Twin Cam Engine Block Basic's

Tech chat w/ Marc Matzer
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Marc
Posts: 268
Joined: Tue Mar 21, 2006 1:15 pm

Twin Cam Engine Block Basic's

Post by Marc » Fri Jun 23, 2006 6:37 am

Fiat Twin cam engines used in the 124/131 series cars and beyond were built with five different combinations of bore and stroke.This gave us stock displacements of 1438cc,1592cc,1756cc and 1995cc.
Two different stock bores and four different strokes are used in five engine sizes.The 1438cc,1592cc,1608cc engines all have a stock bore of 80 mm.The 1756cc,1995cc have 84mm bores.
The strokes are as follows:1438cc-71.5mm,1592cc-79.2mm,1608cc-80mm,1756cc-79.2mm,1995cc-90mm.
The 1438cc and the 1608cc have the same bore and spacing.The 1608cc block is taller to accomodate the longer stroke and the rod journals are larger by .107 inch.
The 1592cc,1756cc and 1995cc all have the same bore spacing,which is greater than that used on the 1438cc/1608cc engines.
The 1592cc and 1756cc engines use the same crank and rods and the same block height.They,basically,differ only in bore size.However,the 1592cc cannot be bored to 1756cc as the water jacket is different.
The 1995cc engine has a taller block, a larger crankcase and longer rods as well as a longer stroke.
The engines are refered to as "Small blocks" and "Big Blocks".The 1438cc,1608cc,1592cc,are considered to be "Smallblocks"."The Bigblocks"are the 1756cc,and 1995cc engines.
The cylinder head combustion chamber spacing is the same on all of the twin cam engines.This spacing is matched to the 1438cc,and 1608cc series engines.Hence the end bores are offset somewhat from the centers of the combustion chambers on the 1592cc,1756cc,1995ccengines.The basic cylinder heads are interchangeable between all the different size engines except for the water jacket opening at the front of the head at the head-block interface.Which means the 1438cc and 1608cc heads have a larger opening at this location which is too close to the front cylinder to be used on the 1592cc,1756cc,1995cc blocks.

LANCIAHF
Posts: 137
Joined: Sun Dec 26, 2004 10:26 am

1756 differences?

Post by LANCIAHF » Thu Jun 29, 2006 4:03 pm

Marc,

Nice article! Didn't some of the earlier 1756 engines have a shorter crank nose than the later 1756 engines? I found this out the hard way when I tried to interchange cranks from different years. The crank journals were in the same spot, but the early 1756 crank nose would barely clear the front of the block.

Ralph

Marc
Posts: 268
Joined: Tue Mar 21, 2006 1:15 pm

1756 differences

Post by Marc » Thu Jul 06, 2006 6:49 pm

Yes you are right.There are differences in the block crank nose as well as the Flywheel had different size bolts[larger] on the 1756 blocks just before the change to the 1995.many of these engines were used for various models built that had ac,power steering,etc..131,lancias etc.I will try to find out the production change time .The triple pulley wheel type vs ythe single pulley type/small/large; flywheel bolts

Anonymous

Nice car!

Post by Anonymous » Sun Jul 09, 2006 6:19 am

Hi Marc
Nice car! I didn't quite realize what I had till I saw the pictures of yours... Eight years ago I got a Spyder as part of a divorce settlement but since then it has been sitting a barn gathering dust. It's a shame because it really is a beauty. Last I heard it wouldn't start and needed some work on the engine. I thought about selling it but wasn't sure what it's worth. I see you bought yours for 300?? Is that right??

Heather

Marc
Posts: 268
Joined: Tue Mar 21, 2006 1:15 pm

Hi Heather

Post by Marc » Mon Jul 10, 2006 9:02 pm

Thanks for noticing my car!What year is your car?I did buy it for 300.00 dollars.I was intrested in finding a car that wasnt in an accident.I could have spent alot more and purchased a pretty clean car but i enjoy working on them.This one had alot of rust which I cut out and replaced it with new metal,then added alot of money in parts to bring it to my the way you see it now.Do you drive your car much? If you have any questions i wouild be glad to help! Marc

Guest

Post by Guest » Sun Jul 16, 2006 5:36 pm

I really have no idea what the year of the car is. It has no rust at all on it. I haven't driven it yet. Could you tell me what it's worth? What information would you need? Someone should start a mechanics list on here....it would sure help.

For anyone else who maybe of reading this and willing help a damsel in distress please let me know of any well-known mechanic in eastern PA or central NJ.

Maybe we could start a post for cars for sale...maybe there is one and I just missed it.

LANCIAHF
Posts: 137
Joined: Sun Dec 26, 2004 10:26 am

Help?

Post by LANCIAHF » Sun Jul 16, 2006 8:39 pm

Maybe I can help, I'm near Trenton NJ. Not a mechanic by trade but I have been playing around with these cars forever. What is the problem?

Ralph

bigaun
Posts: 0
Joined: Sat Apr 14, 2012 8:48 am

Re: 1756 differences

Post by bigaun » Tue Apr 17, 2012 11:40 am

[quote="Marc"]Yes you are right.There are differences in the block crank nose as well as the Flywheel had different size bolts[larger] on the 1756 blocks just before the change to the 1995.many of these engines were used for various models built that had ac,power steering,etc..131,lancias etc.I will try to find out the production change time .The triple pulley wheel type vs ythe single pulley type/small/large; flywheel bolts[/quote]


You said Flywheel had different size bolts . This is where you lost me. What do you mean?


[quote="LANCIAHF"]Maybe I can help, I'm near Trenton NJ. Not a mechanic by trade but I have been playing around with these cars forever. What is the problem?

Ralph[/quote]


Lucky. Hope I live in trenton. :( any help for some newbie guy here.

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