An Uphill Struggle !

[elmose]

Hi all,

I've got a Road Rally spec Nova with a C14SE bottom end and a 12ST carb head on top to up the compression and improve performance while enabling me to run the twin choke 32/34 Weber as the road rally rules dictate. I've been trying to diagnose a problem that I've had for a few months now and I'm hoping some of you guys will be able to throw a few ideas my way as I'm starting to run out of possible solutions myself !

I fitted the Kent AST2 cam to it a while back after reading all of your guys opinions and feedback about it and I have to say that most of the time the engine pulls like an absolute dream however I have encountered problems going uphill. The type of rallying takes place in country lanes and the rally organisers tend to like to make us go up difficult, usually off-road hills and make you stop at controls on them which is where my problem really causes trouble. The car really seems to struggle pulling off from a standstill on anything other than reasonably flat ground, bogging down and fluffing with no power. If I'm lucky and momentum allows then sometimes the revs slowly build before reaching roughly 3k RPM where the cam kicks in jerking the car forward like a rocket as if nothing was wrong. I've tried dragging the clutch and revving it to 6k before trying to pull off but every time it just bogs down and stalls unless I can catch it with the clutch again. I know the rev band of the cam is 3k-7k RPM for optimum BHP but I didn't expect to lose all of my low down power, well enough to stop the car from pulling off on steep hills ? Has anyone else had a problem with this cam or engine setup like this ?

I had the car rolling roaded to try and remedy the problem where it made a respectable 96BHP with the distributor being changed for a version with a preset advance profile so the vacuum isn't relied upon but that didn't solve the problem either. I've recently tried an electric fuel pump as I thought fuel pressure may have been an issue but that too didn't work. The car is running with an F10 SCCR gearbox, LSD and a 4.5 CWP so it should fly off the line but it isn't uphill !

If you managed to read all of that then thanks for taking the time and any thoughts will be much appreciated as I'm beginning to get frustrated as it's stopping me from entering rallies because it's pointless if I can't even make it around the route !

[Southie]

How did your engine run before fitting the cam?

How old is the clutch, could be slipping under load.

Have you tried advancing the dizzy so it's revving a little higher than normal?

Have you tried a larger jet in the carb so it's getting more fuel through?

[mowgli]

have you checked the workings of the twinchoke carb? it sounds like its fuelling is out at low revs to me.
also, what is the dizzy timing like? the old delco dizzy was a sod for the advance retard diaphragm failing, and people always massively advanced the timing to try to hide it.

other things to look for

split fuel line

blocked fuel tank breather

crap in the tank/ fuel line

worn fuel pump

coil is shot, which is quite common on older carb models.

plugs and or ht leads & rotor arm/cap need swapping for decent quality new ones

[elmose]

Yeah the engine ran fine before the cam although I never did many rallies or go up the kinds of roads with it like I do now to really notice but I'd say it was better in terms of pulling off than it is now.
The clutch has been in for a while and I do have a paddle clutch ready to go in the next time the box is out but the way the engine bogs down would suggest there is sufficient friction from the clutch to engage the gear properly and not slip ?
I haven't messed with the dizzy since the RR session as I presumed he would've set the timing to its optimal position and he also marked positions clearly on the cam carrier and dizzy casings so he definitely adjusted it.
Again I haven't messed with jets since the RR session although from memory he may have changed the jet in the first choke to a bigger size. The carb was a brand new item from webcon for a 1.4 nova about a year ago as my last one was leaking air through the spindle so I'm reasonably confident it's in good nick.

Cheers for the suggestions, do you think the clutch may be to blame ?

[elmose]

Mowgli, the dizzy was changed for a Bosch red cap item as the telco item was a bit erratic like you mentioned.
The fuel lines don't look split around the engine bay at least and I would've noticed any damage or perished hoses when I've been replacing pumps. I also changed the original mechanical fuel pump for a new replacement item before trying the electric facet pump, neither have made a difference.
I have thought that it may be fuel tank related as I've never had it off or cleaned but my logic was that if there was any crap in there then when I'm parked uphill then the objects would go towards the back and bottom of the tank whereas the fuel outlet to the pump is at the front near the top ?
i haven't changed the coil or leads and they have been on there a little while now, it just seems weird that it's at low revs and under load but not on the flat or downhill.

[jimbob-mcgrew]

does it rev smoothly when stationary ?

sounds like it might be the advance retard / timing to me, although could be a number of things like people have mentioned.

maybe the RR guy set it up for top end ?

another thing that crosses my mind, could it be over-fueling low down ? causing it to stutter

[elmose]

I have thought about that and there is a slight smell of petrol when the car stalls but I just put that down to the fact that there is some fuel hanging around after it has stalled. I have thought that jets could be wrong in that choke although from memory it was only changed to a slightly bigger jet but the stalling problem was around before this anyway.
The car revs fine when stationary although there is a slight delay in response when you blip the throttle hard from idle although I just put that down to the fact it's a carb and I'm probably comparing it to the modern injection throttle response in modern cars.
I think he has must have set it up for top end as it literally flies through the gears from around 3k RPM onwards, maybe some adjustment of the dizzy is required in that case.

[jimbob-mcgrew]

maybe try marking the dizzy in its current position, to give you a reference point, and try the car out a couple mm's either side, to see if any different.

as long as youve got it marked, you can always set it back if it doesnt change anything.

[Southie]

As regards to under or over fuelling what colour are you plugs going?

As above alter the dizzy a little and see if you gain anything.

The clutch may not be an issue but if your having to dip it a lot to get going you maybe doing more damage than good too it.

[jimbob-mcgrew]

As regards to under or over fuelling what colour are you plugs going?

i thought that too, they might be black and sooty if so

[elmose]

Thanks all, I'll have a mess around with it again this weekend so I'll try altering the dizzy slightly to see where it gets me and check the colour of the plugs. Things like leads may be the next avenue to explore as they have been on there for a while and hopefully the clutch hasn't taken too much of a battering when I've been trying to pull off, I'm willing to try anything at the moment !

[jimbob-mcgrew]

like mowgli said, the coil could be another suspect, there difficult to diagnose, cos they can run fine, but cause issues.

rather than buy one, just for the sake of it, if youve got a spare you can try out, to rule it out, worth a try.

what fuel are you running on too ? .. as with ramped up compression like yours, super unleaded will be needed, or premature ignition will occour.

[elmose]

Yeah the coil may be another area to look at although I haven't got a spare one at the minute.

I''m already running super unleaded and a millers octane booster to try and minimise any pinking. It used to be a slight problem under really heavy load before the timing got changed at the rolling road session.

[garyc]

If its running OK on the rollers ie flat then I would be looking at the fuel system as the ignition timing would be OK. check the float height in the carb, with an electronic pump I would think about a pressure regulator.

[elmose]

Regulator has been fitted straight after the pump before the carb. How do I check the float height ? I've taken the carb apart briefly before and I could see the two floats but didn't take it apart any further as I didn't have any spare gaskets around. It's interesting you should suggest it's carb related, it's a brand new carb from Webcon for my engine so I wouldn't have expected there to be problems already. One thing to mention is I've read on a land rover forum who use the 32/34 that they've talked about float height and also about a small aperture in the carb that when the vehicle is on a hill excess fuel can spill out of the bowl and into the barrel, have you ever heard about this or anything similar?