At wit's end!!! help please!!!

[Billy Smalls]

Hi
Despite having a new unleaded head with new valves, seals and springs 800 miles ago, my B20A single Stromberg engine is not behaving itself at all. When I had the work done the garage didn’t touch the carb or points or timing. It’s not pinking, it’s not misfiring, but is lacking power and is a pig to hot start (may just be the hot weather, so that could be a red-herring) it also struggles at idle. I want to eliminate some simple fixes before I take it to a mechanic, so here goes.

I’ve been running it on 97 and 99 octane fuel since the work, could this effect running?

Would a new coil help?

How much can be done with the carb? It’s the one with a simple plug in the bottom and the coffin shaped yellow temp compensator.

The dizzy plate turns when I tighten up the points screw?

I’m frustrated, as after spending A LOT of money, it’s running like a sack of poo!!!

[dingov70]

Because the head was removed to work on , it is most likely you have an air leak between the inlet manifold & the head mating face or between the carb & inlet manifold . Get it running & spray wd40 or similar around the joint faces of the inlet mainfold , if it revs up or smooths out , you have found the source of your air leak ( if that is the problem ) Check the black diaphragm for any perforations . make sure all vacuum pipes are fitted . Also ensure you fitted the thick heat resisting insulator between carb & manifold with new gaskets .

Being a pig to start when hot would indicate an extremely weak mixture , pull out choke a touch & see if it bursts into life , because the mixture is richer .

[john.wigley]

I seem to recall all of our carburettor fed 140s (bar our 145E, which was FI) were difficult to start hot in period. It was explained to me that this was due to fuel vaporisation, but as they always started in the end I didn't pursue the matter exhaustively. Are modern fuels perhaps more prone to this tendency, resulting in your starting problems? No substance - just a thought! The cars were all also very sensitive to the quality of plugs and points used.

Regards, John.

PS Just reread your post and note that you have a Stromberg carb - split diaphragm maybe?

[Derek UK]

"The dizzy plate turns when I tighten up the points screw?"

Instant reaction to that is that it shouldn't do that but I would like more details. There are 2 screws which go through the dizzy body into a pair of tabs which fix the points plate. What is happening may affect your timing hence poor start and lack of power. I know you retarded the ignition to get rid of the pinking so perhaps start from scratch again on the timing.
Yes, check the diaphragm.

[Billy Smalls]

Thanks Dingo, John and Derek!

I did a few checks last night; as expected and hoped the compression across all 4 cyclindars is a healthy(ish) 130psi, so that's good.

The diaphragm was replaced about 6 months ago and is fine.

The mechanic said that there may well be an air leak between the new head and the exhaust outlet but didn't mention the inlet / head interface. I removed the carb before the work and cleaned all the old gasket off and replaced the paper gaskets either side of the thick gasket - which looks to be a bakerlite type material as opposed to rubber. I will try the leak test with some carb cleaner.

However, I think the dizzy may be to blame. The little screw that holds the points onto the plate has cut through the thread in the plate (the threaded hole has been stripped from years of tightening) so I had to use a 4.5mm self tapper to hold the points. This was a few weeks ago and the gap had closed to almost nothing already - BINGO!!

I set the points again and it runs a lot better this morning but haven't had to hot start yet.

The dizzy was looked at 3 years ago by a chap on this forum who stopped the plate from turning when I tightened the points up.

I think a new dizzy is needed and am slightly tempted by a 123 electronic system - I know they are expensive but fit and forget would suit me to be honest - I can concentrate precious time on the bodywork then!!

Either way the dizzy needs sorting and I see that Simon at Brookhouse doesn't do new ones???

Thanks again

[Derek UK]

PM swedishandgerman, search/find him on the 120 section, he might be able to find you a replacement plate or another distributor. The screws that fix the plate are the ones that hold the 2 cap retainer springs. Easy to swap in a replacement. No need for a 123 unless you have money to burn.

[Billy Smalls]

Originally Posted by Derek UK

PM swedishandgerman, search/find him on the 120 section, he might be able to find you a replacement plate or another distributor. The screws that fix the plate are the ones that hold the 2 cap retainer springs. Easy to swap in a replacement. No need for a 123 unless you have money to burn.

Thanks Derek - ah yes, SwedishandGerman is the good fellow, down in Exeter, who did it 3 years ago.

However, I have decided to go for 123 as the little time I have to spend on the car needs to be with bodywork. Don't have money to burn but thought I'd treat myself, especially as I've just had a new head fitted. Might as well go the whole hog and get 123 and a new coil.....

has 123 on my old Citroen Ami6 and it was one less faff....the car's in constant use and whilst purist may curse me, I need it to be a smooth reliable runner every day.

thanks for your help Derek, much appreciated

[Whitey889J]

Hi Billy,

I have a spare carb (see picture) which you can have if you are interested. Although grubby looking it was working fine when last on a car (approx 12 months ago) and is surplus to my requirement so might assist in isolating the problem. It would be collection only from Toddington in Gloucestershire which is not too far from junction 9 on the M5.

Kind regards

Ian

[Billy Smalls]

Originally Posted by Whitey889J

Hi Billy,

I have a spare carb (see picture) which you can have if you are interested. Although grubby looking it was working fine when last on a car (approx 12 months ago) and is surplus to my requirement so might assist in isolating the problem. It would be collection only from Toddington in Gloucestershire which is not too far from junction 9 on the M5.

Kind regards

Ian

Wow, thanks Ian, that is very kind of you. I am just south of Bristol, so would be easy for me to come and get it. I see you are a new member, so you may not be able to pm me - I'll pm you my phone number. thanks again...

Will

[Whitey889J]

Hi Will,

Got the text thank you and there is no rush from my point of view so let me know when you can make it up here.

Ian