B18A Engine Block queries

[sleek lemur]

Thanks 142 and Kay,

If the engine had been apart before, it must have been a long time ago. There's quite a rim on the cylinders and everything else is in a real state (I paid £50 for it as a fun winter project). It did turn smoothly. It would be good to understand how the damage occurred before spending money!

Following your comments, I will do battle with the plugs again, tomorrow. The holes in the B18A ones are definitely square!

Oh, and yes, I will be changing the bearings!

[Derek UK]

It sounds as if there is a rebore and new pistons on the cards. Things will start to get very spendy if you go that route with what appears to be just an exercise in engine building. There is a cutter called a ridge reamer but that isn't much use if the bores are worn to a rebore stage. Remotely, someone might have a usable set of, say, +40 pistons that can be matched up to a rebore. Machine shop would have to measure those pistons and approve them for use before committing to a rebore to suit.

[sleek lemur]

Thanks Derek, I do plan to do a full rebuild and am aware of the costs of I want to do it properly.

So, I definitely want to rebuild the engine to as high a quality as I can. The next step hasn't been decided. Maybe sell it afterwards, or fina a pair of SUs to rebuild. Or maybe, if I can find some space, find a complete car to rebuild.

Early days yet, I haven't even got it fully cleaned yet!

Really appreciate you taking the time to advise. This forum is superb.

[142 Guy]

Covid 19 has left a lot of people with time on their hands and cash for things such as travel and entertainment which is now parked. Rebuilding a B18 seems like an entertaining way to spend some time. Compares quite favorably to baking sourdough bread, taking up knitting or binge watching NetFlix.

If you want to go high quality, consider changing to valves (and guides) with the later B20 stem diameter which will accept modern valve stem seals as opposed to the umbrella 'things' on the B18. A little more complicated; but, we all seem to have some unplanned free time. Once you start down that path it opens up a complete field of 'improvements'.

[sleek lemur]

yes, 142. V wise. Half the umbrellas were missing on my engot, so will certainly go for the later setup. Will go for 10.1 compression ratio and K cam or similar. Timing gears, flywheel, hmm... Try for something really nice and useable.

[Derek UK]

142's comment about the valves is noted but remember that the B18 and B20 valve arrangements are different. Firstly, when the valves and guides are good the rubber caps work fine. The B18 has a long valve guide. The B20 has a short guide. It is possible to get B18 guides that are grooved to take the B20 type of seal. Best if these are bronze rather than steel. But, the long guide benefits from a little oil leakage to keep the valve stem lubricated. The b20 guide being shorter may get away with less lube but as it wears there is more side to side movement of the valve head. That causes the seat match is then poor. The B20 combustion chamber is a little wider and does allow bigger valves. The B18 valves have seats that are very close together so fitting lead free seats (plan to do that) has to be done carefully. Exhaust only needed. If you try and fit them to the inlets as well they have to be trimmed to fit alongside each other. Best not to go there. Not easy to increase the size of the inlet valve either for the same reason but they can be reshaped quite a bit behind the valve head to increase the flow.

[blueosprey90]

Perhaps you've seen this.

http://volvo1800pictures.com/sweden/...6_5emqDbNoR6z0

[sleek lemur]

Thanks vm, BlueOsprey. Yes, that's a fantastic site, isn't it?

I wonder though, is the 10.5 CR still advisable with unleaded fuel?

The document reminds me, can anyone help with the specification for skimming the head? Slightly complicated, as I reckon the top of the block will benefit from tidying up.

[sleek lemur]

https://www.volvoforums.org.uk/showt...ight=Skim+head

This is good!

[Derek UK]

The Volvo booklet is interesting but is now more of a historical document. Its advice is based on factory parts available at the time, nearly 50 years ago. 100 octane available everywhere. Things have moved on. Even with the best pump fuels, Esso have just announced one which I read is ethanol free currently although that doesn't appear on the pump info, 10.5:1 IMO is a bit too high. 10:1 likely better. Blue printing an engine is an expensive operation. e.g. matching piston heights and facing off the block to get maximum usable squish. Headwork is limited by badly flowing exhaust ports that can't be remedied by just grinding. You have to build up the port floor and start over. Expensive.
Some good reading here. http://www.vclassics.com/archive/index.html
Note the how not to build an engine article. Also on the same useful site
http://www.vclassics.com/mppe1.html
Even these articles have some age to them now. Check out the whole of the site.
http://www.vclassics.com/contents.htm
Getting all of the moving parts matched and balanced probably the best value especially you get the flywheel/clutch done along with the crank. Again IMO. Standard factory balance is good but can be bettered.