Imp a Long way from home

[GeneralSpecific]

Hello all,
I just joined as a member recently and I’m hoping to introduce myself. My car is a 1969 Imp Super. Thread title is a pun on my last name (Long) and the fact that I’m in the middle of the United States!
I came into ownership of the car unfortunately via inheritance. My fiancé’s father had purchased the car shortly before he passed and he never really got the chance to enjoy it, so I plan to honor him by fixing it up and enjoying it as much as I possibly can, like I think he would have.
I understand that this car was originally brought across the pond via a US serviceman, apparently they fell in love with it in the UK and had a fair amount of engine work done on it, then some more work yet to put an aluminum radiator up front and some other mechanical odds and ends. I know it’s got some parts from Malcolm on it already based on receipts that came with it. I think it needs a lot more parts.

So far, I’ve done a fair amount of work it and it’s running much smoother and safer I’ll have to get to that in another post.

I’ll try to remember to get the registration code next I’m in my workshop for those who want it; perhaps someone here already knows all about it?

Best regards from Wisconsin,
Allen

[David Sage]

Allen,

Welcome, I hope you will enjoy your car and all the helpful lads and lassis on the forum. I been with the club for just over a year and the forum members have been enormously helpful on countless occasions as I struggle to get my Sunbeam on the road. I have some work to do on the drive shafts this weekend but hope to take the car on its first trip in the coming weeks. In my past working life I worked for two American companies one was Motorola the other Chevron both looked after me and my family in different jobs across Africa. Good to have you on board.

DS

[GeneralSpecific]

Thank you, David! I feel very welcomed to the Club.

I thought I'd start by mentioning what I've done to the carburetors. Or, perhaps I should now say - the carburetor.
When I first got it, it had twin Strombergs in it. Started up and sounded good, at least when I drive perhaps a mile up the road and back - until I smelled something funny. Upon closer inspection, at least one of the two was leaking fuel on to the exhaust pipe.
Fortunately, the car came with some spare parts including two intake manifolds, a clutch plate, what looked like a nice rebuilt Weber 28/36, and another Weber in poor shape (missing gaskets and in dirty condition). The Weber looked good and I confirmed it did not leak, so I set about removing the Strombergs and their manifold, replacing them with the intake manifold that appeared to suit the Weber.
I found that the choke line is mostly seized up, attempting to move that results in really nothing much happening, so I eventually left it disconnected. I also had to find a throttle cable adapter to hook up to the Weber; Lokar S-1034 did the job. Then I had to figure out the throttle return spring situation. The springs on the Weber aren't strong enough to return the throttle to fully shut, so I had to improvise on a test drive... made shifting difficult!
I decided to drill a tiny hole in the heater hose barb on the manifold and hooked up a fairly robust spring. This "solution" doesn't sit well with me, but it's good enough for me to test and drive until the winter when I'll park the car for more in-depth fixes. (spring is not shown in the after picture)
So, after driving the car I found it had a TERRIBLE flat spot, if I attempted to lightly accelerate it would absolutely fall on its face and probably die. If I mash the pedal, it did fine. Cruising was OK too so long as the pedal was either left alone or mashed... I did some looking on Imps4ever and found several sets of suggested jets; I ended up settling on the jets suggested for "Janspeed single 28/36 DCD" on https://www.imps4ever.info/tech/carbs.html#table
I ordered all the jets (I think every jet on the carb was different than the listed items) from Pierce Manifolds out of California because they seemed to have everything... and they did, except for the pump jet. So I've had to stay with the .55 pump jet rather than the listed .50. Also, I removed an adjustable jet in favor of a fixed size one; I think I've seen mention of that modification somewhere but I wanted to stay with the fixed jet size on the site before getting ahead of myself.
Installed all the new jets, filter, and neddle&seat, and it runs MUCH BETTER. Flat spot is significantly reduced, though I can't say that it's definitely gone. I think I will install a wideband oxygen sensor this winter so I may better tune the car next spring.
I'm not against the Strombergs, perhaps I should locate a couple rebuild kits and have them on standby should I desire to switch back.

[moose]

Welcome to the forum. Cold start choke not really required on a 28/36, pump pedal to floor 2 to 4 times and the pump jet will squirt fuel to give the richness required to start then turn key and keep revs at 2000 rpm for 30 seconds to a minute and it should then idle if idle circuit correct. It should be lumpy and rough at idle as it still really needs more fuel. If it runs smoothly then the idle circuit is too rich. The lumpy and rough running should even out as the engine temperature rises. Have a good look at the ignition system it needs to be perfect and with a big spark otherwise you will be altering the jetting to suit a weak spark that is also possibly arriving at the wrong time. Set spark plug gaps at 30 thou and only use NGK bought from a reputable supplier as lots of fake copies out there. BP6 is the correct heat range the reason you can leave gaps as supplied at 30 thou and not close them up to manual 25 thou is that the modern materials in the plugs is far superior to when the manuals were written so if the coil and condenser are good quality items then you will have a big spark that is able to jump the larger gap. To compensate for any wear in the ignition system rev engine to 4500 rpm and set timing at 30 deg. Then make a note of the idle timing, Drive the car and see how it performs you can add a degree or two more but be aware that more modern fuels burn hotter and you can get pinking if the car performs well at say 32 deg and no pinking, pulls cleanly through the rev range then retard 2 deg at a time until you feel performance drop off. If performance drops at 28 deg go back to 30 deg. You may find that adding advance all the way up to 36 deg makes it quicker but you need to be very careful of pinking sometimes you cannot hear it at high revs. Take a note of idle timing again and then if you ever change or re-gap the points you can re-set the timing to idle figure you made a note of. You should also check the advance curve on the dizzy to make sure it is matched to the engine cam, compression and valve sizes. Even an imp sport head and cam needs the curve altering and the factory fitted different dizzy to suit over the years anything could have been changed so you may have a sport head with a standard dizzy which will make the car flat to drive. Looking at the work done to the car, front rad etc the motor maybe tuned and the dizzy already altered to suit, there is a good UK company called Aldon automotive who will set the advance curve and overhaul a dizzy for you if you give them the engine spec I am sure there will be someone in your country who could do the same. When you have a proper spark arriving at the correct time then you can fine tune the carb. Flat spots can also be caused by too large a choke size for the spec of engine as the larger size choke allows more air in but at a slower speed so does not draw the fuel into the mix properly. Keep us updated with your progress. I will try to find a picture of the correct linkage set up for you. The good manifolds which yours looks to be one used the imps basic solex linkage with a longer rod this linkage has a spring built in and returns the primary throttle shaft back to throttle stop properly as the weber carb actually relies on the linkage to return throttle to the stop there is no spring return built into the carb to do this.

[moose]

28 36 dcd.jpg

As you can see there is a upstand for the cable to go through in this picture taken from internet there appears to be a brass screw inserted where the cable should go, then you have the quadrant from the solex this has the solex clock spring arrangement to return primary shaft to idle stop. It gives a very nice light pedal with positive spring return to idle stop and as the quadrant is designed for imp the pedal travel matches throttle movement so if the pedal has not been bent or modified in any way this should give you wide open throttle with pedal on the floor without stretching the cable and correct amount of slack when pedal up.

[Bobbycham]

Welcome to the forum Allen , you have a wonderful resource here for any of your problems to be answered , any parts needed etc.
Look forward to hearing more of your journey.

GJ Bob

[edgedj]

My advice is to perfect the throttle actuator as much as you can. These are utter garbage out of the box on the 28/36 especially at low/part throttle, the manifold is great with lots of torque in power delivery low down but the angles on the cable are not great.

Flat spot is odd, might not be fuel as others have said, I found the accuspark ignition system to be a game changer for flat spots when I last ran carbs,

[knac1234]

Hello Allen,

Although I haven't posted in a while, welcome! I enjoy driving my Imp, but have been sidetracked with another Reliant I've been fiddling with!

I too am in the US (Tennessee now), and also have a Super Imp (1971). While I am no expert, I have a few bits and bobs in the shed and might be of some help with a few things. There is a lot of support on here....I know many have helped me countless times over the years! Malcolm Anderson is a great resource too (must give him a ring some time!).

PM me at some point if you'd like my direct contact info.

If nothing else, it's great to have another connection in the US!

Julian

[GeneralSpecific]

Welcome to the forum. Cold start choke not really required on a 28/36, pump pedal to floor 2 to 4 times and the pump jet will squirt fuel to give the richness required to start then turn key and keep revs at 2000 rpm for 30 seconds to a minute and it should then idle if idle circuit correct. It should be lumpy and rough at idle as it still really needs more fuel. If it runs smoothly then the idle circuit is too rich. The lumpy and rough running should even out as the engine temperature rises.

Thank you for the great walkthrough. I think my idle circuit must be OK; I followed your startup procedure and it behaves exactly as you suggest it should. I had noticed that it does even out as it has warmed up, just so! I will have to check the spark plug gap. I think my plugs are BP6... I can get any particular type of BP6 here, is there a particular part number I should look for? Example, BPR6S?

Have a good look at the ignition system it needs to be perfect and with a big spark otherwise you will be altering the jetting to suit a weak spark that is also possibly arriving at the wrong time. Set spark plug gaps at 30 thou and only use NGK bought from a reputable supplier as lots of fake copies out there. BP6 is the correct heat range the reason you can leave gaps as supplied at 30 thou and not close them up to manual 25 thou is that the modern materials in the plugs is far superior to when the manuals were written so if the coil and condenser are good quality items then you will have a big spark that is able to jump the larger gap. To compensate for any wear in the ignition system rev engine to 4500 rpm and set timing at 30 deg. Then make a note of the idle timing, Drive the car and see how it performs you can add a degree or two more but be aware that more modern fuels burn hotter and you can get pinking if the car performs well at say 32 deg and no pinking, pulls cleanly through the rev range then retard 2 deg at a time until you feel performance drop off. If performance drops at 28 deg go back to 30 deg. ...

Regarding the points and condenser, the previous owner has replaced that with a Pertronix electronic points/condenser electronic ignition. One more thing, I cannot find out where to check the timing? I am familiar with domestic (hah, domestic to me ) where there's an indication on the fan pulley but I do not see any markings where I can look for timing. Perhaps my car is missing a part?
I know of a place to get a distributor adjusted; I converted my 1967 Ford F100 pickup truck to run on propane and that requires a different advance curve, so I'm no stranger to that.

That manifold picture looks very much like mine; the difference is that mine has a tube on the bottom for the water to circulate. I don't have that clock spring arrangement/quadrant setup. Is this something that would be available through the Club spares?
---
Few recent observations -
On another topic - recently I serviced the brakes. One by one, I removed the wheels and drums, took apart all the mechanism inside and did my best to free up a few stuck cylinders along the way. I got most things adjusted but I'm going to want to replace some of it, the front has one cylinder that I think has come unstuck since I drove it again, at least my braking performance has improved a great deal from what it was before. Normally, I would have replaced all the springs and clips since it is all so rusty and full of brake dust. Surprisingly, all the pads are fine. The previous owner must have done a "pad slap"...
So that was a week or two ago. Today, the weather was very nice so I decided to do a quick run up the road to the nearest town, about two miles away. I find, instead - that the car won't start! Just a click, nothing else. I'll spare the diagnosis, the root cause was a rusty connection from the starter solenoid to the starter... Anyhow, I ran in to more troubles on the way. About 3 miles in, I notice a coolant smell, so I came back. Leaking hose on the front radiator, quick tighten and all good again.
The previous owner had installed (badly) a Davies Craig water pump / fan controller. I replaced it shortly after I got the car when I noticed that the pump never turned on. I set the temperature at 72°C based on what I've read elsewhere; do have that about right? I'm not sure the cooling system can keep up; the temperature got up to (I think) close to 80. What's a good setting? What's a danger zone I should watch out for?

[ImpManiac]

Hi Allen.

Okay. Roy McBride ("African Imp" on here) has the following photo of the Imp timing pointer. Perhaps yours is missing. Anyway, it should be clearly visible from the rear of the engine as you look under the rear compartment cover. (I really wanted to say bonnet! ) If yours is AWOL, a replacement should be straightforward to source from the UK.

On another topic - recently I serviced the brakes. One by one, I removed the wheels and drums, took apart all the mechanism inside and did my best to free up a few stuck cylinders along the way. I got most things adjusted but I'm going to want to replace some of it, the front has one cylinder that I think has come unstuck since I drove it again, at least my braking performance has improved a great deal from what it was before. Normally, I would have replaced all the springs and clips since it is all so rusty and full of brake dust. Surprisingly, all the pads are fine. The previous owner must have done a "pad slap"...

I would seriously consider replacing the slave cylinders. All of them. Alternatively, if you know what you are doing (and you seem to ), you could remove and dismantle them, and then carefully clean them up with some fine Emery paper. Grease them up with some rubber grease (the red stuff), reassemble them and enjoy lovely, smooth, surprisingly effective brakes.

About 3 miles in, I notice a coolant smell, so I came back. Leaking hose on the front radiator, quick tighten and all good again. The previous owner had installed (badly) a Davies Craig water pump / fan controller. I replaced it shortly after I got the car when I noticed that the pump never turned on. I set the temperature at 72°C based on what I've read elsewhere; do have that about right? I'm not sure the cooling system can keep up; the temperature got up to (I think) close to 80. What's a good setting? What's a danger zone I should watch out for?

Did you replace the DC coolant pump with another DC unit? Just curious. They have a good reputation and seem to be a good design. Temperature-wise, (note - please correct me if I am wrong ) a standard Imp apparently runs best at 75 deg-C (167 deg-F). Competition engines run better at 70 deg-C (158 deg-F) or even cooler. Road-going Imps came with thermostats regulating temperature to 82 deg-C (180 deg-F), I think . (Again, someone please correct me.)

IM

[GeneralSpecific]

My timing pointer is definitely missing. Seems like it may have been removed in order to install the alternator. Suppose I’ll need to get one!! Maybe I could fabricate one if someone got a clear photo of a loose one perpendicular to it’s face with a ruler in the same photo to scale it properly?
I think this winter I’ll remove the cylinders and have another look. I got them all freed up but I never went back in and checked the last one, seemed sticky yet.
I didn’t replace the pump; the actual control box was faulty. It would turn on but it wouldn’t activate the pump,I found that out by looking up the pump to the battery manually. $200+ later and I’ve got a working controller… Oh well, I’m just glad it works.

[moose]

Hi Allen. If you use a DTi in the spark plug hole to find true top dead centre and mark the block in line with the notch in the pulley it will be more accurate than the triangle standard plate and save you making or buying one.

The quadrant and spring are from a standard solex imp carb so there may be a spare one in the USA if not club spares will sort one for you (if I had one spare I would send it to you)

If you have the pump and controller working now, make sure there is no thermostat and set for a max temp 75 deg C. I would also run an expansion bottle (non pressurised ) from the take off where the filler cap is send the pips to a 1 litre bottle half full and vented to atmosphere. Fill rad system full and when the system gets hot air and water is expelled and bubbles through the expansion bottle and when it cools down only fluid is drawn back in a few hot to cold runs will expel as much air from the system as possible which will optimise cooling ability of the system. Ducting of air into the front rad and just as important back out without heating up the fuel line, fuel tank or brake pipes needs to be done. Will see if I can find the info I wrote and posted on this forum about coolant systems and frond rads.

BPR6 ES or S will be fine