Sunday, 12 May 2013

2012 Sprint engine installed

All the usual hoses and wires connected up to the new Sprint motor with no problems but I had to fiddle about with the exhaust.  I had used the scruffy mild steel manifold that came with the engine and the car already had a stainless sports system so I had to make up a sleeve to join the two together. Not difficult but getting it all lined up and hanging nicely was a hassle.

I had read the clearance between the manifold and the chassis rail is sometimes a problem but I had a whole quarter of an inch!

I cranked it over on the starter a couple of times and saw oil pressure on the gauge so the big moment came - and it fired up easily after a couple of turns.  Phew !!   No nasty noises and no more smoke than usual with a new engine installation. Excellent.
Let it run for a couple of minutes and then checked around for any leaks the noticed the oil pressure was a bit high, in fact, much too high.  I was seeing  80psi running and even 65-70psi at tickover. Hmmm.

This seemed it might be a problem so I asked around on the Triumph Dolomite Club forum and they all agreed too much for a normal engine.  The consensus pointed to the oil pump so I whipped it off and found someone had fitted an uprated spring in the relief valve. It was longer and stronger than standard. This might be OK for competition but really not necessary for a normal engine and can cause premature wear to the timing chain tensioner so I just swapped to a standard one and normal pressure was restored.  I now had about 55psi running and 35-40psi at tickover.  Much more comfortable.

Completed Sprint engine installation

A quick road test found it was a bit flat above 3000rpm so I obviously needed to get the carbs and timing set up properly but otherwise everything worked OK..  It ran sweetly enough but needed a tune.  At this stage it still had not got the air filters and it was on standard needles so I booked a session on my local rolling road to get it running just right.

Couple of days later, K&N filters fitted, I took it to Maynard Motorsport rolling road in Nailsworth to sort it out properly. I have known Mark Maynard for years since before I rented some space in a spare corner of his workshop to build my Sierra Cosworth rally car in the early 1990's. He has a good engineering machine shop and can make almost anything you need for a car.

If you have never been to a rolling road it is a bit of a shocking experience first time.  The sheer noise and violence of a car running flat out whilst you stand a couple of feet away is pretty scary. You will not believe how loud it actually is.  I knew what to expect but it had been a few years, so I stood back with my fingers in my ears, whilst the car was given a good thrashing. Carb needles were swapped for some richer ones to match the K & N filters and the tubular manifold and ignition timing adjusted slightly to optimise everything.

Result was 134bhp at 5800rpm and a smooth flexible engine, see printouts below.


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