Sparky's winter/spring/summer/autumn work

quattro

Administrator
Staff member
Amazingly the performance was not down much just on primaries, but with the whole lot wide open at the top end, things happen very quickly.
Bit scary? :cool:

Sparky is pretty quick, but has a certain something missing, perhaps just a bit of fine tuning required, but he does seem to pull back just a little.

The RP4 camshaft is designed for a heavy 4x4 auto, and has a power band of 1000-4800. I do think that replacing it with a fast road cam like an MC1 would perk him up bit and make the whole experience a little more lively. Before I start spending too much money, I am having a play with anything else that may detract from the experience, hence the throttle linkage experimentation. The EFI has certainly awoken the engine, but I do think there's a bit more to be had :)
 

cobraboy

Well-Known Member
Bit scary? :cool:

Sparky is pretty quick, but has a certain something missing, perhaps just a bit of fine tuning required, but he does seem to pull back just a little.

The RP4 camshaft is designed for a heavy 4x4 auto, and has a power band of 1000-4800. I do think that replacing it with a fast road cam like an MC1 would perk him up bit and make the whole experience a little more lively. Before I start spending too much money, I am having a play with anything else that may detract from the experience, hence the throttle linkage experimentation. The EFI has certainly awoken the engine, but I do think there's a bit more to be had :)
The Cobra has a Real Steel Viper Typhoon cam which is very strong, really likes to rev, but the car is only 1000kg. The P6 has a re profiled Kent H224 cam, I can feel a late 'rush' with this cam, but that could be the secondaries coming into play ? Both are fast road.
Beware you may have to change valve springs to avoid going coil bound, and carry out a piston / valve clearance check.
Going for a peakier cam will mean that you will be chasing the revs more :D, but I understand that you want to get a nice punch.
 

quattro

Administrator
Staff member
I removed the cable, ‘home made’ linkage on the inlet manifold, and the gubbins on the side of the plenum, then found a couple of suitable bolts and fitted them into the now missing bolts on the manifold.

IMG_0853.jpg

When I rebuilt Sparky, I had the engine out for a while. This is a pic from back then and shows the bracket forming the front part of the throttle linkage.

carblinkage2_zps6bc583f8.jpg

So I thought if I just bolted it back on, it would line up with the bracket on the steering idler and I would have a sound base to construct a neater, more direct throttle. But no, that would be too easy; it just would not bolt back on. I knew I had the pic above somewhere so found it out and yes, I was trying to fit it correctly? Now it didn’t help as it was down the back of the engine and difficult to get to, but it should still bolt back on – it just wouldn’t. After a lot of head scratching and mumbling, I discovered that the EFI inlet manifold had a slightly larger footprint than the old four barrel mani, and overhanged at the back by some ¼”. This was in the way of the bracket. I tried using a ¼” spacer but then the front hole wouldn’t line up, and as it had already been modified by the previous owner I didn’t bother with messing around with it even more, just made up a new bit. This is held on by two bolts on the back of the cylinder head. The mani overhang is obvious in this pic. I did notice that the original bracket has a 3 degree “allowance” on it to line it up with the rear bracket, as the engine sits slightly down hill at the back. So I had to build in a 3 degree bend in my new bracket.

overhang.jpg

The accelerator shaft is an Auto one, which Sparky started out as. It’s not long enough for what I am looking to do, so I have scouted around trying to find one from the manual car which is a lot longer. If I push this one back far enough to get a split pin in behind the steering idler bracket, the forward end is flush with the nylon bush. There is nothing to stop it moving forward so I do need that split pin. I found a shaft on ebay at £21.20 and one from a P6 supplier at nearly £30, so just bought a 5/16 shaft from ebay at £2.99 and made one up. I used the crank from the original, then tacked it on, cut it to length, and was away.

IMG_0881.jpg

The nylon bush is the original one but there is nothing to stop it working its way out and possibly jamming something up, so I drilled a couple of holes through a washer, the bush and the bracket. Two small bolts will hold that in place.

I found the plastic/nylon top of the throttle push rod, screwed it on, then connected it up to find that it’s around an inch too short. At first I thought it may be the PO who modified it (chopped an inch off the end) but it may have been me when I made the linkage for the weber. I bought a short length of studding thinking that I could just screw the top onto that and somehow fix the lower cup onto it as well. But no, I had bought a stud with 24TPI and needed 32TPI. I just welded it onto the original bit and then cut it to length. It didn’t take much to break it though as there is very little to weld to, and I am not an expert welder. So plan B – cut a bit off the original, weld the new studding on again, then clean the weld, slide a piece of steel tube and weld both ends of that.

IMG_5937.JPG

IMG_5938.JPG

This is nothing like as easy as I was hoping it would be :confused:

When I was under the bonnet, I have been spurned into cleaning out the steering idler by another post on here. The oil on the top was clean and seemed quite new, but on dismantling I found thick grey sludge at the bottom. So I gave it all a good clean, including the little ball bearing valves, then refilled with fresh EP90 and put it all back together.

IMG_0854.jpg

IMG_0856.jpg
 

cobraboy

Well-Known Member
Trying to get all the links to work is certainly taxing, I just had another go at mine which was not giving full throttle. I got that sorted then wanted to raise the pedal a bit higher to aid heel and toeing. I thought, Ill just get two hands round it and give it a tug, er no, Rover have made that pedal assy so strong I could not bend it. I decided it was a job for another day.

Let us know if your new linkage is better than a cable.

I think I would have been tempted to lop the end off that manifold with a 1mm disc.
 

quattro

Administrator
Staff member
Let us know if your new linkage is better than a cable.
Will do

This bit was a bit easier. I just unbolted this assembly from the SD1 plenum and bolted it onto the plenum on the car. Now, the bar which is turned by the throttle has a ball on the end, which fits into the hex bit on the throttle lever still on the plenum. The little dogleg bit on the bar, meshes into the throttle lever and does the turning of the butterfly. The Range Rover system, which Sparky has is different though so nothing to mesh with.

IMG_0841.jpg

I pulled the spindle out of the SD1 plenum and found the other end was different to the Range Rover one where it ran the TPS so I couldn’t just change them over. I almost lopped the end off the SD1 one and cut a slit in it to get it the same, but I noticed the lever was actually held onto the spindle by the hex bit which is a nut. So, I just undid the nut and changed the lever over.

SD1 spindle.jpg

I don’t know if the spindle was slightly different and the lever was fitted at a different angle, or the PO of this bit ran it with the butterfly slightly open, or it was damaged or whatever but the throttle was open by a small amount. I had measured it prior to starting this project, and the bottom of the butterfly was 71mm from the mouth of the plenum. It was now 76mm.

Luckily the stop which positioned the butterfly when closed was a bit of metal on the new assembly and could be bent with a sharp tap or two of a hammer. The butterfly is now in exactly the same position as it was with the old assembly

Everything seems to line up nicely :)

IMG_5926.jpg

Turning the butterfly by the newly positioned lever would take it past WOT and start to close it again, so I made up a simple throttle stop to stop it at WOT.

IMG_0888.jpg

Coming along nicely now :)
 

cobraboy

Well-Known Member
At least you had more travel than req and could limit it, having less travel is when it gets interesting.
Excuse me for being thick, but in pic 3 the new bulkhead shaft and the new manifold shaft do not line up ?
 

quattro

Administrator
Staff member
in pic 3 the new bulkhead shaft and the new manifold shaft do not line up ?
Oh yes they do :p

If I bolt one of those clamp on crank thingies to both shafts, I can fit a short bar with a ball joint on each end to join them up. The picture is actually taken from a bad angle, but they will join up nicely.

I hope ;)
 

quattro

Administrator
Staff member
All I need now is a couple of spindle clamp lever thingies, but the only ones I can find are very expensive, the wrong size or in Australia. So I found the one I had started with and hammered it flat.

IMG_0905.jpg

Well they look easy enough to make. I cut out a couple of bits of 1mm steel, and just bent it into shape by hammering it flat over a ¼” plate, drilled a couple of holes and cut a slit with a 1mm disc, and hey presto

IMG_5935.JPG

I made them 35mm centres to match the one on the accelerator shaft, as I couldn’t work out how to calculate it, and could always adjust them later. Bolted them on, then had to remove them and cut the slit a bit wider. Now they fit and are as tight as hell, shouldn’t be any slippage there. To stop too much movement on the accelerator shaft, I made up a small nylon bush to fit between the large bush and the clamp.

IMG_0904.jpg

Fully open –

IMG_0908.jpg

Of course, the idle valve which sat on the end of the rocker cover, no longer fit there so I had to find somewhere else for it. To make it easier and hopefully neater I wanted to mount it on the same plane so that the hose from the back of plenum would fit, after chopping some of it off. The other hose from the air intake was nowhere near right so I managed to find an SD1 plenum hose, which was the correct shape to loop up around the throttle mechanism and to the right area for the idle valve. Chopped that off as well and it fits. The valve is sitting there in this pic just by resting on the hoses, but does need a better way of fixing it.

IMG_0897.jpg

After a great deal of trying to work out how to do it, I just grabbed a piece of box section and an angle grinder, and came up with this. I cut the end off the original bracket, which was a huge thing bolted to the holes in the back of the cylinder head, where the new bracket for the front of the accelerator shaft now fits. Welded this bit onto the new piece, and it fits just perfectly :)

IMG_0902.jpg

After painting, it fits quite neatly the back of the plenum

IMG_5967.jpg

Plugged the wiring back in to the idle valve and it put too much strain onto the loom as it is now in a different place, so I had to unwrap a short piece of it and reroute the wires. Also the SD1 hose didn't look quite right, so I cut 1/2" off the air intake end and it now fits a lot better - I didn't get a picture of this after as I got all excited and went for a drive :cool:

IMG_5963.jpg

All working, :)
 

cobraboy

Well-Known Member
As you are relying on your new home made throttle links - which are excellent BTW, you may need to adjust the limit stop under the pedal so the pedal is limited on travel, otherwise when the red mist descends during your next traffic light drag race the new links may be overcome by the forces at the pedal if the pedal has more travel than the links.
 

quattro

Administrator
Staff member
All the years have been driving these wonderful machines - never knew there was a throttle stop under the pedal :cool:

At present the pedal only moves the lever until it just touches the home made stop, and that's if you push quite hard on the pedal, so no immediate problem. I do have some 2mm plate and was thinking of using that, but the original one was 1mm, so I am trying that to start with.

I will be driving it about a bit before fine tuning the links, and will then adjust that stop if needed, appreciate you letting me know about it.

BTW, it is a lot more responsive, I mean WOW. I was hoping it would be a bit more exciting, but it sailed past 'a bit more,' knocked, 'a lot more,' over a hedge, rushed past, 'rather scary,' and was approaching, 'utterly terrifying.' I will have to drive around a fair bit more to check everything is ok, but certainly worth all of the work, and TBH, there was a lot more work than I had envisaged :oops:
 

quattro

Administrator
Staff member
Perhaps you were not attaining WOT before, and have liberated sleeping ponies ?
I had a full WOT prior to the linkage change but the control was lacking. I had to work harder to get any 'pick up.' Now, the response is instant and the throttle is very light and easy to use.

I did get out on the road today and found a problem though. Racing about in the car park was a bit scary because I wasn't used to that amount of response, but road was different. The transition between tickover and pulling away was a bit bit notchy. It felt as thought the butterfly was sticking and took a bit of pressure to free it, then whoooshh. I hooked up the lap top computator as I am running Megasquirt and you can see what is happening under there. Easing the throttle down slowly, I watched the TPS (Throttle Position Sensor) and found it went 4, 4, 4, 4, 28, when it should read 4, 5, 6, 7, i.e. it should be smooth upward reading and not all or nothing. I thought maybe the upper home made link could possibly be too much of a straight line with the uplink, so I removed it and mounted it a bit higher, lengthening the bar by 4mm. Hesitation gone - perfect. But then didn't get full WOT :oops:. Made a new upper link with 31mm between centres instead of the 35mm, and now have no hesitation and also full WOT.

Bit of a palaver but just a bit of fine tuning in reality.

Back on the road, the throttle response really has awoken the beast, the whole car feels lighter and more agile.

Utterly terrifying sounds like a result :cool:
Not quite so scary out on the road, but a lot of fun :)
 
Sounds like you have cracked it. I have a very long accelerator pedal travel, due to my reluctance to change too much from stock in a permanent way. Now yet another induction install is proven I think it is about time I perhaps speeded things up a bit. By playing with linkage lengths I should be able to get a faster pedal response without it becoming an on / off switch.

I am assuming that as you have quite a quick response now it gives the feeling that the car is really hooking up well, good result.
 
Top