327 starts and runs when given gas, won't idle.

[nick333]

Hello all!

 

So I picked up a 79 C10 Shortbed with a 327 in it a few days ago. Yesterday I accidentally filled up about 6 gallons with 87. After that it sounded like it was having a tough time idling. Try to start it up today and it start fine and runs  strong if given gas, but can't idle and putters out. So I siphoned 5 gallons out and put in some octane booster, and refilled with high octane gas. Didn't seem to help at all.

 

I'm wondering if i have to keep repeating the process or I'm gonna have to check out the carb. Also when I start it up the oil pressure gauge is pegged however its old and a couple other gauges are out. I completely forgot if the oil one didn't work before this or that's linked to this issue. I got this truck to learn more about working on vehicles and I'm somewhat new to this, so I'm not really in a hurry. But I would like to see if anyone here has any ideas on the issue. I did read somewhere the ethanol could have left a film on the carb float, but it was only sitting over night so I'm not sure.

 

Thanks,

 

Nick

[riverbanks]

Has it been sitting? just thinking water,how about Changing the fuel filter?and when it sputters,any raw fuel smell or is it starving for gas?

[nick333]

I was running it the day prior just fine. I will give a fuel filter change a shot. I'm not smellin any raw fuel when it starts to die. It wont idle even for a couple seconds. 

[nick333]

Update on the situation. I was just able to keep it running giving it a little gas and drove it around the block. What was happening was and I would give it throttle it would rev up a second and I would hear air compression release somewhere as if you were to tap a compessed air nozzle really fast, then it would continue to rev up and they do the same pressure release. I heard it 4 or 5 times when trying to give some more gas. I'm gonna start checking hose seals. If that gives anyone any other ideas please share!

[riverbanks]

Maybe a faulty check valve in vacuum booster line

[garagerog]

Not addressing your idle issue now, but if you're truly wanting to learn automotive I'd like to suggest a couple of starting points. Are you sure your 79 C10 has a 327 in it rather than the 350?  The last year for the 327 was in 1969, a decade before your truck was made. If it truly is a 327, it could have come out of anything as the 327 was a very very versatile and even ubiquitous motor, it could have come out of anything from a Corvette to a MF 510 combine. Does it have a two or four barrel carb? You might look for an engine stamping code, might be found on a pad below the passenger side cylinder head. And yes, good idea to check all your vacuum lines for leaks.

[nick333]

Okay I'll take a look at the vacuum lines

 

Yeah! I'm aware they didn't come with the 327. I've read it is essentially the same block but shorter pistons rods and cams? The prior owner swapped it 10k miles ago when it was 'freshy rebuilt' how true that is I'm not sure. I will check the stamping code! 

 

Thanks for the replies, friends.

 

By the way it has a 4 barrel carb.

[garagerog]

54 minutes ago, nick333 said:

Okay I'll take a look at the vacuum lines

 

Yeah! I'm aware they didn't come with the 327. I've read it is essentially the same block but shorter pistons rods and cams? The prior owner swapped it 10k miles ago when it was 'freshy rebuilt' how true that is I'm not sure. I will check the stamping code! 

 

Thanks for the replies, friends.

 

By the way it has a 4 barrel carb.

Hard to say what cam your 327 has, the crankshaft is the big difference between the 327 and the 350 with the 327 having the shorter throw, both had the same 4" bore if I recollect right. Equipped with the right heads, cam, and lifters, the 327 was a Rev Monster with it's short stroke.

[nick333]

4 minutes ago, garagerog said:

Hard to say what cam your 327 has, the crankshaft is the big difference between the 327 and the 350 with the 327 having the shorter throw, both had the same 4" bore if I recollect right. Equipped with the right heads, cam, and lifters, the 327 was a Rev Monster with it's short stroke.

Copy that, good to know. Thank you

[nick333]

Vacuum lines were fine. Kept running it sitting and putting high octane back into it trying to get all that low octane out of the fuel system. Slowly came back to life. Running and idling fine now.