Head Gasket Blown between cylinders

Road-race engines and ancillaries - general discussion
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Spider 1969
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Head Gasket Blown between cylinders

Post by Spider 1969 » Sun Oct 26, 2014 9:07 pm

My 1608 Fiat TC has blown the head gasket in between cylinder 3 and 4. See attached pictures. The engine did feel a bit odd the months prior to this happening but having checked timing and carburetor (Twin IDF's) synchronition did not reveal or improve anything. Then during starting (warm engine) it blew. I drove 2 kilometers to a garage near by (detonated badly on load) to have it stored prior to shipment home. Probably shouldn't have done that as the head now needs to be skimmed and possibly the block also.
This isn't the first time; about 65.000 kilometers/thirteen years ago it happened too but than it was between cylinder 1 and 2. At that time it was on full throttle going up a mountain in southern France.
Friend of mine also had this problem on his 1800 Fiat TC.

We both run twin IDF 40's with K&N filters. Availability of 98 RON fuel has deteriorated here in Holland and sometimes I have to run 95 RON but can not detect detonation when doing so. Apart from maximum (+1 mm) bore pistons the engine is otherwise standard and runs a non standard 4 to 2 exhaust collector with a european spec standard 1800 exhaust. The car is a 1969 Fiat Spider.

I would like and appreciate some advice on the cause and how to prevent this.

Regards,

Charles
Attachments
Head Gasket Gone Between 3 and 4-002.JPG
Head surface prior to clean and strip
Head Gasket Gone Between 3 and 4-002.JPG (170.93 KiB) Viewed 1386 times
Head Gasket Gone Between 3 and 4-001.JPG
Gasket on block after lifting the head
Head Gasket Gone Between 3 and 4-001.JPG (146.01 KiB) Viewed 1386 times
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Guy Croft
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Re: Head Gasket Blown between cylinders

Post by Guy Croft » Tue Oct 28, 2014 7:43 pm

When they blow this is where it happens. No mysteries here.. With front coolant exit the back of the head is the hottest part. preignition or mild detonation has occurred here.

Solutions:

1. Ducted air intake. If you are using the OE air filter - not a disaster but you are still drawing VERY hot air from the under hood. Is an airbox available? NO! You have to make one.
2. Machine head AND block flat. I know you will not like that!!!
3. Buy a low temp thermostat and race grade head gasket and bolts from me.
4. Modify the coolant galleries in the head. All GC prepped heads get this.
5. Use Fiat Pink Paraflu coolant additive.
6. Use a Facet interrupter electric fuel pump if the engine currently has a mechanical pump. With the latter the gasoline boils at high ambient temperatures and high altitude making the mixture over-lean. If this applies to you email me at guy.croft@btconnect.com

GC
Guy Croft, owner

Rallyroller
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Re: Head Gasket Blown between cylinders

Post by Rallyroller » Wed Oct 29, 2014 4:00 pm

Hi Charles
cannot really offer any comments ( and Guy is the expert) but I was wondering why one set of valves is clean and one set covered in carbon? If they are cyclinders 3 and 4 then they are off the same carb. ( Or I may be missing something)

Nigel.
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Spider 1969
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Re: Head Gasket Blown between cylinders

Post by Spider 1969 » Wed Oct 29, 2014 9:35 pm

Guy,

Thank you for your advice and I will e-mail you on the parts needed.

Nigel,

Yes hey are being fed by the same carb (different chokes though). Reason for the clean valves (and piston) on #4 cylinder is that it has been "cleaned" by steam being formed due to coolant leaking into the cylinder.

Regards,

Charles
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Rallyroller
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Re: Head Gasket Blown between cylinders

Post by Rallyroller » Thu Oct 30, 2014 3:43 pm

Hi Charles

That would do it. - So if you can desgin a steam cleaner for inside the engine it would save on a decoke!

I ran my 1608 Spider for 4 years as my everyday car and also road and staged rallied it back in the 80's. Never had a problem. Gas flowed head, 4 branch, Piper cams and re jetted 40 IDF's. ( all done before I bought the car). I suspect the jetting was for power rather than economy. Is this more of a problem on twin carb cars? perhaps they are driven harder?



Nigel.
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Spider 1969
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Re: Head Gasket Blown between cylinders

Post by Spider 1969 » Thu Oct 30, 2014 8:46 pm

Twin IDF's should be more economical compared at equal speed to a single carburetor. Mine drives 12 kilometers per litre on average which isn't bad. It doesn't improve if I limit my speed to 80 km/h and I really need to push real hard to make it worse.

Charles
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