1969 Fiat 124 SpiderAS 1800 conversion

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Guy Croft
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Guy Croft »

Hi Charles - will get on this soon as I can.


very sincerely,

G
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

OK Guy, I know you're even more busy than normal so take your time!

Very sinceerely,

Charles
GC_26
Guy Croft
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Guy Croft »

1 The operator did not want to rev the engine above 7500 rpm even though he felt it did not yet run out of breath. What would be a safe rev limit for an 1800?

- if not on race pistons and rods I would cap it at 7800

2 Looking at the AFR graph it is a tiny bit lean above 5500 rpm. Would a smaller air correction jet yield result or is it too close to the optimum power AFR line. (I should have asked the operator yesterday and will do but would like your opinion also)

- yes


good work Charles!

GC
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

Many Thanks Guy!

very sincerely,

Charles
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

The event:
Last week when accessing the motorway in a u turn and accelerating fast suddenly a knocking sound occurred. I took my foot of the throttle and away it went until accelerating again. Oil pressure remained close to 60PSi so no bearing issue. Coolant temperature was 76 degrees C. I left the motorway on the next exit driving 60 km/h, parked at a fuel station and called a lorry to take the car and me home.

Circumstances prior to the event:

Short recap of the engine spec: 1756 cc TC, CR 10:1, GC modified head, GC2B inlet cam, OE exhaust, GC forged pistons, twin IDF 44, Filter King regulator and fuel filter, sealed cold air box with duct to remote air filter in front of car, 123 electronic ignition, low coolant temperature in head thermostat, aluminium radiator. 157 Bhp@7326rpm, 173Nm@5755rpm.

First start up April 2016, driven 10.000 km since then.

During engine life I have experienced a couple of times that the engine did not run on all cylinders on minimal throttle opening during cruising at low speeds. When opening the throttle (driving faster) it went away. The speed range above which varied from 95 km/h to 120 km/h. I suspected that the progression holes in one ore more carburettor barrels got partial clogged. Usually this phenomenon stopped after a while or after driving very fast or accelerating to 7500 rpm a couple of times. Last two times this occurred I noticed that cylinder 3 and 4 were not contributing on idle as I could pull the plug lead without effect on idle speed. I thought this to be caused by debris in the idle and progression circuit. I have never found debris however in the carburettor fuel bowls and fuel wells so it may also be the carburettor synchronisation off tune.

First 3000 km’s I have driven the engine on a wrong timing curve which had the effect that total ignition advance @ 3500 rpm and above has been 46 degrees where as 36 is considered to be maximum for the TC.

Coolant temperature has been fluctuating fast between 65 degrees C and 86 degrees C depending on ambient temperature, (air)speed and load. Below cruising at 90 km/h it can be 80 degrees C and when I accelerate to 125 km/h air speed to the aluminium radiator increases and it cools fast, depending on ambient temperature, to as low as 65 degrees C sometimes.

Fuel used has always been 102RON octane which is locally available (and methanol free so no issues with perishing tubber materials, no water in fuel etc.)

In the week prior to the event I noticed bubbling in the coolant expansion vessel. There was no oil in the coolant nor sludge in the oil. Compression test did not indicate a leaking head gasket (at that time) as all 4 cylinders gave 170 Psi.

The cause:
Once home I executed a compression test which confirmed my suspicion of a failed head gasket between cylinder 3 and 4 as the pressure in cylinder 1 and 2 was 170 Psi and in 3 and 4 it was 40 Psi. After head removal this was indeed observed. Gasket has not been damaged in other areas. The observation of gas in the coolant expansion vessel probably has been a precursor of the event caused by gas migration through the soft part of the gasket after the fire ring had been initially damaged.
Fortunately gasket faces of the block and head were not warped or locally damaged.

This leaves the question about the underlying cause of the head gasket failure. Possible causes of head gasket failure are:
1. Detonation due to high temperature of air intake and or high coolant temperature: not likely as engine has sealed cold air intake and low temp coolant thermostat.
2. Detonation due to wrong ignition timing. As the engine has seen too much advance in the first 3000 km’s of its life it may be possible that the damage has been initiated at that time. One would expect however that damage is not limited to the gasket part between cylinder 3 and 4. Curve has been set at 34 degrees including 10 degrees static advance.
3. Detonation due to wrong octane fuel: not likely as 102 has been used throughout.
4. Detonation due to over lean fuelling: possible as the engine has not been running on all cylinders during part throttle on a couple of occasions due to fouling and or wrong synchronisation between front and rear carburettors. Rear cylinders have been observed not to contribute on idle; the location of the gasket failure. Plugs and combustion chamber were black and not whitish as expected to be from lean mixture. The black carbon and soot may however be formed after the gasket failure. Action: check synchronisation and adjust if needed after start up.
5. Gasket degradation due to steep coolant temperature transients that have been occurring. Possible but one would expect however that the gasket damage would not be limited to one location. Action: To be further examined and air flow through the radiator to be optimized at lower speeds by adding an engine under tray.
6. Gasket failure due to mechanical parts not fit for purpose or incorrect installation. Not likely as GC race head gasket, GC 12.9 grade race head bolts and washers have been used. Head has been modified and skimmed by GC and a new old stock engine block was used (also checked for flatness prior to use). Installation has been executed according to GC instructions.

I have to conclude that the root cause cannot be solidly confirmed at this point in time. Some preventive measures can and will be taken however. Lesson learned is to consider gas in coolant as a precursor of head gasket failure followed by corrective action before stranding on the side of a road.

Corrective action

Gasket faces on Head and engine block cleaned with solvent and scotch brite. Head bolts have been cleaned as well the female threads in the block. All parts needed have been delivered so the head will be installed next.
Attachments
Ready to take it home after stranding
Ready to take it home after stranding
IMG_1662.JPG (128.05 KiB) Viewed 44760 times
Compression test confirmed head gasket failure between cylinder 3 and 4
Compression test confirmed head gasket failure between cylinder 3 and 4
IMG_1665.JPG (121.47 KiB) Viewed 44760 times
Failed head gasket
Failed head gasket
IMG_1707.JPG (96.19 KiB) Viewed 44760 times
No damage between cylinder 1 and 2
No damage between cylinder 1 and 2
IMG_1708.JPG (107.29 KiB) Viewed 44760 times
No damage between cylinder 2 and 3
No damage between cylinder 2 and 3
IMG_1709.JPG (62.6 KiB) Viewed 44760 times
Damage between cylinder 3 and 4. Arrows indicate possible leak path of gas to near by coolant gallery through gasket after initial damage and before total failure.
Damage between cylinder 3 and 4. Arrows indicate possible leak path of gas to near by coolant gallery through gasket after initial damage and before total failure.
IMG_1710.JPG (88.99 KiB) Viewed 44760 times
engine deck cleaned, stained but flat (galvanic corrosion between cast iron and graphite in gasket?)
engine deck cleaned, stained but flat (galvanic corrosion between cast iron and graphite in gasket?)
IMG_1704.JPG (123.7 KiB) Viewed 44760 times
Gasket face Head cleaned, stained but flat (galvanic corrosion between aluminium and graphite in gasket?)
Gasket face Head cleaned, stained but flat (galvanic corrosion between aluminium and graphite in gasket?)
IMG_1706.JPG (126.56 KiB) Viewed 44760 times
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

Last week I installed the head. Though on the engine stand using guide bolts for the head works quite well it turned out not to be possible in car to use because the head is situated under a beam on the fire wall. For the rest is the installation, commissioning and start up were uneventful operations.

Mismatch in synchronisation was identified to be one of the possible causes but measurements did not reveal an issue. First 20 kms after startup the pick up was not good giving slight misfiring/not running on al cylinders/detonation(?) on progression phase as described before but this vanished and now it is running as before and a joy to drive again. This remains a worrying issue though and I will flush the fuel system once again. Any suggestion from the readers about the origin of or experience with this intermittent problem is highly appreciated.
Attachments
Though initially installed these guide bolts did not work due to the head fouling a beam on the fire wall
Though initially installed these guide bolts did not work due to the head fouling a beam on the fire wall
IMG_1720.JPG (113.93 KiB) Viewed 44710 times
Check on front to rear carburettor synchronisation did not reveal a difference
Check on front to rear carburettor synchronisation did not reveal a difference
IMG_1732.JPG (132.75 KiB) Viewed 44710 times
Last edited by Spider 1969 on April 13th, 2018, 7:39 pm, edited 1 time in total.
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

Update: no work on the Spider this winter as I have been working on a MGB GT inherited from my late father. This has been in a barn for 24 years and I replaced all brakes and overhauled the engine. (No intention of starting up an engine after all these years and the engine strip revealed rust in the bores so once again proof that one should not start up engines after standing idle for long) Engine will be installed and started up within the next week so after that I can start working on the Fiat again as the MGB has been parked under the lift the Spider is on! Bit of a hassle to push the MGB out, I prefer to drive it out ;-)

Today I received a beautiful exhaust header as supplied by a GC agent for the next upgrade on the Spider. Next step is to design and construct a stainless steel 2.25" exhaust system. Looking forward to develop my TIG skills!
Attachments
Shiny Thing Alert!
Shiny Thing Alert!
Header-001.jpg (98.3 KiB) Viewed 44287 times
Last edited by Spider 1969 on April 30th, 2018, 6:55 pm, edited 1 time in total.
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Will01
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Will01 »

What a beautifully looking crafted exhaust!
Good luck with the rebuild
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

Thanks Will!
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

It turns out that the exhaust header does not fit a Spider with the pre 85 steering mechanism. So I will have to convert to rack and pinion steering. As spring has started I want to drive the Spider instead of initiating a modification project. The conversion will be done next winter which also gives me time to plan and gather the parts needed.
Attachments
The primaries blocked by the steering mechanism
The primaries blocked by the steering mechanism
Header_MCA-006.JPG (122.03 KiB) Viewed 44051 times
Last edited by Spider 1969 on May 9th, 2018, 9:12 pm, edited 1 time in total.
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Guy Croft
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Guy Croft »

MODEL POST dear C de V!

Thank you very much for sharing this important information..

I wish a few more would post and bring interest!

GC
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

Yes indeed dear GC! I wish I had some interesting project running to post about. Rebuilding a MGB engine, albeit with a bit more attention to detail than the average DIY engine builder, isn't. Next winter will be better.
Sincerely,
C de V
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

Update from this winters work up until now:
Objective is to upgrade the exhaust header to a GC approved design. In order to make it fit also a change to rack and pinion steering had to be made.
Basically this involved removing the original steering parts and installing as using as much original steering parts available from the post May 1985 DS1 Spider. Parts that were needed were:
• DS1 front suspension cross member with steering rack supports;
• DS1 post may 1985 steering arms (left and right, these are very rare, it took more than three months to source)
• Steering Rack, ball joints, steering rack mounting rubbers and steering rack brackets
• DS1 post May 1985 Steering linkage
• DS1 post May 1985 Upper steering column
• DS1 post May 1985 Pedal Box as the angle of the steering column is more horizontal. This was proven impossible to find however. Later on I discovered that the later pedal boxes no not align the same way as my early spider AS to the fire wall. (earlier design aligns perpendicular to fire wall as later designs are located at an angle towards the center of the car). This would have made a post May 1985 not usable in my AS.

In order to install the parts also the next modifications needed to be made:
1 Modify the DS1 cross member to AS specification as the cross member is located 5 mm lower with respect to the body and sump on CS2/DS1 two liter cars.
2 Modify the AS pedal box steering column angle to post 1985/5 design
3 Relocate the firewall steering linkage hole
4 Modify the brake pedal to clear the steering linkage
5 Modify the location of the steering rack on the DS1 crossmember as it turned out to be dislocated 10 mm’s to the right.
6 Modify the gear box cross member as I had to increase engine height to clear the sump from the steering rack.
7 Modify the carburetor throttle linkage as the old (BS1?) design had one bracket located on the steering box that has been discarded.
In next posts I will elaborate a bit on all these modifications up until where progress is at present.
Attachments
Some of the parts needed
Some of the parts needed
RNP_STEERING_SHAFT-001.jpg (91.97 KiB) Viewed 42152 times
Last edited by Spider 1969 on May 18th, 2019, 7:10 pm, edited 2 times in total.
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

1 Modifying the cross member:

The two liter models (CS2 /DS1) have their cross members lowered with respect to the sump and frame rails. Reason being probably to create room for the two liter sump.
Fiat did this by adding a 5 mm strip to the part that bolts to the frame rails and by adding a 5 mm strip under the part taht holds the engine mounts.

I did not want to fit the DS1 crossmember this way to my early style body.

So I dismantled the engine mount brackets and removed the 5 mm strips and welded the brackets back on. I aligned the brackets by bolting the cross member and brackets on the car and then tack welding the brackets in the right location. Also I removed the strip on the frame rail brackets. See below photos.
Attachments
Added strips between Frame rail and cross member
Added strips between Frame rail and cross member
FIAT_Rack and Pinion-001.JPG (87.14 KiB) Viewed 42152 times
Engine mount bracket removed
Engine mount bracket removed
FIAT_Rack and Pinion-002.JPG (95.95 KiB) Viewed 42152 times
Both brackets and strips removed
Both brackets and strips removed
FIAT_Rack and Pinion-003.JPG (113.29 KiB) Viewed 42152 times
All welded back before paint
All welded back before paint
FIAT_Rack and Pinion-005.JPG (100.25 KiB) Viewed 42152 times
Last edited by Spider 1969 on May 9th, 2019, 7:42 pm, edited 2 times in total.
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Spider 1969
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Re: 1969 Fiat 124 SpiderAS 1800 conversion

Post by Spider 1969 »

2 Modifying the pedal box:

Due to the different steering shaft design the angle by which the steering column is mounted under the dash to the pedal box is more horizontal on the DS. I found that if one tries to use the original angle ones foot will interfere with the steering shaft while braking. Needless to say this is "undesirable".

So I took off the plate on which the steering column is bolted , modified the angle of the side plates and welded the plate back again. See below photos.
Attachments
Modified before paint
Modified before paint
RNP_PEDAL_BOX-004.jpg (103.4 KiB) Viewed 42152 times
Original and modified side by side
Original and modified side by side
RNP_PEDAL_BOX-005.jpg (57.23 KiB) Viewed 42152 times
Note the more horizontal angle
Note the more horizontal angle
RNP_PEDAL_BOX-006.jpg (58.33 KiB) Viewed 42152 times
Last edited by Spider 1969 on May 9th, 2019, 7:42 pm, edited 1 time in total.
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