Torque settings for Navigator head

Previously wrote:

I'm slowly getting my '61 Navigator into working order (every time I fix one problem another one appears) but one thing that slows down progress is a lack of technical information. I've got hold of an original handbook but it is somewhat lacking in some of the finer details. The most common problem I've had is making the engine oil-tight and after replacing various seals and pipes I am left with one slight issue. There is a small oil leak coming from the base and head gaskets - it's not enough to affect compression or power but just enough to spit out oil when the bike goes about 50 mph. I know the gaskets haven't long been changed so I think the bolts on the head,which have be tightened in sequence, need tightening since the various components have settled. The problem is I don't know the torque settings for these bolts (the one's that go straight down through the cylinder) and I don't want to over-tighten them. Can anybody help?

The 'Twin Cylinder Manual' says 25 foot pounds, but this is when the head is re-fitted after strip down, dont know what a second pull down is but this would be a good starting point.

Good luck

Steve

Hi Sam

I will add to your dilemma.My Twin cylinder manual gives the torque setting as 15 foot lbs for the Lightweights and 25 ft lbs for the heavyweights.Also there is a tightening sequence for the six studs.Hope this helps

Regards

Stan.

BEWARE!! As Stan says, the torque setting for the heads is 15 foot pounds, not 25!! It's fairly well hidden on page 30 of the "Twin Cylinder" manual at the top of the right-hand column. This assumes clean, dry threads of course. Many car engines with alloy heads used to have the instruction to tighten the bolts/nuts 1/4 or 1/2of a turn after 'X000' miles. On a bike I would go for no more than 500 miles for a re-tighten.

For the head to "spit out oil" I would say you have a problem. It sounds like a warped heads(s) or uneven tightening. I doubt that your problem will be fixed by re-tightening. I would replace all the nuts & studs if it was a major overhaul. Use original steel rather than stainless if possible. You might need another new head gasket as the existing one will get damaged by the oil & gas pressure.

Good luck, Lionel

Unfortunately, failing to re-tighten the head bolts after the recommended mileage is the second most common cause of warped headswith cars and bikes! The first is failing to tighten them evenly and in the correct sequence. Once it's warped and blowing there's no easy way to undo the problem. 15ft lbs isn't much of a torque so I doubt whether it will seal the gas blowing. You might be lucky though! If not, it's heads off time! Check them with a straight edge but probably worth getting them skimmed anyway. Then you should be able to refit them properly without gasket cement. Yep, it will be expensive with a new head gasket and bolts!

Probably a silly question, but why didn't you have a go at retightening the heads having been told that they would need it? Even not knowing the correct torque it would have been better than nothing! Yeah, I know! Hindsight is a wonderful gift!

good luck, Lionel

Previously wrote:

I'm slowly getting my '61 Navigator into working order (every time I fix one problem another one appears) but one thing that slows down progress is a lack of technical information. I've got hold of an original handbook but it is somewhat lacking in some of the finer details. The most common problem I've had is making the engine oil-tight and after replacing various seals and pipes I am left with one slight issue. There is a small oil leak coming from the base and head gaskets - it's not enough to affect compression or power but just enough to spit out oil when the bike goes about 50 mph. I know the gaskets haven't long been changed so I think the bolts on the head,which have be tightened in sequence, need tightening since the various components have settled. The problem is I don't know the torque settings for these bolts (the one's that go straight down through the cylinder) and I don't want to over-tighten them. Can anybody help?

Although there's supposedly aposting from Andy for Saturday April 9th it doesn't seem to have appeared! JustSam's original text!

I would just like tomention that everyone who works on their bikes or cars should invest in a steel straight edge and always check the head flatness before re-assembling and fitting. Has anyone ever seen a Jaguar XK series (3.4 to 4.2 litre) alloy head in the flesh? Those are the engines I mostly worked on from 1972 to about 1992. They are pretty big so they need a bit of a straight edge, but you don't want one of those blowing a head gasket! Interestingly their valve guides are the same O.D. as the Dommie's so I was able to use the same drift and reamer for both! Another coincidence - the Jaguar Mk10 front wheel bearings were the same size as a Mini's - so you won't break an old Mini's wheel bearing unless you drive it off a cliff or tow it behind a Jumbo Jet on take-off! Probably not even then!

Cheers, Lionel

Previously wrote:

I'm slowly getting my '61 Navigator into working order (every time I fix one problem another one appears) but one thing that slows down progress is a lack of technical information. I've got hold of an original handbook but it is somewhat lacking in some of the finer details. The most common problem I've had is making the engine oil-tight and after replacing various seals and pipes I am left with one slight issue. There is a small oil leak coming from the base and head gaskets - it's not enough to affect compression or power but just enough to spit out oil when the bike goes about 50 mph. I know the gaskets haven't long been changed so I think the bolts on the head,which have be tightened in sequence, need tightening since the various components have settled. The problem is I don't know the torque settings for these bolts (the one's that go straight down through the cylinder) and I don't want to over-tighten them. Can anybody help?

The correct Torque setting is 15Ft/lbs = 180 in/lbs = ??N/m (Do not be tempted to tighten any more than this figure.

I have tried twice now to post this information - failed twice - wretched system!

Head Tightening sequence attached as a file (I hope).

If you can find them, use stainless steel replacement studs - with your original long nuts.

Use thick washers underneath to spread the load - there is a milled recess to accept these washers.

Tighten the head again (once cold) after the first 20 -50 miles, driven gently.

Tighten the head again (once cold) after the next 500 miles, driven gradually less gently. - but still on a light throttle. You can allow the engine to rev a little when liughtly loaded - just do not make it slog up hill in top.

Make sure the ignition timing is spot on - there is a whole otherchapter on that subject alone!