Returning after a long time.

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ramzi
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Re: Returning after a long time.

Post by ramzi » Thu Feb 01, 2018 3:46 pm

Jim,

I actually have said offset pistons in my 2.0L and happen to keep on on the desk as a Fiat club business card holder (left) next to a common HC piston (right). You can see the comparative amount of offset for the valves. But again a more efficient combustion chamber would align to the cylinder bore.... I recon thats only a dream though.

Chris,

A very common modification for the 1756 or 1995 was to use a cylinder head from a 1974 Spider (1592cc). All the passages align, it afforded marginally higher compress as I recall and the best part is that it had no emission ports so it was a "clean" conversion.

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Ramzi
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1939 Fiat 508CM (Military)
1939 Fiat 508C (Civilian)
1966 Fiat 500F
1967 Fiat 500F
1966 124 Sedan RHD (Oldest in N. America)
1972 124 Spider 2.0L
2017 124 Spider Abarth
2018 Alfa Romeo Stelvio Ti
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vandor
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Re: Returning after a long time.

Post by vandor » Thu Feb 01, 2018 7:07 pm

I think you meant 1973.
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Re: Returning after a long time.

Post by ramzi » Thu Feb 01, 2018 7:59 pm

You are of course correct. ‘73 Spiders being the only year to wield the powerhouse 1592cc
Ramzi
Auto Ricambi, LLC
www.autoricambi.us
1939 Fiat 508CM (Military)
1939 Fiat 508C (Civilian)
1966 Fiat 500F
1967 Fiat 500F
1966 124 Sedan RHD (Oldest in N. America)
1972 124 Spider 2.0L
2017 124 Spider Abarth
2018 Alfa Romeo Stelvio Ti
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cgranju
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Re: Returning after a long time.

Post by cgranju » Thu Feb 01, 2018 9:58 pm

Well ok & yeah I thought you meant 73...BUT, you could have also meant a '74 124TC! Let's give at least partial credit on this one.

I have experience with the 1756 head on 1995 block, but not 1592 head on that block. Interesting knowledge I may never do anything with!
Chris Granju
sunny East TN
owner of a number of Fiats built prior to 1986
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ramzi
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Re: Returning after a long time.

Post by ramzi » Thu Feb 01, 2018 10:23 pm

Well as Signor Truscott can attest the 1592 found in the 1974 sedan is an emissioned head similar in appearance to the 1756 of the 74 Spider.

He should be posting photos in a few days I’ll bet
Ramzi
Auto Ricambi, LLC
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1939 Fiat 508CM (Military)
1939 Fiat 508C (Civilian)
1966 Fiat 500F
1967 Fiat 500F
1966 124 Sedan RHD (Oldest in N. America)
1972 124 Spider 2.0L
2017 124 Spider Abarth
2018 Alfa Romeo Stelvio Ti
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Re: Returning after a long time.

Post by fp55scca » Thu Feb 01, 2018 10:55 pm

bnam2 wrote:
Thu Feb 01, 2018 12:15 pm

+++The holes in the 1608 and 1756 head don't always match in location. For instance, the 1756 has a small gallery to the left of that front central gallery, while the 1608 does not have one there, but a bit further to the back and left.

+++The difference in size of those 2 front central galleries seems irrelevant when both feed the same sized much smaller hole on both blocks. But the difference in location of a water gallery may be the more relevant factor. So, if a 1756 head was used on a 1608 there is at least one gallery in the head and one gallery in the block that are not connected to each other.
------------------------------------------

--Good eye Byas! The additional water port that you see on the 1756cc head, and missing from the 1608, I believe was added when Fiat re-introduced the thermostat into the head, beginning with the 1592cc engine in '73 and continued to '74. It had something to do with insuring sufficient circulation around the in-head thermostat to ensure a timely opening. I think the additional port was later determined to be unnecessary, but Fiat continued to produce the heads with the extra port included, even after the thermostat was again moved to its external location.

--The problem with the large front port of a 1608 head on a 132 series engine is due to the larger 84mm bore of these engines. The large port of the 1608 head is too close to the front of the fire ring of the number one piston.

--Byas, if you intend to keep the 1608 block you now have, if I were you, I would just search out another 1608 head and drop it on there. There are still quite a few of these out there.

--Ramzi, would love to see that photo on your desk, but it didn't seem to post?
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 Fiat 124 Spider
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Re: Returning after a long time.

Post by bnam2 » Thu Feb 01, 2018 11:43 pm

Jim,
Thanks again for posting all these pics. And the others for all the inputs. Now it's much clearer to me what the situation is and what the trade-offs/pitfalls are in the various choices. I will look for a 1608 head.

I think a bare head + valves but no towers may even fit in a suitcase. Not sure of the weight, but it should be under 50lbs I'd imagine. Then, I could carry the head plus a couple of new cams back with me during a trip to the US - and reuse the existing cam towers.

In the meantime I'm going to:
1. check valve clearances
2. I have a suspicion the exhaust cam is off by one tooth -- will check tomorrow.
3. Play with jetting to see if I can get a better mixture
4. Figure out if an electric fan or an electromagnetic clutch driven fan can be added -- current fan is direct driven
5. Figure out if I can retrofit a coolant recovery tank.

Regards,
Byas
Byas
1965 Fiat 1500 Cabriolet with 1600twin-cam
!971 VW 1302LS Convertible in original condition
1965 KG - under restoration
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Re: Returning after a long time.

Post by fp55scca » Fri Feb 02, 2018 12:44 am

--Byas, I'm confused, I thought the Fiat 125 1608 was fitted with an electromagnetic fan clutch? You are saying yours is direct drive?
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 Fiat 124 Spider
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Re: Returning after a long time.

Post by bnam2 » Fri Feb 02, 2018 4:15 am

Oh! I'm not so sure now. After an admittedly cursory look, I thought it was direct driven. I will check this evening.
Byas
1965 Fiat 1500 Cabriolet with 1600twin-cam
!971 VW 1302LS Convertible in original condition
1965 KG - under restoration
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Re: Returning after a long time.

Post by bnam2 » Fri Feb 02, 2018 8:55 am

I opened the valve cover this evening. Was shocked to see the #2 ex lobe. It was worn down by ~4mm. Wow! Need to get an exhaust cam right away. Intake looked ok. A quick search on cams showed vendors carrying cams with the disti drive, but not ones without. Will ones with the drive work in this cam tower?
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The timing marks seem to off by one teeth, but I'm not convinced the marks are in the right place either. Will wait till I can see the front of the cam wheel. The 2 wheels are of different design. I thought there would be some sort of permanent mark on the back of the wheels instead of paint marks.
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These 2 pics show the fan. Seems directly driven (agree?) unless the electromagnetic clutch is an extremely compact unit.
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Byas
Byas
1965 Fiat 1500 Cabriolet with 1600twin-cam
!971 VW 1302LS Convertible in original condition
1965 KG - under restoration
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