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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: JMANC10 on February 06, 2017, 04:21:03 pm
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Hello everyone!
I'm new to the site (Mount Olive, Al) and I didn't really know where this type post belonged. I picked up a 1984 C-10 in the summer of 2016. A previous owner had swapped the original 305 engine out for a 350. The issue I'm having is it usually takes about 3 or 4 times for the truck to stay running after I crank it. It will fire and catch every time, but then it goes dead. If I keep my foot on the gas a bit it will stay running and then after about 30 seconds or so it will idle fine without dying. I assume the issue is with my carburetor and its lack of a choke or that it's not adjusted properly. The carburetor is a Holley 1850-5. It's missing the choke assembly and from the research I've done, it seems that carburetor was equipped with a manual choke. I'm not a mechanic nor do I claim to be, I'm just wanting some advice on what the issue might be. I'm probably just going to buy a new carburetor instead of trying to piece the one I have back together. Thanks for any help!
JMANC10
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Your correct in your diagnosis. Your going to have to get the right carb with the automatic choke. When you pump the gas, your enriching the mixture but the engine burns it right off unless you keep pumping it. Automatic choke keeps you from having to pump the gas. Once the engine is warm, it should run fine.
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Welcome to the site from Birmingham AL. If you are missing a choke it could be the issues. That Holley never came on the truck, it should have a quadrajet on it.
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Thanks for the replies guys. It currently has an Edelbrock high-rise intake on it. Would a quadrajet be compatible with that? Or should I just go with and Edelbrock carb to match the intake?
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personally i wouldnt waste money on a carb if youre not sure if its bad and then it would be cost effective just to rebuild your old one.
i would see if you can add a choke to it, autozone advance and most if not all parts stores sell manual choke cables and kits. another thing to check on is the size of the carb. some just put the biggest carb they can find on a sbc when its over kill. example would be even a 500 cfm carb for a 305 is too much for a racing engine hitting 5000 rpms. i would go for only 300 cfm or so for a 305 hitting 4k.
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That's very helpful info as my dad has an 84 Scottsdale with a 305 and a 600 cfm Edelbrock. He's been saying that he thinks its running too rich and needs to get a smaller one. He just didn't know what size to get. He used to have an 83 Silverado(my avatar). He said it had a 2 barrel and it didn't have much power at all. I'll look into some choke kits though. Thanks!
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if you have any questions about the cfm heres (https://www.summitracing.com/expertadviceandnews/calcsandtools/cfm-calculator) a calculator
also take a read on this
A note about carburetor flow capacities (http://forum.73-87chevytrucks.com/smforum/index.php?topic=31377.0)
and some info on timing can be found here (http://forum.73-87chevytrucks.com/smforum/index.php?topic=32085.0)
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That carb is rated 600cfm so it will be fine, it should be vacuum secondary, so it will only pull what it needs.
It is probably just time for a rebuild.
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Hello from Cullman and I just replaced the choke thermostat on mine (electric choke on an Edelbrock 1407 carb). It was doing the same as yours until I fixed the choke.
Man. we need to have an Alabama meet up XD
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Hello from Cullman and I just replaced the choke thermostat on mine (electric choke on an Edelbrock 1407 carb). It was doing the same as yours until I fixed the choke.
Man. we need to have an Alabama meet up XD
Actually I was born and raised there. Just moved to Mount Olive last year. I'll be up that way this evening. If you're out near 278/31 around 630 you'll hear this baby roaring by LOL. Had a new exhaust system installed from Cullman Discount Muffler. He did straight duals all the way from the manifolds back, but I may have him go back and do a 2 into 1 into 2 style. It sounds great but it's a tad bit on the loud side and I feel bad for my neighbors in my subdivision sometimes when I fire it up later at night. :-[
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Update: Ok, so I bought a Holley electric choke kit and installed it. It appears to be working properly. Took some time getting the set screw on the fast idle cam right so it would catch and idle high on startup. Here's the thing though. I have found that I have to pump the gas about 10 times on a cold start just for the truck to stay running. I tried doing one pump to set the choke(which it will do) and that didn't work out. I tried pumping 4 or 5 times and that still didn't work. It would fire and run for 2 or 3 seconds and go dead. From a lot of what I've read you aren't supposed to have to pump the gas that much. Also I have noticed that if the truck runs for a while and I shut it off for more than a couple of minutes(Like after refueling at a gas station) that it won't crank right back up. I still have to pump the gas several times. I am really thinking about just getting a new carb. My first vehicle was a 1986 Silverado and I can't remember that truck having these starting issues. :-\
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Purchase or download a manual for your carb, check the float level and then verify all of the choke settings are correct.
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Old carbs wear out. Get a Holley 600cfm pt# 80457-s /4160. 'NThey work great. Should just put on and Adjust idle speed. It has elect choke.