Rochester 2bbl to SBC 350 4bbl manifold
Thread Starter
CF Beginner
Joined: May 2019
Posts: 12
Likes: 0
Rochester 2bbl to SBC 350 4bbl manifold
This will probably sound like an inane question, but recent purchase of a 1975 C30 tray with SBC that has a 4bbl manifold.
Whoever had this rig before had it set up with LPG, which has since been disconnected.
They bolted a 4 bbl Holley to the manifold with an adapter plate, circumvented all the pollution gear and this is where I ran intro strife.
We have a very strict roadworthy set up over here in Australia, talking to the bloke who is going to do the inspection, if I go back to straight petrol all the pollution gear has to go back on.
I can get hold of a Rochester 2GC carby relatively easy, we used them over here on the locally assembled GM products, but am thinking that I will have to utilise some sort of adapter to go between the manifold and the carby, with a port in it for the recirculation gear.
I neither want, nor need a 4 barrel carby, truck will only be going on club runs, so I'm thinking that the low to mid range RPM with a 2bbl will be more than adequate for my needs.
Not a petrol head, been diesel all my working life, even current vehicles are both diesel. Been about 30 years since have even looked at a petrol engine. The 350 SBC in the C30 goes like a clock, so just want it to continue running sweetly with a modicum of reliability as well as a bit better economy.
I realise most blokes want to go the other way, increasing HP and all that, I'm trying to keep it simple and also keep the authorities on side.
So, have seen some of these adapters around, in fact there is one currently on the truck between the Chev manifold and the Holley carb, must be something available to go from 4bbl Chev manifold to 2bbl Rochester??
Appreciate any comments,
Thanks Dave64
Whoever had this rig before had it set up with LPG, which has since been disconnected.
They bolted a 4 bbl Holley to the manifold with an adapter plate, circumvented all the pollution gear and this is where I ran intro strife.
We have a very strict roadworthy set up over here in Australia, talking to the bloke who is going to do the inspection, if I go back to straight petrol all the pollution gear has to go back on.
I can get hold of a Rochester 2GC carby relatively easy, we used them over here on the locally assembled GM products, but am thinking that I will have to utilise some sort of adapter to go between the manifold and the carby, with a port in it for the recirculation gear.
I neither want, nor need a 4 barrel carby, truck will only be going on club runs, so I'm thinking that the low to mid range RPM with a 2bbl will be more than adequate for my needs.
Not a petrol head, been diesel all my working life, even current vehicles are both diesel. Been about 30 years since have even looked at a petrol engine. The 350 SBC in the C30 goes like a clock, so just want it to continue running sweetly with a modicum of reliability as well as a bit better economy.
I realise most blokes want to go the other way, increasing HP and all that, I'm trying to keep it simple and also keep the authorities on side.
So, have seen some of these adapters around, in fact there is one currently on the truck between the Chev manifold and the Holley carb, must be something available to go from 4bbl Chev manifold to 2bbl Rochester??
Appreciate any comments,
Thanks Dave64
CF Monarch
Joined: Oct 2017
Posts: 4,605
Likes: 268
From: USA
This will probably sound like an inane question, but recent purchase of a 1975 C30 tray with SBC that has a 4bbl manifold.
Whoever had this rig before had it set up with LPG, which has since been disconnected.
They bolted a 4 bbl Holley to the manifold with an adapter plate, circumvented all the pollution gear and this is where I ran intro strife.
We have a very strict roadworthy set up over here in Australia, talking to the bloke who is going to do the inspection, if I go back to straight petrol all the pollution gear has to go back on.
I can get hold of a Rochester 2GC carby relatively easy, we used them over here on the locally assembled GM products, but am thinking that I will have to utilise some sort of adapter to go between the manifold and the carby, with a port in it for the recirculation gear.
I neither want, nor need a 4 barrel carby, truck will only be going on club runs, so I'm thinking that the low to mid range RPM with a 2bbl will be more than adequate for my needs.
Not a petrol head, been diesel all my working life, even current vehicles are both diesel. Been about 30 years since have even looked at a petrol engine. The 350 SBC in the C30 goes like a clock, so just want it to continue running sweetly with a modicum of reliability as well as a bit better economy.
I realise most blokes want to go the other way, increasing HP and all that, I'm trying to keep it simple and also keep the authorities on side.
So, have seen some of these adapters around, in fact there is one currently on the truck between the Chev manifold and the Holley carb, must be something available to go from 4bbl Chev manifold to 2bbl Rochester??
Appreciate any comments,
Thanks Dave64
Whoever had this rig before had it set up with LPG, which has since been disconnected.
They bolted a 4 bbl Holley to the manifold with an adapter plate, circumvented all the pollution gear and this is where I ran intro strife.
We have a very strict roadworthy set up over here in Australia, talking to the bloke who is going to do the inspection, if I go back to straight petrol all the pollution gear has to go back on.
I can get hold of a Rochester 2GC carby relatively easy, we used them over here on the locally assembled GM products, but am thinking that I will have to utilise some sort of adapter to go between the manifold and the carby, with a port in it for the recirculation gear.
I neither want, nor need a 4 barrel carby, truck will only be going on club runs, so I'm thinking that the low to mid range RPM with a 2bbl will be more than adequate for my needs.
Not a petrol head, been diesel all my working life, even current vehicles are both diesel. Been about 30 years since have even looked at a petrol engine. The 350 SBC in the C30 goes like a clock, so just want it to continue running sweetly with a modicum of reliability as well as a bit better economy.
I realise most blokes want to go the other way, increasing HP and all that, I'm trying to keep it simple and also keep the authorities on side.
So, have seen some of these adapters around, in fact there is one currently on the truck between the Chev manifold and the Holley carb, must be something available to go from 4bbl Chev manifold to 2bbl Rochester??
Appreciate any comments,
Thanks Dave64
This adapter plate will work if your engine originally came with a Rochester Quadrajet as GM used 4 Barrel Holley's as well. There are lots of other adapter plates for the Holley 4 BBL to Rochester 2 Barrel carb online as well. Nothing wrong with the 2 Barrel Rochester's at all, but I never have liked the 4 Barrel Quadrajet as it's a bear to tune and the gas mileage is worse then a good Holley 4 barrel which stays tuned and easier to work on as well.