I have a 1756 Fiat TC but which one do I have??

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Lee67
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I have a 1756 Fiat TC but which one do I have??

Post by Lee67 » Fri Jan 06, 2017 3:50 pm

Hi all,

Hopefully there's a straightforward answer to this - my 1756 engine has a somewhat unknown history, according to certain sources my block and head casting numbers check out as it being an 1800 Coupe/Spider engine from 1973-77, 9.8:1 compression, 118 bhp.

However my engine has flat top pistons with valve reliefs and not domed pistons, I am under the impression that the HC engines all had domed pistons of some kind, or is this incorrect? is there a difference in combustion chamber size/shape between the heads fitted to LC and HC engines?

My block is cast as 132 AC1C - which I believe is 124 Sport Coupe/Spider 73-77
My head is cast as 132AB9A 4277590 2S62 - which I believe is 124 Sport Coupe/Spider 73-77
My pistons are 84.0mm and are cast as Fiat MONDIAL 2472L - I can't trace this number.

The combustion chambers in the head are reportedly 47.2cc
Photo of piston and CC attached for reference.

Has anyone any info regarding what I actually have here please?
Lee
1800cc.jpg
1800 Piston
1800cc.jpg (48.51 KiB) Viewed 428 times
piston1.jpg
1800 combustion chamber
piston1.jpg (39.2 KiB) Viewed 428 times
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Guy Croft
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Re: I have a 1756 Fiat TC but which one do I have??

Post by Guy Croft » Fri Jan 06, 2017 6:05 pm

Hi Lee

heads and crankcases these days? One can never be sure they are original to each other.

The first thing I noticed was the holes in the ex port. These were used for ex gas recirculation on US models only. As I said, heads have been swapped around.

The pistons used in the 1800 in original trim varied in style. In Europe the 124 1800 had a big dome, the later 132 1800 a much smaller one. The US models were really quite low CR and had flat-top pistons like the ones you showed, with huge valve reliefs.

Hope this is of some help.

GC
Guy Croft, owner

Lee67
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Re: I have a 1756 Fiat TC but which one do I have??

Post by Lee67 » Fri Jan 06, 2017 6:27 pm

Hi Guy

Thanks for that, I had my suspicions that it wasn't going to be an HC engine even though the numbers suggested it was.

The EGR holes in the ex ports - can they just simply be plugged in some way? presumably so as I won't be using any of that poor.
Pistons - It'll be just a fast road engine so now I'm thinking something like euro spec 124 Coupe 9.8:1 standard items or whatever I can come across of a similar type. Am I on the right lines here and stick with this 1800 head?

Thanks again
Lee
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Guy Croft
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Re: I have a 1756 Fiat TC but which one do I have??

Post by Guy Croft » Fri Jan 06, 2017 8:13 pm

Thanks for that, I had my suspicions that it wasn't going to be an HC engine even though the numbers suggested it was.

Sure! Mind you it would be a 40+ year old HC engine! Don't expect miracles! That's like running a D Day 1944 Willys Jeep in 1984 and expecting it to run well!

The EGR holes in the ex ports - can they just simply be plugged in some way? presumably so as I won't be using any of that poor. Yes, they can be blocked off on top of the head by sealing off the EGR tubes..


Pistons - It'll be just a fast road engine so now I'm thinking something like euro spec 124 Coupe 9.8:1 standard items or whatever I can come across of a similar type. Am I on the right lines here and stick with this 1800 head?

I can tell you there are NO SUCH OE pattern pistons available anywhere despite claims for any sold in the USA or anywhere else except for the od set that comes up on auction sites! GC forged or nothing.

Please don't do what others still do with the Fiat TC - 'it's only a cheap Fiat'.

Do it professionally as I do - you'll have to walk a very very long way to replace a world-class unit....

GC
Guy Croft, owner

Lee67
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Re: I have a 1756 Fiat TC but which one do I have??

Post by Lee67 » Sun Jan 08, 2017 7:53 pm

Thanks for the advice and pointers Guy, very much appreciated.

I'm keen not to fall into the "only a cheap Fiat" trap but likewise am on a restricted budget. I'll be quite happy with a 125-130bhp 1800 engine just to perk up the performance of my 124 Special T, I'm aware of the weaknesses of the 124 5 speed box so don't want to go mad and don't want to swap in a 131/132 box either.

Lee
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