Boring and 1850 block to 2 litre?

[PaulB]

I am presently dismantling and very rusty 1850 auto. It shows 24000 miles which judging by the condition on the interior and engine appears to be the genuine mileage.
I am also building another Sprint and was wondering about the feasibility of boring the 1850 block to standard size for the Sprint.
According to the parts manual, the 1850 and Sprint blocks both appear to be linered and this does appear to be the case with the 1850 engine.
Does anyone know if the outside diameter of the 1850 and Sprint liners are the same. If they are, it should be possible to bore the 1850 engine for use in the Sprint?
Any thoughts would be appreciated.
Thanks.

[tony g]

i looked into this last year Paul. I havent got the numbers handy but if an 1850 is linered, the outside diameter of the liner is bigger than 90.3mm so sprint size unless going 060" thou oversize its not worth it. Just need to add that iron blocks are only linered if the original bore was rubbish and needed correcting. All sprint blocks Ive seen have never had liners and 1850's would only have them for cock up reasons. I went to rimmers to buy an 1850 block I was told was non linered and inspected it and found liners so was not happy. Any iron block with liners is weaker than an iron block bored to size. Losing the parent material from the block weakens it no matter how tight they are pressed in there. Its worth cleaning up the deck surface enough to see the liners' edge. A good worn out 1850 with no liners is the way to go for reboring. HTH

Tony

[xvivalve]

Surely despite the OD being more than 90.3 mm you take out the 1850 liners and put in Sprint ones?

I changed the liners on the quicksprint engine back to standard to utilise the NOS set of standard pistons I had; conversely to Tony's experience, I've not knowingly seen a slant block without liners! Infact the factory parts book shows them with part number 158700, 4 off required.

[tony g]

Liners typically are around 1.5mm thick (060 thou ish) so its possible sprint liners will work. I have 6 blocks in my workshop or cars (2 from you Alun) and none of them have liners. When oems cast grey cast iron blocks the idea is to bore them and fit pistons job done. Liners are repairs to bad core shift or bad boring and later to return worn std bores back to std (from the factory or dealers usually).
We need a poll on liners or not

Tony

Surely despite the OD being more than 90.3 mm you take out the 1850 liners and put in Sprint ones?

I changed the liners on the quicksprint engine back to standard to utilise the NOS set of standard pistons I had; conversely to Tony's experience, I've not knowingly seen a slant block without liners! Infact the factory parts book shows them with part number 158700, 4 off required.

[TahitiSPRINT]

I can confirm that to have Sprint pistons fitted in a linered 1850 block, the 1850 liners have to come out as they're not thick enough to rebore to 90.3 mm Sprint size. And new Sprint liners require a rebore of the block as the outside diameter is bigger. So extra costs yes, but cheaper than a “new” Sprint block. I bought a new "crate" 1850 short engine from Rimmers a couple of years ago (which was linered) and went this route to rebuild my Sprint engine with new std size Mahle pistons.

As for the discussion on linered vs. non-linered: If your machine shop leaves an edge at the bottom end of the cylinder for the liner to “rest” on, and the head is keeping the liner in place at the top-end, there’s nowhere for the liner to move to if it were become loose from the original pressing. Also, I’d like to think that the liners are of a more homogeneous material than the original cast block with possible patches of carbon or air bubbles… Experts please advise

[PaulB]

I dismantled the 1850 engine yesterday and it is not linered. So I willbe able to bore it out to STD Sprint size without fitting liners.
Result.

[tony g]

Yes Paul there's enough meat in the block to do that. If uncertainty arises over this bring the block to me and I will ultrasonically test it for you while you wait to confirm wall thickness as standard.

Tony

[gmsclassics]

The current block (and crank) in my race car came from an 1850 auto that was still running standard bore, big ends and mains after over 100,000km. No liner.
Just gave it to my expert reconditioner who converted it. Interestingly he wouldn't bore it out until he had the new Carrillo forged pistons in his hand. Although pistons were to standard diameter he wanted to get the clearances just right.
Ground the crank, new quality shells and balanced with flywheel and clutch. Didn't cross drill.

Running to 7500rpm with block brace, Motul oil and it has been fine.

Geoff

[RobinLedbury]

I purchase a new 1850 block from Rimmers some time ago when they where on a special offer, should have go several at I remember them at £50 , I had the liners taken out and fitted standards size new Sprint pistons, this works fine for my quick sprint , no reason not to go down this route .

[PaulB]

The current block (and crank) in my race car came from an 1850 auto that was still running standard bore, big ends and mains after over 100,000km. No liner.
Just gave it to my expert reconditioner who converted it. Interestingly he wouldn't bore it out until he had the new Carrillo forged pistons in his hand. Although pistons were to standard diameter he wanted to get the clearances just right.
Ground the crank, new quality shells and balanced with flywheel and clutch. Didn't cross drill.

Running to 7500rpm with block brace, Motul oil and it has been fine.

Geoff

I didn't know you can use an 1850 crank in a Sprint. I thought the front section is longer because of the duplex chain on the Sprint?

[gmsclassics]

Definitely identical and a good way of finding a quality secondhand one for use in a Sprint rebuild. It is the crankshaft pulleys that are different, given as you say the timing gear and cover are unique to each model.

Geoff

[PaulB]

I purchase a new 1850 block from Rimmers some time ago when they where on a special offer, should have go several at I remember them at £50 , I had the liners taken out and fitted standards size new Sprint pistons, this works fine for my quick sprint , no reason not to go down this route .

Having taken out the 1850 liners, did you have to fit Sprint liners, or just bore the block?

[RobinLedbury]

the liners where pushed out and a little honing was done at the machine shop to fit the pistons, I don't recall the shop boring out to get the correct clearance on this block