cam causing engine probs?

bombz4

bombz4

Ex. Club Member
my dad ran my engine properly today and its very lumpy under 1500rpm and barely runs with no choke even when warm, ive heard that i should advance the timing one notch is this right? also im going to have to adjust the carb to run slightly richer. once i have this temporarily sorted and an mot il be rolling roading and getting my new carb and manifold set up. will this enable me to iron out the problems?
cheers bomb

(i got a reprofiled cam btw!)
 
thats something yaul have to put up with lumpy tick over,this is the down side of a performance cam.
when you say move one notch do you mean move the cam pulley one notch on before tdc on the belt,,,,,,,then dont its to much......just set the timming about 18 deg advance.
 
cheers bob il borrow a timing light. its the fast road regrind which is 154degrees duration. i cant remember the lobe height but i dont think that it makes a difference timing wise anyways! cheers amy but if theres anyway i can keep it in until after the mot im going to try it as i cant be botherd to spend one more minute on my car! hopefully if i advance the timing and let it run slightly rich it should be okay for the mot. the tester that i go to is quite lenient so i hope that its going to be okay. and as soon as my car has an mot i can go and get the carb changed and setup and hopefully then it'l be better, i understand that a perfomance camshaft can make it lumpy at low revs and i know why it is like it is, but i thought that if it was only a fast road cam it would be okay. bob were there any problems when u put one in with pietros engine? what carbs did you try it with? did you try it without the twin 45s?
 
just move the dissy untill it idles better and when you find the sweet spot tighten the nut and take it for a spin to see how it drives and how it idles afterwards

if not i'd check/redo the cam belt timing again to be sure
 
Your description sounds like it might be something else other than the cam. I think you mean 254 deg not 154 deg? if so it's not a huge amount, you don't usually get a lumpy idle until you are up in the 260 - 270 plus range. I would double check the cam timing and make sure that all the vacuum hoses on the inlet manifold are connected properly.
 
cheers for the advice im back in uni now so its going to have to wait. im going to advance the timing as bob said and also going to richen the mixture slightly, also il check the vacuum hoses. my dad already checked the cam timing and that isnt the problem. and yes i did mean 254 deg oops. TBH im hoping its just the mixture because this is something i havent tried yet and im sure a tiny adjustment could overcome this problem. il explain the answer when i find it!
 
hi mate

have you set the webber up again since you rebuilt the engine? i suspect if you just tune the webber up it will run fine, i had it ticking over steady at 650rpm when the engine wasnt really on top form although tbh the engine wasnt to bad when i gave you it, only used a very small amount of oil and im sure that was cos the sump gasket needed changing.
 
nah the engine wasnt too bad when i first had it, but it still took a while to warm up with no choke. and no since the rebuild it hasnt been touched my father didnt know how to, its the first thing im going to do when i get back, i still havent changed that sumpgasket i cleaned around it and checked it a few times and it all seemed to be fine. i have had loads of probs with the engine since ive had it though! firstly it was the exhaust valve went then the piston ring! but im hoping its all good now though! but its only just bck running and im already regretting not putting over sized pistons in! as long as i can get the car to idle okay without the mixture being to rich and failing emmisions it should all be good because then i can take the car to get the new carb put on and hopefully the guy can sort out idle nicely on it.
 
it should idle fine on those cams. If it doesnt the problem is elsewhere.
 
yeah i hope so its probably just a week mixture and my old man stressing and blaming the cam because it wont idle nice! he came to my uni house the other day and saw the su carb n manifold all hell broke loose on the why do you want to make a micra fast! these ******* cams etc. wasnt ideal! hes anti modding! im sure if i spend some time on it on the weekend I can sort it out.
 
well if you need help setting up the webber mate let me know its a very simple carb to setup and most of the time it can be done by ear ;) paul (fox1983) might still even have the orginal instructions ill check for ya :)
 
Its not so simple if it needs rejetting for example. You cannot make an adjustment for this
 
it should be correctly jetted already as when i sold the car to bombz its was running perfectly and idling better than any k10 ive ever had :) good old webers!
 
All you can adjust externally on the Weber is idle mixture (over a very limited range) and speed. IIRC, it's one of the most complex carbs to set up... you've got main venturi, auxilliary venturi, main jet, idle jet, pump jet, air correction tube, emulsion tube, and some other bits I can't remember... there's over 200 types of some of those. SUs are much, much easier...
 
Bombz bring it to me and i'll convert it to injection lol. £££
 
cheers ed lol would be nice! but i dont think so i cant afford it on my student loan! i havent touched the car since to sort it out as im up at uni but next weekend il be going to sort it, might just put the su on an try adjusting that till it runs ok
 
Bob is correct, just advance the timing as he suggested and all will be fine! The cams make a big difference performance wise!
 

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