Can "carburetor" and "throttle response" be in the same sentence?

[Boone83K10]

So it bogs a lot while driving? and it bogs when you go to start from a stop.

IMO, the bogging while driving is either related to your secondary throttle tip in or maybe the secondary jets.

The bogging from a stop could be a number of things like transfer slot exposed to much, power valve to big, bad fuel mixture, accelerator pump maladjusted, bad pump cam, improper float level.... list goes on.

 

[Kapdin]

Ok, Lets forget about the EGr for now, the reason I mention the heat riser, and the Intake manifold exhaust crossover is because of the low temps you are operating in.
195* thermostat is really important.
The heat riser tube for the air cleaner, helps keep the incomming air at a more ideal tem, and the exhaust heat crossover runs under, and heats the area directly under the carb, to help with fuel atomization. Too cold, and the fuel comes out of suspension, and puddles,,which can cause a rich bog, amongst other wierd ****.
In my opinion, for your situation,,I would try to find a couple of TBI Air Cleaners.
Their diverter doors dont rely on a valved vacuum source to operate....which is helpful, if you dont have those vacuum lines anymore.
And just a side note, Stock GM manifold designs have a fuel distribution issue, especially to 1,3,7, and 8. Notice how the stock manifold T's out at those farthest cylinders. Aftermarket pieces have a nice smooth Y, which take care of this issue.

Huh, good to know bud. well i can rob the stuff off the 91 tbi. .....hummmmm IDEA! think this out for me jim..... just swap the tbi stuff over???? to the 400 i mean.

 

[Kapdin]

So it bogs a lot while driving? and it bogs when you go to start from a stop.

IMO, the bogging while driving is either related to your secondary throttle tip in or maybe the secondary jets.

The bogging from a stop could be a number of things like transfer slot exposed to much, power valve to big, bad fuel mixture, accelerator pump maladjusted, bad pump cam, improper float level.... list goes on.

it doesn't bog while driving, just when the sec i need some hp from crusin (not all the hp just more) it bogs and then picks up. and the 79 bogs when u punch it from a stop.... and bucket might be right with the weak pump shot cus when doing a roll-on stomp it works perfect.

 

[Jims86]

Huh, good to know bud. well i can rob the stuff off the 91 tbi. .....hummmmm IDEA! think this out for me jim..... just swap the tbi stuff over???? to the 400 i mean.

Like the air cleaner...yes. The injection, yes also, but you will need an adaptor for the TBI obviousely, because I think the 400 has a steam crossover at the back of the manifold, tbi manifold doesnt. 350 injectors may be fine, because the 400 might be a little closer to what the TBI 350 output. Might even think about some 454 injectors.
But its doable.
Tuning the chip should be easy if needed, I know of a few tbi 400s running pretty good right now.

 

[Christian Nelson]

Is the transmission kick down adjusted properly? I am assuimng automatic, not manual tranny.

That would get rather boggy, if it's not down shifting as it should.

 

[Kapdin]

Is the transmission kick down adjusted properly? I am assuimng automatic, not manual tranny.

That would get rather boggy, if it's not down shifting as it should.

This might be a small part on the 79 but the th350 is pretty tired but the 77 with the th400 shifts smooth as butter.

 

[Kapdin]

Like the air cleaner...yes. The injection, yes also, but you will need an adaptor for the TBI obviousely, because I think the 400 has a steam crossover at the back of the manifold, tbi manifold doesnt. 350 injectors may be fine, because the 400 might be a little closer to what the TBI 350 output. Might even think about some 454 injectors.
But its doable.
Tuning the chip should be easy if needed, I know of a few tbi 400s running pretty good right now.

this really intrigues me jim. So, new manifold $200ish, new 454 injectors $??? and a "Jim's wiring harness job!"

 

[Jims86]

this really intrigues me jim. So, new manifold $200ish, new 454 injectors $??? and a "Jim's wiring harness job!"

Nothing needs to be new, it can all be done with wrecking yard items. I say use the 400 manifold, because I think it has a coolant crossover on the back of the manifold, where none of the sbc TBI manifolds do.

 

[Kapdin]

wrecking yard...... remind you were i live at the moment lol, but true a adapter sounds like cake walk. found one on jeggs for $45. And for the time being just swap the 350 onto the 400 and let it buck? If this works it will be perfect cus when the time comes its going into the 79.

 

[Kapdin]

Im trying to find an carb to tbi adapter for my 400 sb with 2" bores. Do they make one?

 

[Kapdin]

also jim i put the stove pipe air cleaner with heat riser tube and vac line to it back on and then messed with the air mixture screws and idle. I went from 1 turn out to 5 1/2 and back again. i settled on 3 1/2 but nothing helped the off idle bog. i also took an air hose to every port on the carb. Ive got it a hair better but deff still not right. I hooked my vac gauge up (cheap one) but its stable. The 77 doesn't miss nor stutter or fluctuate rpm's. The choke works great and the 4bbls open on que.....

 

[Jims86]

On the idle screws, you want to come out evenly on each screw until the idle speed just slightly dips, then run them back to the higher rpm and to the smoothest point. As far as setting the trottle blades themselves, i use a vac gauge or put my thumb over the port for the vac advance hose, and set them so you see or feel vac, but then close them right to the point to where the vac dissapears. you never want to have them open any farther than that. I think most of your problem might be coming from, like Bucket(i think) said, and its an accel shot issue, and Its been a while, but I think you can bend the q jet accel pump teeter arm to adjust, as well as moving the pivot point with a choice of 2 or 3 more holes....someone with more recent q jet experience jump in here. Does that air cleaner still have the thermal vac switches? You dont want straight vacuum to the damper.

 

[Kapdin]

ight, ill give it another shot but were they sit now seems to be smoothest. as i brought them out to 5ish turns the idle no longer relied on the idle set screw. Like it started to idle up based on the air mixture screws.

One other thing to, its been 5 degrees and colder here lately and knowing my 79 has nothing but a air cleaner on the carb and every thing ripped off. I have set the choke in every position possible. I have come to the conclusion that its so cold that it wants to have the choke on (just the slightest). When i set it to come off after several miles it falls on its face every time u take off. but if i set it so it never really comes off she's a champ at taking off. any thoughts?

 

[Jims86]

Well, Thats what I was getting at with the heat riser and exhaust crossover. The choke system has a vac line coming off the metal casting part of the choke body, to a nipple on the rear top base of the carb, that samples intake air.
Some of these go through a vac line coil in the exhaust crossover to help warm the choke up faster, if this is not hooked up, it may be the reason the choke is not pulling off.

So, if the choke is closing a little, and this is causing the engine to behave, I would say that you should increas the throw on the accel pump teeter, by going to the next hole(moving the teeter towards the pump rod, to the inside of the carb) that will increas the amount of shot.

BTW! have you confirmed that everything with the vac advance and advance weights are working properly in the distributor? If not, it could throw off what we are trying to do.
Check/set base timing with the engine warmed up, and in drive. Dont want to set it in park, because the higher rpms will throw the weights out in the dist., making your actual base timing lower than what it is intended to be.

 

[Kapdin]

BTW! have you confirmed that everything with the vac advance and advance weights are working properly in the distributor? If not, it could throw off what we are trying to do.
Check/set base timing with the engine warmed up, and in drive. Dont want to set it in park, because the higher rpms will throw the weights out in the dist., making your actual base timing lower than what it is intended to be.

yes i set both trucks timing fully warm in the shop with vac advanced plugged and brother in truck in drive. And the dizzy is brand new in the 79 (ur question on weights).

this is the 79 setup. also before the egr got a block off plate and thats the old dizzy.

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i will try that teeter idea and how about the kick-down linkage on the 79? how tight should that be? i mean i don't want it to kick down every single time i tap the gas. But the 79 compared to the 77 is slower to down shift.