2.1L B20 build for Paul

jamesinc

@paul0075 has not been able to drive THE JAFFA for the past year or so due to a worn-out engine. Paul's a good friend, and I really like the Jaffa and I don't want to see it languishing, so I agreed to build a new B20 for it.

For the past year and five days, I have had a B20 sitting in pieces in storage bins in my garage, waiting for its turn, and at last the day has arrived.

Objectives

Rebuild head and block - replace freeze plugs, gaskets, seals, all bearings
Overbore to 92mm for B21 flat-top pistons
O/S 37mm exhaust valves
Hardened exhaust valve seats
Clean up ports in head (not an extensive port, just smoothing out the cast surfaces and seams)
K-grind camshaft
Twin-carb setup
Upgrade to modern rear main seal design

Replacement B20

The replacement motor is a bit of a mix. The bores are very worn, and are already a second overbore with Mahle 89.65mm pistons. The big end journals are out-of-spec. The crank main journals are actually good, they are just in spec for diameter and in-spec for roundness, but the #1 bearing has surface damage from moisture sitting under it, so we may ultimately have to grind the crank undersize, but hopefully we will get away with just polishing it.

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Crank pitting from moisture sitting in the oil gallery inside the bearing shells:

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Measurements

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I have most of the parts required for the rebuild. I still need to check the small end bearings on the rods, and I'll get 1st o/s big end bearing shells.

I checked the front and rear cam bearings, I don't have a bore gauge that can get deep enough into the block to measure the centre bearing, but we are replacing these bearings anyway so this is mostly for my own edification. The cam front bearing measured 46.92mm and the rear 36.66mm

The replacement B20 also came with a crate of spare parts, the next step for me is to finish going through them all to work out what other parts will be needed to complete the build and acquire them. Then the block will go to the machine shop, and I'll get the head ready for machining.

Stay tuned!

jamesinc

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Have also now finished tearing down the block, for freeze plugs there are many ways to remove them, I drill a hole off-centre than use an open ended spanner to lever them out. Just be careful not to crash into the bore when the drill goes through, a stepped bit is good for this

Ex850R

This looks like fun!

Can the crank pitting on the bearing surface be metal sprayed?

Roinik

Is that pitting on the running surface or within the oil groove of the bearing? It may not need any treatment at all, aside from cleaning.

Also, remember to leave the floor of the exhaust port alone. Focus on the roof and sides.

jamesinc

Roinik it's just in the groove, and yes that is my hope also. I'm sure my machinist will tut tut about it though. @Ex850R spray welding I'm sure would work but wouldn't be cost-effective as it would incur all the costs of undersizing the journals plus the cost of spray welding.

paul0075

Firstly I would like to thank James for doing this. It's something well beyond my capabilities, either due to lack of knowledge, somewhere to do it at my apartment complex, my physical ability (still recovering from significant back injury from January) and mentally (a lot of my plate, and awaiting ADHD work for meds).

Secondly I am really excited by all of this and hopefully will be able to cruise the mean streets of Canberra in the Jaffa again. And grateful to have a mate like James willing to do the work. Without his support I probably would've just up and sold the car and moved on disappointed.

Thirdly I have first hand experience of James' engine work and I can safely say it is better than most engine rebuild shops. His attention to detail is outstanding and his ability to think outside the box when needed is impressive.

The Jaffa turns 50 this year. Even though it's now too late to get it over the line in time for its approximate build date (mid-June going by stamps on several parts), it would be awesome to see it at a show and shine again sometime before the end of the year or early next year.

jamesinc

Bottom end is back from the machine shop, it's had everything done. I've wrapped it up in WD40 for a few days while I wait for the paint (@Major Ledfoot it is Volvo Penta Red OEM aerosol). I won't mess around, I want to get the engine buttoned up without delay. I will run it through with bottle brushes and compressed air, seat the freeze plugs, and paint the block. I've also got the sump, I had that hot dipped same as the block, need to wire wheel off a few bits of rust but I'll paint that at the same time as I do the block.

Once that's done, I'll install the rotating assembly, oil pump, cam and button the sump up.

As usual, stay tuned for more updates!

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242GT

There was a place in Hornsby I used to buy my B20 2.1ltr head gaskets from

jamesinc

Freeze plugs installed with Permatex 80008:

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We went with OEM red

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An hour of masking, a bunch of prepwash and tack rags and the block is looking pretty röd!

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I still need to install the rear cam plug and paint inside the bellhousing area, for that I have to take the motor off the stand, I don't have any time until Sunday afternoon so that will give this paint a few days to setup fully before I start handling the block again.

242GT

Looking nice james

Major Ledfoot

^ Nice job. It's interesting how the Penta Red looks somewhat orange to my Beholding Eye, and rather more orange than the B230 engine in the background of the pics.

Not a bad thing, really, considering the engine's future home.....

What's your plan for the initial start-up and the breaking in of the cam and lifters? Doing this properly is critical to the longevity to the valvetrain and cam of a solid lifter engine, and these setups are not common configurations any more. I'm pretty sure I stuffed up this process 35 years ago.

paul0075

Major Ledfoot I had the same issue with orange paint for the bodywork of the Jaffa, it took a few days before the colour looked close or right.

jamesinc

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The B230 is VHT Engine Enamel in Bright Red

The B20's colour looks awesome in real life.

VolDan

The Penta colour looks 'right' on the B20 jamesinc well done!

jamesinc

I've now installed the cam plug and painted inside the bellhousing.

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I also painted this, which I think is the oil separator?

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I dropped it in a tin of paint thinner for a few days which took care of all the crud inside it and hit it with a wire wheel to remove the last bits of paint and some surface rust.

gavinh

looks awesome, and following with interest. Maybe once it's finished and run in @paul0075 you might be able to drive it over to Perth?

paul0075

gavinh That's the plan. Because the car's been sitting for 18 months, it's going to need to have the brakes sorted out, and I also need to order the new radiator from Sweden (now there's someone making 1972 onwards radiators again), and I also need a new exhaust and the steering box serviced. Not sure what to do about the diff, I am not intending to change it over once the auto is swapped for manual, but I guess it will need to be serviced in some form.

gavinh

paul0075 if you come over here I have a complete car with all the parts on it that's been rearended, bought it for spare for my 145.

jamesinc

Do you have reason to suspect there is an issue with the diff? Otherwise just change the oil and carry on!

paul0075

jamesinc No but I don't think it's seen a service for quite some time. I know that I do get a bit of a yawning sound occasionally when the car changes gear, but I also had that on my 75 244.