Rochester carburator question..
October 19th, 2023, 04:48 PM
#41
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A great source to find Delco GM carburetor build sheets is the URL link below. There are many books, pamphlets, etc. - but, I've found this site to be excellent & many are unaware of its usefulness. Click on the "GM" drop-down menu and browse by year. Have fun (sorta). You can d/l any of these .pdf files.
GM Carburetor Build Sheets
GM Carburetor Build Sheets
October 19th, 2023, 05:02 PM
#42
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That missing port is the ported vacuum source for the distributor vacuum advance on my carburetor (7041250) . It is capped off and I have the line for the advance canister connected to manifold vacuum. I wouldn't send the carb back just for that missing hose nipple - check as much as you can and let the overall assessment guide your choice to send it back or not.
October 19th, 2023, 05:16 PM
#43
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That missing port is the ported vacuum source for the distributor vacuum advance on my carburetor (7041250) . It is capped off and I have the line for the advance canister connected to manifold vacuum. I wouldn't send the carb back just for that missing hose nipple - check as much as you can and let the overall assessment guide your choice to send it back or not.
The 7043250 spec are .069 jets, 53C pri rod and CG sec rod
Note: the engine as non stock "J" heads so....
With some research, the 7041250 is closer for 455 eng, same jets and prim rod, sec rod is AS vs AK for original. (could change them if it's that bad).
I don't mind returning it to get the 7041250 for that and the missing port.
What do you think ?
Thanks
October 19th, 2023, 05:24 PM
#44
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You're essentially asking if it's OK to exchange your 7043250 for the 7041250. I'll just note both carburetors were designed for the 350 cid engine. You have a 455 cid engine. I don't have the knowledge to suggest usage of 455 cid jets & rods for either of those 350 cid carburetors. I'd not have a problem suggesting the opposite - using a 455 cid carburetor on a 350 cid engine though - I just don't have the experience. Sorry. 
EDIT: And, I suppose, my quandary exists in me not knowing whether the idle circuit is the same which may make a difference.
EDIT: And, I suppose, my quandary exists in me not knowing whether the idle circuit is the same which may make a difference.
Last edited by Vintage Chief; October 19th, 2023 at 05:26 PM.
October 19th, 2023, 05:39 PM
#46
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You're essentially asking if it's OK to exchange your 7043250 for the 7041250. I'll just note both carburetors were designed for the 350 cid engine. You have a 455 cid engine. I don't have the knowledge to suggest usage of 455 cid jets & rods for either of those 350 cid carburetors. I'd not have a problem suggesting the opposite - using a 455 cid carburetor on a 350 cid engine though - I just don't have the experience. Sorry.
Can you believe the current carb on the 455 is from a 1980 Buick rivera V6 and the fuel bowl empties in 24 hours after stopping the engine !!
I can have one from I-5automotive but $$$, the price just rise from 425$ to 592$, I'm in canada so it's a 113$ more for shipping + exchange !!
It's my friend's car, so his decision, but I need to give him some option soon.
I can probably find a used one on ebay and rebuild it.. will see
Thanks again
October 19th, 2023, 05:57 PM
#47
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Makes me think the right way I think !
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