I should just find a friggin dyno tune place because I CAN'T GET THIS

 

Acceleration enrichment problems can be a real pain in the *** to solve.

I personally think that checking the ignition system over to make sure you have good, strong spark and the correct advance would be the first things to do. Next would be to make sure you dont have any type of fuel starvation problems.

After that, start tinkering and see if you can get rid of it. Doing it yourself would be best. Plus, youd have to learn, anyway, since this sort of stuff is affected by the engine combo, and you may have to repeat this all over again if you change your intake or something.

 

You're right. I'm going to make a long day of this tomorrow if it doesn't rain.

 

Alright, I marked my balancer. I measured the circumference of it (6.75 x pi = 21.2) and divided that by 36 (for ten degrees per mark). It's approximately 5/8" per ten degrees. Each line on the timing tab indicates two degrees, correct? That looks about right then. Here are the readings I took, with the engine warmed up:

- Base timing: 14-16 degrees at 700-800rpm
- Idle with vac: 38-42 degrees at 1000-1100 rpm
- 3000 rpm: 34-38 degrees
- part throttle, 2500 rpm with vac: 46-50 degrees (???)
- Idle with vac to WOT: dropped down normally to about 16-18 degrees

- Secondaries are opening
- Pump shot set to the top hole (of three)
- Fuel pressure is sufficient (6psi)
- Spark plugs are brand new (200 miles)
- Choke opens fine (electric)
- No vacuum leaks, 95% positive
- Manifold vacuum for the advance
- 93 octane in the tank
- Loosest (gold) springs for sharpest advance curve

I am noticing backfiring when I rev it to around 3-4000 and let off really fast. Is this indicating a lean state? There are no exhaust leaks. Potentially an ignition problem? I have a minor burn on one of my spark plug wires. Would this have anything to do with my problem when I mash the pedal?

How much timing is too much? How much is too little? I'm picking this up as I go. How much fuel is enough? Even when feathering, as soon as I hit WOT it doesn't feel like it's doing its job. My modded 305 could take off better when I downshifted it manually.



On a side note, I am concerned about something else however. I am hearing what sounds like knocking. The sound is steady with rpm, but does not get any louder. The exhaust and even air rushing through the carb drowns it out. I can typically hear it better at lower rpm. If I put my hand on the manifold or valve covers I can sort of feel something. My 305 died of a similar sound, however it got louder as RPM increased. I have not pulled the valve covers off to see if it's a valve lash problem, nor have I pulled the inspection plate to see if it's a torque converter bolt gone missing. This is a whole other concern of mine right now and I'll keep you posted on this... but is there any way it could be caused by too much advance? Like I said, I'm upwards of 50* advanced at times.

 

It sounds like there's a lot of travel to your vac can, like maybe 18deg or so. That might be excessive.
1) What is the advance at idle with and without the vac hose connected?
2) Do you have one of those vac advance limiter devices under your cap (the semicircular gizmo)?

 

1) I noticed, it seems about 18-20 degrees from the vacuum alone.
2) Advance at idle is 14-16 without vac, and 38-42 with.
3) I did not see the semicircular gizmo.

I have recorded a video of my acceleration. You can see I bog, almost stall (drops to ~200rpm) then it takes off. I spin the tire (2.73 open) through 30 mph and then it shifts early (tv cable is set properly) at 4000rpm. I just left it in 2nd gear when I did this. I could have taken 1st farther if I manually shifted, but you get the idea of what happens. To me, the acceleration isn't what it should be, until 2500-3000 rpm, obviously including the bog.


short video (2.2mb)
You may have to right click and save as.

 

If you set up the centrifugal advance the way dimented24x7 said a few posts back, that will be a good baseline curve that should work until you can fine tune it later, if nessecary.
The vac has more travel than nessecary and you should plan on getting a limiter for that some time. But that wouldn't be the source of your trouble with the hesitation anyhow, so you can deal with that later.
If you can get bigger acc pump squirters, then that might help.
But I'm beginning to think that your converter might be too low of a stall speed for your combo. It sounds like your engine just isn't into it's powerband when you punch it.
You could give it more low end by advancing the cam, if you felt like it.
If you have an open spacer under the carb, remove that and some low end would be gained.
Other than that, I'll have to say I can't make any more suggestions. I'm not that familiar with the specifics of your combo, but there are others who are more familiar, I'm sure.
It kind of sounds to me like there's some low rpm stumble just from the size of your cam, and matching the converter would help just by putting it right up there on the power band where it likes to be.

What happens when you punch it at 3000rpm?

 

My converter is 2000-2400 though, that seems plenty high. The duration of my cam is 220/230 (with .544 lift).

 

With that cam spec a higher stall (maybe like 2500+) and 3.73's or 4.10's (if you already dont have them) is what Id run with. JMO. That engine looks like it is indeed way out of its powerband, especially on the 1-2 shift with a 700-R4. A higher stall may also help eleviate some of the bog as it wont be starting off so low.

I too ask what happens when you stab it at a higher rpm.

 

The problem still exists at any RPM that I mash the pedal with. Does this for sure indicate it's a fuel problem? Can I rule out the possibility of being rich? I mean, the carb is set up to be lean on its own. My guess is still not enough fuel from the pump shot. I just ordered my calibration kit as well as compression tester from Summit today.

I'd imagine my gearing (2.73) would have some negative effects on this too, but it shouldnt be happening at "any rpm" like it seems to.

 

The highway gears definatly have to go with that cam.

 

Yeah, eventually. But it does it like this even in neutral.

 

Whatever your problem is, there's a reason for it, and you have to go through a process of elimination to locate it.
That means one by one getting each the systems of your engine 'in the ballpark' so you'll know that system is not the trouble source.
I think a check for true TDC is a good starting point.

https://www.thirdgen.org/techbb2/sho...92#post1832892

Use one of those TDC locators along with a degree wheel to check your timing marks.
After that, double checking your cam timing with a dial indicator might be a good idea.

Your carb might be the culprit too, some bigger squirters for the acc pumps might fix it.

If you check all the things that have been mentioned in this thread, one of those things will fix it. It's just a question of which one.
I think that all of the possibilities for what it could be have already been mentioned in this thread.
It's not an infinite list, it only seems that way. You just have to make a checklist of probably less than 20 things that need to be checked.

Look at the bright side, at least you aren't taking your car to a shop and shelling out $65/hr to have them make a worse mess of it.

 

This TDC tool... how exactly does it work? I'll call summit and see if they can add one to my order... since it costs less than their damn handling fee (which they need to STOP RAISING).

I ordered the following items

 

Wow thats alot of reading, sorry but I'm not feeling like reading it all.

Chasing the timing down doesent sound like its going to solve your problem, it's a good idea to know where your at but it's not causing this. Are you sure you have the correct ballancer? You mention 6in one but the timing tab might be for an 8in.


It does sound like the carb isnt playing nice. Sure it's easy to tune one as long as you have the experiance to do it. If I rember correctly you have a 1406. You mention the sec's arent opening a few posts up, I'd start there. A couple edelcraps Ive had in the distant past had linkage issues preventing the choke linkage from fully operating hence locking the secondaires closed even when the flap on the air horn was fully open. Back off the fast idle screw and check the linkage to make sure everything is ok.

 

The gears obviously wont solve that problem, but they will help out alot. In the video, the time it took from the engine to finally go to the car reaching 60 mph was around 8 secs. With the tc and stock trans, by the time the engine starts pulling, it shifts and the engine is dumped back out of its powerband. With the rear gears, your not using your trans' gears to their fullest potential.

 

I can launch a lot harder if I let the engine spool up a little higher while using the brake, but I get far less traction. One wheel peel, yay.

Yeah my 700r4 shifts early. I would manually shift it if I had an extra hand (holding camera) and it tends to be a lot quicker on shift from 5000 rather than 3700-4000 (obviously). My TV cable is as tight as I can get it- is there anything else I can do? Will better rear gears hold first until a higher rpm this way?

 

Hopefully it comes with instructions
A degree wheel is a good thing to have in addition to that, they're pretty cheap too

 

Read this too
http://www.tvmadeez.com/pressure_test/index.html

 

hmmmm... i'll check it out.





This thread ended up like this:

 

I Love It!

If I'd had one of those I would have used it

BTW don't just check out the Bowtie Overdrives site... Take Heed.
700R4s have a reputation for being faulty because of TV cable misadjustment.
A friend went through 4 or 5 expensive rebuilds when he put a 700R4 into his '70.
He said it worked fantastic but it would only last a few hundred mi.
I showed him that bowtie overdrive site and there were no more troubles.

 

When I did heads and cam in my car the 600 Edelbrock I had wound up with a horrible stumble if I just floored it. They seem to need a bigger pump shot. Maybe you can get bigger jets for the acc. pump. My problem was just while driving though and it got better when I lightenned the wieghts on the air valve in the secondaries. Maybe this helps, maybe it does'nt.

 

Hmmm... So there are others out there with this problem. How did you lighten those weights? Pull em out and grind em down? I'll consider this if there's nothing else that solves my problem.

My carb kit should be here tomorrow

 

I got my carb kit today, and I put in the pink springs. The hesitation seems to have significantly gone away but it's still there. The difference between the pink and the silver (silver stiffest, pink second stiffest) was nothing so I went with the pink.

should I try going a stage or two richer than stock in power mode?

 

I've never tried an edelbrock carb, but I've had some carters and there were never any problems with hesitation. In fact I thought they were good carbs. The basic design of the two is the same, and it makes me wonder what edelbrock did to screw up an otherwise good carb?? Maybe they jetted it for smog, or something ridiculous like that.
Just wondering if some higher vol pump nozzles came with your kit?
If not, drilling out the ones you have may help.
Maybe someone else who has more experience with that will chime in.

 

it only came with rods, jets, and springs.

 

okay, that did not work at all. It didn't get any better changing the springs (it also didn't make it any worse). I still have tremendous hesitation, and the car will still try and die if I'm not moving and I floor it.

It's not anything physically wrong with the ignition, I confirmed. The distributor is brand new, with the coil, with the spark plugs, and also the wires. It can't be a problem "getting" the spark, and we've already been over the timing of the spark.

Well here's an overview of everything I've checked or tried:
Base timing: approx 14 degrees @ idle
Total timing: approx 32 degrees @ 3000 rpm
Pump shot: top hole
Springs: pink (7" Hg)
Jets and Rods: stock





What next? Put different rods/jets in there? Should I run a compression check just to make sure or would that be a waste of time? As I said before, it's not a problem with gearing because it does this even in neutral. I don't want to rule it as a bad choice of intake manifolds, because the RPM air gap is supposed to be one of the best street manifolds on the planet (especially for higher duration cams). It's not a problem with "throttle response" either, because it will still go fairly well if I give it part throttle.

I can really roast the tires though, if I were to start the acceleration doing a brakestand. It's just if I don't feather the damn thing it will bog or die. I've got about a dozen one-wheel-peel marks all through my area from tuning and testing. I love the feel of this torque converter, that's for damn sure.

I've got a pair of new videos though, maybe they can help identify my problem. You can definitely see the bogging in the second video. The first one I am feathering it, as to get a proper comparison. I was holding the camera and wheel with my left hand and manually shifting the 700r4 with my right. You can see the car accelerates fairly well aside from WOT at idle speeds. In the second video, I had to back off or the car was gonna die. I hammered the pedal, then it bogged so I let it up half way, and put it back down from there.

Video 1 (2.3mb)
Video 2 (800kb)





Thanks guys

 

It's possible that the secondary jetting could be too lean.
It's a progressive linkage with an air valve that controls the air flow on demand to the secs.
That means the secondaries open all the way when you punch it, like a holley double pumper, but that air valve stays closed til there's enough air flowing through it to suck it open.
Still, if the sec jetting is too lean, the air valve will be opening wide but the fuel flow won't be there to support it.
A test you can perform that might tell you something, would be to disconnect the sec linkage, thus making your carb into a 2bbl. If you get better bottom end response with the secs constantly closed that will indicate that there's a problem within the sec circuit. Lessening the likelyhood that the pump or anything in the primaries is the trouble source.
The primaries will still need some fine tuning, but you can isolate the problem that way.

 

oh wow I overlooked that. I mean I thought of it at one point but I didn't think the secondaries could be jetted. I can disconnect the linkage and check it out tomorrow.

 

http://www.carburetorfactory.com/expvw04.html
http://www.mergetel.com/~fraso/RasoE...-AFB_SetUp.htm
Dave Emanuel's Carter Carbs book mentioned in one of those links would help out a lot if you really want to get it right.

 

Also, I wasn't suggesting that there's something "wrong" with your intake, only that the carb with it's out of the box jetting could be (probably is) a mismatch for the RPM air gap. The small edelbrock carb is one of their performer line parts. That would mean it's jetted for an intake that has a lot less volume than yours

 

Power mode 3
Change from base: Rod #1458 (075 x 037)

Power mode will be two stages richer then... sufficient?

 

That might be right
But the sec jetting is uneffected by the rods and power pistons and such.
The sec jets are #33 on that exploded diagram in the above link.

If the sec jets are way too lean, it could cause the entire intake tract to go lean when the sec air valve opens.
The engine would actually be more powerful with the secs closed entirely.
Why not go out there and unclip that linkage, and put it to the floor. If I'm right about the sec jets being lean, your car will take off like a raped ape. And that will mean the secs need some work.
When you change the jets on those, you don't have to get a new gasket each time, I've re used a gasket like 10 times. That's something that's cool about carters er... edelbrocks.

 

hahaha awesome

 

The car still bogged horribly when i disconnected the secondaries. I also tried running the car with the vac-adv disconnected. Same stuff, different day.


ALSO, my brand new shift cable BROKE AGAIN. I don't know what the hell is going on but I am really pissed

 

Here's a thread with some good tuning links on it
https://www.thirdgen.org/techbb2/sho...ght=carter+800
You probably need to order a larger vol pump nozzle.
Obviously, at this point the trouble has been isolated to the primaries, right?
That doesn't mean that you won't have to do any work on the secs later.
But get the pri right for now. Might as well leave the sec disconnected til you do get the pri jetted, that way your pri jetting won't be influenced by the sec.

You said you're running your TV cable as tight as it goes... no wonder it breaks. Set it up like it says in that TV made EZ link, and you'll be happy. If you haven't destroyed your tranny already.

 

It's the shifter cable, not the TV cable that's breaking. I don't understand why it's doing it, but that's a whole different thread (see transmissions for my rant lol)

But yeah, we have ruled out the direct cause being the secondaries. I tried swapping to a really rich rod (just to test) and that didn't solve anything. I didn't notice any difference from the problem in either pair of rods. I am looking about the pump shot thingy, but the link is killing my 56k modem.

I just came in because it started to rain.

 

The edelbrock site shows the 1406 as being "jetted for economy"
while the 1405 is "jetted for performance"
Maybe if you jetted your carb like the 1405 or even a bit richer, you'd see some positive results.

 

Just went to summit: EDL-1475 acc pump nozzle kits.

"These Edelbrock accelerator pump nozzle kits will allow you to fine tune your carburetor. They include three tube style nozzles and the required gaskets. The kits include one 0.024, one 0.033, and one 0.043 accelerator pump nozzle."

I'd call and verify it fits, but looks like what you need.

 

Electric Choke (#1406)
CALIBRATED FOR FUEL ECONOMY
Designed for small-block and small displacement big-block engines, these carbs are recommended only for stock to Performer level applications.
They are not recommended for use on RPM or Torker II intake manifolds.
Match with an Edelbrock Performer or Performer EPS manifold and other brands of similar design.
Calibrated 2% leaner than #1405.
Includes both timed and full vacuum ports for ignition advance. Comes with: Metering Jets – Primary .098, Secondary .095; Metering Rods – .075 x .047; Step-Up Spring – yellow (4" Hg).

Manual Choke (#1405)
CALIBRATED FOR PERFORMANCE
Designed and calibrated for optimum street performance in small-block and some big-block engines.
Match with a variety of manifolds that include Edelbrock Performer, Performer EPS, Performer RPM, RPM Air-Gap, Torker II and other brands of similar design.
Includes both timed and full vacuum ports for ignition advance. Electric choke #1478 can be added if needed. Comes with: Metering Jets – Primary .100, Secondary .095; Metering Rods – .070 x .047; Step-Up Spring – orange (5" Hg).

This and the pump nozzle kit... And I'll bet your problem is cured.
It might not be a bad idea to put a bigger sec jet in there, as long as you have the top removed from the carb - if you have a pair of .98s or .100s

 

Thanks man, I just ordered the kit

 

Fixed it!

I just put on the .043 nozzle and it cleared the hesitation right up. Thanks to everyone with the patience to help me, especially Streetiron85, StealthElephant, Sonix, and Lo-Tec. Okay, that's pretty much the only people who replied, but hey. Thanks again.

I've got the carb tuned to "two stages richer" for power mode, and it's at stock for cruise mode. I didn't touch cruise mode at all because my car gets excellent gas mileage cruising, and I didn't want to mess that up. I am two stages richer, because it seems like a good number. Poor logic? Yeah, probably. But it works. It's the most rich I could go without affecting the cruise mode, so I said screw it. I've got the pink (7" Hg) springs in still, also.

MORE TUNING YAYYY. I *really* need to ditch this POS 2.73 open rear though.

 

Congrats!
It sounds like you're pointed in the right direction. And you're more familiar with your carb and dissy now, for sure.
Keep tuning it til it's really sweet. Be careful about mixture distribution issues that can arise from having the secs too lean,causing the rear cyls to run hot.
Do searches on google for edelbrock and carter tuning info, there's lots there. Sometimes tricks for holleys can apply to your carb too, or generally any other 4bbl carb.
http://www.mortec.com/carbtip1.htm
So how is your fuel economy, anyhow?

 

Thats great!

I think you need to have a friend hold the camera while you do a "gratuitous burnout"!!

You'll **** your pants when you put gears in that thing!!

 

I get about 16mpg so far, between driving and tuning.




Lo-Tec, for sure I can't wait for gears.