PSJ Posted May 19, 2011 Author Share Posted May 19, 2011 Well since putting the new coil pack on the car defo feels better and now reached 90/95mph no problem! (speedo may be out) Before it wouldn't budge past 70mph so this indicates that the new coil pack was the main problem (old one was full of fluid!?) and car doesn't seem to be back fireing anymore since I took plugs out and cleaned them?? The Dellorto's seem to spit now and again but not offen, they might need fine tuned to sort that out and help performance even more! Also need cam timeing sorted and I think the car will be more or less back to normal (fingers crossed). Also i will get a fuel pressure regulator fitted ASAP. JACK FLASH - hello !! Ditto, nice to meet someone with the same engine. Can you tell me anymore info on the engine as it's all abut vage to me, is it a certain version which has a name?? All I know is that it's a lotus twin cam on a crossflow bottom end and a 50cc spacer making it 1598cc (1.6), bigger bore for the sprint pistons?? ..Does it have different cams?? Or standard TC cams. And any other different internals!? Id love to know exactly what type of twin cam I have to clear things up etc. Thanks. Piers. Edited by - PSJ on 19 May 2011 10:39:39 Link to comment Share on other sites More sharing options...
Area Representative skeetsy Posted May 19, 2011 Area Representative Share Posted May 19, 2011 Regarding the details of your twincam engine I will try to give you a bit of background as best I can but if others on Blatchat want to pick me up on details then it's always good to learn The Caterham 7 S3 was produced with the Lotus twincam engine between 1974 and 1983. Initially the engine used was the same MK 2 Lotus twincam which was found in the MK 2 Cortina, MK 1 Escort and later Elans, etc. however, supply of the original L engine block dried up and from 1978 the twincam engines were built up from an alternative 1600 crossflow block and these were generally known as "Tall block" twincams. In a Tall block engine build you start off with a standard crossflow block and remove several millimeters of material from the top of the block (this is called decking) a bit like skimming a cylinder head. however, when you have gone as far as possible without fear of breaking into oil and waterways you are still left with a cylinder block which is about 5mm taller than the old L block and as a result you need to lengthen the cam chain and add a spacer between the chain cover / water pump housing and the front portion of the cylinder head. I don't think the cams are different for this engine to the original sprint engine in an Elan, however, tall block Twincams were never fitted to Lotus cars from the factory. The crank and rods are standard crossflow 1600 items I believe but the block is bored to take the original twincam pistons and it is the longer stroke which gives the additional 50cc capacity. The original power figure would have been quoted as 126 Bhp, however, everyone will tell you that this was an 'optimistic' figure and the probable output was between 105 and 119 Bhp (manufacturing tolerances weren't great back then ) In terms of setting up your engine, cam timing is a very tricky job involving offset dowels (unless you have verniers fitted) and unless the engine has been apart it won't have changed from the time it was put together originally. The engine I played about with had L1 cams and was ferocious 😬 but was an early MK 1 engine, it gave about 140 Bhp and was fitted to a MK 2 Escort, which felt like a flying machine 😬 but even so your standard lump in a Caterham should be able to leave most things for dust If power is your aim (beyond just getting your engine running sweetly) then you will definitely need to consider a cam change, but before you go down that route (and all the expense entailed) your aim should be to get your twincam running well All the best Richard Link to comment Share on other sites More sharing options...
PSJ Posted May 19, 2011 Author Share Posted May 19, 2011 Thankyou very much Richard. Nice bit of info there. If anyone knows anymore details that would be great! My dad had trouble getting piston rings when it was 1st rebuilt and had to send the pistons off to get rings to match as the original twincam pistons rings didn't fit!? I rang the garage that said to the timeing was out, as I was going to get it booked in to get it reset. But he said it was 10degrees "advance" so it's not actually out, it's correct. I just didn't understand what he ment when he 1st told me. Oops. My dad did have it on the rollers years ago and it made 117bhp, but not sure what the torque figures were or what they are ment to be? Iv got it booked in this sat for a rolling road to see what it gets now. I can't see it being anywere near 117bhp just yet mind. Cars been running rich so iv learnt tonight. So I have had a fiddle with the setting screws on the Dellorto's and have got rid of the black smoke Which it would throw out (when rapid on and off throttle at low revs) and i hope to be rid of the 3 black dry sooty plugs (#2,#3 and #4) from when I checked them earlier. I also checked plug #1 and it was slightly oiled but only a little?? Yet on the compression test cylinder #1 is the strongest (both times) which is slightly confusing. All plug rings/seats have slight oil sitting in them if that means anything?? Thanks, Piers. No I'm not after huge power just want it to be running strong and healthy. Edited by - PSJ on 19 May 2011 21:09:10 Link to comment Share on other sites More sharing options...
Area Representative skeetsy Posted May 19, 2011 Area Representative Share Posted May 19, 2011 If your Twincam was pushing out 117 Bhp then it sounds like it was a good one In terms of torque you should expect somewhere around 110 to 115 lb ft If you've got time on the rollers booked then hopefully the place you are going to will have various size chokes, jets, emulsion tubes, etc. to try and get the best from your Dellorto carbs but really (assuming they are the original ones) 117 Bhp is right at the top of the range for your engine without going for different cams so it should just be a case of making sure the fuel delivery and ignition are correct and away you go. Let us know how you get on 😬 All the best Richard. Edited by - skeetsy on 19 May 2011 22:01:00 Link to comment Share on other sites More sharing options...
PSJ Posted May 19, 2011 Author Share Posted May 19, 2011 Yea, he let a guy called John pringle (owned an Lotus 7 S4) drive it back in the day (from the old 7 meets) who so iv been told knew twincams very well, and he said it was a strong engine. But like I say I don't think it will be pulling that now. It's only booked for a power Run as they are busy on sat but if they have any spare time I'm going to see if they can tweak the Dellorto's up properly to get the best out it. Thanks :) Piers. Link to comment Share on other sites More sharing options...
Derek Price Posted May 21, 2011 Share Posted May 21, 2011 Try Burton Power or Vulcan Engineering. Both in London. Both excellent. These Ford engines are best looked after by people who know how they were originally built and specified..these two outfits are long standing specialists. Not the cheapest but if you are doing it properly you will only want to do it once. keep it original..good luck. Link to comment Share on other sites More sharing options...
PSJ Posted May 23, 2011 Author Share Posted May 23, 2011 Cheers The car made a very disappointing 73bhp and 75lbft. A Leak test was done and cylinder 1 is perfect, 2 is border line ok (25%), 3+4 are 80-95% leaking!! Hence the 40-50bhp down on power. Car is running VERY VERY rich also!! So this week I'm Going to remove the head and take a closer look inside to see what needs replacing etc (will get pictures up on here). Hopefully I don't need to take the whole engine out to get the bore liners re-bored. I think it's mainly down to piston rings and exhaust valves but we shall see! Piers. Link to comment Share on other sites More sharing options...
JACK FLASH Posted May 23, 2011 Share Posted May 23, 2011 Hi, Doesn't sound so good but look at it on the bright side. Things, performance, can only get better. I am really curious about the pistons and piston rings you' ll find in there. As I said earlier, we changed the Hepolite pistons in order to use the normal rings for Kent pistons. As we are talking about Twin Cam trouble. Sunday I did 40 km with my Twink and I discovered something new. When pushing the car hard followed by hard braking, for example for a U turn, the engine seems to have trouble to pick up revs again. As if it doesn't get enough fuel when engaging the throttle again. After a few seconds and playing with the throttle, it starts to pull cleanly again. Any ideas? Jack Flash j.jackflash@hotmail.com Link to comment Share on other sites More sharing options...
Pooh_R Posted May 24, 2011 Share Posted May 24, 2011 The leak down test should show where it was leaking, as well as how much? Interesting to follow your story! Link to comment Share on other sites More sharing options...
jonboylaw Posted May 24, 2011 Share Posted May 24, 2011 To JackFlash.... sticking float valves in the Carbs ? Carbs a little too lose?, engine mounts lose ? Jon Link to comment Share on other sites More sharing options...
terryp Posted May 24, 2011 Share Posted May 24, 2011 Hello What plugs are you running? NGK BP6ES normal driving NGK BP7ES very spirited driving If you have fitted BP7's and poodle around they don't clean. I have BP6ES in my Elan as do many others and they are fine Just a thought! Terry Link to comment Share on other sites More sharing options...
JACK FLASH Posted May 25, 2011 Share Posted May 25, 2011 Guys, Thanks for the first couple of ideas. Plugs, I have to check because I do not remember which type we used when rebuilding the engine a couple of years ago. The sticking float valves in the carbs ... seems logical. Problem is how do I make sure that this is the fault? Jack Flash j.jackflash@hotmail.com Link to comment Share on other sites More sharing options...
JACK FLASH Posted May 26, 2011 Share Posted May 26, 2011 Hi again. Just by accident I saw pics of your Twin Cam on the internet. The chassis plate is very interesting. You have chassis number CS3 3844 TCRS and I have CS3 3851 TCLS. So there is only a difference of 7 cars between them and both have the RS2000 Mk2 rear axle. There us even a possibility that they have been together in the old Caterham site up the hill during the building. A great opportunity to compare these Sevens and exchange information. Jack Flash j.jackflash@hotmail.com Link to comment Share on other sites More sharing options...
elie boone Posted May 27, 2011 Share Posted May 27, 2011 To check a float valve, take the carb cover off, hold the float in the full position and blow on the fuel inlet, if you release the float you should be able to hold trough. JF are you doing the lotus Ypres tour on the 2th ? Link to comment Share on other sites More sharing options...
PSJ Posted May 27, 2011 Author Share Posted May 27, 2011 Jack - very interesting! We should meet up someday! Also what plugs to you run? Spoken to Redline further about the TC issues after Checking ignition and fueling out further last night. Found out that the carb jets are the wrong size (current ones - 7772.10 and 58's) and the plugs being the wrong ones. I should be running BP7ES's instead of the BP6ES's that iv currently been using which keep getting sooted! Why these plugs were in the car i dont know!? Hopefully the new NGK BP7ES plugs I have bought today may sort the problem out abit more. Slowly but surely getting there. Piers. Link to comment Share on other sites More sharing options...
Area Representative skeetsy Posted May 27, 2011 Area Representative Share Posted May 27, 2011 Quoting PSJ: I should be running BP7ES's instead of the BP6ES's that iv currently been using which keep getting sooted! Why these plugs were in the car i dont know!? Hopefully the new NGK BP7ES plugs I have bought today may sort the problem out abit more. The BP7ES and the BP6ES are effectively the same plug but with a different temperature range. The numbers on NGK plugs help to identify the temperature range but confusingly the higher the number the cooler the plug. This means that you are putting a cooler operating plug into your engine (which incidentally is the recommended plug for the Twincam) but as stated by terryp in his earlier post unless you drive in a spirited fashion (i.e. more revs more of the time) they will have a tendency to soot up more quickly than the hotter BP6ES. I suspect your sooting is mixture related rather than plug related, and in terms of the woeful lack of compression in two cylinders are you burning much oil? if the piston rings have failed then this will normally result in increased oil consumption (and blueish smoke from the exhaust) whereas if the valve seats are to blame there won't be as much oil smoke. BTW if the rings have gone the bores are likely to be badly scored and you may be able to check this out if you can find someone with an endoscope like this - a friendly local garage may have one All the best Richard Link to comment Share on other sites More sharing options...
PSJ Posted May 27, 2011 Author Share Posted May 27, 2011 well i since i had left the TC with a friend who worked for a rally team, he and his son (who currently works at the same rally team- malcom wilson) has been on the case in diagnosing the engine. issues we found out last night -Fuel pump needs a regulater (already stated by you guys within this forum thread) -the jets are the wrong size and the carbs need set up properly. -plugs were BP6ES's instead of BP7ES's. -Cam timing IS wrong, was at 10degrees advance but meant to be 12 degrees dead centre. issues they have come accross today since taking the TC head off and taking a look inside. one of the exhaust valves is lifting (i think thats correct term) further than it should be. also most of the exhaust valves have slight damage. but il let the pictures do the talking. we think the soot/dirt is from the fuel addative to make it leaded but not 100% http://a3.sphotos.ak.fbcdn.net/hphotos-ak-snc6/251635_10150268585160931_694385930_9419198_548_n.jpg http://a6.sphotos.ak.fbcdn.net/hphotos-ak-snc6/249695_10150268587825931_694385930_9419212_8134348_n.jpg http://a3.sphotos.ak.fbcdn.net/hphotos-ak-ash4/252155_10150268588650931_694385930_9419217_8005304_n.jpg http://a6.sphotos.ak.fbcdn.net/hphotos-ak-ash4/247380_10150268589820931_694385930_9419225_8279225_n.jpg http://a1.sphotos.ak.fbcdn.net/hphotos-ak-snc6/252525_10150268590655931_694385930_9419228_885833_n.jpg http://a5.sphotos.ak.fbcdn.net/hphotos-ak-snc6/254420_10150268591820931_694385930_9419235_5787371_n.jpg http://a7.sphotos.ak.fbcdn.net/hphotos-ak-snc6/252350_10150268592680931_694385930_9419243_236795_n.jpg http://a8.sphotos.ak.fbcdn.net/hphotos-ak-snc6/253635_10150268593570931_694385930_9419247_6845982_n.jpg http://a4.sphotos.ak.fbcdn.net/hphotos-ak-ash4/247535_10150268594450931_694385930_9419251_6479985_n.jpg piston bores and pistons all seem absolutly fine, no markings or damge in anyway which is a good sign as we dont need to touch the bottom half. just work needed on the head. so packing the head up and sending it off to get sorted out and converted to work on unleaded fuel etc etc this next week. also going to order new head gaskets from redline etc too. Piers. Link to comment Share on other sites More sharing options...
JACK FLASH Posted May 30, 2011 Share Posted May 30, 2011 Hi everyone, Very interesting thread but also confusing about which type of NGK plugs are the best for a Twin Cam. Is there perhaps a difference between the "normal" TC in an Elan and the tall block in our Sevens. The NGK website gives the NGK BP7ES or the NGK BPR 7EIX (iridium). Has some-one got experience with this new iridium type? Elie, the lotus Ypres tour on the 2th is impossible for me. This due to a massive workload and several commitments for the daughters. I am happy to have a one hour blat each weekend, just to keep the Twin Cam running. Jack Flash j.jackflash@hotmail.com Link to comment Share on other sites More sharing options...
JACK FLASH Posted June 1, 2011 Share Posted June 1, 2011 Hi again everyone, Finally I found the time to take the plugs out and I also discovered NGK BPE6's. Since I want the Twin Cam to have optimal performance in its standard specification, I am going to try the NKG BPE7's. They are not that expensive, so why not trying to see if there is a difference. I checked some websites and found following NGK plugs "7" Twin Cam engines: NGK B7ES : short tip, fast road NGK BP7ES : fast road NGK BPR7ES : resistor? NGK BP7EVX : fast road platinium NGK BR7EIX : iridium (replaces B7EVX), short tip? Who knows the difference and who has experience with these types? Jack Flash j.jackflash@hotmail.com Link to comment Share on other sites More sharing options...
PSJ Posted June 1, 2011 Author Share Posted June 1, 2011 Iv bought some BP7ES plugs ready to fire in for when I get back my cylinder head. You will have to let me know how they compare to the 6's as you'll no doubt be out and about in yours before I get mine back together. Edited by - PSJ on 1 Jun 2011 14:41:43 Link to comment Share on other sites More sharing options...
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