bobdunn Posted March 22, 2012 Share Posted March 22, 2012 Hi I,m in the process of making a 1500 engine for my (mkiv 75) . All with small money. I started with a dolomite block, i,ve put a mkiii 1300 cam in on canley bearings . i,v put pinto seals on the inlet valves . i,m using a 1300 flywheel with bored out fixings (this saves 1.5 lb on std 1500 ) All bright ideas are welcome . I have fitted a small fan in the inlet , and lastly got an air die grinder to polish stuff . Link to comment Share on other sites More sharing options...
Nick Jones Posted March 22, 2012 Share Posted March 22, 2012 Sounds good so far - with the possible exception of "a small fan on the inlet" - not sure what you mean by that? Do get the crank properly measured and ground if necessary. This is an engine that likes to eat bearings. Balancing is a very good idea if the buget will stand it. Bearings need to be Tri-metal - King/County HD is probably the best you'll find now. Also worth carefully measuring the various clearances in the oil pump (even if new!) and lapping the gears and housing on a sheet of glass to minimise the end float. If re-using a pump, any scores in the end plate can be taken out the same way. Nick Link to comment Share on other sites More sharing options...
mattius Posted March 22, 2012 Share Posted March 22, 2012 Get the whole thing dynamically balanced like nick said, not just static. It makes a world of difference. Appart from that prep work prep work prep work, make sure everything is right before the final build, i build my 1500 some 4 or 5 times before the final build making sure everything is perfect. Don't skimp on gaskets or bolts they will come back to bite you! Link to comment Share on other sites More sharing options...
bobdunn Posted March 23, 2012 Author Share Posted March 23, 2012 Yes the fan. just an idea from talking to an expert, all this porting and polishing is to get air to flow more quickly or maybe a ram pipe from the front scoop . One mod was forced on me by the lorry driver who turned up with the engine , the wax stats were bent, so i have new std jets and needles . In the 70,s a pal of mine at LandRover was working on water injection and i also hear that it has been used in irish rallieing .This engine is a bit like the guy who built a boat in his front room, its on a strong wooden bench 36" from a wooden floor and its getting heavier . One plan is a shopping bag winch from my sister in laws car. Hands up if you have any experience of shopping bag winches . Link to comment Share on other sites More sharing options...
JohnD Posted March 23, 2012 Share Posted March 23, 2012 Bob, I fear that you have been impressed by a succession of snake oil salemen. Induction. A fan in the inlet. There have been a number of atempts to sell electric computer cooling fans as "turbos". Such a fan cannot generate any pressure at all to drive gases into the combustion chamber. "Ram air". While it feels that the onrushing air towards a car in motion must 'push' air into inlets - I mean it's obvious isn't it, you just put out your hand and feel it! - this is an illusion. The absolute pressure on the front of your hand is only very slightly more than atmospheric, whereas the pressure behind is significantly less. THAT's what gives you the wrong impression. The term "ram air" is also used to describe tuning the length of the inlet duct to a range of engine revs, so that the column of air in the duct resonates, to improve pressure and flow at the inlet valve. This is a completely different concept to the above. Water injection. Truly turbo charged engines, or engines that have been designed to use a high compresison ratio, can suffer from overheating in the combustion chamber and detonation, with disastrous damage. Water injection into the intake can cool the gas charge and limit that effect. The technique has no value, unless your engine is so extremely highly tuned. But after I've been the third honest user of this site to offer you sensible and valuable advice, I read your last sentence. A "Shopping bag winch"?! You're having a laugh - on yer bike, you've been rumbled! John Link to comment Share on other sites More sharing options...
bobdunn Posted March 23, 2012 Author Share Posted March 23, 2012 Sorry about the winch , my sister in law had a winch fitted to her honda jazz to get a grant . it weighs 2stone and lifts 25kg and you think i am having a laugh ! . I took it out the other day . i,ve found a pal with a big compressor so die grinding time . Link to comment Share on other sites More sharing options...
mattius Posted March 23, 2012 Share Posted March 23, 2012 last time i tried to lift a triumph engine it weighed over 25kg! im glad i won't be standing near that when you try to lift the engine. I just realised about the fan in the inlet oh dear! i didn't think anyone bought those things off ebay. Make a proper ram induction system for the su's can be done for next to nothing with some alloy sheet and some patience with some large bore conduit to feed it from the front. Link to comment Share on other sites More sharing options...
bobdunn Posted March 24, 2012 Author Share Posted March 24, 2012 Die grinder works fine . the winch part of the set up looks ok and over designed ,I hope to use it and two rollers . Link to comment Share on other sites More sharing options...
bobdunn Posted March 24, 2012 Author Share Posted March 24, 2012 ok i figured out pictures , that,s me with my 500 euro mkiv 75 spit, bought stripped down to the chassis . in Ireland you can,t sell the nice number plate . not brave enough to add up Canley invoices . But this is my saturday escape from the school run . Link to comment Share on other sites More sharing options...
kenben Posted June 24, 2012 Share Posted June 24, 2012 If you increase the pressure at the intake you need to increase it at the float bowl otherwise it will go lean as the pressure gos up. Either enclose the hole carb or attach the carb vent to the intake duct. Very common on motorcycles. Also the air pressure in front of the radiator is higher and cooler it’s a good place for the intake. Link to comment Share on other sites More sharing options...
motov8id Posted June 24, 2012 Share Posted June 24, 2012 a strong shed beam or tree limb can hold 8 1/2 stone. Just need a 3/8 chain an a stout wench. Link to comment Share on other sites More sharing options...
Millstone10 Posted June 24, 2012 Share Posted June 24, 2012 (edited) If you increase the pressure at the intake you need to increase it at the float bowl otherwise it will go lean as the pressure gos up. Either enclose the hole carb or attach the carb vent to the intake duct. Very common on motorcycles. Thats an interesting one, haven't heard that before. So for the usual SU float bowl arrangement, the vent would be connected to the airbox rather than a tube dangling down? Do you have any bike links for that? It sounds good. Nigel p.s. Welcome to the forum KenBen Edited June 24, 2012 by Millstone10 Link to comment Share on other sites More sharing options...
kenben Posted June 25, 2012 Share Posted June 25, 2012 I don’t have any links but when I raced gokarts and friends that raced bikes considered it common knowledge if the relative pressure his higher at the intake than the vent it will try to push gas back in the bowl . Makes a significant difference at high speed probably not much around town driving Link to comment Share on other sites More sharing options...
GT6Steve Posted June 25, 2012 Share Posted June 25, 2012 Back in the seventies I was JUST able to lift the engine, sans head, out of the Spitty by myself. Definately not recommended and definately out of the question these many years on..... I DO like Moto's idea to use a stout wench. They're always good to have around. Link to comment Share on other sites More sharing options...
Nick Jones Posted June 25, 2012 Share Posted June 25, 2012 Done a few Herald engine swaps, including 1500s which are a bit heavier, with two guys, a scaffold pole and some rope. IIRC we used to swing it in and sit the sump on a piece of timber sat on a large trolley jack and use that for the more delicate lining up. Renting an engine hoist can definitely reduce the risk of personal injury and collateral damage. These days I mostly deal with 6 pot boat anchors where manual handing is not an option! Nick Link to comment Share on other sites More sharing options...
kenben Posted June 25, 2012 Share Posted June 25, 2012 Nigel visualize it as the opposite of a butterfly choke when the coke is closed the pressure is higher in the bowl than on the engine side of the carb so more fuel flows. I didn’t use it my self was agents the rules in the classes I raced in. also I was told that the air box should be 10 times the displacement of the engine . Not all were some I saw were big. Not sure about SU carbs this was on 2 cycle engines between 125 and 350 cc karts raced on sports car tracks top speed of 150+. Link to comment Share on other sites More sharing options...
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