drofgum

Hi,

Increasing the master cylinder bore will make the pedal travel less, but you pay the price with a harder pedal. The larger piston displaces more fluid. But the advantage of a small master cylinder is that the same pressure on the smaller piston area makes the total force on the master cylinder piston less. The pistons at the wheels all see the same pressure as the master cylinder piston unless the system is boosted. If the wheels have double the piston area they have double the force on them, but only move half as far. The area ratio is normally much more than 2:1. This is why proper adjustment of drum brakes is so important. It minimizes lost motion before the shoes reach the drum.

Cheers,

Paul

On 01/05/2024 at 13:59, Eric JS said:

Why bother with tapping out the stud holes, it’s only a flange on a exhaust pipe - just drill out the holes with a new drill, then buy 3 stainless steel bolts, nuts, flat washers and spring washers - job done.

Ric

Ric,

Bronze nuts would be better, Mating stainless nuts to stainless bolts risks galled threads. Bronze nuts avoids the trouble.

Regards,

Paul

Hi.

Note the tracking marks on the rotor.

 Regards,

Paul

Johnny123,

That distributor could be from an early Spitfire, they used a Delco dizzy. The easy way to tell them from the usual Lucas part is the main body of the Delco is pressed steel, Lucas used die casting.

Cheers,

Paul

Steveant1,

The shorter reach plugs would be used with the 1147 and earlier engines. 1296 and later got longer reach plugs.

Regards,

Paul

3 hours ago, 65redspit said:

The HE stands for High Efficiency 

65redspit,

I understood it to be H for high compression ratio and E for engine.

Cheers,

Paul

Adrian,

The larger reservoir was introduced when disc brakes were added. Wear of the pads could lower the fluid level too much with the smaller reservoir.

Regards,

Paul

23 hours ago, abandonearth said:

Morning folks, and seasons greetings. 

Now the Spitfire (1971 mkIV) is mechanically happy, I thought it was about time to stop the water getting in. 

I've been browsing parts catalogues looking at the a post (windscreen) seal. Currently the car has furflex from the top of the b post all the way round to the top of the windscreen. From memory this doesn't seem correct. 

Should there be an additional rubber seal (see https://rimmerbros.com/Item--i-620403) and then furflex, or just furflex up to the bottom of this seal? Or is the furflex satisfactory?

And - should the door check strap gaskets be attached to the door or the a post? I'm sure on my 1500 (twenty years ago) they were attached to the latter, on the mkIV it's the former. 

Thanks in advance. 

Hello,

There should be two seals on the windscreen post. The furflex running from the windscreen capping around the door opening to the B post capping. The second is a "P" shaped seal running parallel to the furflex, but outboard. Together these form a channel the door glass fits into when fully closed. The bulb of the "P" shaped seal is placed away from the furflex with the flat section running under the edge of the furflex. The "P" shaped seal continues below the level of the dash for several inches.

The check strap seal would have been on the A-post originally.

Cheers,

Paul

Harvey,

You could check the Canley Classics catalogue pages for both to check the front sections of the chassis frame for part changes. If the chassis frames have no changes the bonnets should interchange.

Cheers,

Paul

16 hours ago, Nick Jones said:

Have a suspicion that that exactly what would have been there from the factory. Two identical 5/8” master cylinders with the small, extra angled reservoirs.  
 

No real downside so long as you check the fluid levels regularly. Used to be possible to get plastic screw-on extensions to gain a bit of capacity but possibly too tall in this case.

Nick,

No, they weren't the same. Triumph changed the brake master cylinder for the Mk3 Spitfire to one with a larger reservoir at a right angle to the bore. The one Glang posted a pic of looks right.

Even the Mk1&2 had different master cylinders for brake and clutch. The reservoir on the brake cylinder was about 12mm taller. 

Regards,

Paul

On 13/09/2023 at 08:33, JohnD said:

The Pi cars were intended to run on "Five Star" fuel - 100 octane!

Part of lead's action as a fuel additive was for anti-knock, or pinking, and without it 98 is the best that is available, unless you live near a race circuit or aerodrome where AvGas at 100 octane may be sold.     My Vitesse has Pi, and a CR of 10.5, which is at the limit for low octane fuel, but I find it runs fine, no pinking, on 98 Octane.   I favour Shell's V-Plus.

BUT, to get the octane rating up there, modern fuels have additives that are volatile, when tetra-ethyl lead was not volatile at all.   Today, fuel that has sat in the tank for more than a month or so may no longer be at 98 octane.    Run your tank down to the minimum before winter storage, or else add a 'fuel stabiliser'.

John

PS Europe uses the "RON" (Research Octane Number) to classify fuel.     In the US they use MON (Motor Octane Number). which gives a lower number for the same fuel.  (98 RON is the same as 90 MON)  J.

John,

We don't use MON here in the USA. Nothing that simple. We use "pump octane" This is found by adding RON to MON and dividing by two.

I just filled my Spitfire with 93 "pump octane" fuel. The RON and MON ratings are not displayed at the pump. 93 is the highest octane available in my part of the States. Other sections have only 91.

 Regards,

Paul

Hi,

A point that hasn't been touched upon is the difference between the gearbox and differential requirements. The differential requires EP additives because the hypoid gear set has a wiping action where the gear teeth slide over one another. The gearbox is better served with an oil that doesn't contain EP additives because it depends on the friction between the synchro rings and the cone surfaces on the gears to match their speeds. EP additives decrease that friction and can lead to slower synchro action. The modern GL4 oils meant for manual gearboxes don't have EP additives that will reduce the friction in the synchros.

Regards,

Paul

Julian,

As I posted on 11th July high revs with the throttle closed show a vacuum leak. On the Mk3 and later Spitfires the two nuts below the inlet manifold are difficult to reach and are often found looser than they ought to be.

 Cheers,

Paul

Julian,

High revs on start-up usually means there is a vacuum leak or the throttles are being held open slightly somehow.

Nice to learn you have gotten it to start however briefly.

Regards,

Paul

20 hours ago, J J said:

Thanks Paul that made perfect sense and the job is now done 

however now it won’t start but I noticed that the coil centre connection is arcing to either the +ve or -ve terminals when I turn the distributor which I’m guessing is stopping it starting, could this be a coil problem?

it reads 3.5 ohms across the terminals 

best Julian 

Julian,

That could be a coil problem. But first give the top of the coil a good clean to make sure there is nothing to aid the spark going to the primary terminals. Then check the timing to make sure the rotor is pointing at least close to the number one post on the cap when the engine should fire. If the spark has no easier way to ground than jumping on the top of the coil that is what it will do.

Regards,

Paul

On 07/07/2023 at 06:41, J J said:

I meant to add that I took the rocker cover off to check and the pushrod on No2 valve was loose and the valve was stuck down, I managed to free it and it popped up

I set do that no1 and no8 were rocking which I think is right 

JJ,

You missed it. There are two ways to get the valves at the right position to set the clearance. One is to turn the engine until the valve that will give a sum of 9 when added to the valve to be adjusted is fully open. So, for example, to adjust valve 3 you want valve 6 fully open.

The second system is to have pairs of valves "on the rock" to adjust a second pair. Those pairs are as follows:

Open valves ............................... Adjust valves

1 and 3..............................................6  and 8

2 and 5..............................................7 and 4

6 and 8..............................................1 and 3

7 and 4.............................................2 and 5

If you find any of those pairs on the rock when you start, you can follow in the order I have given them to adjust all of the valves. This minimizes the number of times you must turn the engine to complete the process.

Regards,

Paul

Tom,

Have you tried the non-functioning bulbs in the sockets where other bulbs worked? That will show whether the bulbs are the reason or if there is some problem with the sockets.

Regards,

Paul

21 hours ago, Matthew said:

Finally had time to do some work on the Spitfire after what feels like an eternity. I’ve painted the bulkhead in the car’s original Triumph White and have started cleaning up all the ‘furniture’ to go back on it so that I can look to get the car running again. This is the first time I’ve seen the car wearing its actual colour as I bought it in surface rust covered primer, so this feels like a milestone hit.

When dismantling the clutch master cylinder to fit an overhaul kit, I noticed something I don’t think should be there - the nut at the bottom of the picture was inside (as though it was a spacer to the pushrod, assuming that is the right name). I’m guessing this isn’t right?

Matthew,

You are right that nut doesn't belong there. It is a bad sign. A common reason to add length to the push rod is to make the clutch release when the engine thrust washers have failed and dropped into the sump. You should check the end play of the crank shaft. If it is more than barely noticeable the thrust washers are badly worn. If it is something over 1mm the thrust washers probably are in the sump. When they drop, the crank rubs directly on the  engine block when the clutch pedal is depressed. That does the crank and block no good whatsoever.

I hope you are lucky enough to find I'm wrong.

Regards,

Paul

Harveyzone,

I think you are going to need to insert a diode into each supply wire to those LED bulbs. That way the applied power will not be able to go back out on the other line.

 Regards,

Paul

Hello,

It is also possible to build a switch onto the original that will operate an electric pump. The original pump must be removed from the switch and a momentary contact push switch mounted in its place. That switch is wired to run the electric pump.

Regards,

Paul

1 hour ago, Clive said:

 

Plan b is to temorarily fit a lucas, but you need the dizzy pedestal too. You will lose the rev counter drive, but that is a sacrifice worth making to be able to use the car.

Clive,

No need to change the whole pedestal. The clamp plate is the part that was changed when the Delco was dropped for the Lucas.

Cheers,

Paul

14 hours ago, Ed H said:

Not sure if you can get a product called POR15 in the UK.  I primed an outdoor railing with it about 15 years ago, and it's still holding.

It does have some drawbacks.  If you get any on you, you'll be wearing it for a while.  If you only use part of a can and re-seal it, chances are that you won't be able to get the top off again.

Ed

 

Ed,

This is interesting. The one caveat I have seen about POR15 is that it doesn't withstand ultra-violet light. To use it where it will be exposed to sunlight requires top coating in my understanding.

Regards,

Paul

Nick,

The Mk1 and early Mk2 Spitfire blocks had smaller bores for the camshaft in them. The cam was the same size as used with the cam bearings. Triumph increased the bore in the block when they introduced the cam bearings. After that the Spitfire blocks all had the same size cam tunnel, but the camshaft journals were enlarged when the bearing inserts  were dropped.

Regards,

Paul

16 hours ago, thescrapman said:

Only FD 1300 Spitfire blocks take bearings. And the FWD equivalent.

Sorry,

This isn't true. Camshaft bearings were introduced during the Mk2 Spitfire production run at engine number FC61023. So most of the Mk2 Spitfire run would have had cam bearings from the factory.

Regards,

Paul

Hi,

In the case of bolts Triumph used that have Triumph six digit part numbers there is something special about them. Stock hardware bolts had part numbers designating their size both length and diameter with a prefix that told what particular type of bolt they were. HB and BH seem to have been used interchangeably for hex head bolts. In the case of the driveshaft bolts both the smaller and the larger ones have Triumph part numbers. The smaller being 129361. the larger being 132023.

I understand that the unthreaded shank of those bolts was sized to act as a locating dowel might,  holding the flanges aligned rotationally, preventing slip that would have worn the holes oval.

Clive,

In the case of the Subaru you need to remember the full power doesn't go through either differential unit. It gets split between them , though the greater part may go through either unit. I find the diameters of the driveshafts on many moderns look small when compared to the Spitfire driveshafts.

Kind Regards,

Paul