Stromberg suction chamber screw specs?

[Richardsona39]

I have Stromberg 175 CD2 carbs in my +2, and the screws on the top of each carb are pretty worn and a couple are close to stripping. I took one of the screws to my local home center to check the threads, and so far as I can tell they are M5-0.8, and 14mm long. Most stuff on a Lotus is SAE/Imperial, so I was a little surprised to find these appearing to be metric based on my fit test in the store.

So I got some new screws (stainless), and did another visual check comparing the threads. But when I put them in they'll engage the first 3-4mm of thread but then start to get quite tight, and I stopped as I was worried I was cross-threading. I tried several holes, all the same.

Anyone able to confirm the spec? Was I just being too cautious? I didn't apply any grease to the threads initially but I could also try that.

[cliveyboy]

If you put the two bolts together if the pitches are very close it will most likely be 10/32UNF
If the M5 has a much finer thread than the original then try a 10/24UNC

Clive

[JonB]

I'm also looking for a definitive spec for these screws. Mine are rusted and one has nearly lost its "cross drive" recess, so is tricky to tighten / loosen.

By the way, I would expect them to be UNC (coarse) threads as they are screwing into aluminium. But happy to be proven wrong.

(Edit: Thought I'd do a search and found an alternative to Burlen who appear to sell more than just overhaul kits: http://www.gowerlee.dircon.co.uk/Stromberg.html.)

(Edit 2: Found an expensive set on eBay: https://www.ebay.co.uk/itm/151555997139.)

[Billelan]

Just checked mine, certainly not metric. They measure 3/16”dia, 32TPI (threads per inch).
So they are 10-32UNF. If you can’t source locally then they come as part of a service kit.

[Richardsona39]

Thanks all, very helpful. I'll see what I can source locally (I'm in US) - can always go for McMaster Carr if I don't mind paying several multiples of the item cost for shipping

[mbell]

You can pick 10-32 hardware up at at Lowe's or home depot or any bolt store in the US.

[cliveyboy]

If they are 10/32UNF and about 14mm long and look like JONBs picture
I would search for 10/32 x 9/16" UNF cheese head screws. These will give you a screwdriver slot
Some one said they had lost there "cross drive" If that means you need philips, pozidrive/superdrive heads then search for pan head screws

Clive

[JonB]

The eBay seller also sells them with a slotted head. I opted for cross head for originality.

[Richardsona39]

Yep, got exactly as suggested from Home Depot - did have to order them as they didn't have the 9/16" in my local store, they should arrive in the next few days and I'll give them a go.

[JonB]

The cross heads I ordered arrived today and fitted perfectly. Expensive for 8 little screws but they look nice.

[mbell]

Yep, got exactly as suggested from Home Depot - did have to order them as they didn't have the 9/16" in my local store, they should arrive in the next few days and I'll give them a go.

My experience is that the hw section in Lowe's is better than home depot. Somewhere like Ace hardware is probably even better.

[The Veg]

My experience is that the hw section in Lowe's is better than home depot. Somewhere like Ace hardware is probably even better.

Exactly true in my experience as well.

[Richardsona39]

Just a follow-up to confirm that #10-32 UNF and 5/8" length are the correct fit - just installed them this morning.