B20A top speed

[Burdekin]

Yes vac advance. It’s the model from Amazon cars with their unleaded fuel curve. It was installed by a mechanic before I got it so have emailed Amazon cars for the static timing info so I can check it. I also ordered a correct coil for the 123, new fuel pump, fuel and air filters. It’s still going through recommissioning.

[Burdekin]

Meant to ask, what symptoms does a cracked Stromberg diaphragm give. Don’t think it is that old but believe they can go at any time.

[Clan]

Originally Posted by Khe Sanh

Meant to ask, what symptoms does a cracked Stromberg diaphragm give. Don’t think it is that old but believe they can go at any time.

oh yes that will prevent full power they should be replaced every 24000 miles or 2 years , also is it set up properly , is it an emission one the same as on the 144 B20A ? The diaphragm is unlikely to be as good a quality as the factory ones at the time.

When the 1974 model year 140 B20A came out with the 240 rear end they went well , I remember a customer saying that he couldn't get his car to go over 100 mph all of a sudden , he could not do it in the usual place he did it on the M4 ... anyway the plastic undershield was broken off under the engine , after replacing that he could once again get his 105 mph !

[Burdekin]

Originally Posted by Clan

oh yes that will prevent full power they should be replaced every 24000 miles or 2 years , also is it set up properly , is it an emission one the same as on the 144 B20A ? The diaphragm is unlikely to be as good a quality as the factory ones at the time.

When the 1974 model year 140 B20A came out with the 240 rear end they went well , I remember a customer saying that he couldn't get his car to go over 100 mph all of a sudden , he could not do it in the usual place he did it on the M4 ... anyway the plastic undershield was broken off under the engine , after replacing that he could once again get his 105 mph !

Yeah it’s a 71 142. It was checked over by a reputable old Volvo mechanic in Exeter before I got it. I’ll check with the previous owner if he changed the diaphragm.

Also read a thread here about the throttle linkage not set up properly and not getting full throttle. Emailed Amazon cars for the static timing setting and will check timing is changing with revs.

It has new spark plugs and leads.

That’s the obvious things for me to check, if anyone has other ideas please let me know.

[Clan]

Originally Posted by Khe Sanh

Yeah it’s a 71 142. It was checked over by a reputable old Volvo mechanic in Exeter before I got it. I’ll check with the previous owner if he changed the diaphragm.

Also read a thread here about the throttle linkage not set up properly and not getting full throttle. Emailed Amazon cars for the static timing setting and will check timing is changing with revs.

It has new spark plugs and leads.

That’s the obvious things for me to check, if anyone has other ideas please let me know.

is it mustard yellow or that dark blue or dark green ? I never saw a 142 in colours other than that , they were not as popular as the 144 and 145 though

If it is a later engine i think the timing is 10 degrees at idle . how about a blocked exhaust if it's decades old ... the fibreglass padding inside used to break up and come out and come out of the tail pipe .

[Burdekin]

Originally Posted by Clan

is it mustard yellow or that dark blue or dark green ? I never saw a 142 in colours other than that , they were not as popular as the 144 and 145 though

If it is a later engine i think the timing is 10 degrees at idle . how about a blocked exhaust if it's decades old ... the fibreglass padding inside used to break up and come out and come out of the tail pipe .

Sarfari/mustard yellow. Not many about.

Thanks, will get the timing light out this week. It has a new exhaust. The previous seller isn’t sure if he changed the diaphragm so will just go ahead and do it. The filter was filthy so maybe diaphragm is old too.

[Derek UK]

The diaphragm is very easy to check. They can be split and a small split will stop the piston from rising fully so not much speed or acceleration. They can also look distorted/rumpled and that doesn't allow the piston to rise smoothly or predictably. Older diaphragms or NOS replacements may be affected by the latest fuel. Maybe Burlen could advise on that or again, maybe Rob. Your 123 should be fine. Rob has a video on fitting on his YT channel.
Red, white and blue 142's are around or at least were!

[Burdekin]

Thanks Derek. I have a spare diaphragm so will go put that in this afternoon. That seems like the obvious first thing to check with the Stromberg. Will also check the carb linkages and accelerator are set correctly, you never know I suppose. I’ll see what the idle and high rev timing readings are. To me it sounds like it is running nicely and it starts first time no problem.

I had seen the video but wasn’t sure that the static timing would be the same, this is info back that I asked for from Rob if folk are interested:
Our unleaded curve is #3
Set to 17deg BTDC
Should give a maximum advance of 32deg at around 3500rpm.

I’ve ordered some new bits and bobs for the engine so will fit them when they come. One being a filter cartridge for the sealed housing, it is very dirty and no idea how old so can’t be helping.

[Burdekin]

Last I checked only 9 142 registered in the U.K. and some maybe LHD. Pretty rare in the U.K. these days. Mine is a 71 and they didn’t import them and would have had to been special order. Mine is weird as was a Swedish RHD car.

[Burdekin]

Changed the diaphragm and the accelerator bar inside was missing a screw so replaced that too, seems to be quite responsive without the filter, and seems less with the filter on. Idle timing looked about 15 and max about 32. My old hand held tachometer had given up so need to get another. The carb dies a bit when I lift the carb piston so need to adjust that as well but don’t have the tool.