Truck feeling like it is under load?

[philo_beddoe]

I had a similar issue with my 85.  I have a 350 with the stock quadrajet and the truck idled great, but had serious issues bogging out, shifting, basically ran like crap under load.  After changing the fuel filter and the vacuum lines, with no positive results I decided to buy a new carb. Since the motor is still basically stock I decided to try a rebuilt quadrajet from National Carburetor.  Price was $175 plus shipping.   Took all of 30 minutes to install and holy crap it was like driving a brand new truck.  I had fought that carb for 3 years and I'm just kicking myself because if I would have know that $175 could get you this much return I would have done it day one.  The carb looked brand new and the customer service was excellent.  Trust me, the results were amazing.   So, if you like me and using it for a daily driver now, but potentially looking to upgrade later, this is the way to go.  I decided that when I'm ready to turn the heat up, I will probably buy a different carb and intake, but for now I'm extremely satisfied with the performance and mileage that it provides.

I also got my carb from nat'l carburetor, it was like brand new, paid like $190 and kept my old edelbrock, sold for a lot more. (Instead of sending in for a core). Superior customer service, fast delivery and packaged well.

[rich weyand]

What is your base timing set at, what advance can are you running, and where is your vacuum advance plugged in, manifold or ported vacuum?

[Irish_Alley]

What is your base timing set at, what advance can are you running, and where is your vacuum advance plugged in, manifold or ported vacuum?

timing was my biggest problem then i plugged my vacuum advance to the manifold vacuum and now my truck runs like she never did before.

[philo_beddoe]

What is your base timing set at, what advance can are you running, and where is your vacuum advance plugged in, manifold or ported vacuum?

timing was my biggest problem then i plugged my vacuum advance to the manifold vacuum and now my truck runs like she never did before.

Irish, i just did the same thing, as you can see from another post i have a fast idle, kick down issue.  (another timing question) And not that it may or may not have anything to do with. But i know my engine and it sure runs better since i moved it to manifold.

[Irish_Alley]

when i was driving the carbed truck everyday it was plugged into ported vacuum. since rich came along and now its just a mud truck (wish i would of knew better before) it acts like a different truck now. much much much better

[philo_beddoe]

Yes! I totally agree, and thanks to rich, who I think is a expert on where these hose connections should go (ported vs. manifold) back when I first got my truck I had a long thread going on that issue that rich set the tone on. Anyway, I gotta get back to that other post and update my results.


Romans 8:2

[rich weyand]

Not an expert, just an old fart.  Old enough to remember when GM and Ford, after 30 years of using manifold vacuum, switched to ported vacuum to accommodate the pollution controls, and how hard it was to tune a car to run decently after that.

My dad had a '63 Ford, and would have run it a few more years, but decided to buy a '68 Ford when the imposition of pollution controls was looming on 1/1/1968.  He ordered the '68 Ford in September 1967, and specified that it had to be built by the end of the year so as not to have those changes.  If it was a post-1/1/68 build, he wouldn't accept it.  He came home with it on December 23, 1967.  So you could get a 1968 without the changes, because they cost the mfrs extra money, and they didn't put them on until they had to. That 1968 Ford Country Squire had a Z-code 390 FE 4-barrel that was really sweet.  A friend of his bought a similar car after 1/1/68, and it was a completely different animal.  Sad.

Later, when those pollution-equipped cars were available used, people would change the vacuum advance, advance the base timing, and disconnect the AIR pump, to get them to run decently.  Of course, they were always hooked up properly for emissions testing....

This was the car, but he didn't have a roof rack on his, because he couldn't see punching holes in a perfectly good piece of sheet metal.



Then, in 1975, my dad was in the market for a new car, but by then the pollution stuff was on all the cars and on the C-10 and F-150 trucks.  So my dad bought a 1975 F-250 with a 462 Lincoln engine and a rear-end ratio for pulling his big trailer.  That thing would haul .  When I mentioned how quick it was, he said, "So that's why my fishing gear is always all the way in the back after you drive it."  "Well, I'm just trying to make it more convenient for you to get at it." 

Yeah, he had Fords because the Chevy dealer in town was a prick and the Ford dealer was a great guy, with a great back shop.  When I was growing up, though, he had a Chevy 210 wagon.  Oh, and from 1940 to 1950 he had a 1936 LaSalle Series 50.  Cadillac wouldn't have vacuum advance on the LaSalle until 1939.



My own truck now is a 1978, the last year before pollution controls were extended from 6000 GVW to 8500 GVW, so the K10 had no pollution controls in 1978.  So it's legal as is anywhere in the U.S.

[philo_beddoe]

That car is a gem. Thanks for the update and short story rich, all makes sense to me. Well, my favorite is a 64 impala ss. Thats  going to be my retirement project when i'm an "old  fart".  Happy new year and stay healthy!

[Eastonfrench]

Hey Guys,

After digging my truck out of a barn this last summer (2015), I have FINALLY figured out why the motor wasn't running well!

When I first got her running, the old farmer that owned it, as well as my old man, both kept going on and on about how powerful the truck would be, and how much I would love it. After months of replacing parts and making adjustments, i just COULDNT get the thing to have any kind of power. She ran fine, but when you wanted to accelerate, it was pretty gradual.

I had all but given up on it (still driving it every day, albeit slowly) when my dad said "bud, pull your truck in and let's take another look.

We put the back end on rollers, put it in drive and gave it some gas, and we noticed the secondary air valves weren't opening! I had suspected this before, and already knew how to adjust them. I loosened them up, to the point they were almost falling open. We took it out on the road, and when you put the pedal to the floor, it bogged, and died.

Dad gets out (we are on a gravel road in the snow), and stands next to the fender, looking into the motor.

     "Gun it. I want to see if these dang things are opening".
I held my foot on the brake and put it under load, and he confirmed they were not even budging.

We took her back to the shop.

"You're running that thing on two barrels of a four barrel carb boy," he told me.

Then we saw it. I flipped the secondary air valves open, and pushed on the accelerator. The secondary throttle valves didn't open. Not even a little bit.

Somehow, the metal arm on the accelerator bracket had bent, and was never opening the secondary throttle plates. Not only was I running on two barrels, i was running on the two small barrels!

Now the thing is a BEAST. I advanced the timing a bit, and I am having a ton of fun being heavy footed at every stop light. I hope this helps someone someday.

[Irish_Alley]

Congratulations on finding and fixing your problem. This will give someone else something to look for thanks for the update