Lethargic 1300

[Ralph]

OK, I know a 1300 isn`t going to be a road burner, but I have had a few spitfire and herald 1300s, and with the lower diffs fitted they were quite sprightly. There is not much difference in weight with a Dolly, but my 15,000 miler 1979 car just seems reluctant to "get up and go", and needs revving right through the gears to get decent momentum. I have checked timing, points, plugs etc, and I am wondering if the carburettor is the fault. Mine has the waxstat jet assembly, and I know that all manufacturers were striving for good fuel economy at that time, and indeed mine is very good on fuel, but I am wondering if the set up is too lean and sapping power. Any ideas?
Ralph

[yorkshire_spam]

What colour are the plugs after a good run?
Single or twin carb?
Any signs of general engine health? (Exhaust smoke?) Ever had/done a compression test?
What fuel are you running on?

[jackharper]

My (untuned) 1300 engine keeps up with modern traffic up to about 50mph - after that it runs out of puff, which is to be expected for a car of its age I think!

To add to what Sam is suggesting, you can probably also bin off the waxstat element to rule it out - done easily with a pair of 1 pence coins in place of the original wax puck thingy.

[Ralph]

What colour are the plugs after a good run?
Single or twin carb?
Any signs of general engine health? (Exhaust smoke?) Ever had/done a compression test?
What fuel are you running on?

Single carb, plugs are white, no exhaust smoke, using Esso super (no ethanol where I am), engine is sweet having only done 15,00 from new.
I have been doing a bit of research on Burlens website, and between 1976 and 1980 there were 3 different carburettor needles , all spring needles. All get progressively weaker when you compare their profiles on a needle chart.
All the carbs for the Dolly were "waxstat" jet types, that weaken the mixture even more as they heat up.
1976-77 used ABF needles
1977-78 used ADM needles which were much leaner on the first half but actually slightly richer towards full throttle.
1978-80 used ADQ needles which were pretty much the same as ADM at low throttle openings, but weaker at the top end.

Given that my plugs are N12Y which are running white, it is fairly clear to me that the set up on my 1979 car is running extremely weak and the ADQ needles should be the ones in my car. As a quick experiment therefore I have ordered an ABF needle from Burlens which is an easy swap and will see if that makes a difference. I know it will increase fuel consumption, but it might restore some Va Va Voom.
Ralph

[yorkshire_spam]

What colour are the plugs after a good run?
Single or twin carb?
Any signs of general engine health? (Exhaust smoke?) Ever had/done a compression test?
What fuel are you running on?

Single carb, plugs are white, no exhaust smoke, using Esso super (no ethanol where I am), engine is sweet having only done 15,00 from new.
I have been doing a bit of research on Burlens website, and between 1976 and 1980 there were 3 different carburettor needles , all spring needles. All get progressively weaker when you compare their profiles on a needle chart.
All the carbs for the Dolly were "waxstat" jet types, that weaken the mixture even more as they heat up.
1976-77 used ABF needles
1977-78 used ADM needles which were much leaner on the first half but actually slightly richer towards full throttle.
1978-80 used ADQ needles which were pretty much the same as ADM at low throttle openings, but weaker at the top end.

Given that my plugs are N12Y which are running white, it is fairly clear to me that the set up on my 1979 car is running extremely weak and the ADQ needles should be the ones in my car. As a quick experiment therefore I have ordered an ABF needle from Burlens which is an easy swap and will see if that makes a difference. I know it will increase fuel consumption, but it might restore some Va Va Voom.
Ralph

Assuming it's a single SU not a Stromberg (Based on the needle codes which look like SU codes) - I wouldn't start with changing the needle, I'd look at just tweaking the adjuster down 2 flats and richening the mix as is. If you can't get it "close" at tick over without it being too rich/weak higher up then maybe look at a new needle.
My guess would be your engine has been tuned to pass an emissions test rather than be drivable.

Sorry can't comment on what the "right" needle is for a single carb, my fast road twin SU HS4 1500 engine (Spitfire) is on AAU after a rolling road tune. (But makes quite a bit more than standard!)

[xvivalve]

Reminds me of the time Jod Clark's 1300 went lethargic and he couldn't work out why, but had to finally (and bravely) admit he'd stuffed a cloth into the air filter inlet and hadn't removed it when tasks completed.

[Ralph]

I think they were definately chasing good emissions figures in the late seventies, the sticker under the bonnet testifies to that. Probably memories of the fuel shortages of a few years earlier were still fresh in minds. I will replace the waxstat with a couple of pennies first which at least will stop that messing with results. I have already turned the jet adjusting nut down 1 full turn without any noticeable difference, but may give it another turn and see.
Ralph

[xvivalve]

Look at your bulkhead where the accelerator pedal mounts to see if it has fractured allowing the pedal to move laterally. Also check that full depression of the pedal is reflected with full operation of the carburettor.

[yorkshire_spam]

I think they were definately chasing good emissions figures in the late seventies, the sticker under the bonnet testifies to that. Probably memories of the fuel shortages of a few years earlier were still fresh in minds. I will replace the waxstat with a couple of pennies first which at least will stop that messing with results. I have already turned the jet adjusting nut down 1 full turn without any noticeable difference, but may give it another turn and see.
Ralph

If turning the nut down isn't making any difference then I'd suspect that there's something wrong with the fuel pump or the float level - it could be that the fuel level in the jet is just far too low.

[Jod Clark]

Reminds me of the time Jod Clark's 1300 went lethargic and he couldn't work out why, but had to finally (and bravely) admit he'd stuffed a cloth into the air filter inlet and hadn't removed it when tasks completed.

A funnier one I heard recently with a Volvo that wouldn't run properly, after many hours of trial, error and head-scratching was traced to a baby owl wedged inside the air intake.

I reckon this problem will be float chamber related, level too low or restriction in the weeny pipe between the float chamber and the jet. whip the carb off and give it a jolly good clean. the ultra low mileage isn't necessarily a good thing sometimes and all sorts of weird stuff can happen to an underused car... Check also that the exhaust hasn't become restricted, a collapsing silencer baffle perhaps.

[cliftyhanger]

OK, I know a 1300 isn`t going to be a road burner, but I have had a few spitfire and herald 1300s, and with the lower diffs fitted they were quite sprightly. There is not much difference in weight with a Dolly, but my 15,000 miler 1979 car just seems reluctant to "get up and go", and needs revving right through the gears to get decent momentum. I have checked timing, points, plugs etc, and I am wondering if the carburettor is the fault. Mine has the waxstat jet assembly, and I know that all manufacturers were striving for good fuel economy at that time, and indeed mine is very good on fuel, but I am wondering if the set up is too lean and sapping power. Any ideas?
Ralph

How did you check the timing?
Firstly, watch how the timing advances with revs. With and without the vac advnace connected. If the baseplate is sticky, that will cause a lack of power. Vac advance I usually just suck the tube to make sure it works.
Then set the timing by ear. Drive the car, keep advancing the timing until you get pinking under load. Knock it back a smidge, and that will be the best setting.
Only then start playing with needles.

[Ralph]

I reckon this problem will be float chamber related, level too low or restriction in the weeny pipe between the float chamber and the jet. whip the carb off and give it a jolly good clean. the ultra low mileage isn't necessarily a good thing sometimes and all sorts of weird stuff can happen to an underused car... Check also that the exhaust hasn't become restricted, a collapsing silencer baffle perhaps.
[/quote]

I am not ruling anything out at this stage, but the sluggishness is on initial pull away, but once underway the car will happily run at 60 and I would think a blocked exhaust or a restriction in fuel flow of any kind would not allow high cruising speeds.
Ralph

[Ralph]

How did you check the timing?
Firstly, watch how the timing advances with revs. With and without the vac advnace connected. If the baseplate is sticky, that will cause a lack of power. Vac advance I usually just suck the tube to make sure it works.
Then set the timing by ear. Drive the car, keep advancing the timing until you get pinking under load. Knock it back a smidge, and that will be the best setting.
Only then start playing with needles.
[/quote]

All good advice. I use a quality timing light that can be pre set to ignition advance required for those cars that only have a TDC mark on the crank pulley, or used in standard setting for cars like the Dolly that has multiple timing marks. Checked after dwell angle set on points and spot on 10 degrees BTD at idle and increases as engine is revved up so I assume advance unit is working OK, although that could be just the bob weights in the distributor and not the vacuum unit, so I will have to check that today.
Ralph

[yorkshire_spam]

Sure, I get that timing needs to be good for decent performance - but if the plug colour is so radically wrong then it's not /just/ a timing issue.
Problem with the needle / jet / fuel level is my bet if turning the jets down isn't making a difference.

[Magenta Auto Sprint]

Are N12Y the correct plug? I thought they should be N9yc