Triumph straight six help please!

[mylittletony]

Afternoon all,

I've been rejuvenating a Marlin kit car over the past year at my old school. link here

We sourced a points dizzy, timed it up right, discovered it was 180 out after a week of head scratching, timed it up actually right and finally we got some life out of it. Success! It ran up really quick as we'd wedged the throttles open, so I pulled the ignition lead to kill it. That was the last joy we had...

There's a lot of fuel in the throat of the carbs (Stromberg CD) which leads me to believe it's flooding, can any Triumph wizards give me some guidance on any issues with these carbs? I'm thinking MrSpeedy might be able to help??

It's been stood some time, where should I be focusing my attention?

Many thanks in advance

Tony

[MrSpeedy]

Hmmmmm,
There shouldn't be any real quantity of fuel sitting there, but a little wetness isn't a worry.
If there's a lot of fuel there, t would suggest that you possibly have sticky needle valves in the float chambers.
Usually it'd still fire tho. Are you absolutely sure the ignition is correct?
Pull a spark plug after you've tried to start it to see if it's wet or dry.

[steveg]

Shortly after buying my 2000 saloon the carbs flooded and that was down to sticking float jets. The Stromberg carbs have rubber diaphragms in them which can split as well.
Back to basics really, I have to think about it all now, check to see if you have a decent spark, check to see if you get a constant supply of fuel. Things like points, condenser coil and fuel pump could be suffering after standing about.

[mylittletony]

I was thinking a stuck float due to the amount of fuel, it's puddled in the main orifice...

It has run with the ignition set as is, so 95% it's timed reasonably well. I set it to 8-10° BDTC as a starting point. We've got new points, new distributor, condenser & coil are old though, but getting a pretty fat spark, plus it's fired and sounded keen.

The pump is pretty good too, we removed the hose to try and dry the carbs, but forgot to blank it, Massive squirt of fuel, ignited by a back firing carb! Good job that happened during the school holidays and didn't flambé a 15 yr old - lolz

I'm gonna whiz the carbs apart and check diaphragms and floats - thanks for the help.

I wound the jets in then back out 3 full turns, is that right for starters??

[MrSpeedy]

I think I started at 2 turns from the holder being level with the bridge in the choke.
I'm assuming we're talking about the bottom adjustable carbs and not the emmision control version.

I forgot to mention the diaphragm, but again, they usually cause rough running rather than complete failure to start

Also, a backfire can be a sign of incorrect timing. Wouldn't hurt to double check. 8-10deg static is standard

[mylittletony]

Yes, bottom adjustable ones. I wound them in trying to feel if the piston rose, but they bottomed out in the thread. Then I backed them out 3 turns

Will check diaphragm as had the same problem on my bike mikunis.

backfire(s) happened before realising our mistake with the timing, but proof the pump works!

Will report back next week, I'm there again Tuesday.

[mdh]

"I'm thinking MrSpeedy might be able to help??"

Not offended at all.... :-P

[MrSpeedy]

Sept 11, 2013 18:05:43 GMT mdh said:

"I'm thinking MrSpeedy might be able to help??"

Not offended at all.... :-P

Neither am I lol

[steveg]

Its been yesrs since my car had Strombergs on it. I seem to remember them having some sort of cold start device on the side of them, is there some sort of link pipe as well ? If it doesn't have choke flaps in the carb it could be something to do with this as well possibly.

[retrobarmy]

The diaphragms can also stretch with age. They almost always need changing if they have been stood for a while. Take the whole lot out and check. They should be flat and have no holes in them. Hold them up to a light to check as even pinholes will cause them to fail. Also check that the slides move up and down freely. Check all the rubber seals for perishing. (They are little perishers aren't they!)

This link may help:-

LINK CARBY

Also I presume that you have oil in the dashpots?

[mdh]

Fit SU's instead.

If its flooded really badly, whip the plugs out and get them hot - blow torch hot.

[mylittletony]

Thanks again guys.

Slides are pretty stiff, but do move. Will investigate diaphragms and generally clean them up

had a look at su setup, but it needs a new fanimold would some sort of adaptor work instead?

blow torch is a good tip, link looks handy too - Cheers!

[mylittletony]

Also, sorry for implying any preference for advice, you're all wonderful :-D

[MrSpeedy]

Fairly straight forwards to redrill your manifold to suit SUs. There's a lot of slating done of Strombergs but I feel it's underserved. I literally haven't touched my CD175s for over a year and it still runs as well, if not better, than it did.

I believe you have CD150s which, I believe, don't have the external enrichment device like mine do but I can't totally remember off hand.

[mdh]

Triumphtune used to sell adapters to SU HS6s (1 3/4") carbs.

I had them on my Vitesse and the difference was night and day, at least until one carb fell off.

That's Triumptune for you!

[retrobarmy]

This may also be of use:-

club.triumph.org.uk/cgi-bin/forum10/Blah.pl/Blah.pl?m-1231192209/

Mike

[popuptoaster]

Had a pinhole in a stromberg diaphragm on my Hillman Hunter, it would start and idle but not rev and it took me ages to sort it out, everything id' owned before that had a weber on it, my old man walked past on about the fourth day and said "hole in the carb diaphragm" and walked off.

pre-internet stuff was HARD, you had to KNOW things. lol

[MrSpeedy]

Had a similar thing when I was a teen and borrowed my mum's 244. Started running like a sack of wibblepoo and wouldn't rev. It was left to me to fix cos dad was 'too busy'. Someone suggested the diaphragm and indeed it was.

[mdh]

Sept 12, 2013 23:25:29 GMT MrSpeedy said:

Had a similar thing when I was a teen and borrowed my mum's 244. Started running like a sack of wibblepoo and wouldn't rev. It was left to me to fix cos dad was 'too busy'. Someone suggested the diaphragm and indeed it was.

Whats your point? I don't get it...can you repeat it?

[BenzBoy]

I think changing the carbs is a bit overkill, personally! I like Strombergs and I think a lot of their reputation comes from people back in the day neglecting them over the years and then blaming the carbs when components fail. Much like Lucas electrics.

My advice is to just give the carbs a rebuild and see how you go from there.