Question about engine types

[arcturus]

I don't think the power difference on the road between B18b & B20b would not warrant the expense.

[classicswede]

You can still use the B18 head but best to open out the combustion chambers and fitting B20 inlet valves (you need to change the guides to do this)

Makes sense to upgrade to B20B spec

[Ron Kwas]

Meegs;

If you are going to bore the B18 to B20 dimensions, then you should consider putting a B20 Cyl Head on it as reworking a B18 Head to work with a B20 would be expensive (Comb Chambers must be resized, as mentioned, Valves and Guides would need to be changed) and ports would remain as still a big limiting factor in the end, as resizing those is risky and only a job for an expert with Volvo specific experience (if you get it wrong and break into the cooling jacket, you're toast!).
Just to be clear, what makes a suffix A,B,C,D engine is the Cam, Comb Ratio, Carb(s), and Manifold (single or double downpipes)...

Good Hunting!

[northNH]

Ron, just to be clear(er), shouldn't it read "what makes a suffix A,B, or D engine (no C) is the Cam...and Distrib?

[Ron Kwas]

nNH;

Yeah, you're right of course...a B18A has an A Cam, a B18B has a B Cam (I believe), but there is no B18C, and a B18D has a C Cam in it...do I have it somewhat right now? ...point I was trying to make that outside Cam in the Block and height of the Head, much of what determine engine configuration is external to the motor...such as Manifolds and Carbs...

Cheers from the Maine Coast...should I stop by for lunch on the way home?

[northNH]

...would love to share a bucket of steamers and thank you for all the help you provide this community.

But soon, winter's on the way...

[meegs68]

Originally Posted by Ron Kwas

Meegs;

If you are going to bore the B18 to B20 dimensions, then you should consider putting a B20 Cyl Head on it as reworking a B18 Head to work with a B20 would be expensive (Comb Chambers must be resized, as mentioned, Valves and Guides would need to be changed) and ports would remain as still a big limiting factor in the end, as resizing those is risky and only a job for an expert with Volvo specific experience (if you get it wrong and break into the cooling jacket, you're toast!).
Just to be clear, what makes a suffix A,B,C,D engine is the Cam, Comb Ratio, Carb(s), and Manifold (single or double downpipes)...

Good Hunting!

Thanks!

The way I see it (and I agree with Arcturus), I either leave the engine as is (a non-standard B18A) and give it a general overhaul (glaze over the cylinders, new valves, etc.) or go the whole length and upgrade it to a double-carb engine.

I realise that the second option might set me back 10-times the expense of keeping it as is...

Wouldn't you agree?

meegs

[meegs68]

Originally Posted by arcturus

I don't think the power difference on the road between B18b & B20b would not warrant the expense.

Obrigado!

[Airspeed]

Sorry to resurrect an old thread (at least I started it!), but I have another question about these engines.

The reason I ask is I have a low mileage May '68 2 door Amazon, which came to me badged as a 122S. The vin starts 13334 which would suggest a B18B, which would have richer needles, a C cam, and a 10:1 CR. However, my V5 gives the engine number as B18D4112, which would indicate lean needles, and A cam and an 8.5:1 CR. This is indeed the number on the engine, and I have no reason to believe it has ever been changed. However, using the Amazon Pictures engine number decoder, the full engine number cast and stamped into the block (4968 71 4112) decodes as a B18B.

I can safely state that I am completely confused now, and am not even certain whether my car is a 122S as badged, or a 133 (as on V5) with twin carbs.

The whole point of this is that I find the performance a little 'flat'. I built the car with a tubular manifold and a Simons exhaust I had lying around, so it should have at least a little more fizz about it, accepting that I haven't changed needles yet (compressions are good and it runs well). My previous Amazon was a twin carb B18 and seemed a lot livelier.

Can someone please advise me what I have?