Triple Webers or PI?

[Stephen Jones]

This next photo shows a little better the 25 degree angle of the carbs when the float bowl is level. Bonnet clearance is very close, but the strombergs used to touch the bonnet. The steering column just misses too,so I got away with it just.

[TriumphV8]

Very good job! Looks perfect!

[Guest]

First, welcome to the forum.

 

I don't have a 6. Only a modest 3A. Since you were so lucky to find a proper car in good shape, I would use 2017 for proper driving and reading. Just drive the car, iron out all niggles and try to get to know as much as possible about the PI (this posting is a good one!). And start remounting (or not...) the PI next year.

 

Have a great and safe 2017

 

Menno

[TriumphV8]

I did see a PI system being fitted to a 4 cylinder.

Very nice job by modifying all TR6 parts.

 

So maybe an interesting idea to combine TR3 & PI

[Guest]

There are a few I-systemed 3A's out there. I haven't seen one with the PI though. And tbh, I think that I would somewhere else if I had to make the choice. There are more modern systems around, I think.

 

Having said that, I would go out and search for a Mikuni carbs system

Edited January 1, 2017 by Menno van Rij 2

[Andy Moltu]

You are so wrong Andy sorry.

Lost count of the number of high Alpine passes I've done in the 6! Run rich yes but never had a problem. When Stanpartman had it on the rollers it had enough fuel to make 6300 rpm.

 

As for the Lucas pump - it was not the one originally intended for the TR. It was a compromise to keep the costs down to that dictated by Triumph. I stand by my assertion that a generic Bosch equivalent is better than the Lucas and almost cheap enough to bin when you change the filter at 20000 miles. You can get a lot of pumps for the cost of a reconditioned Lucas.

 

I don't deny that a good Lucas works but many aren't good and are more hassle than they are worth. Cooling coils are of limited benefit as anyone who lets their tank run low on a baking hot day will find out.

 

The blight of the Bosch pump is resonance, which can be deafening. Changing the flexi pipe or swapping to a diaphragm PRV resolves that.

I ran a cheapo after market PRV (£18) from eBay as a trial (after market item sold for modern Nissan 3000 engines) and the most expensive item was the braided high pressure fuel line. At that point the pump, filter, PRV, pipes and unions in the boot came to a little over £110. The PRV gave way to a better quality diaphragm unit as the plastic gasket holding it together seemed too flimsy so I opted to replace it before this years Grosetto trip.

 

For me eFi is a step too far for a car that was on Pi originally. Also I can carry all the bits with me to fix anything on the PI system myself if on holiday. I don't know how to sort eFi ( assuming I could get the parts in the middle of nowhere, and the same applies to Webers these days as understanding of these amongst your average RAC mechanic fades)

Had it been on twin carbs I would go eFi over Webers or Dellortos. Obviously the mechanical Lucas system is flawed in that there is no atmospheric pressure compensation and depending on cam there are flat spots of sort in the torque curve which are possible to reduce but not dial out totally. But in the end it's nearly 50 and has the technology of its era.

[Peter Cobbold]

There are a few I-systemed 3A's out there. I haven't seen one with the PI though. And tbh, I think that I would somewhere else if I had to make the choice. There are more modern systems around, I think.

 

Having said that, I would go out and search for a Mikuni carbs system

Menno, I'd much prefer Stephen's Keihins. They have butterfly that helps fuel atomisation at part throttle. And the needle-jet fit in Mikuni is measured micron by micron - that doesnt leave room for home tuning or wear.

Peter

[TriumphV8]

Worth a discussion if Keihin carbs are more narrow to original than EFI.

EFI can use most of the original PI equipment and in my opinion gives the closest look to original.

Only the fuel metering is changed and improved with modern parts millions of other cars use.

 

In the MegaSquirt for example the same chip does the work that normally watches the

airbag system. So why having worries in the oldtimer while giving his life in the hand

of the same CPU in the daily driver?

 

Also 90% of the used parts can be sourced very easily, the fuel pump for example

or an injector can be bought very easy because its in use in many cars today.

 

If somebody wants it perfect he can carry a second CPU but although I had several

defects in 15 years of EFI use these have been never CPU related.

 

One was a broken rubber ring in the pressure regulator

another a lost plug connection at the temperature feeler.

One was the wrong setting for high altitude, what PI does not have at all

and the last was a melted fuse body, not the fuse itself, for the fuel pump.

All are repaired without external help or spares.

 

The good thing was that the laptop or smartphone shows in most cases

what is going wrong. Even when defects occure seldom you can

make a log of all data over a longer time. Finding the defect is now very

easy and can be done even when its raining from inside the car.

 

All adjustments like fuel metering and fan start or ignition timing can

be done from the passenger seat. I feel pretty safe with that solution,

much more safe than original. Just keep in mind that ignition coils will

no longer get hot because they are fired with the dwell time they need.

Fuel pump makes 3 bars instead of 8 and grabs less power from that

what normally is fully dissipated from the fuel that starts boiling in summer.

-There are so many improvements for reliability and help to find a defect

that I wonder why this in opposition to the facts is blaimed to be a risk on the EFI-

 

Despite MegaSquirt is often blamed to be the CheapCharly with no

automotive grade at several positions I can say for me it is fit & forget.

After some years I did not even take a spare CPU with me.

 

Its like a modern car where nobody starts with the feeling something will

brake when leaving the garage.......... Simply perfect!

 

If there is a EFI-problem at all it starts in the beginning. Fitting and setting

needs skill. Using it later is simply fun without worries.

 

All that with no doubt is no claim against the Keihins.

That is still a pretty nice work and individual runners

for each cylinder is the best solution for an engine.

[Stephen Jones]

hello again

The Keihins were a low tech low cost alternative to EFI. I wanted the individual runners like the original PI, but the list of parts needed for an EFI conversion was quite large. Not to mention my understanding of technology stopped in about 1970. I just bolted the carbs on and the car started first time. It was running rich and fouled the plugs up after 5 minutes, but solving this was simply a jetting issue and easy to understand. If I had to start plugging in a lap top, I would be out of my depth. This was just a back yard conversion and didn't require the car being off the road at all. I made the new set up on the bench to fit a spare cylinder head and when I did the installation, It was simply a case of removing the strombergs and bolting them in place. I have been running them for a few months and they have been absolutely reliable, although if the car hasn't been used for a few days it requires cranking over a bit longer than it used to. Probably because I now have 6 float bowls to fill.

 

Cheers Steve

[Guest]

Pics Steve!? Looks great I presume!

*surfing now to a web address for second hand motorcycle parts*

[Steves_TR6]

Thats really cool steve, and i have three twin cylinder motorcycles in the garage so must have all the required parts!

 

What i dont have is the engineering skills!

And i love the Lucas PI system

 

Please add some pics for us to ogle !

[Stephen Jones]

Hello

I left a couple of pics on a few posts ago. they are on page 3

 

Thanks

Steve