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#1 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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3rd gear bogging
1985 350 Holley 600 carb weiand intake that I just had built and a turbo 350 also built about 2 months ago. Truck ran like a top then I left a buddies house late about 11 PM it was chilly about 55-60 degrees here in VA. First was fine, second fine, third I noticed a problem. It started to bog down, hardly any power. Stomp on it it shifts to 2nd then back to third bogging. I figured it was the cold but it's still acting up 2 days later. What gives? Why is it doing this? I can manually shift it and 1-2 are great then 3rd its ridiculous. I don't know much but if you can point me in the right direction I can figure it out. There's a show Saturday that I'm going to so I wanna have it fixed. I'm taking it to the guy who did all my work if I can't figure this out. I sunk over 3 grand in it and now I'm getting a little angry
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#2 |
Registered User
Join Date: Nov 2013
Location: Natchitoches, LA
Posts: 70
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Re: 3rd gear bogging
Vacuum secondaries? Sounds like maybe they are not opening and/or choke issues.
CT |
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#3 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
Would that cause problems only in third? Idle is fine and like k said first and second are ok wether you manually shift or automatically let it in drive. How do I check? Didn't see any loose lines but maybe I'm missing one
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#4 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
Anyone else?
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#5 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: 3rd gear bogging
Could be your fuel pump.
Hold it in second and put the pedal to the metal. If it starts bogging(runs out of fuel), it's the pump. |
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#6 | |
Registered User
Join Date: Nov 2013
Location: Natchitoches, LA
Posts: 70
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Re: 3rd gear bogging
Quote:
If mechanical, it could have a pinhole in the diaphragm bypassing. If electric, well you know, they fail too! CT |
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#7 |
Registered User
Join Date: Aug 2012
Location: Oklahoma City, OK
Posts: 2,541
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Re: 3rd gear bogging
Assume nothing, check everything. Especially the trans fluid level when hot. Loose hoses? If using external to fuel tank pumps, check the suction hoses from the tanks to the metal fuel lines.
Is it humid or misty when the problem happens? Could be carburetor icing. The stock GM air cleaners included a THERMAC system to help with this. "Performance" open cleaners and unheated intake manifolds can have this problem. The fact your problem started with chilly weather supports this. If you reused your existing HEI distributor, check the button in the center of the cap that routes the spark to the rotor. |
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#8 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
It's got a brand new fuel pump AC Delco lol it better not be bad already.
It acted up the first night when it was chilly but then the next day it was hot out and did it again. I reused my HEI distributor, I'll check that. Thanks for the tips I'll try them and see where I get. |
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#9 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
I ran medium octane gasoline as told to do so by my mechanic & switched my fuel filter. He said possibly the problem was my old one was too small. Didn't change much.
My problem is hard to explain. The best way I can describe it is say you have a stick shift, it's in 4th gear at about 25. That luh luh luh luh and the truck jumping is the problem because it's in too high of a gear for that speed is the best way to describe it. Once my 350 turbo hits 3rd it does this. It acts like it has overdrive and is in the wrong gear but there is no other gear! ![]() |
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#10 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
Third gear is still sluggish. Once it hits third its hard for it to accelerate. Any other ideas...?
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#11 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: 3rd gear bogging
What's your initial timing?
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#12 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
Not sure. I paid a guy to do all my work. Built my engine and transmission. Ran like a top like I previously said. Everything is great! Except for 3rd gear and it just happened one night.. The evening before was fine, turned key to leave and it hit third gear and bam surprise.. Sluggy! My mind is blown/ no explanation for it
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#13 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: 3rd gear bogging
Time to get a timing light and learn how to use it!
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#14 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
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#15 |
Registered User
Join Date: Jul 2015
Location: La Quinta, CA.
Posts: 131
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Re: 3rd gear bogging
You could check the fuel pressure, or float height in carb, it might be sucking the bowls dry by the time you get to 3rd.
__________________
Paul |
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#16 |
Senior Member
![]() Join Date: Jun 2015
Location: Atlanta, GA.
Posts: 737
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Re: 3rd gear bogging
Could be an intake gasket leak. Bolts could have loosened up. Or it was cold that night so things could have constricted enough to the point that a piece of the intake gasket broke. Under higher revs, it can over come the leak but under load it becomes apparent. Just thinking.
Also check carb bolts and gasket for the same thing.
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Jay Gesner Atlanta, GA 1985 C10 Long Bed 4X2 LS 5.3, 4L60E Father/Daughter Project |
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#17 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
I did notice something.. On my intake around a bolt in particular every couple days it has oil sitting on the intake and I have to clean it out with a rag to soak it up. They're arp intake bolts. Could that be it?
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#18 |
Senior Member
![]() Join Date: Jun 2015
Location: Atlanta, GA.
Posts: 737
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Re: 3rd gear bogging
More than likely the oil is a leak. you could try pulling it out and using teflon tape or sealer of some sort.
But, if that bolt backed out, some other may have also resulting in a vaccuum leak.
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Jay Gesner Atlanta, GA 1985 C10 Long Bed 4X2 LS 5.3, 4L60E Father/Daughter Project |
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#19 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
I'll find out this week. Going back to my mechanic
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#20 |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
So I still haven't gotten this fixed yet. Just to make sure we're on the same page, turbo 350 lockup with 2500 stall converter, less than 1000 miles on complete rebuild. 1st gear great 2nd gear great 3rd gear great when it wants to be! Sometimes it'll shift into third and I have great power other times it'll bog down and be very sluggish and can barely make it up hills or even accelerate. As previously said, it was fine for a week or two after my engine build then bam! Started bogging itself. People have told me fuel, timing, carb issues, fuel filter, everything!
My question is how is it fuel/ fuel filter when it runs AMAZING until 3rd? How is it timing when it runs great until third? How is it the carb when it runs great until third? I bypassed the fuel filter with a piece of brass, didn't change a thing. It shifts into third with a nice shift then a second after its in third, it slips into this unknown slug mode. It is driving me crazy. My schedule won't work with my mechanic with night school going on and other things. It blows my mind because its only sometimes too. The other day I drive thru town and on the highway and it ran great. Today, its done it all day. Is there a band you can adjust? WHAT GIVES? Does all my linkage look correct? I'm new to this stuff, I paid a well repped guy to build this. Maybe something came out of adjustment. ![]()
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85' GMC Sierra Classic Built 350; Weiand intake, Holley 600, Thumpr Cam Built 350 turbo with shift kit & 2500 Stall Thumpin' away Last edited by Zach079xxx; 10-09-2015 at 04:51 PM. |
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#21 |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: 3rd gear bogging
Linkage looks fine.
I keep thinking timing. When it gets cold, and metal shrinks, the distributor clamp can loosen enough to let the distributor get pulled retarded. Then performance depends on vacuum, but I wouldn't expect it to change back and forth. Still, GET A DAMN TIMING LIGHT and check the timing. 12-14* BTDC, at least. Weak spark, maybe. Did you put a new coil in it when you did all this work? New cap and rotor? New wires? I can recommend the Accel 8122 cap and rotor, Accel140013 coil, and Taylor 74206 solid wires. (No need for resistor wires when you use resistor plugs!) Pricey, but you only get what you pay for, and sometimes less.
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Rich Weyand 1978 K10 RCSB DD. |
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#22 | |
Registered User
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
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Re: 3rd gear bogging
What's the process of checking timing? I got a buddy in town tomorrow that's going to help me. It's got a coil less than a year old along with plugs and wires cap ect. Less than 1000 miles on them.
Quote:
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85' GMC Sierra Classic Built 350; Weiand intake, Holley 600, Thumpr Cam Built 350 turbo with shift kit & 2500 Stall Thumpin' away |
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#23 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: 3rd gear bogging
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#24 |
Registered User
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,227
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Re: 3rd gear bogging
Going out on a limb - try a run with the gas cap off. Perhaps (long shot), that the tank isn't venting enough to keep up with the fuel needed, creating a partial vacuum. A cheap test anyway, on your way to buy a timing light (grin).
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1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS 1977 Silverado: Shortboxed & dropped, potato-potato V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag Lotus Super 7 Replica: Scratch-built street-legal rollerskate |
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#25 | |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: 3rd gear bogging
Quote:
Except it's a 1985, so it should have sealed gas caps and tank vent lines to a vapor canister. Now if the vapor canister was removed and the vent lines capped, maybe even back at the senders, then it will need vented gas caps. When would this be the biggest problem. Why, when it gets cold, and the gas shrinks and creates a vacuum in the tank.... When it gives you trouble, stop and open the gas cap. If you get a whistle of in-drawn air when you remove the cap, that's probably the problem. Put the cap back on and get back in and see if it now runs fine. If so, just run a 1/16" drill through the center of the gas caps.
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Rich Weyand 1978 K10 RCSB DD. |
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