Only a tuning issue?

corazon

corazon

Well-Known Member
Hi everyone, thought it about time i made a post, my '72 V8 Auto cameron green has started to run very poorly after making some changes.

I'll put it in perspective.
I bought the car in April of this year, with only two previous owners from new. Had a friend weld the underbelly and replace a cracked exhaust manifold to get through the MOT. Ran great up until now, apart from overheating in traffic, mainly from a weepy radiator and i believe an inadequately small kenlowe. The rad has now been soldered and i put on a new cap. I have also fitted a metal blade original style fan, as this had been removed when kenlowe was fitted. Is there a good reason why they removed the original? Add to that a new fanbelt, and temp hasn't even reached the middle of the green even when in traffic.

So with that done, i thought i'd replace points, condenser etc as points were really old, one was badly pitted. After nearly a day of trying to remove the wrong size screw holding the points plate down(!), i had the new parts in. I also had to replace the makeshift dwell angle adjuster, a threaded screw and two nuts, with a similar set up. Set the gap with feeler guage and everything fires up ok.

Having noticed the transmission fluid was extremely low, i topped up with the only bottle of tqf i could get my hands on nearby.

However, now everything is up in the air!
The idle is extremely low, between 3 and 4 and obviously wants to stall all the time. The choke doesn't seem to help at all. Performance is now hilarious.
Pulling out a junctions is a scary proposition, as it takes about five seconds to pick up any kind of speed (it used to fly like a rocket).

Gearchange is a lot smoother now, hadn't realised how smooth it was meant to feel! But is erratic in changing.

Do i just need to retune everything up? I'm still very new to working on cars, and don't have any timing or carb balancing tools. I could always take it to someone to tune, but was just wondering if you guys had any opinions on the matter?

Thanks, i've been reading posts on here for a couple of months now.
Jim
 
Hello Jim,

Welcome to the forum!

The engine driven fan whether it be the five bladed fixed steel arrangement or the 13 bladed nylon with viscous coupling will move significantly more air than one or more comparable thermatic fans during normal driving. Where the thermatic fans have an advantage is at idle and especially when in traffic on a hot day. Fan speed is not limited to that of the engine in these conditions, so better cooling can be offered.

With regard to the points and condensor. Are you positive that you set the gap correctly? Did the problems start immediately after you changed them? Something to consider in the near future would be their entire replacement with an electronic ignition system which will provide an improvement in all areas from ease of starting to improved performance and reduced fuel consumption, not to mention....no more ongoing maintenance with gapping points.

With regard to the transmission,.."the changing is erratic". Can you please elaborate? Be as detailed as possible.

Ron.
 
Re: engine driven fan blades, I took a gamble and removed mine altogether on the old car. I had no overheating issues afterwards, got a smoother engine sound and a couple of extra HP. The fan made the V8 whirr and whoosh like a Volvo at mid-to-high RPM, which I found most unbecoming... I assume it is made to shift a lot of air due to the smallish radiator.

The old car also had a 15-year-old Lumenition ignition kit fitted, which worked really really well. Recommend that.
 
Thanks for the reply Ron.

To clarify, when i go to set off in D, there's hardly any pick up at all, even if my foot is on the floor. After five or so seconds it starts picking up some speed staying in 1st for much longer than it would previously, doesn't stay in 2nd for long, and when in top there's hardly any throttle response, forcing me to kickdown if i need more speed.

I'm not entirely sure the points are set correctly, but i set with 0.015 guage on the highest part of the cam leaving a gap just big enough for the feeler to drag slightly. I forgot to mention the vacuum advance pipe is a little dodgy, it was so brittle a few months back that it just broke in my hands. I just extended it with a slightly larger pipe that fitted tightly over it.

As soon as i get the funds, the electronic ignition is top of my list i think. The Pertronix ones that fit inside the standard distributor look good.

With regards to the fan, why do some people remove the original when they fit a kenlowe? Do you think it affects performance or fuel consumption?

As you can probably tell, i'm learning as i go along with this car, i have the Haynes manual, but it doesn't compare to first hand knowledge.
Thanks again!

Jim

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Thanks Tor, i was writing that reply when you sent that so didn't see.

I was recommended to refit the original fan by a friend when the car was overheating badly. To be honest I just tried to do everything possible to keep the temp down, new fanblades, belt, rad cap and flushed and changed antifreeze, but didn't test the reconditioned rad on its own (it never overheating before when driving normally, just in traffic.) At the moment the kenlowe is still in situ but the temp sensor is just routed near an exhaust manifold, i was planning on changing it to a switch so i could turn it on and off when needed.

Oh, and i have new plugs, but am holding back on fitting them until i try and sort this out.
 
The points need to be set using a dwell meter, the feeler guage will just enable you to get it running in the first place. Did you fit the correct type of points, there are 3 types, the earliest which were very small and can't be confused with the later larger type, but those (the later ones) can be fitted incorrectly, and the wrong type can be used, the ones without the locating pin on the bottom can be fitted in error instead of the correct ones with the pin on. (But not vice-versa) You need to set Dwell, timing and then carbs, in that order. Refitting the engine driven fan will significantly reduce the idle speed. Get the engine running correctly before even considering any faults with the transmission, as in all likelihood there aren't any.

Looks a nice car.
 
I ordered the points from Geoff @ Wins International specifically for my car, and yep they had the pin on the lower of the plate. Like i said, whoever fitted the previous points used the wrong size screw and it was well and truly stuck.

Glad you mentioned that the fan will reduce idle speed, that makes sense to me, but i was only guessing. I may try removing it and taking it for a run, see what difference it makes. I just threw too many variables into the mix at once.

I'll try and take it to someone who has the equipment to set timing and dwell tomorrow.

Thanks for the reply
 
corazon said:
and yep they had the pin on the lower of the plate.
Thanks for the reply
Click to expand...

It's possible with that type to fit them with the point on the bottom missing the hole in the link from the vac unit, and that allows the baseplate to move all over the place, throwing the timing out and causing runniung problems.
 
"replaced points, condenser etc. " - did you replace the plugs as well ?

If so check that the replacement plugs are the same length ( thread ) as the old ones - if a previous owner has upgraded the heads in the past you need the longer plugs otherwise the spark won't have much effect.
 
Hi Jim,

That does look handsome... For sure, it's a smart thing to refit the fan as it does do a good job. But as soon as everything else works my bet is that you can remove it. There are postings about where to fit the Kenlowe sensor, if I understand correctly in that you have manifold heat interfering with cut-in times?? Getting a working sensor and then fitting an override switch in addition to that should give you peace of mind. If I had a fan fitted I'd definitely make an effort to get it to work as intended.

My idle speed didn't change when I removed the fan, in fact it was always rock steady. I'm a complete novice on old-school ignition but I really think once everything about your distributor is set you'll have much more to go on in terms of sorting running temp and finding fault with the transmission - if any. Seems you do have some investigating to do, but I'm sure it'll be fine.
 
Thanks for all the replies guys.

Tried removing fan, no major difference. So refitted for now.

Re-examined what i'd done with points. Funnily enough, i'd set the gap to 0.0015 instead of the correct 0.015! Hence the trouble! :oops:

It's not perfect, but so much better. I have a feeling the vacuum advance isn't quite working as it should...How would this manifest itself?

Tor, my kenlowe sensor was fitted in the top radiator hose, but it wasn't sealing properly. I'll put it back into the loop soon. What kind of switch can i use as an override?
 
The vacuum advance unit is an economy device, so won't have any real effect on performance if it's not working.
 
Funnily enough, i'd set the gap to 0.0015 instead of the correct 0.015!
Click to expand...
I know someone that used metric instead of imperial feeler guages and that makes the gap smaller still
If you've fitted the points with the pin not in the hole for the vacuum advance arm the baseplate will move to and fro without resistance and you'll see the arm not moving
A dwell meter is the answer - make sure you read the 8 cylinder scale though
 
Hi Jim,

I've not had a Kenlowe fan myself, but I believe it requires a relay to which you can connect a regular 'flip' or toggle switch (don't recall the proper designation here) to control/override it when desired. If no relay, ask your supplier for one, or a switch that'll take the amperage of the fan, and connect it with an appropriate-gauge wire to one of the dash apertures. If your positive lead, not the sensor, runs near an exhaust manifold that wouldn't affect operation as such but could fry the insulation and should be routed out of its way for safety.

I've tried running the car once with the vacuum advance pipe off, and the difference was noticeable. The ignition timing doesn't advance as inlet vacuum rises with the RPM, and the motor lacks the 'edge' when accelerating. That is, if it's otherwise in a good state of tune.

If you want to test the vacuum unit, unclip the distributor cap. Then disconnect the advance tube elbow from under the LH carburettor, put in mouth and make your own vacuum (suction - some effort needed!) while watching the vacuum advance arm in the distributor - there should be movement. Plug the tube with your tongue and it should stay or return slowly. Let go and it should snap back. If movement occurs as described, your vacuum advance is working. If it won't move and you keep drawing in air, you might have a cracked tube or rubber elbow, which should be replaced. But your car should run sweetly once the points and dwell alone are set up to spec. I'll have to attack this bit myself soon, with a little aid from my garage...
 
Tor said:
I've tried running the car once with the vacuum advance pipe off, and the difference was noticeable. The ignition timing doesn't advance as inlet vacuum rises with the RPM, and the motor lacks the 'edge' when accelerating. That is, if it's otherwise in a good state of tune.
Click to expand...

Maximum vacuum is at idle, or with the engine on the overrun, it relies on the throttle butterflies being shut, and it reduces as the RPM increases, so the only way that disconnecting the vacuum unit pipe could affect performance would be if you didn't plug the pipe and caused it to run weak. It's the mechanical advance that increases with RPM
 
My car is fitted with a weber carb which has the vacuum port for the distributor just the atmospheric side of the butterfly. So at idle I have very little, if any, vacuum. At cruise, i.e. at any speed when just touching the throttle, the vacuum is at its highest - some 18 in/mg.

The vacuum then decreases with throttle openings and engine speed.

I have assumed that the SU worked in the same way,as I thought (I can't check because I don't have one) that the vacuum take off was just to the atmospheric side of the butterfly.
 
Hello Richard,

The vacuum system for the SU as it applies to the Rover V8 does indeed function in the same way as your connection on the Webber, in that both use ported vacuum.

Ron.
 
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