Tuning a 918?

for those with Series MM sidevalve cars produced between September 1948 and February 1953
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youngcamper
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Tuning a 918?

Post by youngcamper »

Good Afternoon Chaps,

As per the thread title really, are there any ways to get a bit more grunt out of the old 918 ? (bar alta head and suchlike)

Cheers,

Will
Will
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bmcecosse
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Re: Tuning a 918?

Post by bmcecosse »

They were known to be supercharged back in the day..... :D
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mike.perry
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Re: Tuning a 918?

Post by mike.perry »

I suggest that you move this to the Series MM section
Try reading "Tuning Side Valve Fords" by Bill Cooper. You will see that the engines are very similar, some say that the Morris is a copy of the Ford.
The two engines have the same port spacings so Ford Aquaplane accessories will fit.
The engine needs to be in good condition as does the distributor. Internal work can include slightly oversized inlet valves, polished ports and raised compression by skimming the head although care should be taken not to take to too much off or you will be too close to the water passages and this can lead to stress fracures above the pistons. The alternative is to fit a Derrington Alloy head.
The biggest single obstacle is the exhaust manifold with its right angle bend so a decent 4 into 2 into 1 downpipe with an inlet for twin H1s or a single H2 (keeping a period look to the engine) should work wonders.
You should be looking to improving low rev torque rather than top end power, considering the long stroke and piston speed and the fact that the engine is revving at 4000rpm at 60mph, a speed that it is quite capable of maintaining.
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youngcamper
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Re: Tuning a 918?

Post by youngcamper »

Thank you Mike for taking the time to write a long and detailed reply, it certainly gives much food for thought. I am quite supprised by the number of parts suitable for side valve tuning. From the sound of things a Derrigton head, aqua plane inlet manifold and twin H1 carbs would be a good starting point combined with a suitable exhaust manifold (aquaplane again or possibly home made)

I must make sure I get hold of that tuning for side valves book. Now where did I plant that money tree...

Cheers,

Will
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bmcecosse
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Re: Tuning a 918?

Post by bmcecosse »

Supercharging will be by far the easiest - and most effective - way to go... It also has the benefit of increasing power throughout the rev range - whereas the mods suggested above will only show significant increase at decent revs.
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youngcamper
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Re: Tuning a 918?

Post by youngcamper »

bmcecosse wrote:Supercharging will be by far the easiest - and most effective - way to go... It also has the benefit of increasing power throughout the rev range - whereas the mods suggested above will only show significant increase at decent revs.
How would one go about supercharging an engine BMC ? I am open to all suggestions :D
Will
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bmcecosse
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Re: Tuning a 918?

Post by bmcecosse »

Buy supercharger, fix it to the engine, arrange belt drive from crank, attach carb to supercharger - and hold on tight! It was done to 918 engines back in the day - I'm sure there is a story about it in one of the old Minor books -I'll try to find it later.
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mike.perry
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Re: Tuning a 918?

Post by mike.perry »

Keith Luck is the expert on supercharging side valves, he runs a convertible with an Alta head and a Shorrocks supercharger and I know from his installation that there is a little more to it than bolting on a supercharger and a few drive belts.
There are several articles on tuning side valve Minors in Morris Minor Series MM and Series II Brooklands Books and also a chapter in Paul Skilleter's Original Morris Minor
Last edited by mike.perry on Fri Jan 11, 2013 11:40 pm, edited 1 time in total.
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orb596
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Re: Tuning a 918?

Post by orb596 »

How about writing an article on this subject for Minor Matters Mike? I think it would go down well with us MM owners as they are not the fastest machines in the world!! :-?
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youngcamper
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Re: Tuning a 918?

Post by youngcamper »

Agreed!

I personally would be very interested in hearing more about modifying the good ol' 918.

On that subject, are there many Derrigton heads about ? I'd quite like to get my hands on one if possible :)
Will
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mike.perry
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Re: Tuning a 918?

Post by mike.perry »

youngcamper wrote: On that subject, are there many Derrigton heads about ? I'd quite like to get my hands on one if possible :)
Join the queue - behind me.

A few tips on tuning the side valve, some are stating the bleeding obvious, some you may not have thought about.
Make sure that the engine is in good condition and all 27 1/2 horses are present and correct, you are wasting your time tuning a knackered engine

Do a compression test, as a guide I was getting 130psi on a newly rebuilt engine
Service the engine, plugs, points etc
Make sure that the distributor is in good condition with no sideways movement of the cam or excessive rotational slop.
Check the distributor drive dog for wear, they are replaceable, and also check the slot in the top of the jackshaft, this can be closed up with a drop of weld and filed to a good fit with the distributor drive.

The book says set the timing to TDC and road test, easy enough if you do not have a water pump, if you have then you cannot see the marks on the crankcase or pulley. If you have a USHM3 engine there are distributor timing marks around the distributor hole, the total range of marks is 50 deg of distributor rotation and each graduation is 5 deg. Mark the position of the distributor with Tipex or similar so that you have a reference point to go back to if you lose track of your adjustments. Forget about advancing the timing until the engine pinks, with 6.5:1 compression the engine will be well out of its power band by the time that happens.

Before you road test get rid of any excess baggage, trolley jacks, axle stands, the missus - sorry Series MMs were built before political correctness was invented.
Check that the wheels are rotating freely and the brakes are not binding
Find yourself a nice steep test hill and drive up and down it, adjusting the distributor a little at a time until you feel that you have got the best out of the engine.
The engine will run smoothly over a range of timing but it goes a lot better if you can find the optimum setting

The Series MM has a reputation for being slow but I think that this is because the owners assume that they are slow and are not prepared to give it a bit of welly. If you anticipate the road and wind up the speed before a hill then progress can be quite respectable and 60mph should not be beyond the car's capability.
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smithskids
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Re: Tuning a 918?

Post by smithskids »

Where can one get a shorrocks now a days, ebay I suppose. I have seen pictures of this type of installation, I think there is a picture of one in Vizards book.
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