Terry Field Posted June 10, 2005 Share Posted June 10, 2005 Took the XF to Steve Greenald at 'Road N Track' to get the new 1700 sorted. It couldn't be done because the dizzy (off the old 1600) had too much mechanical advance. I have been talking to Aldon about having the dizzy recalibrated because at £70 odd, it seems the cheapest option. The other options are to buy a Bosch distributor which has much more 'on the car' adjustment of the springs, or go to fully electronic (which I can't afford/justify at the moment), but first I will try Aldon. The engine has a massive 11.7:1 compression ratio, and the compression test was in excess of 150psi on each cylinder (it actually went off the guage on Steve's tester!) I have a Maxflow 1B head and a 244 cam with DCOE 40's Steve has suggested that the spec for the dizzy should be 7deg mechanical advance," with some fairly strong springs". This is to give clean pulling in the lower revs without all the poping and banging that happens now. It then needs less advance at around 3500rpm, and probably more advance as it goes up the rev range, although were unable to verify this due to the timing difficulties. Aldon will obviously calibarate it as they think fit, and I am trying to get them to send me some additional springs as well, so that Steve can experiment with different settings on the rolling road. I know that quite a few Blatchatters have been down the Aldon recalibration route, so I would welcome any feedback on your experiences, and in particular how you agreed the spec with Aldon, and whether the spec actually worked in the car. AND SPOTTED!! Steve had K8 TRM on the rollers producing 196+ bhp. He was chuffed to bits with the result! Terry 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
Graham Sewell Posted June 10, 2005 Share Posted June 10, 2005 When I talked to the folks at Aldon, I was told to speak to the person who would actually do the work. We then discussed the state of the engine and what they thought were good values, and Ithen suggested values provided by Roger King. These were set up as requested and the car is now far better than I would have expected for such a cheap upgrade. In your case, as you have ideas of the idle advance and max advance, if you can also give the start/finish points for the ramp then you can get the dizzy set up pretty much as you want. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Geoff Dixon Posted June 10, 2005 Share Posted June 10, 2005 K8TRM is mine. Picking it up in couple of hours. Steve said engine was really sweet one and complemented whoever built it. Little does he know what difficulties I have had and how much it has cost me. Bit sad really I wanted over 200bhp. However I have got quite mild cams. No way do I dare spend any more on the thing. Link to comment Share on other sites More sharing options...
Terry Field Posted June 10, 2005 Author Share Posted June 10, 2005 Geoff, Enjoy it, I bet you won't miss 3.5 bhp 😬 Terry 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
Terry Field Posted June 10, 2005 Author Share Posted June 10, 2005 Graham, I think that is good advice. the chap who will do the work is on holiday for two weeks, but I will ask to speak to him before the work begins, and bounce his ideas off Steve. The start and finish points are what Race 'N' Road have suggested, but we haven't discussed any intermediate points. Can you remember what values you used? What spec engine do you have? Terry 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
Dickie Normuss Posted June 10, 2005 Share Posted June 10, 2005 Geoff Long time no see Is it still 1600 or did you go bigger 🤔 Seek forgiveness, not permission. Rules are for the interpretation of wise men and the obedience of fools. Link to comment Share on other sites More sharing options...
Graham Sewell Posted June 11, 2005 Share Posted June 11, 2005 as a dizzy is quite a crude device (a couple of springs, a couple of bob-weights and a tab to limit max advance) you can only really specify the two end points of the ramp. In my case it was 14deg at 1000rpm and 35deg at 4000rpm. The ramp is fairly linear between the two. My engine is a near normal spec 1700 supersprint although since I had a Vulcan unleaded conversion my compression test figures have risen dramatically. used to be around 14atm now closer to 16atm. Have had to start using Superunleaded to prevent pinking. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Terry Field Posted June 12, 2005 Author Share Posted June 12, 2005 Thanks Graham, I think they are the same limits which I would be looking at, i.e 7deg mechanical advance giving about 14deg at 1000rpm at the crank. Clearly the only way to get away from the linear progression is to go to full electronic which may be a later option - can't afford it at present. I usually run super unleaded in nay event. Incidentally do you know how 16atm converts to psi? Terry 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
Geoff Dixon Posted June 12, 2005 Share Posted June 12, 2005 Ric, blew the engine back end of last year, did the crank, rods and liners in. Have had block rebuilt by Scholar, new liners, and forged rods. Replaced crank with VHPD one, now 1.8. Had the head re shimmed. When will this stop. Still have a shopping list a foot long. Redline at Caterham did most of the work. Nothing but praise for them. They were truely excellent although i dont think this was their favourite job this year!! Link to comment Share on other sites More sharing options...
Graham Sewell Posted June 13, 2005 Share Posted June 13, 2005 16atm is about 210psi !!!! That is after 10 compression strokes. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
J A T Richardson Posted June 13, 2005 Share Posted June 13, 2005 16atm - ah, that makes me feel better. My compression readings are 208, 205, 203, 210 - after new rings, honed block etc, which made NO difference. My view: ovewr 200 is fine; a few % variation is not a problem. Stinky toy driver - and proud of it! Link to comment Share on other sites More sharing options...
PAC Posted June 15, 2005 Share Posted June 15, 2005 Terry psi = Bar X 14.5 Paul Link to comment Share on other sites More sharing options...
Terry Field Posted June 15, 2005 Author Share Posted June 15, 2005 Thanks paul 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
Terry Field Posted September 19, 2005 Author Share Posted September 19, 2005 It's been a long Sevenless summer, but here is the update. Having had the dizzy recalibrated by Aldon,it still proved to be impossible to tune out all the pinking, especially under load in third. A conversation between Steve Greenald and Steve at Vulcan led to me taking the engine back to Vulcan for inspection. All credit to Vulcan, they strippped and checked the engine but could find no obvious fault. They did remeasure the compression ratio and found it to be 12:1 (previously thought to be 11.7:1). The accralite pistons were skimmed around the edge and in the bowl and some small reprofiling done. The result was a compression ratio reduced to 11:1. The engine is back in the car and runs so much better. Even with my home spun set up it feels more willing to rev and pull, and no hint of any pinking. The true test will be when it goes back on the rolling road in a couple of weeks, but I am pretty confident that the problem has been solved - I just hope it hasn't been at the expense of too much power. As no specific problem seems to have been found, I suspect that the dizzy just wasn't up to the job, whereas electronic ignition would probably have been able to cope. Why that should be I just don't know, although there are undoubtedly better technical brains out there than mine who may have an idea. Anyway, we are back on the road and at last I was able to enjoy a long blat in the sunshine at the weekend (including being SPOTTED!) 😬 Terry 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
I.Mupferit Posted September 19, 2005 Share Posted September 19, 2005 I am getting a real feeling of deja vue on this. A friend of mine (and 7er) had his X/Flow rebuilt by Vulcan a few years ago and ended up with too high a CR, causing the engine to go into self destruct mode ❗ Brent 2.3 DURATEC SV Reassuringly Expensive R 417.39 😬 Link to comment Share on other sites More sharing options...
Terry Field Posted September 19, 2005 Author Share Posted September 19, 2005 Brent, it's weird isn't it? When I originally cast around on Blatchat for advice on builders, lots of votes came in for Vulcan, and they have obviously built lots of XFlows in the past successfully. A few people in the Club have told me what good engines thay have had built. In some ways I wish some 'obvious' fault could have been found and corrected. The finer points of the interrelation between compression ratios, cams, valve timing and carburretion etc are too much of a black art for me to form a view on, so I am still in the dark. Time will tell if it is a good engine or not, but don't get me wrong, I am not knocking Vulcan. They recognised that there was a problem and appear to have fixed it without any quibbles. Things do go wrong sometimes, and to me the important thing is that they took responsibility and fixed the problem instead of trying to avoid the issue. Terry 1700XF - Team Lotus with flares. Link to comment Share on other sites More sharing options...
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