3tg rolla Posted June 6, 2007 Report Share Posted June 6, 2007 ok ive got a 2tg with twin 45mm webers on it, I'm having trouble with it holding at constant revs roughly 3000rpm it back fires through the carbies, it revs fine but holding it at a constant rpm she doesn't love it! also once under load it has nothing just doesn't rev. she's got all new plugs, leads, points, condenser, coil tested fine and just checked vavle timing tonight and its all ok. any sujestions cause i have no idea when it comes to carbs :D cheers :P Quote Link to comment Share on other sites More sharing options...
Clapped out Posted June 6, 2007 Report Share Posted June 6, 2007 Hey there, this doesnt sound good at all, your symptoms are the same as what i had with my 3t-g when i first got it, you done a compression test yet? Quote Link to comment Share on other sites More sharing options...
3tg rolla Posted June 6, 2007 Author Report Share Posted June 6, 2007 Hey there, this doesnt sound good at all, your symptoms are the same as what i had with my 3t-g when i first got it, you done a compression test yet? nar not yet, should be alright its only a pretty fresh motor! and carbs are brand new basically!! what was wrong with yours?? Quote Link to comment Share on other sites More sharing options...
Clapped out Posted June 6, 2007 Report Share Posted June 6, 2007 when i first bought my old 55 with the engine in it, it too was popping through the carbs and out the exhaust, so i gave it a major service, still doing it? off to the carby place to get the twins tuned, and the told me it was low on compression, so off to the mechanics and found out i had bent valves, thats what was causing it to "pop", when it tried to fire on the compression stroke, since it had bent valves it didnt have a good seal and when it fired it escaped back through the carbs and out the exhaust, this was caused through the camshafts not beiong timed properly and the valves had been hitting on the top of the pistons, i really hope this isnt the problem with your motor, you checked to see if the carbs might have picked up a bit of crap from the fuel tank? Quote Link to comment Share on other sites More sharing options...
flat out Posted June 6, 2007 Report Share Posted June 6, 2007 could also be a choke on, this happend to my mates 2tg on the weekend and made it run like shit Quote Link to comment Share on other sites More sharing options...
chrisandliz[RL] Posted June 7, 2007 Report Share Posted June 7, 2007 (edited) pray it's not the valves, i know some one how can rebiuld it for you at a cost for $700. but if some one put the head on with it on top dead centre, with the cams still in you'll bend them hella easy. even if the head was on and the cams are in and you roll the engine over it will F**k them. 2tg's are easy to kill heads Sorry Chris p.s. valves http://cgi.ebay.com/ebaymotors/New-Stainle...sspagenameZWDVW Edited June 7, 2007 by chrisandliz Quote Link to comment Share on other sites More sharing options...
Clapped out Posted June 7, 2007 Report Share Posted June 7, 2007 That is so true chrisandliz, they could have made them a stronger head, i guess we will have to wait and see! Quote Link to comment Share on other sites More sharing options...
foc64 Posted June 7, 2007 Report Share Posted June 7, 2007 Check your mixtures, it sounds like it's running lean to me, your idle stage needs to be spot on as it not only controls the idle mixtures but also affects the midrange until your main jets come on strong (about 3000rpm and up). Try a Google search for Weber jetting as there's heaps of info available if you look. You should also check your fuel pump/fuel pressure as this is another area that can cause the symptoms you're experiencing and will stop the engine from revving freely Good luck Chris Quote Link to comment Share on other sites More sharing options...
3tg rolla Posted June 7, 2007 Author Report Share Posted June 7, 2007 thanks fella's for your help. I'm hoping its not the vavles pretty sure its not because the vavle timing is spot on. ill have another play with it on the weekend see how we go. thanks heaps :P Quote Link to comment Share on other sites More sharing options...
Medicine_Man Posted June 7, 2007 Report Share Posted June 7, 2007 My twincarbs did this too, Found out the valves were not adjusted properly. Ended up with some burnt out valves, Had to get the head machined.. Also another part of the problem was a vacuum leak in-between the softmounts and the intake manifold/carbs.. Quote Link to comment Share on other sites More sharing options...
3tg rolla Posted June 7, 2007 Author Report Share Posted June 7, 2007 My twincarbs did this too, Found out the valves were not adjusted properly. Ended up with some burnt out valves, Had to get the head machined.. Also another part of the problem was a vacuum leak in-between the softmounts and the intake manifold/carbs.. was this your vavle clearances or vavle timing. well i have new soft mounts and a new maniold gasket but some thing eles to look at cheers Quote Link to comment Share on other sites More sharing options...
Medicine_Man Posted June 7, 2007 Report Share Posted June 7, 2007 valve clearances.. Quote Link to comment Share on other sites More sharing options...
old corolla bloke Posted June 7, 2007 Report Share Posted June 7, 2007 sounds lean to me... or the progression is wrong...try this its fairly easy. warm up the engine set the idle mixture correctly{as a guide it should be 3/4 to a full turn out} now run the engine to the rev range that the miss JUST begins to happen.......hold it there with the idle adjustment screw now wind the idle screws out....richer . say 1 full turn if the miss cures then she is too lean on the low speed jet. I would guess the jet should be a 50f9 or a 45f8 the other thing to check is the secondary venturi......the front bit in the barrel that slides in last check the stamping......I recommend a 4.5, if yours is a 3.5 or a 5 your can get this type of dramas cheers old corolla bloke Quote Link to comment Share on other sites More sharing options...
Clapped out Posted June 8, 2007 Report Share Posted June 8, 2007 the other thing to check is the secondary venturi????????????????? sorry old corolla bloke, i don't understand? i must have miss interpreted you wrong? side draft webbers don't have secondary throats? sorry to hijack your thread 3tg rolla! Quote Link to comment Share on other sites More sharing options...
3tg rolla Posted June 8, 2007 Author Report Share Posted June 8, 2007 (edited) the other thing to check is the secondary venturi????????????????? sorry old corolla bloke, i don't understand? i must have miss interpreted you wrong? side draft webbers don't have secondary throats? sorry to hijack your thread 3tg rolla! she's cool this is real helpful info :wink: so what jets and air's venturies and stuff would ya reccomend for 3tg high pistons bigger cams. i have no idea. did a bit of a google search and got a bit of a idea Edited June 8, 2007 by 3tg rolla Quote Link to comment Share on other sites More sharing options...
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