There are three causes to bog at midrange.
1. Fuel pump is delivering enough fuel.
2. The secondary plate may be clog with some debris.
3. The spring for secondary is too light. You may have to replace the spring the next step higher level.
I'll bet it will be the spring.
There is a 4th
Check the fuel line filter.

 

New pump, new filter, and don't see any debris in the carb.....new build I only have like 600 miles on the engine. I'm waiting on the spring kit and quick change cover to arrive from summit, but didn't know if I could try other stuff before it gets here.

 

New pump, new filter, and don't see any debris in the carb.....new build I only have like 600 miles on the engine. I'm waiting on the spring kit and quick change cover to arrive from summit, but didn't know if I could try other stuff before it gets here.

You mentioned disconnecting the secondaries- if you want to try that, there's a C-clip that attaches the diaphragm rod to the secondary throttle shaft. Remove the C-clip and then the rod, wire the throttle shaft so vacuum won't pull it open and keep the rod out of the way and give that a try.

C-clip is seen in the foreground, right of center.

 

thanks Cobalt...I'll try that.....also correct me if I'm wrong....I should see smooth acceleration all the way through the power band with just the primaries right?......

 

I used to step up one size on the squirter on the ones I ran.

 

thanks Cobalt...I'll try that.....also correct me if I'm wrong....I should see smooth acceleration all the way through the power band with just the primaries right?......

That is correct. Nice, linear acceleration that will flatten out at the top end somewhat- you're running on half the carb's CFM, give or take- so this is to be expected.

Good luck.

 

I'm going to lay my money on lq1969's #1 ... fuel delivery problem.

I know that a 700R4 has a very low 1st gear, and the light load might be factor.

Here's my theory, though.
When he stabs the throttle from a dead stop, the fuel bowls are likely both full. If the delivery volume isn't up to task, they're likely just "marginal" or close to empty when it shifts to second.

"Backing off" allows them to fill again. I'd like to hear what happens when he (leave the gear selector in "2", backs off for a second or two) and then hammer it again.

More questions:
===========
Electric or mechanical fuel pump?
Do you have a fuel pressure regulator and guage?
Does this holley carb have side-hung floats and a transfer tube, or soes it have center-hung floats and dual fuel inlets?

When you say "bog", is it just slow at picking up RPM (Making the "moooo" sound) ... or is it falling on it's nose?

Backfires / mis-fires?
================

A 350+ cu inch and a 600 CFM carb should be able to handle a fairly light secondary spring. I was running a 3310 (750 cfm) on my 351C ... and the purple spring seemed to be the "sweet spot" for that application.

(68 Torino, 351C, Rough idle -- can't recall the specs --Speed-Pro cam, Torker intake, C6, 2500 stall, 3.50 gears)

 

Not to get ahead of things, but concerning the ignition advance- does your HEI have mechanical and vacuum advance? 1986 was the last year I'm aware of that might have had a "normal" HEI.

The total advance set to 36º is fine, and the initial at 12º is probably OK as well. But you might find that bringing in the timing quicker will help.

You'd like it to be all in, as early as the engine/gearing/fuel, etc. will allow- 2500 RPM is a place to shoot for. This can be adjusted by using softer mechanical advance springs.

Is the vacuum advance (if applicable) hooked up to manifold or ported vacuum?

FWIW, the silver spring is a fairly heavy one- sometimes a purple or yellow is used in similar applications.

 

Ok going to try to answer everything.........

New stock mech fuel pump......and brand new filter

This Holley is the 80457s model, here is the link with the specs http://www.holley.com/data/Products/Technical/199R7948-5.pdf

It has a single fuel inlet on the front driver side

I believe it has center hung floats........not from the link I provided there is no external adjustment for the floats and it apparently has some new needle/seat design...

No fuel pressure regulator or gauge

I have ran the initial advance all the way up to 16' but it responds better at 12'....I will note that I'm running an edel-2102 cam which only has 204 int./214 exh. at 050 inch lift.

I did put a curve kit into my aftermarket non computer controlled distributor and had the greatest performance/response with running two of the lightest springs........so my timing should be coming in as quick as possible

I am running ported vacuum.......i have however ran it on full manifold vacuum and couldn't get it to idle as low as i wanted to

When I say "bog".....I'm not getting any kind of backfire or miss or funny sounds its just like it falls on its face and does nothing....like it quits accelerating until i let up a little.....

And another note I swear I hear the secondaries coming in even at part throttle.....thats why I thought I might need a stiffer spring......this truck is heavy being 4WD......

 

And another note I swear I hear the secondaries coming in even at part throttle.....thats why I thought I might need a stiffer spring......this truck is heavy being 4WD......

The secondary coming in way early just may be happening- even w/a silver spring- if the check ball that is under the lid of the vacuum can is missing or not seating properly.

When your parts gets in, be sure to look for the check ball- and don't lose it! lol

What can be done- but requires an old or disposable check ball- is the ball is inserted into position, then by using a small punch, the ball is tapped down into its seat. This will correct any deformaties that may be causing it to not seat correctly.

This doesn't take a lot of force!

 

UPDATE

Just got home an removed the clip and arm from the secondaries like cobalt suggested and its a whole different truck........from a dead stop punched lit up the wheels for a couple seconds and flew smoothly threw gears without a hiccup. Power was gradual but quick really sufficient for in town driving. The only thing that bothered me is when i got into some traffic and I was light on the throttle in 2nd and when i let off it shifted early into 3rd.....a couple secs later when I gave it some gas to go again it accelerated crappy until i got higher in rpms.....*kind of the similar effect when you start a manual transmission in second* if you know what I mean......so i'm not sure if I should readjust the tv cable or if that will help......

I dont know what you guys think but the spring thing seems pretty evident to me....if anyone has other ideas about this or that premature shift let me know. Also, it should be noted I had the 700r4 rebuilt when I was putting the engine together.......It does have a pretty deadly 2nd to 1st downshift if I have it in D instead of OD, but it has a corvette servo and a shift kit......I should probably put that in a separate post....

 

One more thing....I got to thinking about the low power when it prematurely shifted and it kinda made me feel like it had too much timing when it was doing that so I just disconnected the vacuum advance and went for another spin and it still shifted early on really light throttle but I didn't have that lack of power. So would that suggest maybe I'm to light on the springs for the curve kit? I apologize for so many different questions, but I just want to get all the bugs out...

 

One more thing....I got to thinking about the low power when it prematurely shifted and it kinda made me feel like it had too much timing when it was doing that so I just disconnected the vacuum advance and went for another spin and it still shifted early on really light throttle but I didn't have that lack of power. So would that suggest maybe I'm to light on the springs for the curve kit? I apologize for so many different questions, but I just want to get all the bugs out...

It may have an excess of timing at lower RPM. The great thing is, a spring swap is easy to do- try it for sure!

Don't forget to see if that check ball is there and seating right. If it is, a stiffer spring is called for, but the next stiffer from silver is brown- and it is STIFF!

There's a chance that your carb was assembled w/a different spring than a silver. Even if it IS silver, be sure to compare it to the silver one in the kit you ordered in case the spring in the carb now isn't what it appears to be.

 

Ok here is what I have now.....I still have the secondaries disconnected as I want to get the primaries right.....anyway I was thinking the same as you on the springs......so i threw in one stiff and one medium spring for the advance curve and rechecked the timing and that seemed to make a considerable difference....but it still wasn't as responsive as i wanted......so I backed off the nut on the accelerator pump a 1/4 turn at a time and it all came together at a full turn out.....i'm really amazed at how much those two things changed....i'm going to wait for the spring kit to get here to tackle the secondaries...

 

it still wasn't as responsive as i wanted......so I backed off the nut on the accelerator pump a 1/4 turn at a time and it all came together at a full turn out.....i'm really amazed at how much those two things changed....i'm going to wait for the spring kit to get here to tackle the secondaries...

I'm curious to know if you now have any play between the adjustment nut and the pump arm, when the carb is at the "idle" position.

You really don't want any play at idle, and at WOT you want about 0.015" just so the pump diaphragm isn't damaged.

If there IS plat at idle, this could be pointing to a too large shooter, if you're using the white cam.

 

Actually i don't have any play at idle and it was suppose to be preadjusted out of the box....but I've come to find out that's not the case at all. I did check the clearance at WOT and I was still able to drag a .015 feeler gauge threw it. I didn't look to see what color cam I have on it. I'll have to do that tomorrow. The other thing I was wondering about isn't there something called a squirter between the primaries that helps the transition between the idle and main circuit or is that what you mean when you say a bigger shooter?

 

The other thing I was wondering about isn't there something called a squirter between the primaries that helps the transition between the idle and main circuit or is that what you mean when you say a bigger shooter?

No play at idle is good.

Shooter is a squirter, or vice versa. :thumbup:

 

OK, here's a picture of your carb.

I see what you mean about the non-adjustable needle & seat, and that sucks.
The Carb Numerical List list a part #6-506 needle and seat which might be retro-fitted into your carb?

The numerical list also agrees with the first sheet that you posted stating that the carb comes out of the box with a BLACK secondary spring, which I believe is the heaviest one available, isn't it?

The bowls appear to be of the side-hung float variety, but the feature that I was interested in is the single fuel inlet with a fuel transfer tube that carries fuel to the secondary bowl.

Going back to my fuel delivery scenario, it makes sense to me that there might not be sufficient fuel volume to fill the front bowl first, and then transfer to the rear bowl.

Now that you have the secondaries disconnected, the rear bowl will fill -- and not get emptied --- so all of the available gasoline is "dedicated" to maintaining the fuel level in the primary bowl. Because the secondaries are now disconnected, they are not adding more air to lean the mixture way out ... and the engine is "happy" with the stoic ratio.

I think it's time to do a pressure and volume check on the fuel pump. If that passes inspection, I'd be taking off that rear bowl and inspecting the float and needle/seat operation.

Just my hunch.

 

yup thats the one......how much fuel pressure should I have with a stock mech pump if its working correctly...

my paperwork shows that it came with a plain spring but depending on what paperwork i look at online some say it comes with black and some say plain.....however if it is black that is the heaviest spring.....

my next question is if i'm getting adequate fuel pressure and i do infact have the black spring already.....what exactly would i be looking for in the rear bowl?

 

This Holley is the 80457s model, here is the link with the specs http://www.holley.com/data/Products/Technical/199R7948-5.pdf

Looked this carb up, seems it came w/a 0.031" squirter, and a black spring. The black is the heaviest (hardest opening) spring Holley uses!

I'm more curious than ever to see what is actually in it.

If it's a 80457 it came w/69 jets. If it's a 80457-1 or -2, it came w/64 jets.

 

You start with the basics first.

You got idle mixture and timing thats good, your jetting should be set close with the 65's. You might want to experiment up two sizes before the next step. You need to color the plugs properly before tuning the pump, err on the side of slightly rich for now. Shoot for dark brown or grey on the plugs, you can always go down later.

Next you need accelerator pump shot, get yourself a cam kit and try them...I have five or six sets of these cam kits all missing the brown cam so if thats a hint I don't know what is...there are only two positions for the screw try them both as only one will work for your carb.

http://www.holley.com/20-12.asp

After you have done all that you may need to fine tune the previous items particularly the mains since you may have been hiding the problem with mains fuel but 65's are pretty close for a mileage application or near stock motor on 350ci engines. Usually with a bigger cam/larger cubes with that carb you need 67's, factory size for the jets on a 600cfm VS for a 440 Dodge in 1969 was 66 so you know your close.

After you get the pump shot right you can play with secondary springs but those should be right on for your motor, lighter would be OK for a larger cube motor or more cam.

Don't be throwing shooters and doing other crazy stuff oto the carb until you get the basics dialed, those are the last things you change not the first.

Buy the cam kit and let us know how it works.

 

yup thats the one......how much fuel pressure should I have with a stock mech pump if its working correctly...

my paperwork shows that it came with a plain spring but depending on what paperwork i look at online some say it comes with black and some say plain.....however if it is black that is the heaviest spring.....

my next question is if i'm getting adequate fuel pressure and i do infact have the black spring already.....what exactly would i be looking for in the rear bowl?

Pressure should be in the 5 or 6 PSI range, and volume-wise, it should fill a pop bottle in 3 or 4 stokes.

There's something going on there that sure sounds like very little or no fuel in the rear bowl.

Hmmmm ... Do the bowls on this carb at least have sight-hole plugs?
If yes, reconnect the secondaries and drive it HARD. When it bogs out, shut off the engine, and coast to a stop in neutral. Pop the hood, and pull both sight hole plugs. If both bowls are low, it's almost certainly a fuel delivery problem.

If the primary bowl is full, and the secondary bowl is not ... get the truck back to where your tools are.

It sounds like the float design is basically the same as other side-hung floats ... so remove the rear bowl off and inspect the needle and seat. If you slowly and gently lift the float with your finger it should be moving the needle smoothly upward into the seat.

Now invert the bowl so that the needle and seat are at the bottom. The needle should be completely seated now, and the float should hang paralell to the bottom of the float bowl. Lacking any form of external adjustment, about the only thing you can do is to bend the tang on the float. I'd sure be looking at installing the externally adjustable needle and seats if I were you.

"'Next-Gen' float design eliminates the need for external adjustment."

Give Holley a holler, and ask them "What were you thinking?" :nono:

Actually ... Holley has float adjustment procedures available on their website, including your "internally adjustable" model.

Another, more accurate adjustment can be made with the
side hung style float if measuring gauges, such as drill bits,
are available. Here, with the fuel bowl inverted, the primary
float can be adjusted to the point where there is a 7/64" gap
between the “toe” of the float and the bottom of the fuel bowl
surface underneath. The float “toe” is the part of the float furthest
from where the arm is attached. The secondary float
can be adjusted to the point where there is a 13/64" gap
between the “heel” of the float and the bottom of the fuel
bowl surface underneath. The float “heel” is the part of the
float closest to the point where the arm is attached.

P.S.
This IS the most basic of the basics. There is no point trying to adjust ANYTHING until you are SURE that there is fuel available.

 

The only reason I haven't tried adjusting the float is because there is no external adjustment and I wanted to make sure everything else was in check before having to pull apart the carb. There are no sight plugs as far as i can tell. They would be on the sides of the front and rear bowl right?


Btw this is a brand new carburetor....when I called holley they said the floats are adjusted where they need to be regardless of application. Do I need to buy some gaskets before i pull the bowls off to measure the float level or can they be reused?


Just filled a 20oz pop bottle in like 3.5 sec....which seemed adequate to me....idk you guys chime in let me know...

 

Can someone look at the picture above of my carb. Are those sight plugs on top of bowls? Also if so how do you remove them.

 

The only reason I haven't tried adjusting the float is because there is no external adjustment and I wanted to make sure everything else was in check before having to pull apart the carb. There are no sight plugs as far as i can tell. They would be on the sides of the front and rear bowl right?


Btw this is a brand new carburetor....when I called holley they said the floats are adjusted where they need to be regardless of application. Do I need to buy some gaskets before i pull the bowls off to measure the float level or can they be reused?


Just filled a 20oz pop bottle in like 3.5 sec....which seemed adequate to me....idk you guys chime in let me know...

Yeah, I'm not surprised you can't find them, as they'd be redundant on a carb that you can't do external adjustments to.
If they were there they would be on the passenger side of each bowl.

3-1/2 seconds sounds like a lot to me, even at cranking speeds. What did the flow LOOK like? Strong, steady flow or more of a "dribble"? Like I said, it should fill that bottle in about 3 strokes.