different twincam engine heads

[djape1977]

i have several engine heads from fiat twincam engines.
124ac for 1608ccm 80mm bore
124bc for 1608ccm 80mm bore
125bc for 1608ccm 80mm bore
does anyone know what are the differences between these?

also
132 a10 for 84mm bore from 132 1800special. this head has bigger valves than stock 2ltr head! intake in 1.8 is 42mm while in 2.0 is 41mm. intake manifold is 42mm for 1800 and 40mm for 2.0

[Walezy]

Intakes as far as i remember are 41,8mm so it looks to be standard valve.

[djape1977]

nope.
1.8l 42mm exactly, 2.0l - 41mm on these two i measured today. perhaps there's some diference betweeen 131 and 132 engines? while reading a Guy Croft fiat/lancia tc ... i came across a section where he also says tha 1.8 head on 2ltr block gives better performance, among other things because of smaller compression chamber.

[Tas131]

The later model 131 heads in Australia had 43.5mm inlet valves.
There is a list (not complete) of head casting numbers here.
http://www.mirafiori.com/faq/content/headid/headid.html
It doesn't give details on head specifications though.

[djape1977]

list is of some help but it's incomplete and missguiding.
1608 heads 124ac and 124bc and 125 bc have different center-to-center combustion chamber spacing than 132 aba10 from 1756 and 449---- from 1995ccm. i took the head gasket from 1756 and aligned it to first cyl on 124ac head. second was off by couple mm.... to fourth which was off for whole cm.

btw, when fitting a 1756ccm head with 42.3mm intake valves to standard 2.0 block on which was head containing 41mm valves, pistons and valves collide as i found out today. small mod was in order. pistons needed a bigged valve groove.

[Testament]

standard inlet valve sizes are 41.8mm, 42.4mm and 43.5mm. I haven't seen a good list of what got the 42.4mm valves, but I'm guessing 124 sports and some early sportier models of 132 and 131 maybe. Maybe some lancia beta's too. the 124AC has 1438cc engine not 1608cc, but the heads are probably very similar. the 43.5mm valves werent until the 1980's

[miro-1980]

Testament,

Have you got the GC bible ?

Look on pages 13 and 14 for lists of all different possibilities for fiat twin cam heads. 

Based on this  42.4 were used between 1973 and 1977 on 1592 engines and between 1970 and 1973 on 1608 engines in 124 coupe and spiders.

45,3 were used on most Detla and some Beta models as well as all 150 TC and 130 TC .
 
If you need I can send you details on his.   

Miro

[miro-1980]

I have looked at some of my stock and found the follwoing :

- casting number : 5992169  has  43,5 mm valves - looks like 105/130 TC  but the number seems to high ! Maybe Argenta ?

- casting number :  5991740  has  42,4 mm valves   - looks like 124 spider, but again the casting number  number looks too high for  this size valve which was last OE installed in  1977 in 1992 cc engines .

According to GC the 42.4 mm valves were on 1592 cc (1973-77)  and 1608 cc (1970-73) in 124 spider and coupe.

I admit I am uttrely confused on all the different head types.

But there is only one question to me : which ones I can use for my 2 liter block?

Miro


 

[djape1977]

not from 1608ccm. or for that matter any head from the block containing 80mm pistons. they're shorter. engines with 80mm pistons have shorter engine block and therefore engine heads too. also, inlet manifolds for two webers that came as standard with some of 1608ccm 124 spiders can't be used either.
engine heads from any 84mm engine (1595, 1756, 1995ccm) are interchangable.
as i postd above, some 132's 1800 also seem to have heads as in 124 1800. mine is from 132 1800 special '75. and it has 42.3mm (or perhaps 42.4?) inlet valves. also, there's several diferent inlet manifold types: 40mm dia, 42, and i have one with 44mm and abarth casting on it.

[miro-1980]

The ones I have ( described previously)  are definitly 84 mm bore.

So I can use them !

The 42.4 than  must be from 1592 cc, than 

Miro 

[djape1977]

just goes to show that no one has all the knowlege in the world, not even me 

will check that info 

[kkkango]

I have a 131 2L engine131B2000 1125887 that I fitted a 1980's lancia delta 2L injection head on about 4 years ago (using the carb not injection). I very soon fitted the 131 exhaust cam and box to get rid of the unused lancia distributor drive which started chattering and allow the oil drain out.
the front and rear water port holes are smaller but still aligned with the gasket.
this combination has driven a reasonably hard 30,000 miles and came off the other week for new piston rings to be fitted due to heavy breathing and oil consumption.
reading this I shoud have done more research first ,appears that I just been lucky.
will have to check the head part number sometime.

[Aussie131]

Guys i don't want to be rude but have any of you ever pulled one of GC's big hp race engines down?
His race engines will be lucky to do 350-500km before they blow them selves to pieces and at the price of a replacement, head, pistons, rods and if ur unlucky a crank then the engine is just not worth the hassle,
we have built a fiat 2L engine that goes to 8000-8500 rpm all day long with out the slightest hint of oil surge or a puff of white smoke out the exhaust and guess what its got a wet sump in it to, Have not see GC do that, all of his big engines rely on a dry sump oiling system, the head work he does is great for big power over short periods of time but he under cuts the valve seats and weakens everything, ok there fast but far to expensive to maintain