1968 307 carburetor

[wwc]

I need a carb for my 1968 chevy c10 307 engine. Looking around online I see lots of 2 bbl carb for 307's, but most for sale are for 1970-1975. What is the difference in the manifold on 1968 vs 1970? Is there an adaptor?

[notsolo]

Got a photo?...Manual choke?...Most I have seen were auto choke and a number of variations...heat riser tube in the manifolds etc.

[54blackhornet]

Go to National Carbs on line

[Corts60]

I would be leery of buying any re-manufactured carb. The quality these days is really terrible. This includes the rebuild kits; they are generic and poor quality. I would buy a new production carburetor or have a legit carb guy (old grey hair) rebuild you an original. My .02.

[Astro-Balls]

Try
https://www.customrebuiltcarbs.com

Ask for Phillip.

[WorkinLonghorn]

My book for chevy car v-8s shows that in 1970 they had the CCS controlled combustion system which used a leaner carb setting. There were also other emission systems that required additional vacuum ports such as the EEC evap fuel system and the TCS transmission controlled spark and even the AIR system with the air pump that requires a vacuum connection at the carb. I don't know which of these applies to the trucks of 1970 but if it was me, I'd get the 1968 carb or upgrade the manifold to accept a 4-barrel.

[Dirt's72]

http://67-72chevytrucks.com/vboard/s...d.php?t=789487

I have this one for sale. Should be a good candidate for a rebuild.

[wwc]

Thanks for the response. National carb says the 1968 2 barrel manual choke, was only made one year. All the websites I have checked for carbs indicate the 307 carbs they sell will only fit 1970-1975's. Finding an adapter plate seems unlikely, so it seems either I make an adapter plate, or send the carb I have to be rebuilt for about $200. I will look into having an adapter and a new carb, before I spend any more on this carb.

[geezer#99]

Here’s some info on 2G carbs.

https://quadrajetparts.com/rochester...r76e9mbq5noib5

Yours is likely the larger base size.

There are 2bbl to 2bbl adaptors available.
Like this.

https://www.holley.com/products/fuel.../parts/1937MRG

Holley 2bbl is the normal swap.
Not a straight bolt on though.
Throttle linkage adaptor maybe needed. Fuel line mods. Stock Air cleaner won’t fit.

I’m curious!
What symptoms does your carb or motor have that you think it requires a carb rebuild?

[weim55]

Here is what I recall when I had my hands in these things every day 30 years ago: your 1968 and possibly 1969 307 2 barrel has an intake manifold that directs crossover Exhaust heat up to the carburetor through a passage on the left and right front corners of the carburetor. The base of the carburetor is very unique and has a hollow passage for the exhaust Heat to transfer. These carburetors were notorious for corroding and failing in this hollow area. Vacuum leaks and idle problems are very common. They also use a very unique gasket and stainless steel metal plate that burns through overtime and causes the damage to the carburetor. I’m pretty sure GM abandonEd this set up and the exhaust passage to the carburetor in 1970. As long as you stay with the smaller 307 carburetor you should not need an adapter with the 1970 up unit. When I serviced these back in the day I would plug both of the exhaust holes coming up to the carburetor when I had things apart. If your intake manifold has these holes you will notice them right away when you pull the carburetor off, front corner left and right.

Steve weim55 Colorado

[wwc]

Looks like there are several choices for an adapter plate to fit either a different two barrel, or four barrel carb to my manifold.
As for my current carb. I am not enough of a car guy to know what causes it to change from idle to fast idle, to stalling. Had a kit installed by small engine repair guy, but it didnt help much. I think being 50 years old may be the biggest problem. Adapter and new carb is the most appealing to me now.

[geezer#99]

If you had a kit installed without any change then that’s a cue you’re working on the wrong thing.
Your ignition system might be the problem.
Not enough initial timing, blown vacuum advance pot, wrong points gap to name a few.

Which carb choke style do you have?
Pics help.

[54blackhornet]

It makes no sense at all that you can rebuild a QJet and not a 2Jet ? Older guy I know said 2Jets are absolutely the worst carb to try to rebuild., and he really knows is stuff about carb / electronics.