450 SLC HT Leads

[maldon]

Hi there - one week into owning a '78 450SLC (absolutely love it!)

The engine is missing a little, especially when cold. Have checked and cleaned rotor arm and interior of the distributor cap, checked all connections to the distributor and the plugs. Engine ran a lot better after the clean up, but is still missing here and there/on and off.

Could this be the HT leads, they seem to be original - were these non-cable type and would they break down over the years?

If this is likely to be the cause of the problems, where would be the best place to obtain replacements? I looked on GSF and thought seventy quid was not cheap - although not having checked with MB I could of course be wrong.

Appreciate any advice.

 

[Francois]

This could very well be the problem.

If you do a search on HT leads on this forum you should be able to get references to webpages and numbers of suppliers for the leads.

You could try www.importecparts.com. Unfortunately they are in the US and you would obviously need to import the parts from them. I don't think this would be cheaper than the 70 pounds you mentioned.

 

[maldon]

Hey Francois

I did do a search around the forum for all things SLC and came up with a few pointers - some simple cleaning of the rotor arm and distributor cap made a big difference, then tweaked the HT leads and we were back to square one. Leads seem to be the culprits.

Ordered a set from expressautoparts, mentioned here - they seems to specialise in electrical. Excellent service, the new lead set will arrive today complete - so may try and fit the new set at lunchtime!

Apart from this and some body repairs (booked into a restorer this weekend) the car is in great shape. Just have to get to the source of the flooding drivers footwell and can then get on with the interior - which basically only needs 20 odd years of cleaning - no rips or tears, all fittings are sound.

 

[NormanB]

Drains

Not familiar with your model but a good generic check when you have flooding is to check you drains - open bonnet fully and examine around the firewall area each side - no doubt you will have a compost heap in each of the drains which will require clearing.

NormanB

 

[maldon]

Fitted the new leads - one hour job and sixty five quid for the parts. Fired her up one slight cough and then all 8 cylinders. Ticking over like a sewing machine.

Went for a quick test drive and we are talking totally different car - a huge improvement. Best is that the auto box is running perfectly, changes down and the kickdown works. So guess the misfiring was causing vac probelms?

Can now feel some play in the propshaft. But had that in our old E200 and a little in the C230Kompressor.

 

[Francois]

These V8's really gives you goose bumps when they fire up properly don't they?

I had the same problem with mine when I purchased it. It had the same set of leads and dizzy for 20 years. Rats had eaten holes in the insulation and this caused really bad misfiring.

I just need to sort out the duo-valve and then everything will be just fine.

 

[maldon]

Francois - I was REALLY surprised with the performance - just wonder how long previous owner had been plodding around with the old leads.

Completely different power to various turbocharged Saabs I have owned in the past and indeed our C230Kompressor - LOVE it.

Now for the problem with the drains :mrgreen:

 

[dakers]

same problem?

Maldon / Francois

Bought a 1977 450SL a few weeks ago. Still in garage but took it for a few drives - pretty sure it's not quite firing on all 8. I think you've posted enough info, but if you've got a second, could you quickly send each of the steps you followed in order to enter V8 heaven!?

Many thanks indeed, Alex

 

[maldon]

dakers

expressparts.co.uk are the lads to get the bits from - replacing leads
quite simple. remove the air filter three studs and remove the breather pipe from underside of the filter. remove the distributor cap - if you have orig leads they should be numbered. marke the the nos on the distributor cap with a felt tip pen. note the cylinder numbers and them sinply replace the leads.

the new leads will not come in a sleeve (you will see what i mean when you remove).

i carefeully sliced the sleeve so it can be used again.

check the corresponding lead lengths on the old ones the new ones were a fair bit longer - its a really simple job allow an hour.

its is probaly worthwhile marking the numbers on the plug boots.

any problems give me a shout.

 

[Francois]

While you are at it, it might be a good idea to replace the distributor cap end rotor arm.

Also a very simple job, as you just unscrew the two screws that hold it there and replace the cap. The rotor arm just pulls off and the new one sticks on. Make sure the gap on the inside of the rotor arm lines up with the rotor shaft.

 

[dakers]

thanks chaps.

when (or if!) I get it back from the garage, I'll be on the case...

 

[Slo-Mo]

Hello all,

I've just got a 80' 450SLC 5.0 as a new 'toy' and I'm impressed with it, very nice, very beautiful and fun to drive!

The car came to me in very good condition, but the engine needed some attention. After some cleaning it is ok, runs smoth with no smokes and no strange noises. The only problem now is when at idle, it runs accelerated when cold and warm. I managed to adjust it, but it just doesn't feel right, maybe the ICU (Idle Control Unit) is faulty? Another issue, very strange, is a vibration when at idle. The engine just vibrates too much, I've checked cables/spark plugs, distributor is cristal clean and so on. I've even replaced the whole distributor with a good one to see if the problem was there, but it was not - I'm glad, that's expensive ;-)

So, do you have any recomendations / suggestions / advice to address these problems?

Thanks a lot!
Cheers,
Slo-Mo