Traveller Tuning

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philthehill
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Re: Traveller Tuning

Post by philthehill »

The fitted gap is 0.007" to 0.012".

Turn the bare piston upside down and insert into the bore to get the piston ring square in the bore and then measure at top and bottom.

All piston rings should be measured for the correct gap. New piston rings are not necessarily correctly gapped for a re-bored cylinder.

It should be noted that cylinder bores should be re-bored to suit the piston to be fitted to that particular bore. I doubt that the re-boring company has graded pistons as BMC originally had and were marked with a 1, 2, 3, or 4. inside a diamond according to the grade.

The grading was nothing to do with quality but all to do with size.

Some BMC engines had different piston grades fitted to the bores of assembled engines. Not all bores are the same size and can vary by several thou even if bored by the same boring bar with the same settings.

Re-boring to the standard size bore plus whatever the oversize piston is no good. The job has to be done properly.

You do need a special file or machine to adjust the gaps - you can only make them larger you cannot make them smaller.

I have a similar machine to that in the link below so as to be able to adjust the piston ring gaps as required.

https://www.ebay.co.uk/itm/TRIUMPH-BSA- ... :rk:1:pf:0

A piston ring tool is an absolute must when removing and fitting pistons rings from the piston. It reduces the risk of broken rings.

I have a similar tool that that in the link below.

https://www.ebay.co.uk/itm/Piston-Ring- ... rk:21:pf:0

Phil

Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

The crank and oil pump are now installed and I am now having a problem getting the first piston into the bore. I am using the standard 'ratchet' type ring compressor, but the oil control rings seem to spring out before they go in the bore. I have checked all the ring gaps as you mentioned.
philthehill
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Re: Traveller Tuning

Post by philthehill »

You need to oil the rings and bores before fitting the clamp round the piston/rings.
The piston ring clamp should be done up reasonably tight.
Enter the piston into the bore - make sure that the clamp is square to and sits on the top of the block.

A smart tap on the top of the piston should see the rings enter the bore.

When fitting the piston rings make sure that there is at least 45 degrees between the ring ends. Ring ends should not be directly above each other.

Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

Bottom end all back together, timing gears and chain all done and cover fitted. Rear engine plate back on and flywheel fitted. I am having a problem with getting the sump back on. I have put the two cork seals in place and trimmed them to 1/16th proud of the flange, but the sump will not bed down so the mating face sits on the crankcase, but is about 8mm away all round, without the side gaskets in place. I can't see that fitting all the bolts and tightening them will do the trick, as they only go to 6 ft-lbs torque. Am I missing something obvious?
paul 300358
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Re: Traveller Tuning

Post by paul 300358 »

Are you sure that the cork seals are fully in the groves. I have always covered them in grease to help them seal and so that they slip slightly both in the sump and the main caps.
Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

They seem to be. I used oil rather than grease, but they can slide in the grooves slightly.
philthehill
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Re: Traveller Tuning

Post by philthehill »

Have you got them the right way into the groove?

The cross section of the cork seals is rectangular and not square.

They should be a reasonable fit into the groove with the gasket protruding either end as per the illustration in the BMC wksp manual.

You do normally have to pull the sump to the block so as to get the cork end gaskets to compress and seal.

Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

They are the right way. They wouldn't fit the other way round. The seals stand proud 5-6mm above the top of the groove.There is a measured 6-7 mm between the sump flange and the block. I can't see any way that the bolts can be tightened enough to take this up. I did soak the seals in oil prior to fitting. Could this have made them swell up?
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Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

I am thinking of making some new ones from the rocker cover cork gasket to see if they fit?
philthehill
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Re: Traveller Tuning

Post by philthehill »

That sump to block clearance is normal without the gaskets being in place - the bolts if tightened progressively will pull the sump down onto the sump gaskets.

Lightly grease the sump gaskets as they will stay supple and more effective for so much longer.

The ends of the cork seals should be cut square so that when the sump is pulled down the ends of the seal are square and the possibility of oil leaking is eliminated.

The cork seals should stand proud by 3.2mm.

Fig A.A. 26 refers to the cork seal housing and not the cork seal. It is known for the welded on lip to be incorrectly positioned from the factory and if it is proud may have to be filed back to clear.
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Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

The engine is re-installed and everything is connected up. I tried to start it today and it turns over on the starter ok, but there is no sign of it wanting to fire. I have set the valves clearances, checked static ignition timing twice. There is fuel in the float chamber and it is reaching the jet. Choke and throttle are working correctly. All plugs are checked and have a spark. I am now bit puzzled. To re confirm, it is a 1098 with 940 head, sintered rockers, standard cam, with Torquemaster type alloy inlet manifold and standard exhaust. HS4 with AAU needle.
panky
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Re: Traveller Tuning

Post by panky »

It could be the dizzy drive 180 deg out, I did the same when building my Commer engine :roll:
Try moving the leads round two positions on the dizzy cap.
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Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

Already done. I never removed the distributor drive, but when I came to do the timing it was out by 180 deg. I set it static on no 1 cylinder and then moved the plug leads until they were correct and in the right order. When the engine was disassembled, I found the distributor flange impossible to remove, so left it be. A visual check of the end of the drive appeared to show it in the correct orientation as per the picture in the manual.
panky
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Re: Traveller Tuning

Post by panky »

Try advancing the timing a good bit and see what happens, if nothing, or it kicks back, then try the other way. Not very scientific but it's worked for me when I changed to electronic ignition.
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Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

Tried what you suggested to no avail. I have tried it with new petrol in case the old stuff had gone off. Just will not fire at all. I just did compression test, with the engine cold obviously and cylinders 1-3 give around 140 and no 4 gives 30 psi, so something definitely amiss. Not that even that should prevent it from running. Rather short on ideas now.
oliver90owner
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Re: Traveller Tuning

Post by oliver90owner »

You could try feeding it with propane, or even easy-start. It should at least fire. If the timing is way out, be very careful. Ether exploding in the inlet maniflod is not a good idea!
philthehill
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Re: Traveller Tuning

Post by philthehill »

You need to go back to basics and determine what is wrong before using any volatile mixture.

Bowie69
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Re: Traveller Tuning

Post by Bowie69 »

... And check valve clearances on #4.
Kittyhawk
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Re: Traveller Tuning

Post by Kittyhawk »

All noted. Thank you. I have tried Easy Start already, but no luck. I have rechecked all the valve clearances again. 0.012 inlet and 0.015 exhaust. I will try a little oil in no 4 cylinder and redo the comp test. As I understand it, it can either be rings, valves or head gasket?
Bowie69
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Re: Traveller Tuning

Post by Bowie69 »

To be 30psi, I would suggest stuck or broken rings, yes. A burnt valve is more likely to give you zero.
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