizard talks about in his book but I'll definitely keep a look out for a good 1.75" carby one day I think. Keen to see how far the 1.5 will get me

The gearbox is a 4 sync rod change. Has been stored outside for the last few years by the looks of it and the main bearing was completely seized. I've pulled it apart and given it a good clean. A refurb kit through this at a later date and it'll be pretty good as all the synchros look to be in pretty good nic (before/after cleaning photos below). The diff.... hmmm... still thinking about this. It currently has a 3.44 in it which I also have in my clubman. Doing 100km/h at ~4150rpm isn't too bad but stretching up to 110 is pretty loud - but then again it's a very different motor.

I would consider dropping to a 3.1 diff for this van engine, but I think i'll see how I like the 3.44 first. I plan on doing a lot more to sound proof the van than I did with my clubby and seeing as though the van engine wont be as powerful, maybe changing to a 3.1 diff isn't the smartest choice... interested to hear anyones thoughts.

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PostPosted: Sun Jan 09, 2022 4:32 pm 
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Watching with interest as I've just built similar spec, except +80 pistons. Kept rockers standard as budget didn't stretch. And have used 3.44 - there was a 4.2 in this gb originally which wouldn't have been fun over 80.

I'm actually envious of your nice clean space. I have my grinder on the other bench and didn't want to build anything near it so set up a 2nd bench that was about 1m sq...enough room to roll the engine over. Im thinking I need to invest in some ply like you cause I'll never get the bench clean, and move the grinder to a smaller bench.

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PostPosted: Sun Jan 09, 2022 5:13 pm 
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Andosoft wrote:
Watching with interest as I've just built similar spec, except +80 pistons. Kept rockers standard as budget didn't stretch. And have used 3.44 - there was a 4.2 in this gb originally which wouldn't have been fun over 80.

I'm actually envious of your nice clean space. I have my grinder on the other bench and didn't want to build anything near it so set up a 2nd bench that was about 1m sq...enough room to roll the engine over. Im thinking I need to invest in some ply like you cause I'll never get the bench clean, and move the grinder to a smaller bench.


Nice work Ando. How does it go? any specs or things you'd do differently if you had your time again?

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PostPosted: Sun Jan 09, 2022 5:51 pm 
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Literally just built, about to give it a lick of paint and can drop it in. Should be able to tell you in a bit

Have gone with dellorto rather than su. Gotta love the Italian induction sound, realistically won't make much difference, su probably more drivable.

I would have liked to do some work on the crank (wedge etc), maybe lighter rods. Did go with a ultra light flywheel though. Also had an almost new 3 synchro with QL uni joint - would have liked 4 synch + pot - but it will probably do for starters, at least until the wife strips first gear

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PostPosted: Mon Jan 10, 2022 10:26 am 
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I think mine would have been just as good with a 3.1 instead of the 3.44. First gear in mine feels really short and you don’t really need it apart from a complete stop. The rpm range is also a bit shorter than other engines (2000-6000rpm) so having some slightly longer gearing would help stretch them out a bit.

I’ll also agree with the plywood work bench top, in a couple of years when it gets messed up you just replace the top layer. Mine was always a bit covered with stuff though!

I’ve heard mixed reviews on “Vizard spec” carbs for road cars. You’ll definitely get an increase in flow from the mods, but I’ve also heard they can make the part throttle a bit compromised. I’ll be keen to hear how yours goes.

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PostPosted: Mon Jan 10, 2022 11:28 am 
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I built my 1098 originally and didn’t fit new baulk rings, it crunched from Third down to second gear, engine had to be removed and new synchros fitted. And a 3.1 diff while I was there. It’s a good all round ratio.

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PostPosted: Thu Jan 13, 2022 9:39 pm 
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Andosoft wrote:
Literally just built, about to give it a lick of paint and can drop it in. Should be able to tell you in a bit

Have gone with dellorto rather than su. Gotta love the Italian induction sound, realistically won't make much difference, su probably more drivable.

I would have liked to do some work on the crank (wedge etc), maybe lighter rods. Did go with a ultra light flywheel though. Also had an almost new 3 synchro with QL uni joint - would have liked 4 synch + pot - but it will probably do for starters, at least until the wife strips first gear


I hope you've set it up to use a 1275 head gasket.. you'll have trouble otherwise because the fire rings on the small bore gaskets hang over the top of the bores when you go big with them

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PostPosted: Fri Jan 14, 2022 7:54 am 
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Some gaskets are rated to +100 over. I fitted a standard gasket to mine and it did overlap a bit between 1&2 and 3&4.
http://www.minispares.com/product/Class ... EA647.aspx

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PostPosted: Fri Jan 14, 2022 10:58 am 
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I used a standard gasket, i'm sure i could see the bore ring but it was right on the edge. CR is 10.8, Looks like i should be ordering one of the black fiber ones to have ready in case.

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PostPosted: Fri Jan 14, 2022 1:10 pm 
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I’ve got a Victor Reinz gasket spare for my engine now, they are supposed to be the best quality ones for small bores, but I’ve yet to see how it looks on my block with the 080 bore.

I should probably look up what’s required for the 1275 gasket as I might end up having to do that one day

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PostPosted: Fri Jan 14, 2022 4:52 pm 
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HI all
With .100 thou and 68mm over size i always put a little 45 deg chamfer around the top of the piston.
This saves the over hanging fire ring from getting flattened by the piston and blowing a head gasket.
Graham Russell

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