Question is 800cc just too big for the two cylinder engine? Having got the 795cc Alquati engine back together and running for the first time since about 1985 my initial observation is that the engine runs so hot. I have the engine running on a wobbly table top and so far I have had it going for about 2 1/2 hours in 4 different sessions. The ignition timing is spot on and I have fitted a standard 126 carb at this stage. Put a gas analyser on it and the mixture is spot on to slightly rich. The thermostat will open fully after about 25 mins on tickover with just a couple of brief blips of the throttle. A proportion of the cooling air from the fan is lost due to the gap by the alloy sump so I am going to look into making a cover panel but I am not sure if this or fitting an oil cooler will get the temperature down to a reasonable level.
Tuning It Ain't Half Hot Mum
- Thread starter Toshi 975
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Tuning It Ain't Half Hot Mum
Maybe get it in the car ASAP and drive it around. More cool air entering the system?? Getting the rings to bed in without driving under load could result in glazed bores. ( this happened to my Austin7 engine)
the hobbler
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At 800cc, I am not surprised that it runs a bit hot! Abarth and Giannini both stopped at 700cc (689.542cc to be precise in Abarth's case)---there must have been a very good reason why they didn't go any bigger. In Abarth's case, they increased the stroke and decreased the bore (76mm x 76mm) to get the required capacity for their '695'. It wouldn't have been difficult for them to use bigger barrels to bring the capacity up to about 750cc, but they didn't---WHY?
I am also surprised that with a standard '126' carb (28IMB ?) the mixture comes out as 'slightly rich'---I would have thought that the '28' would not have been big enough to be able to supply enough fuel---Abarth used a 34PBIC on both the '695' and the '595'.
The 'air-shield' at the base of the fan housing may help a little, in the air will be directed over the sump rather than leaking out. Oil can also contribute to engine cooling---what oil are you using. I use a 10/60 oil---Millers 'Nanno drive' oil is a very good oil, albeit expensive.
I am also surprised that with a standard '126' carb (28IMB ?) the mixture comes out as 'slightly rich'---I would have thought that the '28' would not have been big enough to be able to supply enough fuel---Abarth used a 34PBIC on both the '695' and the '595'.
The 'air-shield' at the base of the fan housing may help a little, in the air will be directed over the sump rather than leaking out. Oil can also contribute to engine cooling---what oil are you using. I use a 10/60 oil---Millers 'Nanno drive' oil is a very good oil, albeit expensive.
I feel for you Dave, hot running is a fact of life with these motors if they are modified an any manner!!
I don't consider 800cc to be excessive though - if it was the plethora of mods available to your capacity would not exist. How many suppliers list cylinders + pistons as a bolt on !! I will say that with my present engine at 712cc (80.5mm piston) with ported panda head, 9.8:1 C/R, weber 30 DGF and a racing style big bore S/S exhaust - it gets very hot with the oil temp reaching 80degC quickly and 90degC soon after. I tend to set my cooling fan running when temps get to 85 - 90degC and I have found that the temp will slowly stabilise at just above 80degC with the oil pressure around 3bar. I would council you to fit it soon and include an oil cooler, you will be amazed how much control you have over the running temperature Ian.
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I am thinking something similar re road rather than bench testing. I think that it will be a case of "death or glory" so fingers crossed. The Alquati sump has a large ribbed base for cooling that is getting no air on the table top. Also the jumbo hose being disconnected is listed in the manual as a cause of overheating so that may help but not sure why it should.
A friend, much wiser than me in the ways of engines, once told me not to try running in new rings with fully synthetic oil. So they have been running on mineral oil for the first hour or so then drained and filled with 10/60 fully synth to cope with high temperatures. Friend also said that the rings bed in with the first few revs of the engine so hope that is taken care of. Number 2 piston had showed signs of overheating and the original cast iron oil ring came out in bits. So after restoration that piston is switched to number 1. Spent many hours looking for suitable replacement rings and finally fitted some Toyota rings that I believe are superior to the originals.
Hi Dave, I don't think you will have death or glory to contend with, the 800cc mod is well known and the Italians know their engine and mods well. I did the same as you with initial running in, but used a mineral 20/50 for a few miles and then switched to mobil 1 10w 60 to continue and so far so good. All of my overheating has shown up on the number two piston too so maybe it is a problem with that cylinder running hotter and cooling and the engine design. One thing I do feel is that it is imperative that you minimise cooling air loss from the fan housing and maintain good cooling, keeping the air in contact with the engine cooling fins by having good tinware, I do not connect the heater at all but allow the air to escape from the thermostat housing too. My sump is a 4ltr and as the engine is lowered slightly it is in the underside airflow more. I feel the need for a cooler to control excessive oil temperatures at 80 to 90degC and possibly 100degC if you are trying hard is paramount as a good oil can only do so much.
Ian.
There's got to be a point where you are simply burning more fiuel and therefore creating more heat than the cooling system was designed to deal with.
My baptism with 500s was when my brother came home with one in 1983 and was plagued for days with overheating. It turned out to be missing the big intake pipe and replacing it sorted the problem instantly.
My baptism with 500s was when my brother came home with one in 1983 and was plagued for days with overheating. It turned out to be missing the big intake pipe and replacing it sorted the problem instantly.
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I am running with 10/60 Mobil 1 same as Ian, as you say not cheap.
It does seem strange and rather frustrating that so little is known about the Alquati story compared to the other better known tuning / racing organisations. As far as I am aware the Alquati tuning ideas were developed by Camilo Alquati along with a racing team that focused mainly on the Fiat 500/126 and the twin cam 131 & 132 engines. The heritage lives on with some Alquati reproduction parts still available and original parts much sought after. So I have no idea how successful the team were or if the 800cc engine was the Alquati standard. In a conversation I had some years ago I was told that one of the Alquati team came to work in London for Italtune and Lanciana mid 1980's and was the guy who was most likely to have done the conversions in the UK, I have a name somewhere. There may be three other original 800cc that have survived but only one is traceable at the moment.
The standard Weber 28IMB is perfectly capable of supplying sufficient fuel air mixture to the engine as that is determined by the jetting. Would be exactly the same as running a Weber 30DIC or 30DGF twin choke carb and just giving it half throttle so as not to activate the secondary choke. The restriction would come if you wanted full beans which is not my priority at the moment but I have a twin choke Weber or a Dellorto FZD waiting in the wings
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the hobbler
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I think that the reason that an 'in situ' engine runs cooler with the big air-duct in place is that with it in place you are pulling in (relatively) cold air from outside the car---with no ducting in place you are pulling in air that is already at engine bay temperature. I think, after studying Peter's picture of his 'Alquati' engine running, I think one reason it runs hot is that by sitting on its sump, cooling air is not being blown across it. Some heat will be transfered to the table, which will then help keep the oil warm.
Ian I think that is the first picture I have seen of your engine bay in the earlier post, very impressive. I wanted to restore this engine to the original "tuned" condition without any frills pretty much as a piece of Fiat history. The original fan on the engine when I bought it was a very nice steel backed unit with high density plastic fins. That fan is currently in my 500 but I have only seen one other the same when a guy asked me to rebuild his engine and I have never seen anything like it for sale. I held back from fitting an alloy fan and went for standard at the moment and will also fill the gap at the sump. This original Alquati sump is also 4 litre.
Out of interest apart from this engine I have worked on three others this year that suffered piston overheating , a 499, 594 & a 652cc and in each case the overheating was worse or only on no 2 piston.
That was my worry and why I posed the original question. The guy who commissioned this engine back in the mid 80's told me that he only ran it for less than 3,000 miles and the condition of the bearings after the crank regrind bear that out. During that short time he experimented with different carbs and possibly other mods but he was an enthusiastic racing driver and renowned test pilot with a need for speed. I guess the heat was a problem hence the uprated fan. There was also evidence of pipes being connected at the bottom of the cooling housing going by some "P" clips but none were still there when I got the engine so that will remain a mystery.
Hi Dave, I really would like to see a picture of this fan unit??? I have an alloy fan in my engine to date and it seems to be doing it's job well, but, I am wondering if a tooth belt drive arrangement (from crankshaft to alternator) can increase the speed of the fan to create more airflow???? I don't know what the ratio is??? I must say that there are places where I can improve the airflow around the fins by closing off all the little air flow escape gaps - as they say 'every little helps'!
The problem with the number two piston maybe design related, slightly hotter running at 90degC could mean 100degC !!!!!!! Even a robust engine like these will not tolerate a heat differential across the cylinders of that much for too long. I've had problems acquiring a temperature switch that will actually control my cooling fan automatically, although I have the correct temperature range (on and off) all the switches I have don't operate as I require so I have a little piece of wire to isolate the switch and get the fan running and I don't drive without it
I'm running with slightly richer jets in the carb too, to aid cooling. Ian.
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Definitely right there Tom if the engine is in situ. At the moment mine is sucking in the atmosphere from my garage. Sump cooling is worse than that as I put the engine on a thick spongy layer to try and absorb some of the vibration partly because the table top is not fixed and the engine is unrestrained so I have to keep an eye on it during trial runs as it tends to go "walkies"
I started measuring and making a template to make a cover for the base of the cooling housing then gave up for now as it was driving me crazy. Big gap now covered with Gorilla tape for a test run
So ran the engine again for a little over 20 minutes and it seemed to heat up noticeably slower just with the tape cover in place. Lessons being learned here so I may look into modifying a fan housing that ensures maximum air flow to the upper engine. I believe that the Panda 30 tinware directs most cooling air across the cylinder head.
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You are correct Dave, the Panda (or bambino in Germany) fan housing is much better at directing cooling air to the engine in my opinion, the Panda thermostat housing is much smaller and only fits to the head. The hot air being exhausted from the engine below the housing into the engine bay (a picture of a modified engine by Il motore of Germany shows this well) My engine has a modified 500 fan housing and a modified 500 thermostat housing to do the job, I don't use the heater hoses as they will restrict airflow. I have a bambino fan housing now and a Panda thermostat housing and they will go onto the engine during the winter.
Ian.
