Register or Log In To remove these advertisements. |
|
|
|
Thread Tools | Display Modes |
|
03-10-2009, 09:03 PM | #1 |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Engine Won't Idle--been workin on this for a week
When I installed a new 350 in my truck we pulled the old one and pullled the pan and timing cover and replaced the oil seals, and timing chain and adjusted the valves, then we put it in my dads '72 K20 Suburban. the motor runs OK but it won't idle(i think its flooding)
we Pulled my HEI, wires, spark plugs and my 4160 Holley off my '70 and put them on the engine, the Holley flooded badly at idle and i checked the pump and found 10PSI (might be more, my gauge only goes to 10PSI)at idle, my dad had a generic electric automotive fuel pump laying around so we put that on it (It put out 3PSI) and the engine still wouldn't idle, pulled the Holley and HEI off and put them back on my '70 and it idles just fine. We picked up a new fuel pump(puts out 10PSI too), coil, a set of points and a condenser today and installed them and checked dwell and ignition timing and the thing still won't idle P.S. carb is Quadrajet
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
03-10-2009, 09:13 PM | #2 |
Registered User
Join Date: Feb 2009
Location: Somerset, KY
Posts: 398
|
Re: Engine Won't Idle--been workin on this for a week
I really don't know if this will help any, you probably don't have this problem, but...
I recently had similar trouble. My truck would idle, but contantly flood out at idle. Had Holley on it that was constantly leaking, so I bought an Edelbrock. Same thing was happening. ANyway, what I ended up doing is replacing all the flex fuel line, and flaring out the end of the metal hose where it came up towards the engine. I don't know if yours is like that or not, but I think since mine had been hacksawed off it was getting pieces of rubber up in the carb, enough to keep the carb messed up. Hope that helps, I doubt that is your problem but it is something to check. |
03-10-2009, 09:31 PM | #3 |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Re: Engine Won't Idle--been workin on this for a week
anybody know what the fuel pressure is supposed to be on a Q-jet
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
03-10-2009, 09:42 PM | #4 |
Registered User
Join Date: Jan 2007
Location: Charles City IA
Posts: 1,626
|
Re: Engine Won't Idle--been workin on this for a week
I would guess 5-8. I'd try a fuel pressure regulator, and see if that makes a difference.
__________________
'67 C20, Under the Knife!, LWB, Eaton HO-52, Rear Coil Springs 72' GMC C2500, 350, TH400(?), Dana 60 '67 K10 4-spd., 305, SM465, Dana 44, 12 Bolt, RUST! '65 C60 292, 4 spd, 2 spd Rearend, 15' Grain Box, MINT! 09 Yukon Denali 82k Miles 6.2L/6A |
03-10-2009, 09:47 PM | #5 |
Formerly- 1972SuperCheyenne
Join Date: Oct 2008
Location: Wake Forest NC
Posts: 5,782
|
Re: Engine Won't Idle--been workin on this for a week
Fuel pressure should be about 7 psi. Sounds like a vacuum leak or valves adjusted too tight. Hope it helps.
__________________
--Josh My Build Thread:http://67-72chevytrucks.com/vboard/s...d.php?t=799218 A good crossthread is better than Loctite any day. Life is not about what you have, but who you have to share it with. |
03-10-2009, 11:07 PM | #6 | |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Re: Engine Won't Idle--been workin on this for a week
Quote:
I tightened them until the pushrod stopped turning, then 1/2 turn more
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
|
03-11-2009, 10:07 AM | #7 |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Re: Engine Won't Idle--been workin on this for a week
bump.
guys i need your help with this one!!!
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
03-11-2009, 11:20 AM | #8 |
Registered User
Join Date: Dec 2007
Location: Johnson City TN
Posts: 570
|
Re: Engine Won't Idle--been workin on this for a week
check how many inches of vacuum the engine is pulling.. it should be pulling around 16-20".... if its not you have a vacuum leak and that will cause bad idle..
and 10lbs of fuel to a carb is another problem.. with that much pressure the fuel will overpower the needle and seat in the carb and cause flooding. get your fuel pressure down to around 5 or 6 lbs, and then check your plugs because im sure they are fuel fouled now.. if they are fuel fouled get 8 new ones.. but the first thing i would check is how many inches of vacuum it pulls,and then get your fuel presssure under control
__________________
My build thread--http://67-72chevytrucks.com/vboard/s...d.php?t=300333 |
03-18-2009, 02:32 AM | #9 | |
Registered User
Join Date: Mar 2009
Location: Liberty, Missouri
Posts: 35
|
Re: Engine Won't Idle--been workin on this for a week
Quote:
If you have an old set of valve covers laying around you can cut the top out to gain access to the rockers (this will keep oil from spraying everywhere) and the loosen one lifter at a time and re tighten just till it's quiet and then give another 1/4 turn. Good luck,keep at it you will find the problem. |
|
03-19-2009, 09:06 PM | #10 |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Re: Engine Won't Idle--been workin on this for a week
sorry guys, I haven't been working on the burb, my transmission went out in my '70 and I'm swapping to a 700r4, i should be able to get back on it next week
thanks for the suggestions, greatly appreciated
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
03-11-2009, 11:24 AM | #11 |
Senior Member
Join Date: Apr 2008
Location: Franklinton NC
Posts: 1,309
|
Re: Engine Won't Idle--been workin on this for a week
Ditto on to much fuel pressure.I would also recheck you valve adjustment.
|
03-17-2009, 10:53 AM | #12 |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Re: Engine Won't Idle--been workin on this for a week
I should have checked the vacuum a week ago. Its pulling 10inches I think i got a vacuum leak
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
03-17-2009, 11:13 AM | #13 |
I miss this truck.
Join Date: Dec 2001
Location: Lexington, KY U.S.A.
Posts: 2,863
|
Re: Engine Won't Idle--been workin on this for a week
When you installed the front disks, did you add a booster? It could very well be the source of your vacuum leak. If this truck is an auto, the leaking booster could also manifest itself in poor shifting...
You wouldn't necessarily be able to hear the leak either. A quick check would be to pull the vacuum hose from the booster and plug the end with your thumb. If the idle improves, you're on the right track. Of course, this is a shot in the dark, not knowing for sure if you have either power brakes, or an auto tranny. Edit: Just realized this may be in your dad's burb, but the theory holds, brake boosters are a common source of vacuum leaks, in my experience.
__________________
'07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT. Last edited by Tynee; 03-17-2009 at 11:18 AM. |
03-17-2009, 06:27 PM | #14 | |
Senior Member
Join Date: Jan 2009
Location: Austin, TX
Posts: 1,079
|
Re: Engine Won't Idle--been workin on this for a week
Quote:
__________________
-- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted |
|
03-17-2009, 10:49 PM | #15 |
Registered User
Join Date: Mar 2009
Location: paso robles ca.
Posts: 20
|
Re: Engine Won't Idle--been workin on this for a week
you can spray brake clean around vacume ports and throttle shafts to locate vacume leaks. But 10 lbs. of vacume could be caused by a larger than stock cam an may not be the problem. check the vacume gauge and if it dances than the problem could be your valves. also check the timing and firing order real well. good luck
|
03-18-2009, 01:02 AM | #16 |
Senior Member
Join Date: Jan 2005
Location: SUNNY WARM BIKE RIDING COTTONWOOD ARIZONA
Posts: 2,097
|
Re: Engine Won't Idle--been workin on this for a week
no more than 7psi and 10lbs could be TIGHT VALVES or timing as metioned above.....
|
03-18-2009, 01:44 AM | #17 | |
Registered User
Join Date: Sep 2001
Location: Hacienda Heights, California USA
Posts: 474
|
Re: Engine Won't Idle--been workin on this for a week
Quote:
Was the timing set a multi timing sprocket type? Some sets you can retard or advance the timing. If it is, you may have changed the cam timing by accident. Last would be, that the valves need to be readjusted. After you check the timing gear set. I would also add a fuel pressure regulator. A stock to mild carbed SBC can idle off of 5 psi. of fuel pressure.
__________________
'72 GMC custom camper 350/350 Last edited by spinning wheels; 03-18-2009 at 01:49 AM. |
|
04-04-2009, 12:06 PM | #18 |
Registered User
Join Date: Sep 2007
Location: Fairdale, Kentucky
Posts: 561
|
Re: Engine Won't Idle--been workin on this for a week
Ok, I have to say that valves to tight is a possibility. I just dumped a motor in my 68 and adjusted them just as you discribed and had two off their seat and it would not idle.
Do a compression check, it will let you know if valves are to tight. I had #3 & #4 set to tight and was completely convinced it was an intake leak. Good luck... |
Bookmarks |
|
|