Technical 350 Wont accelerate unless done slowly

Im baffled since I put I everything back to stock, as it was. Never had any issues with over heating, backfiring etc.

 

You haven't crossed a wire up at the cap have you ?

 

Take out your plugs one by one and look at them. They can tell you what the engine is wanting, fuel,air,spark. It will help troubleshoot your problem.

 

nope checked it twice

 

Sit down and write down everything you did. Then try to put it in the order you did it. Don’t leave out any details no matter how insignificant you may think it is.
I know you said you put it all back like it was, but you also mentioned the distributor has new parts in it, so it’s not really “like it was”.

 

took all plugs out.. look good and only one a liitle sooty. Put on wire turned over good spark,,

 

New coil wire and rotor coming tomorrow.. Theses look ok... but....

 

A good meter will tell you resistance and inter connections.

 

Yup took all Ohm readings as well as test for Unilite Module.. Coil tested bad, I replaced. Coil wire end fell apart in my hand.

 

hmm, running lean or very rich. maybe youre getting too much fuel when the accelerator pump hits.

try checking your float level, that was my issue when i had something similar

 

Known to be good or sold to you as being good?
60 years of working on cars both as a hobbiest and a trained professional says that you only change one thing at at a time unless you are building from scratch.
Meaning that if you change the carb, you don't change the igniton at the same time, you fire it up and drive it and make sure that the new to the car carb is working right.
Meaning that you don't start doing wild guesses and throwing parts at something when there is a problem.

Meaning that you absolutely never****UME that something is right, you CHECK to see if it is right.
That includes taking a couple of minutes to hook up a timing light to check the timing.

Vacuum is measured in inches, not pounds by the way.

Most of us who have run Holleys for years full and well understand that if the engine backfires we had best be concerned about the power valve. We also understand that the passageways inside the body and the metering blocks have to be clean and clear of crud. I wouldn't take any used carb that had been sitting for a while and stick it directly on an engine without properly cleaning it and putting a new kit in these days. Any gas sitting in a bowl or passage way turns to varnish or crud all too quick.

 

I was just about to tell a story about having something like that happening to me....
After a lot of chasing my tail, we found a coil-to-distributor wire that ate itself internally, and had a one inch gap to jump inside the wire. That was enough to make the spark at the plug gaps feeble enough to get snuffed out any time I opened the throttle even slightly. We thought it was carb troubles for the longest time.
Now you robbed me of the chance to tell my story....
I guess bad high tension wires happen more often than I thought.
Well, I'm glad you found it.
.... I snuck my story in anyway...

I had jeep that was afraid of driving on damp or foggy days.
That one also turned out to be plug wires that eventually had mud&debris that saturated the insulation even tho I kept them wipedclean after every off-road playday.
I learned the hard way that good looking plug wires still need to be changed periodically.
Once it was the internal carbon fiber conductor eating itself inside the insulation, and once it was a good looking insulation becoming porous and saturated with electrically conducting invisible mud in the pores.
Congrats on solving your prob!

 

Yup checked them both

 

I have 20 years at this also, My carb s are either brand new or rebuilt, Tried everything out after each change. Tested each part by the book. I've had Hollys for years, Rebuilt more than I count.Timing light, ohm meter ans Vacumn gauge are all in place!! Yes Vacumn is in inches. We'll figure it .out
Thanks for the lecture

 

Going back to the original post.

You checked the fuel pressure? Yet it sounds to me like a gas issue. Like a fuel pump that's starting to fail. But who's to say if it isn't mentioned, or pictured in detail to offer sound advice with opinion to what it could be and why.

I'd openly admit that I'm no mechanic, but it seems to me, you and them are throwing stuff with no basis for a solid diagnosis as to the issue yet hoping it sticks.

So lets go back to your fuel pressure testing and before you begin, is it electrical, mechanical, or have you been lead to believe you need both to make it run? What about a fuel pressure regulator, got one of those in there somewhere? If you can afford those parts, can you not attach a picture?

Getting back to testing, did you just see a pressure with turning a key, or was it inline and running? Inline and running, did you snap the throttle, rev it to pull a bit, or just leave it to idle?

Forgive me for saying so... as Mr48Chev mentions

I've got 40...if there's a lesson to be learned you maybe missed it along the way.

 

oh, does this mean that the weak ignition wasn't the whole prob?
Then I'll take some wild guesses some more....

If not a failing ignition from something like an old stock "new" condenser failing from too much shelf-age time, it also sounds like a big leanout from something like a dried up leather on the accel pump, or low fuel pressure, or a passage clog from pouring from a gas can.
I've had a worn rubbing block on a set of points, which let the gap get too small, do something like that to me where I even suspected a timing chain going bad, then it was the points slipping out of whack.
Ok, now I did my part to help confuse or unconfuse, so I'll quit "helping" for now.

I hope the solution shows up soon!

 

is this a holley?

 

Sometimes we get caught up in throwing parts at a problem or start turning screws on carbs. Sit back and remember you need fuel,air,spark and compression all in the right ratios. You say you have spark and timing is fine as well as the plugs look good. Is the spark blue, or a shade of orange? Everyone on the HAMB likes pictures to help diagnose a problem too.

 

Could be waaaayyyy off base here, but I experienced a similar situation where my car was sluggish(!) and, under more effort would even stall. Turned out to be a collapsed/blocked exhaust..! Complete other end of the system from the carb even though I was sure it was fuel or electrical. Food for thought.
Best of luck!

-Dave

 

You said you changed the diaphragm, I think you said for fuel pump , if its a holley , did you loose the orange rubber or steel ball check valve ? Did you invert the carb with the accelerator pump discharge removed ? Theres a brass or steel check needle or ball , without that or the orange rubber piece accelerator pump discharge will be nil

 

And I have 60 + years of experience repairing & maintaining internal combustion engines , its not good form to cop an attitude. With folks that are trying to help you !
If you don't say to yourself , " Duh stupid" once in a while, you aint doing much .

 

Do you guys want to hear a story about a bunch of dealer mechanics that screwed the pooch?
I’ll keep it short as possible , I got the story from my dad. He wasn’t involved until the end.
1968 a 327 impala comes back to the dealership for tune up. Running fine just time for its tuneup. Gets its new parts, plugs wires points fuel filter, air filter and runs like*****. They rebuild the carb, runs like*****, get brand new out of the box carb and runs like*****. My dad was working on another car and just watching.
They decided the timing was off, still*****, the points were off, still*****, well it’s must need a valve job, what else could it be, still*****.
Dad said it’s probably the plugs or wires.***** it they swapped the whole damn engine and still*****.
Asked my dad what he thought, he said the thing was running fine till you put plugs and wires on it, everything you guys did you put the same damn plugs and wires back on it, every time. “Awe they’re brand new” little bit of bickering, top dealership brass in the garage, pissed off customer.
He went outside while the pow wow was going on and grabbed the wires off his car and put them on the problem car. It Ran fine.
told you so,

new problem go back to the last thing you did.

That’s the shortest I could make it.

 

Better throw the Flathead back in it.

 

Pull the air cleaner off and with the engine off work the throttle to see if it's getting a good squirt. If it isn't then check the diaphragm and also check the little flat rubber back check inside the accelerator pump housing!

 

The unilite dist. w / 605 module are sensitive to high secondary resistance (bad coil wire) when you say photocell replaced, I am thinking you mean module. Still runs same, but higher engine temp. BTW, if lean carb wise, thats usually backfire through carb. But your experiencing exh backfire.O.k. Depending on what crate motor it is, 10 degrees is low, bump it up to 15degrees advance, if that little change helps, try a bit more, maybe 18. Adjust idle. Without vacuum advance the engine needs a little help before mech advance kicks in. Retarded timing increases temp. With out being there, I think the original module was failing from current spike, and new one wants more initial (base) timing. I have seen restricted exh cause higher temp, but never backfire, but you would have remarked about overall power loss if it was that bad. 15 " vacuum ? Like you mentioned tad low. Add timing and update.

 

did you check your metering block with a straight edge? if its a little warped it can let a little extra fuel in, making it run very rich.

 

Simple stuff first , before looking for something like a timing chain jumped a tooth . 3 things, hesitation, increase in temp, exh backfire. Common source.

 

still can have weak spots including bad wires, low output bad coil etc....
worth looking at.
more than once I had a module fail by fading away

 

How many volts does the Unilite system need to function at full throttle? I had an issue with an electronic distributor that felt like it would cut out at anything beyond half throttle and would pop and sputter at high speeds, my issue turned out to be my generator failed so the engine was running off of the battery, and at full throttle the distributor didn't have enough voltage to work properly.

It's not impossible, and it's not something most people would look at. It certainly mystified me for a while.