Need information on an odd combination

The forum for all of your technical questions on your classic FIAT autos
FiatHyena
Posts: 5
Joined: Thu Sep 12, 2019 8:16 pm
Last Name: Yun
First Name: David

Need information on an odd combination

Post by FiatHyena » Mon Sep 16, 2019 10:19 am

Hello all,
I just bought a 73 Spider and am looking for any information on my seemingly incompatible engine setup. I'm new to Fiat's so any amount of info would be helpful. So this is what I have:
- 2L block, verified by block casting
- 1608 head, verified by casting - supposedly this is incompatible unless coolant passage was welded. So what's the advantage of going to the trouble of doing this instead of using a 1756 head?
- Block mounted distributor - supposedly only available with the very early 1438?
- No vacuum advance - I think I have the Marelli plex, so maybe that's why?
- Dual plane manifold with 28/36 DHSA 3B. Why go to the trouble of fitting a 1608 head if you're going to use the stock carb?
Also, the center support for the hood has been cut out to clear the engine. Do I lower the engine to its proper position by changing the crossmember, or with a flatter engine mount?
Thanks for any insights you may have. This car has been sitting for the last ten years with an unknown history, so it's kinda fun trying to figure out what's been done, but also a bit frustrating.
User avatar
miker
quattromila club
Posts: 4195
Joined: Sun Jan 24, 2016 7:55 pm
Last Name: Richmond
First Name: Mike

Re: Need information on an odd combination

Post by miker » Mon Sep 16, 2019 11:03 am

It sounds to me like the previous owner put together an engine combination based on whatever they could find, cheap. If it was done 25 years ago before the internet was big thing, one can imagine how it might have been harder to find the 'right things'.

The only thing that made me choke up (because it's not so easily reversible) is the cut up hood. Like somehow Fiat added a center support just for fun.

I'd change the block before I got a 2L crossmember. The 2L is out of character for that car.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
FiatHyena
Posts: 5
Joined: Thu Sep 12, 2019 8:16 pm
Last Name: Yun
First Name: David

Re: Need information on an odd combination

Post by FiatHyena » Mon Sep 16, 2019 12:45 pm

Yup, I have a feeling the PO had a parts car from which he swapped everything over. The interior seems to be from a later year too - probably 79.
What I don’t get is the block mounted distributor. How is that possible on a 2L block with 1608 heads?
The hood kinda chaps me too.
User avatar
friedman
mille club
Posts: 1955
Joined: Wed Aug 24, 2016 8:13 am
Last Name:

Re: Need information on an odd combination

Post by friedman » Mon Sep 16, 2019 1:09 pm

I also have read the 1608 head needs mods to fit on the later 1800/2000 motor but no personal experience. Easy enough to install a later exhaust cam driven distributor if you want to go that route. Vacuum advance is nothing I lose sleep over. If that block mounted dizzy is electronic, you could leave it in place. The early carbs were actually a decently big carb but I'm not a fan of the vacuum operated secondary. The dual plane intake manifold is a horror and should be tossed and replaced with single plane manifold from a 75-78 spider.

I have put two liter motors in all my early spiders and the motor fits without butchering the hood but admittedly I used the small bump hoods. Not sure why he cut out the center reinforcement, can you see where there would have been interference? In every instance I did not change to a 2L cross-member.

Folks have put the 1800 head on the 2L motor for a small bump in compression. What exhaust do you have on the car? If it's a 4-2 manifold and downpipe (has a ring clamp holding the two parts together, then you should consider the 4-2-1 manifold and downpipe (flanged joint with four studs) as it flows much better.
Carl in Virginia
75 spider
83 Bertone
User avatar
18Fiatsandcounting
Posts: 109
Joined: Tue Apr 16, 2019 8:47 pm
Last Name: Balazs
First Name: Bryan

Re: Need information on an odd combination

Post by 18Fiatsandcounting » Mon Sep 16, 2019 4:01 pm

I agree that this appears to be a "FrankenFiat" engine with parts from many different model years. Just a couple thoughts:

1) I have a 1438 cylinder head and a 2L block in my '69 spider, and it works fine in terms of temperature, top and bottom clearance, etc. It's been that way since the late 1980s with close to 100,000 miles on it, and other than a new oil filter mounting flange that I machined in the machine shop at my college, no modifications were needed. The engine does tend to run hot (210 oF) in stop-n-go traffic when the outside temp is over 90, but I always assumed that was because my stock '69 radiator didn't have enough capacity.

2) The gear on the auxiliary shaft that drives the distributor (and the oil pump) is still there on later model years, even after Fiat moved the distributor up to the exhaust cam. So, there's no reason someone couldn't put an older distributor on a 2L block. In fact, on my 1438 cylinder head and 2L block combination, the distributor is on the block as in the original '69 version, and it works fine.

Back when I did the modifications on my '69, I was poor as a churchmouse and basically worked with whatever I could scrounge up and afford, even if not optimal. Young and crazy, I guess. Perhaps that's what the original owner of your car did.

-Bryan
User avatar
davedecker4
Posts: 795
Joined: Sun Jan 24, 2016 11:05 am
Last Name: Decker
First Name: Dave

Re: Need information on an odd combination

Post by davedecker4 » Thu Sep 19, 2019 10:25 am

If your block mount dizzy is an electronic or plex, it could be out of 79 Lancia Beta. An early performance swap to get the electronic dizzy. Used stock parts and was cheaper/more available than aftermarket units.
Dave Decker
a 'couple' Fiats and Lancia's
User avatar
SimcaBertone66
Posts: 689
Joined: Fri Oct 07, 2016 3:28 pm
Last Name: DeGasperis
First Name: Joseph

Re: Need information on an odd combination

Post by SimcaBertone66 » Thu Sep 19, 2019 11:37 am

FYI... the block mounted Marelli from the Beta works in the 1438 pushrod engines as well … one still running in my former 72 124 Special Sedan
Joe DeGasperis
FiatHyena
Posts: 5
Joined: Thu Sep 12, 2019 8:16 pm
Last Name: Yun
First Name: David

Re: Need information on an odd combination

Post by FiatHyena » Thu Sep 19, 2019 6:41 pm

That's so funny, my first car was a 79 Lancia Beta! Of course that was 35 years ago, so I don't remember too much about it. I do remember taking it to a Fiat specialist, whose name was actually Tony. He always had an espresso and cigarette in one hand and would tell me how good the Lancia and Spider were, but how bad the 850 was.
User avatar
davedecker4
Posts: 795
Joined: Sun Jan 24, 2016 11:05 am
Last Name: Decker
First Name: Dave

Re: Need information on an odd combination

Post by davedecker4 » Thu Sep 19, 2019 10:53 pm

That sounds about right. That's been my experience too.
If you find out that your 1608 head has not been welded and want to change to the 1756 head, I'll trade you. I have a couple surplus but now working on an earlier car. Some of these parts are a little easier to track down now. Also some of the techniques have been perfected with different parts available now where some used to be hard to come by and vice versa. Here's an old primer on some of this info. Does not all always apply as some things are unavailable or no longer best practice but gives you an idea.

<https://www.mirafiori.com/pbs/pbsdohc.html>

Betas are great btw 8-)
Dave Decker
a 'couple' Fiats and Lancia's
FiatHyena
Posts: 5
Joined: Thu Sep 12, 2019 8:16 pm
Last Name: Yun
First Name: David

Re: Need information on an odd combination

Post by FiatHyena » Fri Sep 20, 2019 1:47 am

Hey Dave, I'll definitely consider your offer if I pull the head. Having never actually compared the two heads, it sounds like the 1608 would "have" to be welded. Otherwise wouldn't coolant flood the number 1 cylinder?
Post Reply

Who is online

Users browsing this forum: No registered users and 70 guests