[flipp121]

Hey anyone whos reading this, in desperation of carb tuning I have left the safety of the real olds power forum to expand my horizons. Nobody seems to be able to fix my problem.
I have a 1966 oldsmobile f85 with a 330, converted to a four barrel with a f***ing edelbrock 1406. This thing has given me nothing but grief. My car is a stock 2 speed automatic transmission with 2.78 rear end gears. No matter what i do if i floor this car more then halfway quickly i get a bog that lasts all the way up to 4000 rpm. The thing is if i ease into the throttle EXTREMELY slowly the performance is almost decent. I have tried every combo of jets and springs and accelerator pump hole locations. Anyone else encounter this problem with an edelbrock carb?

Let me reitterate, if i floor the gas off the line quickly my car makes a 'bbuuurrrr' sound and accelerates slower then a 1.6 litre honda, and doesnt pick up until my car reaches about 55 miles per hour at 4000 rpm. But if i ease into the throttle its not nearly as bad, providing i stay out of the secondaries.

Any help is truely appreciated as I have been trying to fix this damn carburetor for about 7 months now to no avail.

[mikeweyman]

i am going thru the same crap with an old holley.it's been out to 2 shops so far and has been rebuilt . it's the main reason why my 75 vette didnt see the road this year. next year i will spend 700 bucks and buy the road demon and be done with it.mike
welcome aboard.

[k-star]

How did it run before you changed carbs??? Did it have the same problem???

What is the initial and total timing set at???

Just as a word of caution to you using the "F" bomb is not allow on this forum.........

Keith

[RCastle]

I had an Edelbrock do the real bad bog thing on me too.If I stomped it,it reacted like I was pouring gas in with a funnel.My throttlle blade shaft was wore in the base,preventing the blades from operating smoothly. Plus I had a bad drip inside the carb.It was several years old with plenty of abusive miles on it.I ended up replacing the carb.Might not be your problem,but check the shaft.

[JamesRS]

How does the car idle? Does it start hard? What you've described sounds like it might be a vacuum leak on the manifold. Check all of you vacuum ports on the manifold, and also check your manifold gaskets. A leak on your intake would do exactly what you are describing. An easy way to check this is by spraying carb cleaner around the edge of the intake while the engine is running. If the idle slows down, or stalls then you have a leak. Also do this at the base of the carb.

[Ohio-Dan]

I think you are chasing a timing problem.


It's my guess that the original setup had the distributor hooked to ported vacuum and you now have it hooked to full manifold vacuum. By accelerating at part throttle, you are building manifold vacuum and getting the advance the motor wants, or at least a portion of it. I am also assuming you are still running the stock advance weights and springs that provide a slow, short curve providing the weights are still moving freely. It's not uncommon for an engine that old to have the weights stuck from wear or rust. Dan

[flipp121]

Hey thanks for the reply's everyone, the edelbrock carb is brand new. As far as i know my intake manifold is good its an A4 aluminum one off an '86 buick. The car didnt have this problem untill i switched the manifold and the carburetor. When I hook up a vacuum guage i'm pulling an unsteady 13-15 inches of vacuum. I have been trying to seal the egr with a blockoff plate but when i used that 'make-a-gasket' stuff the ticking from my egr plate got louder then with the original gasket/plate. Is it possible that my timing could make a bog that lasts THAT long? Or is it the egr valve not sealed? Or could it be that i need a larger accelerator pump?

Thanks,
Mark

Oh sorry just one more thing, I am still running points for my ignition.

Edelbrock says that you should use full time vacuum port for cars that don't have any emmisions stuff on them, so thats the port I used.

The car idles fine, the only indication that its a little choppy is from the vacuum guage fluctuates within a few inches as the engine stumbles a tiny bit....
Kay there im done

Geeze i forgot one thing, my old carburetor used to blow a bit of black smoke when i floored it, but wasnt slow at all compared to what i have now. Plus it was an old 2gc with a wiggly throttle body.

[killerformula]

This car is not properly tuned.

What is your compression and cam, what kind of distributor are you running and what is your advance curve?

You can adjust the accelerator pump on the edelbrock right on the arm of the pump itself... just switch to a lower notch (oh higher, for that matter). Are you certain that you don't have a vacuum leak? Vacuum problems can occur all the way at the mod valve in the trans. What are your plugs reading?

Tune this car from the ground up starting with the idle circuit and timing. My guess is that you're going to have to change the vacuum level springs that hold down the rods into the jets. Stiffer springs will more than likely help, but you need to get a baseline first, otherwise you're, to be fank, pissing in the wind.

K

[SAATR]

Sounds like you have a vacuum leak somewhere. With a stock cam you should be pulling 16-18 inches, and it should be fairly smooth. Get a can of carb/choke cleaner or brake parts cleaner and spray it around your manifold ports and the base of the carb. If the engine speeds up/idles better, you've found your vacuum leak. You don't use RTV or " make a gasket" on exhaust related items. Go down to your local parts house and get some gasket material made for exhaust and make your own gasket, if that doesn't work then your block off plate my be warped. You might also try advancing your timing a bit. It also wouldn't hurt to get a performance recurve kit for your dist., the stock curve is set up for emissions, not performance.

[flipp121]

Kay, i'll put in a proper gasket and check for intake leaks. I will also advance my timing as i think its not advanced enough either. I would like to know if it is correct for me to use full vacuum port on my carburetor instead of ported?

[edge]

Originally posted by SAATR
Get a can of carb/choke cleaner or brake parts cleaner and spray it around your manifold ports and the base of the carb.

Avoid using a brake cleaner when checking for vacuum leaks. Why use a cleaner made for brakes on (or around) your carb when they make a cleaner specifically for carbs and throttle bodies? Using brake cleaner will be more likely to dissolve delicate plastic parts and damage an O2 sensor.

Plus, allowing brake parts cleaner into a running engine is a serious health hazard. Some of the chemicals exclusive to brake cleaner when put through a combustion process become in effect a "nerve gas".

Don't chance it, use a spray bottle with water, carb cleaner or a mechanic's stethoscope. Good luck, Ed www.edgesz28.com

[woodz428]

I'd like to put my input on the Brake cleaner. Not all Brake cleaner has the same make up, some are nothing more than the same thing used in electrical contact cleaner. I've used Brake Cleaner/Contact Cleaner for 20+ years and reccomend it over any carb cleaner I've ever used. Carb cleaners don't evaporate as quickly so aren't as flammable, requiring more to be sprayed as well as setting on the engine longer slowly evaporating as well as attacking engine paint and some plastics. I would find a good Contact type cleaner (make sure it's a flammable one) and stay with it. I haven't used Carb Cleaner for over a decade because they seem to have worse vapor hang and have as toxic (or more )chemicals that evaporate slower,which if comes in contact with your skin, can set long enough to cause a reaction.

[edge]

Not all Brake cleaner has the same make up, ...

Exactly, so why chance it. Unless you are a chemist, how do you know if one is "safer" to run through an engine then the other?

I would find a good Contact type cleaner (make sure it's a flammable one) and stay with it.

Surely you meant non-flammable

If a "one size fits all" would suffice, why were two mutually exclusive products developed. Answer: Because each is manufactured for a specific purpose. Let me draw some simple analogies. You wouldn't use gear lube in your power steering, automatic transmission, or brake system. Or 20W50 in the cooling system, power steering, etc. How about mixing diesel and gasoline. I think you get my point.

I mentioned this for one simple reason. Undoubtedly, someone will do a Google search on "how to check for vacuum leaks" and come across this thread. They will think, "I just grab that can of brake cleaner and check for a vacuum leak." Setting aside the health hazards with running brake cleaner through an internal combustion engine, they may have unknowingly damaged their O2 sensor, catalytic converter, or the TPS sensor has softened and is unable to hold its position, or something like that. Then they will have a whole new set of problems to deal with.

Ed.

[SAATR]

Ok, first of all, we are dealing with a 1966 oldsmobile f85. It has no O2 sensor, nor a catalytic converter to poison. My recommendation was made in this context. Brake parts cleaner will kill paint, but I have yet to see it eat through wires or soften any plastic fitting I have ever sprayed it on. It's not going to do any more damage to these things than carb/choke cleaner or throttle body cleaner. If somebody takes it out of context and tries the same on their 96 Camaro and it screws their TPS, then that's their fault for not thoroughly researching the topic, not mine.

As far as harmful fumes, since when is CO not harmful, or oxides of nitrogen, or even carbon dioxide in large quantities? Heck, gasoline is a major carcinogen when inhaled or on the skin. If you are working on a car, especially one that is running, you should be in a well ventilated area anyway. If you're working on a running car in a closed garage, you have far worse things to worry about than some fumes from the brake parts cleaner. To use your own arguement, How do YOU know that something like B-12 chemtool is any less toxic than brake parts cleaner when combusted? Produce some proof and I'll shut my mouth, till then, I stand firm behind my recommendation.

As far as flammability goes, you want something that vaporizes easily and is easily combustible, so that when it is drawn into the engine through a vacuum leak, it causes some kind of noticeable change in the operation of the engine, e.g. engine speeding up, so you know you've just hit a vacuum leak. This is the purpose of using the spray.

And to answer your question spinn, whether or not to use port vacuum or straight manifold vacuum is actually a bit of a debate in the world of hotrods. Some say ported, some say manifold. I myself use manifold vacuum, as it's a better, stronger vacuum signal than port vacuum and more accurately reflects the engines operating conditions. I would just try it either way and see what works best for your combination. Never hurts to experiment a little.

[edge]

If somebody takes it out of context ...

Talk about spin. You would make Clinton proud (lol). Remember, not everyone has your years of experience under their belt.

Produce some proof and I'll shut my mouth ...

How about you show me one "reputable" source that recommends the use of brake cleaner in detecting manifold/car vacuum leaks. I'm not talking about another message forum such as this, but a published/copyrighted source. I found a couple that recommend propane, stethescopes, hose, carb cleaner spray and automatic trans fluid mixed with cleaning solvent. Not one says "brake cleaner". That's for a reason, number one being liability. And, perhaps common sense.

http://www.sporttruck.com/techarticl...03/index6.html
http://www.aa1car.com/library/vacleak.htm

And to answer your question spinn, ... Where did spinn ask a question in this thread?

I've made my point. Ed