2.1L B20 build for Paul

jamesinc · 2024-04-20T02:02:14+00:00

@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'...

Vee_Que

So, what's the combustion chamber size now? Would be a shame if it is under 10.1:1 c.r

jamesinc

Good question - I will CC later this week and math it out

jamesinc

I figured out a setup that I am able to get accurate and repeatable readings from. I'm measuring the mass of 100% isopropyl alcohol (0.786g/mL) transferred to the chamber, weighing the syringe along with it to minimise error. As long as I don't spill any, it works well.

I'm using plexiglass and Vaseline to make the seal.

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I know it is an unconventional setup. I am essentially measuring the mass of 100% isopropyl alcohol injected into the chamber, which has a density coefficient of 0.786.

I can't do the test yet as I need to swap the junk 240 plugs out for correct 140 plugs (shorter thread), stand by.

jamesinc

With the correct plugs installed, I calculated the CR at 9.98:1 with our current .045" head gasket choice, or we could go to 10.47:1 if I switch to a .027" gasket.

The chambers average 51.62cc

However, I think it is actually cheaper to just have the shop skim the surface a bit more.

I measured the area of the chamber (using rulers and Photoshop) and mathed it out that about 12 thou needs to come off to get to 49.62cc and a 10.3:1 CR.

I called my machinist and he said it's usually about 5 thou per CC, so looks like my measurements are pretty good.

242GT

When I modified ghe heads on my B20 motors , Hawker De Haviland had a large snow grinder and also a very nice surface grinder that they generously allowed me to use on my race car engine parts , must get around to thank I no them one day , they even donated the alloy and lathes so I could machine a new thermostat housing out of 7000 grade aluminium.
Great read watching your work James.
Are you going to put a remote oil filter holder on ghe inner mud guard & an oil cooler for our Australian summers

jamesinc

242GT nah I'm just building the engine, it's @paul0075's 144 that it's going in.

242GT

What year model Image description

People do silly things with 144's 😁

Major Ledfoot

242GT People do silly things with 144's 😁

Indeed. 🙂
I did many silly things with my black one... and the silliest was selling it.

jamesinc

242GT What year model

It's a '74 model, it has a thread on the forums here: https://ozvolvo.org/d/7029-the-jaffa-1974-144dl

paul0075

Major Ledfoot yep, wish I kept my 145 🙁

jamesinc

Okay so messed around with the head a bit more and got to 10.1:1 CR with the 0.045" gasket, which I think will work well for the intended application.

I greased up the lifters with molybdenum grease and installed them

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I put the head on with new bolts and greased threads and torqued it down to 29ft lbs.

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This is where it sits now, I haven't put the rocker assembly in or done the final torque, I think I am going to slacken the bolts off and spend a bit more time getting the head perfectly centred over the block.

paul0075

jamesinc Looks amazing! Can't wait to drive it!

Major Ledfoot

jamesinc I'll be most interested to read up about your First Start Procedure - from what I've read, solid lifter engines require a 'break in' period for their first start so the lifters don't eat the cam lobes, and I'd like to know how to do it properly.

242GT

Where are you getting the head gaskets from , years ago there was a bloke in Hornsby made custom B20 head gaskets when they converted to 2.1ltr

jamesinc

@242GT this one (and most of the new parts for this build) came from VP Autoparts

(92mm bore) https://vp-autoparts.com/en/artiklar/cylinder-head-gasket-b20-92-mm-cometic.html

jamesinc

I was thinking about how to do it, I'd like to just break it in on the stand, but it depends on whether I can rig up some kind of muffler as my neighbours will probably murder me if I run an engine at 2000rpm for 20 minutes with no exhaust!

I am also interested whether anyone has specific oils they recommend for break-in (or just generally for a freshly built B20)

VolvoHordz

jamesinc Penrite do a specific "running in" oil. Stocked at Repco amongst other places.

I can't really speak for how good/bad it is. That said, I did a bit over 1000km on it in my 242 before changing it for a regular oil. Cut open the oil filter and didn't see anything worrying.

242GT

I've heard various start up procedures , I used 80/90 gear oil on the solid lifters and cam lobes on first engine turn over but had the coil lead disconnected , just to get contact surfaces comfortable for a better way of putting it , this also got the oil pump primed and pumping before combustion load was applied .
Loctite bearing lubricants were used on crank , rod , cam and gudgeon pin surfaces.
Initial fire up was a lighter than usual engine oil to wash away any fine particles to filter and sump.
After run in , new filter and 20/50 qaulity oil.

jamesinc

Back from Nats and rather than unpacking the Natsmobile I decided to use my day off to start rebuilding the carbs. Carb #1 has been dis/assembled and gone through the ultrasonic bath (thanks to @dano for lending me said cleaner). I can't put the throttle spindle back in yet as the rebuild kits did not contain shaft seals for it, but otherwise that's one carb down, one to go!

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The needle had a bit of scoring on it so time for a new one.

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dano

jamesinc Shiny! What did you use as the cleaning solution?

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