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Setting Points - Why is it so difficult?

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Old Apr 19th, 2018, 23:11   #31

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Laird Scooby
Thanks for the advice on ATF. I've looked through that Service hints document numerous times and missed the mention of ATF. I'll switch over to ATF and go back to Shell V-Power before I try to have another go at the timing.
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Old Apr 19th, 2018, 23:49   #32
Laird Scooby
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You're welcome Phil - since i used ATF all those years ago i've not used anything else in any dashpots, whether it was a Volvo or not. Always had better response, economy and power from all the cars i've used it on.

Once you've got it all timed up etc, can i suggest trying a couple of tankfuls of BP Ultimate instead of Shell V-Power?

I've always found that my Volvos have run better on that than V-Power (and many other cars as well) and the bonus is, BP supply Sainsburys with their fuel so you can buy it cheaper at Sainsburys (Super Unleaded) and save yourself a few quid.

Normally i wouldn't even suggest supermarket fuels let alone recommend them but there's a long-standing supply arrangement with Sainsburys and BP and you get Nectar points on both places too!

On another forum i'm on, we did a "group test" of various fuels ranging from supermarket fuels to BP Ultimate and Shell V-Power including most others available in several different areas.
The two branded fuels that came out on top were BP and Shell with Sainsburys the same as BP (as it should be) but the worst in our test group was Tesco fuel - all other supermarkets were better than Tesco and Shell and BP were the best of the lot with Sainsburys tieing with BP.

That sort of makes it sound as if Shell won the test - it did and it didn't. On certain engines it was better but on a slightly different engine (from the same manufacturer but slightly older version) the BP was better. Some of the people involved in the test had both sorts of the engines in question and they confirmed this as well.

Has to be worth a try once you've got all the other things right! It may or maybe won't be better for yours but there shoudln't be any harm in trying.


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Old Apr 20th, 2018, 07:50   #33
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That is the wrong distributor for that car

Both, in fact all distributors max at the same advance, of course. Thatís why youíre going to have to set that dist to the max setting and really disregard what happens below at lower engine speeds.

The b20a Distributor gives loads more low engine speed advance especially in combination with the vac advance. Thatís because the old Strindberg goes weak one quick throttle opening. This is compensated by lots of advance.

On the contrary the twin SUís dump a load of petrol down the jugs which burns better on not so much advance.

If you can stick a b20b Distributor on there, or my favourite of all of them, a full mechanical advance Distributor from a b18b, youíll get the best results.

All said, youíre not going to notice a huge amount with a few degrees at idle nor low engine speeds. But youíll notice a heck of a difference air the timing is set right at max advance.

Fiddling around with timing and carb settings is my thing, so if I could persuade you to get on the A303 down to Exeter, Iíd be delighted to get that car running right.

For me, itís a no to ATF. Too thin and in comparison to using SAE20 oil, the dampers donít go so crazy.

For me, itís Shell V-Power or standard unleaded with Octaneboist to achieve 100 octane. That way, the old car runs perfectly on 36 degrees advance, no pinking, lots of response and a super smooth idle. 32 to 34 degrees max on standard unleaded, but anything more and thereís some pinking.
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Last edited by swedishandgerman; Apr 20th, 2018 at 07:54.
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Old Apr 20th, 2018, 08:50   #34
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A few points to consider :

Opening the throttle destroys vacuum advance.

Twin carbs dumping a load of petrol means that petrol will take longer to burn. Hence more advance will be needed. This is achieved with mechanical advance with less need for vacuum advance.

I'd love to know why Volvo recommend ATF Type A (one of the older, thicker ATFs) to damp the dashpots and stop them going crazy.

Pinking is also known as pre-ignition meaning the inlet charge has already burned before TDC has been reached. If the timing is too far advanced to start with, poor cold starting will result. That means it's important to get the balance right between having enough advance while running and not so much advance at idle. Too little advance at idle can also result in flooding a cold engine with the choke and lack-lustre performance.

There's a lot to be taken into consideration with timing. Way back when, i ran a modified Cavalier 2.0 and the standard timing mark was at 5 deg BTDC. Through trial and error, i found it not only idled best at 11 deg BTDC but also performed best on the road, not just in terms of power and economy but drivability as well.
For various reasons i lost access to the timing light with advance settings built in so i went and paid a garage to do it. This was allegedly a garage that did rolling road tuning so should have had a vested interest in getting it right. I explained in detail what i needed and why. They gave me the car back and it didn't sound right. It didn't go right either!

I ended up swinging the dizzy round myself and timed it by ear. With hindsight i should have done that myself in the first place and saved my money.

After that i made up a protractor and marked the correct timing for the engine on the crank pulley. Just for reference, that car was running a 38DGAS and not the original Varajet-II carb. It also had a hot cam in and a few other mods and was capable of blowing the doors off a dark blue 3.0 Senator much to the annoyance of the officers inside it! They goaded me into giving it some beans and then had the cheek to take me to court for speeding!


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Old Apr 20th, 2018, 21:29   #35
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Originally Posted by fishyboy View Post
Laid Scooby
Mine is a twin carb B18B car.
Normally I put in Shell V-power which I believe is 98 oct, but current tank is regular unleaded at 95oct. Might try to use that up before I try again.

I'm using the SU dashpot oil from Burlen so it should be the right stuff (

Thanks for the picture? Can I ask where it comes from?

Thanks all
The picture is just a general one from google images . Maybe you can swap your screw with one of the cap clip securing screws with it's washer .
My comments are only based on my opinions and vast experience .
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