2019: September part 1. Trying out new sprint motor

With the engine in and running I had a little tinker to tidy up and check settings etc.  The fancy (and expensive) Mangoletsi throttle linkage seems to be well engineered and was easier to fit than it looked. The engine idled quite nicely and I set the ignition advance at tickover to 10 degrees BTDC as a good starting point.

10 degrees BTDC using the Snap-On timing light.

Driving the car it felt good and responsive and with that fantastic growl from the carbs when you floor the pedal.  Almost worth changing the engine just for that sidedraught roar!  I booked a test in a couple of days time with Martin at Maynard Engines on their rolling road in Nailsworth to check what was really happening with mixtures etc.  A couple of days later I took the car over there and we strapped it down on the rollers.

First run showed it was actually set up quite well.  I had used the carb settings recommended by Matt at Eurocarb who are the Dellorto main agents in the UK. For the anoraks amongst you this is what he suggested as a starting point:-

Dellorto 45DHLA
Chokes    36mm,
Main jets  145,
Emulsion tubes  7772.5,
Air correctors  180,
Idle jets  60,
Accelerator pump jets  42.

I have been reading up on the carbs to try and get a better understanding of what all these numbers mean and how they all work together. This book was my main source of information.

I wouldn't claim to understand them now, but I do have a bit more of an idea than when I started.

Martin found it was running a little rich at the bottom end then went a little lean at the top so he made a few changes. We were not trying to achieve ultimate power but needed it to be a nice engine to drive on the road.

Turns out that folks have differing opinions about setup, Martin prefers to run bigger spec emulsion tubes so changed them from the recommended 5 to an 11 which gave a richer acceleration phase. They have more holes and in different places - see picture - and it certainly worked to make the top end mixture much better.

Dellorto Emulsion Tube Range from 1 ti 17

Driving the car afterwards it certainly felt smooth, with plenty of torque at low revs and pulling all the way up through the range.

Final carb settings are:-
Dellorto 45DHLA
Chokes    36mm,
Main jets  175,
Emulsion tubes  7772.11,
Air correctors  135,
Idle jets  60,
Accelerator pump jets  42.

2019 1st April, New Sprint Engine saga - No Joke

Having decided to build up the original Sprint engine I first started work on in 2014 I began by cleaning up and checking over the block.

"New" block I started in 2014

Cleaned up ready to start work

Checking threads are OK

Bottom end ready for -

the balanced crankshaft

and a set of pistons on balanced rods

Choose your jackshaft

Starting to look like an engine, until -

Curses, pistons are well above the block face

Having made what I thought was good progress with the bottom end of the engine it all came to a sudden stop when I realised the pistons were about 0.025" above the block face at TDC.  This might be OK for a race engine when it is used as a way of getting more compression ratio but I didn't want or need it for a road car.  I discussed the options with Alex at Maynard Engines and we decided it would be possible to machine a small amount off the top of the pistons, so I stripped them back out and took them down to him for machining.

Pistons showing amounts to be machined off.

I also took the head from rally engine head down to be checked for flatness.  The exhaust manifold that came with the engine was also slightly warped where it bolts to the head so that needed to be machined flat as well. 

October 2018, FHC Final preparations for Lombard Rally Bath

The car was more or less ready to go for the Lombard Rally Bath 2018 on 19th-20th October but I did need to get the tyres replaced as the ones on the wheels were the wrong size and too old anyway.  I run 14" wheels and it turns out that the size I need - 195/60x14 - are not as common nowadays as they used to be. This size has the benefit of being exactly the same rolling diameter as the standard TR7 tyres of 185/70x13.  Budget brands were more common but some searching around found some better quality Firestone Firehawk TZ200 at a local supplier.  These seem to be a good result and feel nice on the car with low noise and decent grip levels.

One of the last jobs was to change the standard sealed beam headlights on the car to some more modern Lucas halogen H4 replacements.  Imagine my surprise when I took the rubber surrounds off the headlights and found all new mountings! My previous TR7 experience has been with nasty rusty ones.

Wow, all new. Never seen that on a TR7 before.

The car was now running, but not very well. The carb mounting rubbers did not look very nice with the usual cracks starting to appear so I swapped them for some better ones which improved things but not enough. I booked a quick session on my local rolling road at Maynard Engines where Martin spent a short time setting the carbs up properly and got it ticking over like a sewing machine. 

Car washed and ready for the Lombard.

25th March 2017, Rear Brake Cylinders and Daffodil Run

Not been too much to do on the car over the winter since its last outing on the Ludlow Tour but I decided it would be interesting to try the set of TR8 rear brake cylinders I had to see what difference they made.  The standard 5 speed TR7 cylinders are 0.7" (17.5mm) diameter and the TR8 ones are larger at 0.75" (19mm) and the effect of the larger cylinders is to increase the amount of rear wheel braking which seemed like a good idea.  I had read various opinions about the swap and thought it was worth a try.

Just for reference, the car already has Princess 4 pot calipers with vented discs on the front, an uprated servo/master cylinder and a Ted Schumacher modified pressure limiting valve.

The two types of cylinders look virtually the same but they have a roll pin used to locate in the backplate on opposite sides to prevent fitting the wrong ones accidentally. All that is required is to drill an additional 1/8" hole in the backplate on the other side and they are a straight swap.

I also took this opportunity to clean and lubricate the self-adjusting mechanisms with graphite powder but when I tried to refit the first brake drum it would not go on.  I checked the brake shoes were all fitted correctly and tried again but no good. After the third unsuccessful attempt of taking it all off and refitting I started to wonder what was going on. I double-checked the shoes and springs yet again but they were all correct so what was wrong?   At this point I decided to compare the dimensions of the cylinders in case that revealed something and this is when I found that the pistons on the new cylinder were not retracting fully. Taking it off (again!) I found that the small spring that fits between the two pistons had somehow got itself lodged across the cylinder instead of being in line and was preventing them going back properly.   This time it all flew back together and the drum went on easily. The other side was simple and gave no problems.

Next day I had to deliver some documents to Gloucester about 10 miles away and it was a nice day so a good chance to take the TR7 and try the new brakes.  They felt fine and all was well until a car in front made a right turn without indicating and I had to brake suddenly. This resulted in a lurid sideways moment, luckily with hitting the scenery or the oncoming traffic.  The rest of the journey was OK but I was very careful not to use the brakes too hard and the original TR7 cylinders went back on a few days later.
 ....................................................

25th March.  Daffodil Run

Two days before I took the chance to pop over to my local rolling road at Maynard Engines to get the carbs and ignition settings checked. Some minor adjustments of the carbs got it running better and a final tweek of the ignition timing had it running better and smoother than ever.

 The Daffodil Run is a round of the HRCR Scenic Tour series and starts only about 20 miles from home at Birdwood.  It is a smaller event and is limited to only about 30 cars so I had got our entry in early to ensure a run.  The weather was perfect, cold but with clear blue skies so ideal for open top motoring and the organisers got the day going nicely with hot drinks and bacon rolls at the start.

Our TR7 in good company.

Good selection of cars at the start.

The route took us out through the lanes around the Newent area which is famous for its displays of daffodils at this time of year to a coffee stop at the Yew Tree Inn on the river bank at Chaceley.  Its quite well known for being cut off when the River Severn floods on a fairly regular basis.  Here they served us coffee with lovely home made cakes so it was a bit difficult to drag a ourselves away.

Jo enjoying her coffee and cake.

 The second half of the route went out around Redmarley, Much Marcle and Woolhope before finishing at the Three Shires Garden Centre near Newent.  Here they presented us with some bunches of daffodils and served us an excellent full carvery meal to round the day off nicely.

Daffodil Run souvenir