piston quest

[Tappy]

Ok it aint funny no more , today it seemed that i was ripped of once again with the second hand engine i bought to replace the broken second one ...

while preparing it to get installed earlyer today wire brushed all components firmly , he head came of , a real disaster srr didn't bring my camera but it aint pretty to look @. Al 4 cylinderheads have serious impact damage , gaps where you can fit in a 8mm bold , strangly the head has no sighns of the terror that went on in there so thats probably been changed. the walls of the cylinder (srr dont know the right name for that) are as by wonder still pretty clear , only one minor scratch that con be "honed" out. SO maybe (pls advise) the engine can be saved just replacing the cilinders ? and if so i've notished the vendors that carry them all advertise with piston for the 1800/2000 model , does that mean the heads are the same ? If so that would be a spark in the darkness becouse i still have the other 2l dead engine to recover them from.

So who will bring the GOOD news first

or the bad ...

[Tappy]

no one ?

[racydave]

Im sorry, but sometimes pictures work better than your english. Hope your luck changes!

[Tappy]

i'll reprhase : do pistons from a 1995 cc block fit in to a 1756 cc block ?

[So Cal Mark]

yes

[Tappy]

OK thx Mark , so it would be worth it to transplant them , i've notiched the 1995cc pistons are flat and the 1756cc pistons have a dome , hat would be no problem ?

just checking before i pay my mechanic to make the switch

[So Cal Mark]

if your 1800 has domed pistons they have been replaced. The flat top pistons will have lower compression, but will also allow the engine to freewheel if the t-belt breaks

[engineerted]

The domed pistion from the 1800 will fit in the 2000, but be sure to measure the dia. as they are most likely oversized. Plus also 2L rods are not the same as 1.8l thus keep the 2L rods with the 2L engine. Good luck!


Ted

[racydave]

Under ideal circumstances Pistons are fitted to the cylinders, and wear together. Using used pistons in worn cylinders is risky, and might cause unwanted additional problems. Under best circumstances, the cylinders should be inspected for wear to see if it needs a re-bore and oversized pistons. Maybe you will be lucky, but there is no substitution for doin it correctly once! Im not always lucky! As always, good luck!

[Jim DeShon]

Tappy: In my own humble opinon, I would not put a set of used pistons in any engine. It is just not a good gamble. I can't say I haven't done it on one of my own old junkers, but it's not a good idea. A few questions arise--If flat tops allow free clearance, as MArk said, why does my 1800 with flat tops bend the valves if the timing belt breaks ? Compression tested at 130-135 psi so they go to be 8-1 C.R.. Do the 2000 flat tops have a lower deck height ? Is the rods shorter in the 2000 ?... ...J.D.

[Tappy]

Tappy: In my own humble opinon, I would not put a set of used pistons in any engine. It is just not a good gamble. I can't say I haven't done it on one of my own old junkers, but it's not a good idea..

a new set of pistons would set me back 230€ and shipping so i'll take a try on the used ones if possible , clean them up and use new pistonrings , dont see the harm in that

A few questions arise--If flat tops allow free clearance, as MArk said, why does my 1800 with flat tops bend the valves if the timing belt breaks ? Compression tested at 130-135 psi so they go to be 8-1 C.R.. Do the 2000 flat tops have a lower deck height ? Is the rods shorter in the 2000 ?... ...J.D.

could it be that the valves still interact ? or that the head sits lower on the block then a 2l ? I'll compare the rods later to see if there are any differences , keep you posted

[Jim DeShon]

Thanks in advance for checking that out for me. I don't have any 2000 pieces in the shop to compare. We all know that the 2000 engine is taller. I'm trying to figure out how the factory got about the same compression with 200 more cc's. Is the difference in the combustion chamber volume, the deck height [how far up in the cylinder the piston comes at TDC] or did they change the rod ? These become good questions when you start modifying and swapping parts around. ...J.D.

[Tappy]

i'm srr i'm just back from the garage , the cops showed up for the neightbour claiming he was illigally working in his garage so we quitly moved on before we had to open my mechanics place.

[So Cal Mark]

there were two different pistons used in th 1800s. The early engines up through 76 used pistons with smaller valve reliefs and slightly higher compression. Those are interference engines. The later 1800s in 77-78 had larger valve reliefs and lower compression that allow freewheeling. Milling the head, changing cams , etc have an effect on this

[mdrburchette]

Don't the 2L have a longer stroke so they'd have a longer rod?