Saturday, 18 August 2018

New carburettors - take four

Since fitting the new carburettors things have not exactly been going to plan! I left this bit of TR7 ownership a week ago and with a few hours to spare today I had another go at tuning the carburettors. At least the previous actions did have an effect, as there were no more fuel leaks. But she still refused to idle at a proper engine speed. This time the engine didn't react at all on winding up the idle screws, and kept running at over 2000 rpm! Time to go for a short test drive. Overall the engine runs nicely but when slowing down for low speed corners there was a distinctive petrol smell. But on returning home there were again no visible leaks, which prompted me to have a proper look at the old carburettors. The throttle discs were almost completely closed!
As the reconditioned carburettors have been checked and double checked, I think it is by now safe to rule them out. Though the symptoms could be caused by a faulty float needle valve. Time for a rethink and a browse through my personal notebook, this blog! And that was when I was reminded of a slight problem that reared its head when I fitted this fuel pump only days  before the 2014 edition of Club Triumph's Taith o Amgylch Cymru (or Tour of Wales):

I did have some problems while fitting the pump to the engine. At the time I thought this was purely caused by the lobe on the idler shaft being in the wrong position. And this seemed to be confirmed by the fact that after rotating the crank shaft half a turn the pump slipped in place without any problems. I also checked the new pump's lever arm length against the original pump. The last one was of the long arm variety, fitted with a half inch thick spacer. Well actually two quarter inch ones:

As the new pump had a significant shorter lever I fitted it without the spacer, and headed for Wales. At the time I didn't think much about the fact that the idle speed had risen somewhat to around 1500 rpm. I simply adjusted it till the idle speed was around 1000 rpm and carried on with touring Wales.

Fast forward four years and bearing the above in mind I thought it a good idea to compare the pump fitted to car. For this I used two original TR7/Dolomite 1850 fuel pumps. One with a long and one with a short lever arm, and with the current fuel pump in the middle:

At first glance the two pumps on the right look more or less the same. But after some measurements I found the following dimensions between the pump's mounting flange and the end of the lever arm where the cam lobe touches (from left to right): 57mm - 48mm - 44mm. So it seems like a safe bet that the fuel pressure might be too high, but how high? As I don't have a fuel pressure gauge I think I'll start with a 3 or 4 mm spacer. And hopefully that will get the car driveable enough to my friendly workshop to check fuel pressure and carburettor settings.
At least a scan of a fuel pump gasket enabled me to produce a file for machining the spacer. To be continued ...

Sunday, 12 August 2018

FHC resto nr. 66; Heater rebuild Part 5

It has been a long time since I last reported on the rebuild of the heater for the, by now long term, restoration project of my 1976 TR7 Coupé. And this time firmly caused by a lack of motivation! In my last post on this subject (7 February this year) I reported that only a few remaining parts needed assembling, after which I only had to fit and connect all the activating rods. How wrong I could be!

After assembly of the plastic heater housing I found something wasn't as it should be. While checking the movement of all flaps in preparation for fitting the various connecting rods, I noticed that the air directing flap, sitting on top of the heater's radiator, wouldn't lie flush with the face of the radiator. Even worse, it stood well inside the two round connecting tubes for the fresh air pipes (#715036). And it needed a fair bit of force to get the flap down onto the face of the radiator. There was only one solution left, take the heater apart again. But first I needed a few new bits (mostly consisting of some new pop-rivets) and more important, a lot of motivation. The first part was easy, the motivation took slightly longer. Till yesterday afternoon to be precise. With nothing better to do I decided to give it a go!

Over the past months I had already discovered what caused the problem. At first I thought it might be caused by the custom made alloy heater radiator being too wide. Luckily it turned out to be a fairly simple problem. The steel shroud that keeps the heaters radiator in its position had been distorted during coating. And because the edge adjoining the flap was sitting to high it prevented the flap from lying flush with the radiator. Rather easy to rectify once the heater had been dismantled. And with the shroud back in its correct shape it was time for a second attempt at assembling the heater:

In the pictures above the shroud can be seen, loosely fixated in position with some pop-rivets. It needed only a few attempts to get the shroud back into its original shape. And with the shroud firmly in place, this time there was a final check with the air directing flap, to see if everything was in its designed position. It was, the flap was nicely flush with the radiator!

Remained the final task for the day, closing the lid on the heater unit. All rather straight forward. And this time the final check of the various flaps didn't yield any problems. Next stage will be fitting the various linkage rods and levers, after which the heater unit should be ready to be fitted to the car:

Wednesday, 8 August 2018

New carburettors - take two & three

With the carburettors again removed from the car, and the cause for the problems clear, it was time to address these problems. Which meant replacing all throttle and choke brackets with known original items. And as mentioned some two weeks ago, for these I used the parts that I had already prepared for the engine for the '76 FHC:

But I also swapped the different shaped choke lever link for an earlier model from the carburettors that came of the car. All pretty straight forward except for the fact that the temperatures have been well above 30°C over the past few weeks. So it all took slightly longer than expected. But early last week all parts were swapped and they were ready to go back on the engine.

Sadly while trying to do a basic tune up in preparation for the fine tuning, scheduled for last Saturday, I found out that whatever I did the front carburettor couldn't be adjusted properly. That was when I noticed a fuel leak from the float chamber of this carburettor. It turned out that the rubber seal from the jet assembly had been dislodged while changing the choke lever link. Long and very frustrating story cut short, the carburettors were removed again and I visited a friend for some much needed small parts to stop the leak and get the carburettors going properly!

And these parts (spring clips, seal and stripped jet assembly nut) were fitted to the carburettors over the previous days. Which meant I could use a bit of my spare time today to fit them back on the engine again. And with the practice and experience I got from fitting them several times over the past few weeks, this time it took me less than half an hour to fit them and connect everything. At least something positive out if it!

Remains the final task of fine tuning and balancing them. But that's for another day.

Sunday, 5 August 2018

Weblog statistics

My weblog has been going since 2007. And in all those years I never really bothered how many people read my posts. But this weekend I had a look at the statistics. This made for some interesting reading. Especially the fact that by far the most page views seem to originate from Russia! And this clearly is not in proportion with TR7 ownership in Russia. Looks like Big Brother Vladimir Poetin is watching over me?

Weird to say the least!