In 1998 I bought a Triumph Herald 13/60, here you can read about it's restoration and share in a few photo's from it's travels. Please feel free to leave comments to any of the posts, of even email me if you want to.

Sunday, September 15, 2013

Engine Rebuild (Part 7)

With the engine failing in a major way on our trip up to Gaydon in May, I had to accelerate my plans to get the new unit in. Powderham Historic Gathering was already booked for July and with Michele's cousin Trevor and his wife Jackie coming to stay that weekend, it was unthinkable not to have the Herald running.

Engine damage
I had the old engine and gearbox out, swapped the gearbox over to the new engine and both units back in during the first day. I also managed to get the carbs, exhaust and enough ancillaries on just to see if she'd fire up, which she did quite willingly, but I turned her straight off as I had no radiator attached.

As this wasn't a like for like swap, some messing around had to be done to get the 4 branch manifold fitting nicely with the rear section of the standard exhaust, the accelerator cable from the Spitfire pedal to the twin SU's working and plumb in the water hoses for the heater valve to manifold connections. Once this was all in place it was time to fill the cooling system so she could be run for a while.

This is where a few weeks of niggly problems started. Initially she was overheating very quickly and only happy to idle with masses of advance, somewhere in excess 20°. The excessive advance helped the hot running a bit, but idle was lumpy, something wasn't quite right.

I wasn't entirely happy with the carbs also, they seemed to be sucking in air around the spindles. I fitted a new set of spindles on the carbs, took of the electric radiator fan off and put the old mechanical one back on. I also experimented with different needles and springs on the SU's, starting with AAR's and standard springs but ending up with AAQ's and stronger springs.

Whilst the engine temps were better now, I wasn't happy with the timing having to be so advanced, I had now convinced myself the camshaft timing was wrong. The duplex timing chain gear don't come with timing marks, the method to set camshaft timing in the WSM (which I used initially) is correct but there is a lot of room for error this way. So off came the head, timing chain cover and timing chain and with the aid of a homemade piston stop, degree wheel and dial gauge the timing was set much more accurately.

Got it all back together, reset timing to close to what it should be and to date the engine has run pretty good. Still a rougher idle than I'd like, but this might be down to the choice of needles in the carbs. A re-torquing of the head and resetting of valve clearances recently as it passed its first 750 miles helped significantly. Apart from stemming an irritating oil leak at the back of the head, the increase in power and drivability I was after was starting to show.

Engine all fitted
For those not wanting to read the older posts, the engine modifications from standard 13/60 Herald are:
  • Cylinders bored out to +60 thou
  • Larger Inlet & Exhaust Valves
  • 70/30 30/70 Camshaft
  • Twin SU HS2 Carbs
  • Duplex Timing Chain Conversion
  • Balanced Crankshaft, Flywheel, Clutch Plate and Conrods
  • Lightly ported head.
  • Megajolt to follow soon!
Is it finished?......No. 

One of the reasons for building a new engine was nothing to do with me having a premonition that the old engine was going to fail, but a desire to create an engine that was a bit more drivable. Part of this project was to fit a Megajolt fully electronic and mapable ignitions system, so once this is fitted I'll be calling Tipton Garage in Sidmouth for a rolling road session to get this and the carbs set up properly, it should then be job done. 

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