Do the 74/75 b20 timing cover and rear main seal accept the b21 type neoprene seals without machining?

Two issues:

The REAR crank seal on the '74-5 blocks is machined to take the neoprene seals, and yes it is perfectly usable on earlier blocks.

Likewise, the B21/23 rear main seal housing is a direct fit on the B18/20 blocks and is also fitted with a neoprene seal.

AFAIK (and according to advice from ipd) *NO* OHV 4-cylinder engines came with a FRONT cover that had a neoprene seal. ipd, RPR, and others will gladly make one for you.

I can not address the B30, as my knowledge is too limited.

If by chance you find a felt seal in there, the neoprene seal will not
fit. There are a number of providers of reworked timing covers and seal
housings including myself.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

Didn't the felt seals go away with the introduction of the 8-bolt cranks in '74?
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Don Foster (near Cape Cod, MA)

Hi,
I've got a 1974 (Australian delivery, with Stroms, not FI) that had felt seals. Maybe downunder got the felt sealed engines the rest of the world refused to take?
JohnH

Or it could be that I'm completely screwed up. In years past, though, I rebuilt a number of '74s and '75s and they ALL had the synthetic seals. But that could be 'cuz somebody got there first....
--
Don Foster (near Cape Cod, MA)

Possibly they were part of the emissions controls? After all the oil drips common to the felt sealed cars are really 'unburned HC emissions'!

Hmm. Unburned hydrocarbons.

Interesting idea. I never considered that!
--
Don Foster (near Cape Cod, MA)

Dunno. Got an 8-bolt block but never had an 8-bolt crank, at least
not to work on. I did get one 8-bolt B30 once but traded it off immediately
because I could not afford a flywheel for it. Also had a 74 144 for a few
months but never worked on it.

I think you are probably right but sometimes there are adverse retrofits.
(Sometimes leading to other kinds of fits.)
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

"...but sometimes there are adverse retrofits..."

I always used a machined rear seal housing and machined timing cover on the earlier engines......and still have a rear seal housing around somewhere...

But I think you can use a housing from the later OHC engine on their pushrod ancestors.....must be that common DNA....
--
Don Foster (near Cape Cod, MA)

Btw on another note, It looks like the cylinder walls are sleeved. Is this normal, or did a previous owner have some crazy work done. I guess what I should be asking is: What is the stock spec on cylinder diameter?

"...the cylinder walls are sleeved. Is this normal, or did a previous owner have some crazy work done..."

Don't know, good question.

"What is the stock spec on cylinder diameter?"

Also don't know and also a good question. It should be in any of the service manuals. (Haynes says 3.5"=88.9mm bore for the B20A engine and 3.5008"=88.92mm for the B20E engine.)

I bored out several B20s (both 6- and 8-bolt styles) to B21 diameters, and one was taken to B21 +0.060".

All ran fine. Superduper fine, in fact.
--
Don Foster (near Cape Cod, MA)

They certainly aren't sleeved as stock, and I can't imagine someone doing it to salvage a busted block when you could always just get another block for very little money. Unless someone wanted a REALLY big bore B20?

I've had a couple of B20 blocks bored to B21 size, and I'm using one of those currently in my PV. Works great!

Std dimensions are:
B18 - 84.14 mm (84.64 and 84.89 mm std oversizes)
B20 - 88.9 mm (89.29 and 89.67 mm std oversizes)
B21 - 92 mm (92.5 and 93 mm std oversizes)
B23 - 96 mm (96.3 and 96.6 mm std oversizes)

Machine shops usually seem pretty skeptical about overboring a block 3 mm, but it works well on the thicker than normal Volvo block. I'd guess the 96mm B23 size is not possible, if you want more displacement in your pushrod Volvo engine than the ~ 2.2 liters the 92mm pistons provide then you should probably look to a stroker crank. KgTrimning lists stroker cranks that add ~200 cc's more for a 2.4 liter in combination with a big bore.

Yes.
--
Don Foster (near Cape Cod, MA)

Brevity is king in Don. Enough info to get you going and little else.
--
Justin 66 122E, 71 145S
Read vclassics!

You need more?
--
Don Foster (near Cape Cod, MA)

I didn't say it was bad. I find it somewhat refreshing, actually.
--
Justin 66 122E, 71 145S
Read vclassics!

Cool!
--
Don Foster (near Cape Cod, MA)

I'm satisfied.