Rolling road time again

So we had a long afternoon at the rolling road, where we did runs with the GT supplied head and again after changing the later CR type inlet manifolds for the earlier CP manifolds, which have be machined out to enable the CR throttle spindles to be fitted. Ram pipes have also been fitted to the new manifolds to increase the inlet length.

Torque

Power

Blue run is prior to the head change, but still injection and CR inlets.

Green run is with the new head, but still injection and CR inlets.

Black run is new head and CP inlets and ram pipes.

It is clear to see the improvements with the new higher compression cylinder head, giving more power and for longer and the CP inlets giving an extra eight or nine BHP. The engine is still fitted with the relatively mild stock MkII camshaft.

Surprisingly the fuelling is still alright everywhere apart from idle, giving figures, if I remember right, of 3.8 to 4 over the rev range.

I've still a bit of fettling to do to get the inlets to match the ports properly as we were running out of time and I also need to consider making a cold air feed as it does seem to be quite sensitive to temperature.

I'm pretty chuffed with the results, it's all taken a fair bit of time to get this far and I'm sure there is plenty more to be done, but it has given me the ability to see the improvements and gains by fitting the right parts. Also interesting to see how much can be done with a stock camshaft, goes to show that some of them aren't all that bad.

I'll probably end up fabricating a custom air box to give plenty of space around the trumpets and have a couple of cold air feeds. There are air filter baseplates approximately 500mm long, which would be perfect for this, but the filters that fit onto these are around £125, so I may buy an un-drilled baseplate and fit my own box onto this and have filters in-line or at the end of the cold air feeds.

New towers and head fitted

Got the modified suspension towers fitted in the week, though I still have to fit the wiring and coolant pipes back around them and I'll leave the steering column out until I have changed the head. Not the easiest of jobs to do with the engine in place as you of course have to have the chassis on stands and then support the engine as you swap the towers over. Having the single multi-way plug on the steering column made it a doddle to remove.
Next job is to check torques, fit the wiring and coolant hose back in before checking the starter and swapping the head, then I could thing about finishing off the new engine mounts.

Then it was time for the head change, the old head was removed quite easily before cleaning off the block and a new Payen head gasket fitted before re-fitting the starter and water pump.

So I got the GT6 running again on Saturday with the new head on. Took me a while to get it started as the injectors needed priming and then I must have flooded it in a bad way, so I took the plugs out to clean them up and re-gap (should have done this when I went over to Megajolt ) and left them out while I went for lunch. On returning I wanged the plugs back in and it started up straight away.
With the new head it seems to rev much more freely, being all to easy to spin up to 6,500rpm, where before it was a bit of a struggle to get up to 6,300rpm. There is still a bit of a dip in the torque around 2,800rpm, but it soon picks up again, perhaps this could be ironed out on the rolling road.

Covered an easy 200miles in the afternoon on a drive over to Builth and found some good roads to drive once you get past the people pottering along at 45mph I'm not sure whether it's the car, me or both, but I feel a lot more confident driving the car now than when I did when it first went back on the road, just learning how to drive it?
One thing I did see from the run yesterday was that, despite the reasonably warm weather yesterday, the engine temperature was pretty well pegged at just over half way and the fan never came on, even in the slower moving traffic. Not too bad for a second hand pug radiator, but I may well change it for a new one as some of the cooling fins are looking a bit flaky.

It did reward me this morning by leaving a pool of brake fluid on the floor, a leak from the master cylinder. Fortunately I had a spare master cylinder, but the lid will not unscrew, so I exchanged the piston with seals and re-bled the system and it has been fine since. Makes me wonder if I ought to get in a spare set of cylinder seals just in case.

The next job to do is to finish off the new engine mounts, really don't like the look of the existing ones and how they are cracking.

Head, pipes and towers

I did not buy much at the Triumph show at Stoneleigh earlier this year, but I did collect this:

It's the replacement head re-worked by GT, complete with a set of his valves, a job which he managed to turn around in quite a short time before heading back home. It has been buretted and it looks like the compression ratio is 10:1. My plan is to have another go on the rolling road after fitting this to see what effect it has had, then fit different inlet manifolds while at the rolling road and adjust the Megajolt as required.

My attempt to fit the better hose clamps hit a problem last week, the home-made take-off on the bottom hose was not wide enough to get a proper seal with the wider clamps, so it started leaking.  To get round this, I bought a ready made tee piece from Car Builder Solutions, hopefully it should seal better with this.

Over the weekend I finished modifying the other suspension tower to take the alternative engine mount and then gave them a clean off and paint, ready for fitting soon.

I've decided to crack on with these towers again as to fit them requires the cooling system to be drained as a hose passes through the one on the passenger side and it needed to be partially drained to change the head anyway.