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Are Large Capacity Petrols A Dying Breed

A-AvantGarde said:
The difficult thing to predict is the price of fuel and likely future residuals. Like some others have said, I'd love to tick the V8 petrol thing off my list of things to have done!
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May I recommend scratching the petrol V8 itch via a Westfield or Dax Cobra kit car, or even an E39 M5 or S-Type R? This way the depreciation will be negligible and the driving reward greater. I do believe I saw a Dax Cobra with a 500hp V8 for sale not so long ago for not a lot of money.
 
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A few more weeks here Charles and I'm tempted to get into a big block, just for the h3ll of it to be honest. It is one of the must do's in life. I need a big chassis though, there are tempting prospects on that site........
 
Peter DLM said:
May I recommend scratching the petrol V8 itch via a Westfield or Dax Cobra kit car, or even an E39 M5 or S-Type R? This way the depreciation will be negligible and the driving reward greater. I do believe I saw a Dax Cobra with a 500hp V8 for sale not so long ago for not a lot of money.
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Excellent advice sir!

You're quite right, the V8 itch is probably best served by something else. A petrol V8 doesn't really suit the R Class or the GL...

Have always liked the Dax Cobras, quite like a lot of American metal too :D Hmmm...
 
Damn right ;) I had a 2002 S-Type R. I can recommend them, though I'd like a nice little two seater thing with obnoxious V8 if I were you. :) In my distant past I also had a Trans-Am and SD1 Vitess, probably wouldn't suggest that route again though.
 
Quite a few are the 5.0 + performance heads etc etc = VERY scary
 
Charles Morgan said:
The new engine isn't even run in - 37000 revs in total recorded - so about an hour's running tops. An oil change after 200 miles is for certain. You are right about the heat around the cylinders, dear old Henry designed it with the exhaust in the block, but this has huge water capacity and the radiator is being recored with a much higher capacity, and new water pumps too. The later flatheads really had cooling licked - this one has no rust or crud build up inside the block either, so I am hopeful that overheating (the cause of all the problems) will not be an issue again (digits and member crossed).

Certainly not me causing the gearbox mangling - the whole car has only done about 60 miles in my ownership! There is synchro on 2 and 3rd, but that was such a rotten repro it was ovalled before fitting!

I also suspect lubrication has not been done properly - there are 13 lubrication points around the chassis and it needs to be done regularly.

Thanks on the engine oil - it is much appreciated!
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I noticed (Wiki!) that tuners smoothed the exhaust ports where they pass through the water jacket, primarily to aid exhaust flow. The same will reduce the surface area through which the exhaust heat can be absorbed, and reduce the turbulence which thins the boundary layer and aids unwelcome heat transfer.

Re engine oil. I'm surprised - the Shell oils recommended are multigrades. Shell PDF here >> http://www.epc.shell.com/Docs/GPCDOC_GTDS_X-100_Super_(SGCD).pdf

The flathead has so little valvegear and so low in the engine that the normal cold start requirement of having to pump oil a great height through restrictive galleries as OHV engines require is non existent. As is the requirement for emissions equipment capability, which, often leads to the deletion of good anti-wear additives. For those reasons, I'd consider a straight 30weight. You would take care during warm up, but at 40C the straight30 is still thinner than a 15W/40.
I'd recommend having a look at these two:


Item # 8800, Monolec Ultra® Engine Oil 8800 on Lubrication Engineers, Inc.
This one has API-CJ. I havent seen another oil on the market that surpasses API-CF which is a 16 year old spec.


Item # 8430, Monolec® GFS Engine Oil 8430 on Lubrication Engineers, Inc.
The only thing against this is the Diesel only recommendation but I've known this oil perform where others couldn't in engines running on methane - an incredibly corrosive fuel.

Both oils have the gift of being very tacky on cooling allowing them to cling to components when the engine is shut down - very useful for occasional use motors, and they are exceptionally kind to seals, preventing leaks.

The piston rings have to be thoroughly bedded in for these oils to work though.
 
On exhaust flow, the garage doing the rebuild specifically encouraged me to have twin exhausts to improve the flow out significantly as that is a weakness of the engine (and a tiny original Allard exhaust). I was persuaded by others to ensure they were fully silenced though - this is a whispering V8, I imagine very gangsters in their Ford V8s cruising in near silence with their Thompson sub-machine guns at the ready!

The Shell oil comes from a 40s Shell lubrication sheet for the car. It wouldn't surprise me in the slightest if the specification has changed over time. I would be most surprised if multigrade oils were common in 49, but I could be wrong.

The oil suggestions are going to be researched in full, thank you. I think you have the requirements spot on. The original engine (at 63 years old) showed considerable signs of bore wear (another reason why I decided to replace it - a cracked block and worn bores just pointed to a tired engine that would consume a lot of labour to sort and it would still be old).
 
Oil being a multigrade or not isn't the issue, what you will need to look into is what the plain bearing material is so that modern oil additives don't attack it.

Twin exhausts, even silenced, will passmore gas than a single small bore. If having exhausts made, fit a pressure test point to check for minimum back pressure.
One reason small bore is used is to naturally supress noise without the need to ad more restrictive silencers.
 
Charles Morgan said:
The Shell oil comes from a 40s Shell lubrication sheet for the car. It wouldn't surprise me in the slightest if the specification has changed over time. I would be most surprised if multigrade oils were common in 49, but I could be wrong.
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I've found a bit more info on Shell X 100. On a document dated 1989 it is listed as a straight grade oil with four viscosity grades available. They were: 10W. 20W/20, 30, 40. The second listing is very strange for a 'straight'! API classifications are CC, SF.

Charles Morgan said:
a cracked block .
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One crack or multiple cracks? Where? Does the Allard have thermostat(s)?

Dieselman said:
Oil being a multigrade or not isn't the issue, what you will need to look into is what the plain bearing material is so that modern oil additives don't attack it.
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Fair point DM. What metals do you have in mind as being troublesome? Yellow metals are well known for being susceptable to EP additives, but can't imagine the flathead has yellow in it - but there will be a skew for the dizzy and probably oil pump which could I suppose have bronze.
Strangely enough, if that was a requirement, it would point in the direction of an ultra modern oil shorn of the anti-wear packages deemed poisonous to cats.


Shhh.. But I heard a certain V8 the other day. Sounded like percussion on a biscuit tin. A few months prior I'd noticed a CLS then noticed its sound - all subtle unruffled woofle. I know which I prefer.
 
Have you considered that electric cars may kill off big V8 petrols and twin/triple turbo diesels. As of now you can buy the Tesla Model S in the USA. A five seat big hatch/coupe which will do 300miles on one charge, hit 0-60 in 4.4 sec and is limited to 130mph for $97K.

As long as we can make enough electricity there is no reason why these types of cars may not take over.
 
Bellow said:
I've found a bit more info on Shell X 100. On a document dated 1989 it is listed as a straight grade oil with four viscosity grades available. They were: 10W. 20W/20, 30, 40. The second listing is very strange for a 'straight'! API classifications are CC, SF.



One crack or multiple cracks? Where? Does the Allard have thermostat(s)?
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Cheers - the 20 20 is actually the winter spec for the flathead.

We did a block test after draining and refilling the engine coolant - the water came up beautifully yellow with a hint of green. The Allard has a thermostat on one side of the block, but the water pump on the other side seized (it has a pump for each side) causing localised overheating and while this might well have caused it, there is evidence to suggest the engine had overheating problems before. Given compression was poor it was decided to scrap it rather than spend a lot of money stripping it down and determining it was unfixable.

I have the block but haven't the energy at present to strip it down - the water channels are pretty heavily rusted and silted. The early 21 stud engines were renowned for poor cooling and getting silted up from the casting sand.
 
Charles Morgan said:
Cheers - the 20 20 is actually the winter spec for the flathead.
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Will you be able to find out more re the material content of the engine?

Charles Morgan said:
We did a block test after draining and refilling the engine coolant - the water came up beautifully yellow with a hint of green. The Allard has a thermostat on one side of the block, but the water pump on the other side seized (it has a pump for each side) causing localised overheating and while this might well have caused it, there is evidence to suggest the engine had overheating problems before. Given compression was poor it was decided to scrap it rather than spend a lot of money stripping it down and determining it was unfixable.

I have the block but haven't the energy at present to strip it down - the water channels are pretty heavily rusted and silted. The early 21 stud engines were renowned for poor cooling and getting silted up from the casting sand.
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If the sign of overheating is cracking, there may be another cause.
Some engines (usually smallish 2-strokes) with thermostats suffer from what is referred to as 'cold siezure'. What happens is the 'stat stays closed untill the block/cylinder(s)/heads have fully heated then open and stay open while all the heated coolant rushes past enroute to the radiator. The water entering the engine to replace the evacuated hot water is stone cold though. In a small 2-stroke the sudden cooling causes the cylinder to contract around the hot expanded piston and nips it. On a cast iron block such as yours, I'd expect cracking from the thermal shock. (More than happy to hear the views of other's on this).
Elimination of the stat is the solution (if a problem) but it will then (obviously) take longer to warm up allowing a greater amount of pollutants into the oil requiring the oil to have sufficient detergency to cope. The 'stat removal option is, I think worth thinking about, especially if the car will only do longer trips - which will help alleviate the oil issue also. Thoughts of others on this?
 
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Isn't that waht the small hole in the thromostat flange is there to help avoid.........??
 
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