where do you set the timming to?

[abig84]

i know its kinda a newbie question but i never figure out where the heck to put the timming at.

85 k5 blazer 73 400ci 2bbl carb HEI

the thing is a pain to get started and cant really even drive it till its warmed up. and basicly everything is new, carb, cap/rotor, plugs, wires,

is there a specific number your supposed to put it do or do you just do it by ear?

little more details. when it sits for a week, have to pump it like 20 times to get it going (which has pretty much always been the case with older carbed engines), but when it fires up if you hold the gas at like 1500, itll run fine for like 5 seconds then just die out, if you keep reving it itll eventually like do a pop backfire out of the carb and then run good for another 30 seconds then do the same thing. after a minute of so of that you can hold it at like 1200rpms or whatever and itll stay running. so i dont know whats going on.

 

[obijuan]

sounds like a choke issue but what do i know. also unplug your vac advance hose when setting the timing and set it to where the motor barely shakes at operating temp.

 

[Chevy305]

why buy a new 2bbl carb? There is no way a 2bbl can effectively provide enough juice to get a 400cid going to it's full potential.

But The way I set my timing is to advance it until it starts to detonate, then pull it back a degree or two.

 

[shaun89]

for small blocks with a stock cam the timing is almost always 0-4 degrees.

 

[4X4HIGH]

Sounds to me like you have a vacuum leak somewhere and or also a bad choke. Regardless, most carbed chevy's like anywhere between 4-8 advanced. Make sure you pull the vacuum line and plug it while checking/setting the timing. You also need to make sure the engine is idling at the correct RPM before you attempt to check/set timing. RPM's too high will affect the timing setting.

 

[BoondocK5]

Going by what you said, there i no computer control. Your about to learn the old school method of power timing.
Get the engine running, run it till it's warm and running on its own. get a friend to run the accelerator, loosen the hold down bolt on the distributor so you can just turn the distributor. Leave the vacuum advance hooked up.
Then with engine running, have friend run engine up to about 1800 rpm and hold it there. You need to advance the distributor until you hear pinging at that RPM, make it ping, then back off the timing off, until it stops pinging. Lock it down right there. you are now good to go,
If you check it with a timing gun, it will probably be about 8 to 12 degrees advanced from where base timing is supposed to be, but what I just told you moves it to optimum timing.

 

[abig84]

why buy a new 2bbl carb? There is no way a 2bbl can effectively provide enough juice to get a 400cid going to it's full potential.

i had it rebuilt not bought a new one. i dont even know if you can find new 2bbl carbs. its the factory carb for this engine and ran great up untill about the begging of winter.

 

[abig84]

i think it is a choke problem also, cause you also have to pump the heck out of this thing to get it running. im just trying to weed out anything it could be only reason i havent swaped it to a 4bbl is ive never had any luck with edlebrak or holley carbs in the past, technically this thing still runs so i wantto leave the carb alone for as long as i can.

 

[redhawk996]

85 k5 blazer 73 400ci 2bbl carb HEI


little more details. when it sits for a week, have to pump it like 20 times to get it going (which has pretty much always been the case with older carbed engines), but when it fires up if you hold the gas at like 1500, itll run fine for like 5 seconds then just die out, if you keep reving it itll eventually like do a pop backfire out of the carb and then run good for another 30 seconds then do the same thing. after a minute of so of that you can hold it at like 1200rpms or whatever and itll stay running. so i dont know whats going on.

I had a similar problem with my '86 K5 w/ quadrajet. I changed out the fuel filter with a new unit, after that it would not run. It turns out that the new filter came equipped from the manufacturer with a bad check valve unit. It would not open under normal fuel pressure. After a week of trying other things, I tried running it without the filter to test and it ran fine. I'm not saying that this is exactly what you're going thru, but it's the simple things that can get you. I ended up doing all this work; carb rebuild, tune-up, etc. just to have it be that $4 filter. One thing that kept puzzling me as I was trying to diagnose my truck trouble, was that fact that when I hooked up a clear hose to the disconnected fuel line to the carb, I would get great fuel flow, so I knew that the carb should be getting refilled. But actually, it would not run unless I put fuel down the carb then would die when it used that up. So, if ya haven't yet, try checking to see if ya have a good fuel supply to the carb, then check the filter,etc.

 

[roadnotca]

8 degrees.

 

[bradshawtech]

Where are you and what is your elevation as this will affect the timing setting as well.
Guy's, the setting by ear or feel is a good way to start out but is not at all the correct way to set the timing. If you do not have a timing light of your own, then surely you know someone that does or the parts store might have one to rent or borrow. The harmonic balancer is marked and there is a tab on the front of the engine for a reason.