Author Topic: Is this carb OK?  (Read 5665 times)

Offline Shifty

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Re: Is this carb OK?
« Reply #15 on: May 25, 2023, 09:53:57 AM »
You could try some 2500 grit paper, then polish, but those things never stay clear for long....I'd just do it olde skool, and take the plug loose, and raise your float until it just barely spills out, then back it down a turn.
87 V20 Standard Cab Longbed (current)

87 R30 3+3 Longbed (days of yore)

98 C2500 ext cab longbed

Offline Chevygold

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Re: Is this carb OK?
« Reply #16 on: May 30, 2023, 10:21:19 AM »
Had another go today and the issue was float level too low so now runs a lot better but still weakening off with load so going to 75 in the primaries and the 82 I fitted in the secondaries and see where we go from there.
Now I know the sight plugs screw out I can take them out to set the float level then screw them back in, anyone know if replacements are available as mine are not in great condition?
Thanks
Graham

Offline Shifty

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Re: Is this carb OK?
« Reply #17 on: May 30, 2023, 02:10:01 PM »
Summit, Jegs, or just about any speed shop should have them...
87 V20 Standard Cab Longbed (current)

87 R30 3+3 Longbed (days of yore)

98 C2500 ext cab longbed

Offline Chevygold

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Re: Is this carb OK?
« Reply #18 on: May 31, 2023, 10:53:17 AM »
Found them here in UK so should have them tomorow along with the 75's

Offline Chevygold

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Re: Is this carb OK?
« Reply #19 on: May 31, 2023, 10:56:05 AM »
Got the brass plugs as the plastic ones should only be used for setting then replaced with the brass ones, much safer I imagine.
Graham

Offline Shifty

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Re: Is this carb OK?
« Reply #20 on: May 31, 2023, 01:21:29 PM »
Sorry Graham, I didn't see you were in the UK...I'm glad you got them under control anyway. 
87 V20 Standard Cab Longbed (current)

87 R30 3+3 Longbed (days of yore)

98 C2500 ext cab longbed

Offline Chevygold

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Re: Is this carb OK?
« Reply #21 on: June 01, 2023, 02:33:43 PM »
So I now have the 75's in the primaries and 82 in the secondaries, it now seems a little rich but runs better than before so maybe I need to go somewhere between the 68 that I did have  and the 75 I have now perhaps 72?
Wish I could afford the Holley selection box  :( it would make life a lot simpler!
Any way of knowing when the secondaries kick in as they might be a bit rich too?
Nowhere to go for a good blast as the roads are crammed with holiday traffic just now >:(
Graham

Offline JohnnyPopper

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Re: Is this carb OK?
« Reply #22 on: June 01, 2023, 07:08:49 PM »
Yeah with the cost of petrol these days I would lean them out.

Are the secondaries the same physical size as the primaries?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Chevygold

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Re: Is this carb OK?
« Reply #23 on: June 04, 2023, 03:58:43 PM »
Square bore 1.536" primary and secondary

Offline Chevygold

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Re: Is this carb OK?
« Reply #24 on: June 04, 2023, 04:03:12 PM »
Just ordered 72's for the primaries so will see how it goes when I get them Tuesday.
Graham

Offline JohnnyPopper

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Re: Is this carb OK?
« Reply #25 on: June 04, 2023, 05:23:32 PM »
Ahh yes, square.

The jet sizes for the secondaries seem huge, but I guess that's what you want when you crack those babies.

I just got a Qjet from National Carb's out of Florida, can't wait to hear that familiar drop in vacuum, and then "BuuuWaaaaaaahhh"!
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Chevygold

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Re: Is this carb OK?
« Reply #26 on: June 06, 2023, 10:31:24 AM »
Got the 72's in the primary now and now running much better, should I be reducing the secondary jetting now as well?
Just looked at the standard jetting for the SA 670 and it's primary 65 and secondary 68 a difference of 3 so should I maybe come down to 75 in the secondaries as it seems to be going rich as the revs get up?
Thanks all
Graham

Offline JohnnyPopper

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Re: Is this carb OK?
« Reply #27 on: June 06, 2023, 01:40:29 PM »
I would think with that spread you can use the 75 primary jets for the secondaries. Find a long empty straight away for testing. Video if possible.  8)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Chevygold

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Re: Is this carb OK?
« Reply #28 on: June 06, 2023, 03:27:18 PM »
I'll swap the 75's into the secondaries and see how I get on.
Graham

Offline Shifty

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Re: Is this carb OK?
« Reply #29 on: June 06, 2023, 05:12:26 PM »
Be a great place to have a stoich meter....
87 V20 Standard Cab Longbed (current)

87 R30 3+3 Longbed (days of yore)

98 C2500 ext cab longbed