Technical SBC guys, help me get my 283 runnung right before i put a match in the gas tank

Just so you know there is an online vacuum gauge chart to tell what's going on. Good luck

 

Qoute: "The large vacuume hose goes to a vent fitting on the rear of the block,no pcv."

If there is no pcv and the hose is going to a vent on the block,you have a rather large vacuum leak. Have you plugged that hose and tried it?

 

You don't set the brake that tight that it would stall it, you just apply enough to make the engine work to turn the wheels which put it under a load and simulates driving it!

 

I agree with this, the PCV is spring loaded to control the amount of air entering the engine, you are creating an off-idle lean condition with no inline valve to regulate air flow.

 

I can't figure out why nobody has suggested investing in a fuel/air ratio gauge. When I first got The Judge on the road, I had a bit of an issue and after getting a gauge and making appropriate carburetor modifications she runs perfect now. You can't go wrong by having one. If there is an air fuel ratio issue it will stand out like a sore thumb, and as long as it's a steady 12 to 15 it's not a fuel delivery issue..

 

Have you checked the firing order. Had one as you describe and it was two wires on the wrong plugs.

 

There was ""mention / suggested""
AFR gauge !!
There are many Older ones that do not Believe in this Modern tool ,
I guess because $200 plus range ,
Must drill a hole , Most time weld ,
Or Extra 60-80 for clamp on Option ,
I guess most see a wast of $$$ just to Dial in F-R !!!!

 

Sooo, are you trying to say that after spending thousands of dollars and hundreds of hours, even perhaps thousands of hours to build a ride that you want to love, but you end up stumped over a single issue, and spend time posting looking for help, and we, including you, spend more time trying to help, another $200 and an hour or two isn't worth it? Hahaha...

It's been 3 days and three pages of suggestions that has taken up dozens of hours among us all and at this point the OP hasn't told us that he's found the issue. Everything that others have suggested, he has checked and already done. So what's your suggestion, sir?

 

Well , Yes !!!! Some will Not spend the $$$ after all they Invested ,,

A S I F Y O U K N O W M E !!!!
YOU would Not include me in your statement !!!!

QUOTE ==but you end up stumped over a single issue, and spend time posting looking for help, and we, including you, End QUOTE

HHH MMM ,,
Just looking around , there is Two Engine Combos
With Eight afr One in each Exhaust & a inline 6 with one in each Exhaust,

I salute you 49'Ford Coupe , For setting Me Straight

 

I didn't see it, but just make sure the block is grounded to the battery, battery to frame, block to frame, body to frame or block. Then make sure the ground strap inside the distributor is solid, breaker plate and housing are grounded. You can run a jumper wire from the battery neg to the dist housing to test (assuming the strap inside is good).

 

You are welcome.

 

Yes,I currently have it plugged. No dofference.These didn't have a pcv.It occupies the spot where earlier models had a road draft tube.

 

Thanks, checked the firing order multiple times.

 

Thanks,everything well grounded.

 

since people are still throwing ideas out... is your distributor moving after you apply load to the engine? I bought one of my '56's that had a cheap chrome chinese distributor hold-down clamp that couldn't/wouldn't keep the dist in place. Found a stock dist clamp and it cured the self-adjusting distributor.

 

As a follow up to chicken and Fordors comments , originally the early 60's engines (pre 63) had road draft tubes in the hole at the rear of the block behind the distributor. The first PCV system replaced the road draft with a short adapter that used a hose between the adapter and the fitting in the base of the carb, with a PCV valve in that line. IIRC the PCV had a pipe thread on one end that screwwd into the carb base. Is this what you have?

 

Yes,it is what I have but I didn't realize that odd fitting threaded into the carb base was a pcv. It may not be working because I think I can pass air thru it from either direction.I did realize early on that it may cause a vacuume issue and plugged it ,which has not effected engine performance.

 

Thanks for responding, I have the factory clamp and it works well.Also, in various timing setting I have moved the dist throughout its advance range with no effect on the issue I am having so I'm pretty confident it's not a timing issue.

 

Most of us older folks learned " pre instrument " diagnosis procedures or how to do those things without spending $300 .

 

What spark plugs are you running? Try a set of autolite #85, or 86 would be closer to stock. Gap them no more than .030.

 

Ok, let's assume carb is good, ignition system good to go, you have done timing changes, so at a base setting at 14 degrees, for example, using a adjustable timing light, or degree tape on balancer with standard time light, you need 32-34 degrees of advance vacuum and mechanical advance all in at about 2800 rpm. Check that off the list. If not, find out why. The low and varies? 16" hg. vacuum reading is a concern, an RV cam should be more like 18"hg.+ and steady ,at 850 rpm. you backed off valve lash I believe by a bit, I think perhaps pulling the valve covers, start it up and back off jamb nut, lifter clatter, tighten 1/4 -1/2 turn past quite, give it 30 seconds to stabilize and go to next one, repeat, do both left and right banks, messy but get that out of the way. With a vacuum gauge connected to manifold vacuum port watch for improvement on reading. Hang in there, report your results, by the way, an O2 sensor for A/F ratio might be needed, but you need some baseline diag first. Some more ideas, one step at a time.

 

I’m Sure it will be something small when you find it. When I swapped the flatty out of my 46 for a fresh SBC it ran great for a while. Then would randomly cut out and die. I chased that problem for 3 months. It would get “better” then leave me high and dry. I chased fuel and ignition to no prevail. Then one day it died moving out of the garage and wouldn’t start again. checked for spark and had none kept tracking it back and found that the nut had came off the back of the ignition switch and the wire for the coil was just loose and hanging there. Something so simple was my problem. Cleaned it up and put it back together and it fired right up. No issues since. Good luck!

 

Well nothing has worked yet, has it? When a person gets to the point that he is "spinning his wheels" what then? By the way I'm 79 years OLD, but I don't operate by "pre-instrument" practices when a solution is elusive. Do you just start guessing when a problem isn't reasonably obvious? I didn't bat an eye when I made the decision to get mine, and after I installed it, I knew exactly which jets and rods to swap to in the first ten minutes of a test drive. I didn't bother anyone else about the stumbling acceleration. I didn't have to spend five seconds thinking about any ignition issues.

By the way, Mr. OP, have you considered getting an A/F gauge?

 

^^^^. 79 years YOUNG!

 

Some folks use a calculator , some use a paper & pencil , some use a laser some use a string line . Different strokes for different folks . A fool and his money are soon parted .

 

One of the things that makes "man" different from most other life forms on this planet, is the use of tools. A calculator is a tool, so is a pencil. A laser is a tool, so is a piece of string. Food for thought.
Tom

 

Matches is one option,
The second option is to assume nothing except- operate under the assumption something is wrong and obviously amongst everything you’ve checked and done there’s a mistake in test methods or interpretation of results.
Start at the basics, square 1 and work your way out and up.
First thing is compression test - eliminate an internal problem because like you’re seeing no amount of tinkering can tune around it.
While you got the plugs out do a piston stop test to verify your timing marks.
Install a timing tape.
Get a dial indicator and check the cam’s intake center line. With your dead nuts piston stop test and timing tape you can check that easily.

You have to pass all of that before any tinkering and tuning. All of it.

Next brick in your wood pile is the backwards carb and adapter plate. You are going to have to go over that entire set up with a microscope and make sure there’s nothing wrong there obviously an oddball thing that has potential to work or causes issues.

Get a fuel pressure gauge and verify your fuel pressure, rig it up under the windshield and watch it while driving,
Do the same with a vacuum gauge. Watch it while driving.

There’s more but that’s all I got time for now.

 

Apologies if this was asked, but does it do it when you hit the throttle when parked, or only under load?

It's still sounding like a carb issue to me. Could you find another carb somewhere, install it temporarily the regular direction and see if it solves your problem?

 

On the Rochester 2GC I have, there are several holes on the arm that activates the accelerator pump plunger. Is the link in the "correct" hole. When I freshened the 2GC on my car the new accelerator pump seal had a little spring to spread the lip of the seal. That whole assembly was useless (spring wouldn't stay in the seal) and I ended up re-using the old accelerator pump plunger and seal.

Lynn

 

Through the years I've noticed people instantly assume carburetors are the problem. Usually if you have a stock carb that isn't flooding over I do a wide open throttle run and shut it down under load. If it has fuel in the bowl and the power valve is known to be good mark the carb off the list. I've had the same symptoms with bad plugs. Never assume plugs are good just because they are new. When under load the cylinder pressure goes up and it makes it harder for the spark to jump the gap. If the plugs or wires are weak it will show up under load. Also make sure the mechanical advance is working. If it sticks you get a missfire starting midrange rpm.