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K-Series Gbs Zero


brumster
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:sorry: Is all this peeing about worth it to get rpm that you will rarely use? ok I have done mods cos I WANTED to but its just away of burning money ! :crazy: mick

 

A lot of it - the cams, valves, etc - were actually purchased some time around 1999/2000 :) ! Yes, honestly! When we converted the Exmo to the K-Series, myself and a mate (who were 50/50 in the car) did a group buy on the old se7ens mailing list with a lot of Caterham and Elise owners, and picked up the bits at a bargain price. But like I said above, the original goal was to do all of this after it was on the road, next winter.

 

It's simply a case that the failed head gasket has forced the issue, so I might as well do it all now.

 

If we were all against burning money then I doubt many of us would bother with kit cars at all :D ;).

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I do admire your attention to detail & patience.

It's a fascinating exercise in its own right, & akin to my own

miniature engineering hobby.

 

I have the joyous position of not being in a rush ;). With time pressures come compromises!

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  • 1 month later...

Still waiting on the shims, so tickled away at a few jobs yesterday while I'm waiting.

 

The lambda controller by default had some pretty long cable runs on it but the problem is now, with the exhaust on the side and the position of the sensor being where it is, it's actually a really short run to the ECU and loom under the dash. So I chopped the lengths down and then spent some time soldering the cables and heat-sleeving them back together just to get the cable run more manageable. I then stuck it onto the underside of the battery tray panel.

 

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I then had to redo the wiring for the centre dash panel a little, as the map selector switch I had wired early on didn't actually suit the ECU loom I had - I had basically wired it to run through my custom loom but in reality it makes more sense to just run the three wires to the ECU directly, rather than going via the loom. The Emerald measures the voltage on a single input wire that's tied to 5v. You effectively change the voltage on that input wire to switch between 1 of 3 maps. 5v is one map, 0v is another (ie. you connect it to ground via your switch) and then you can set another middle map setting using a suitable resistor. They recommend a 1K resistor so I just went with that. During the IVA process the switch won't do anything, there will be only one map in the car, but for future use I figured it might be good to at least have a map for "with cat" and "without cat". Not sure what the 3rd one could be, maybe just one with an adjusted rev limiter or something - probably not really needed but... well... maybe a "rain" map if I eventually need one! More a case of "the feature is there so might as well put the wiring in for it" rather than thinking of any actual use for it quite yet :)

 

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  • 3 weeks later...

Still waiting on the shims, so I did the panelling out of the boot at the weekend for something to do.

 

Nothing complex here really - just used some spare cardboard to measure and cut out templates for the side panels and boot floor. I decided not to attempt anything too convoluted in terms of profiling around the filler neck and fuel sender take-off, but just continue from the suspension "turrets" straight back to give angled sides. I decided to bolt the bottom panel in rather than rivet it, just in case it ever needs to come out in the future for diff access/etc (more than likely). Lots of chassis foam and sikaflex used to seal up the panels and ensure they don't rub/rattle against the chassis or other panels.

 

A tip for the newcomers, to translate a hole into a panel when the panel covers it... put some blutak on the hole, press the panel onto it, the blutak should hopefully then come off with the panel leaving you a good imprint of the hole you want to drill into the panel. You can then carefully eyeball the centre spot with a pen at hand, quickly remove the blutak and mark/spot the centre on the panel fairly accurately.

 

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Side panels then rivet in, like I said, at the front where the suspension turret tops (for want of another phrase) are. I'm still bouncing ideas on finishing off the top but I suspect I will make some sort of cover/bracket to go around the rollover hoop base, that covers all of the panel gaps in some suitably tidy fashion. So for that reason, no need to really worry about presentation on the sikaflex between the panels, as it's all going to be covered in carpet or some sort of trim. That's the plan anyway!

 

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I need to do something with the back face which at the moment isn't closed off. This one's a bit awkward because obviously it's all external panel, so I can't really bolt or rivet anything into place on the back face. I suspect what I will try and do is make a panel that follows the top edge, so has a 90 degree bend in it, that I can then bond onto the underside of the rear top edge/lip... and then fasten it to the inner side panels (the ones I've just put in) with some aluminium 90deg angle, or a careful fold. Might be a case of play around and try a few things there.

 

While I had the sikaflex cracked open, I did the windscreen. I kept a list of jobs involving sikaflex so that I could them all together once I'd opened the tube.

 

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Bit of overspill in places but once it's hardened it's pretty easy to trim with a fresh stanley blade...

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Looking good Dan. From experience, I had issues getting the top shock bolts out when I had my corner weighting done, because of the turret panels I had. Ended up having to unrivet the panel and unpick the sikaflex. Now have an `access hole' fitted with a rubber grommet under the carpet.

 

Sure you have already thought of this though.

 

B)

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It's a good point - one of the upsides to the way I've done it, is that the shock bolt can slide out fine - you have under-arch access to it this way. Not entirely intentional, I'll admit, but a happy side-effect :D :D :D

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  • 1 month later...

Sick and tired of waiting, so I spent the weekend with the band saw and milling machine and have made up some suitable vice jaws to hold the shims in place while I shave their heads down :)

 

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So after a bit too long waiting for others to do this for me (no criticism there - it was all being done as a favour so I can't complain) I finally got round to it and "shaved" down my shims today... they just need final fettling to tolerance, and deburring, but looks like I can finally reassemble the engine soon!

 

10 minutes per shim in the Sieg, but I've sped it up x32.... so don't think this is realtime :D....

 

https://goo.gl/photos/7JAXritRPtTspJ7H9

 

Results, on a printout of a spreadsheet I did to work out how much each shim needed to be taken down by... I don't trust my maths...

 

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  • 3 weeks later...

Yesterday was spent timing the cams in, so I'll write up some main tips here for anyone who's never done it before. There's no reason to be put off with the thought of doing the cam timing, or even more basic stuff like changing the cam belt, but I know a lot of people consider it some black art and would rather steer clear, so I'll try and allay any fears you may have :)

 

So my cams come with two essentials piece of information, the only two that I am concerned with...

  • Exhaust full lift at 106deg BTDC (before top dead center)
  • Inlet full lift at 104deg ATDC (after top dead center)

This kind of means exactly what it says - the valves should be fully open their respective number of degrees before or after the particular piston in question is at upper most point of travel. The first thing to do is establish where TDC is, which I thankfully did this before the engine came apart and left it marked up, but if you need to, you basically put something long down one of the plug holes and crank the engine over slowly by hand, measuring the movement of the rod with a dial gauge. There will be a "dwell" period where you seem to get no movement at the piston comes to the top of it's stroke - this is normal - so you should measure the two points where you see the movement stop/start, and then take the middle. So if you see dwell for 10deg of crank movement, wind back 5 degrees to the middle. You can use any piston you like as long as you measure the cam lift on the same one! I used No.1 piston at the front of the engine. Remove all the spark plugs.

 

Once we know TDC we put a timing wheel on the end of the crank so we can accurately measure movement. I made a little tab of aluminium that could be bolted into the block to give me a good reference line to measure against. Since the crank end bolt isn't on massively tight here, it's important to remember that once the wheel is on and in the right position, be very cautious about turning the crank backwards (anticlockwise) by the bolt as you run the risk of undoing it and losing your timing wheel position. I just use the rule that the crank only ever gets turning in the clockwise direction.

 

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Now it's just a case of putting the cams in the right position for the engine. Given the above about only turning the engine forward, I do the exhaust cam first since it opens prior to TDC. In the above image you can see we are at 106deg BTDC (I know it looks like 104, it's the angle of the picture, it's 106 honest!)... think about it, the engine cranks in the clockwise direction, you can see "TOP" is marked around the 9 o'clock position... so at the moment we are *before* TDC... it's "coming around".

 

At this point then, we position the exhaust cam so that it's opening the exhaust valves the most. You can get the general position by eye at first, but then you'll need a dial gauge and the afore-mentioned bracket to hold it... this allows us to see exactly where the valve is all the way down, to thousandsths of an inch. Less of an issue on standard engines with standard cams/timing, but to get the most out of your race cam this needs to be done properly. Best case you'll be down a few bhp, worst case your valves might meet the piston crowns at full chat, and we all know that won't end up being pretty :)

 

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Now move on to the inlet cam. There are marks on the Piper 285 cams (actually lobes used by a cam position sensor) that help me put the inlet cam in a rough position 180 degrees out of phase with the exhaust cam, which makes it slightly easier, but that won't apply to everything. Obviously at this point in the engine cycle it's hard to determine exactly where the inlet cam should be.

 

Put the cam belt back on, making sure the tension is on the downward run of the belt from the cam pulley to the crank. Just follow the guidance for your engine from the Haynes manual. Pull the tensioner up a little to stop it slipping a tooth. Then we turn the engine forward, towards the 104deg ATDC. A word of warning : if you did put the inlet cam in some guessed position, that's fine, but be very careful when turning the engine over that you don't get the valves hitting the pistons if the cam is way out of phase. The moment you sense some resistance, STOP, back off 10 degrees, then loosen the belt to free up the inlet cam and reposition the cam (wind it backwards, most likely) before re-assembling the cam belt. Make note of the tips below about cams "springing" round ;)

 

Assuming you're round at 104deg ATDC, you can repeat the above steps for the lift on the inlet cam. Remove the belt, making a point to note the position of the exhaust pulley in case it moves (which it probably will do), get the inlet in the right position for max lift, then re-assemble the cam belt.

 

When you think you're all done, do another 2 full turns of the engine clockwise through it's cycle, then go round to the points and check them once more. Minor corrections of less than a tooth on the belt are accommodated by adjusting the verniers on the pulleys but don't be lazy and use these to the full extent of their travel as it defeats the purpose of them if you ever visit a rolling road for fine tuning. I managed to get full lift with hardly any adjustment on the verniers, managing to keep them in their central position roughly.

 

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If you adjust or change anything, my advice is to go a cycle around the engine again and check it. Check, check, check. Don't lie to yourself that "oh that's close enough". Get it bob on.

 

Now to all of the above there are some critical tips for you :

  • If you need to move just a few teeth on a pulley, use some blutack (or anything suitable) to mark the pulley teeth (or teeth gaps) that are facing each other on the pulleys, so you have a visual reference. Note the crank position too. Then slowly and carefully remove the cam belt, paying attention to the cam lobes on both cams - if ANY of them are considerably engaging with the followers then that cam will most likely spring back one way or another when the belt is removed (unless the lobes are fully down). Pre-empt this by bracing the cam with a spanner/socket or whatever. If a wheel does pop into another position, you can use the markers to get them back where they need to be.
  • A locking tool (the blue bit above) is not essential but makes things a bit easier, particularly with tightening the cam pulley bolts.
  • Make sure your dial gauges are making use of their full travel, and don't hit/interfere with the cam lobes as they come around
  • Never force the engine "through" any resistance.
  • Do NOT drop any nuts, bolts, washers or dial gauge tips into the engine :)
  • Do NOT forget to apply the cam belt tensioner when turning the engine round
  • Turn it only clockwise
  • Don't let the timing dial on your crank move. When you do your final timing checks, verify TDC once more.
  • Use a new belt. I don't care that Haynes says you can re-use one. Don't :)
  • Don't get frustrated when you find one cam is out by a single tooth. Just work through things and step it forward/back as necessary.

I think that's all the important bits :) took me best part of the day to do, so not a quick job, but well if you're doing these things right... spare a thought for race engine builders and their charges ;)

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