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can't figure it out on my own

SSpev

Supporting Member
Supporting Member
I have been unfocused... but I'm looking at the bucket again. This is an engine issue at part throttle. When cruising about 35 and slowly push the peddle it falls flat and does not recover unless I go further or back off. I think My secondary's are opening with out getting any fuel. At this point I don't think they should be opening. Or how about the power valve opening and causing a flood with out air.

Second thing. After its all warmed up, at idle it reves to about 1600. drop it in gear 500 and want to die. back to park it pick up to about 1000. the slow moves back to 1600. With out the vacuum it goes to 1300.
Any Ideas?
 
Need more info. Vacuum or mechanical secondaries? 1 or 2 carbs?
 
Sorry. Not every one has seen it. 1968 1923 T Bucket
283 bored to 301. 1850 carbs. (wish they where (390s) Built long ago. Cam ??? about 8in vacuum. PV 6.5 (just checked, all I had) need 4.5. secondaries wired closed.
 
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Did it run OK before ?

Have you checked the transition slot, it should look like a square under the throttle plate.

FP04_TransistionSlot.jpg
 
Not to sound condescending or anything, but there could be numerous causes. Without knowing more, it will be hard to help. The low vacuum tells me it either has a huge cam, and, or, has problems such as a vacuum leak, burnt or mis adjusted valves, wiped cam lobes, or is seriously out of tune and missing. I would begin by verifying compression and adjusting the valves (sort of a joint activity), clean or replace the plugs, test the plug wires, check the distributor cap and rotor, you know, basic healthy engine and tune up stuff... set the timing, etc. verify distributor operation, advance, etc, and look for any vacuum leaks... then the carbs would be adjusted or rebuilt, whatever is required. If it has been in storage and not ran, the carbs could be corroded up inside from the ethanol blended fuels we get. I am assuming that it has fresh high quality fuel to start with. The obvious initial thoughts are accelerator pump or timing but the low vacuum, high idle rpm, and lack of low end power doesn’t fit. We really need more info to give more specific help or suggestions, cam profile, engine component combination, engine condition and tune, etc. Best of luck!
 
Did it run OK before ?

Have you checked the transition slot, it should look like a square under the throttle plate.

View attachment 19295
plan to do it again asap

Not to sound condescending or anything, but there could be numerous causes.agree
Without knowing more, it will be hard to help. The low vacuum tells me it either has a huge cam, yes
and, or, has problems such as a vacuum leak, Check with propane. didn't find any.
burnt or mis adjusted valves, Doubt it Compression check had 150.
wiped cam lobes, could be, will check again.
or is seriously out of tune and missing. WELL YEA.
adjusting the valves (sort of a joint activity), clean or replace the plugs, test the plug wires, check the distributor cap and rotor, Done and new pertronix you know, basic healthy engine and tune up stuff...
then the carbs would be adjusted or rebuilt, whatever is required. Done
The obvious initial thoughts are accelerator pump or timing but the low vacuum, high idle rpm, and lack of low end power doesn’t fit. Exactly
We really need more info to give more specific help or suggestions, cam profile, engine component combination, engine condition and tune, etc. Best of luck!
You don't and agree agree agree.
 
plan to do it again asap

You don't and agree agree agree.
Just a note on the Pertronix hall effect ignition sensors:
I have used them numerous times in the past with good results, however on my most recent install, I had a issue where it was missing intermittent under power and had tip in power lag. I thought it was a carburetor issue at first. The sensor actually totally failed with less than 10 hours run time. Turns out I had solid core plug wires and the unit requires suppression/resistor wires, which likely caused the failure. They did not include this information on the installation instructions or troubleshooting web page but when I asked their help rep specifically about it, he told me that solid core wires will cause failure. Just a FYI, something to verify.
 
ARE FLIPPEN A KIDDING ME..... I kinda thought about that but can't be its new:speechless: I have to check that now... I do have it running better. distributor was of one tooth:( ultra fine adjustments ...of to a car show:D:cool::thumbsup:

upload_2020-8-25_21-5-5.png
 
my wires are taylor street thunder. i think those should be alright. I need a spare hei for a test....
another symptom going up a slight grade it would loose power and it would need a stab and release to get going. when it smooth it is smooootthh.
I am thinking about putting a single 4 on.
 
Tuning can be a chore. It’s fun once you figure out what adjustments to make but it really just takes time to figure it out. Make small changes and keep notes on what you did and how it affected it is the best advice I can give. I used to have a favorite road with a parking lot to test and tune before it became incorporated and patrolled. It was about a mile between my shop and the parking lot. Perfect to adjust, test, adjust, test, etc...
 
Tuning can be a chore. It’s fun once you figure out what adjustments to make but it really just takes time to figure it out. Make small changes and keep notes on what you did and how it affected it is the best advice I can give. I used to have a favorite road with a parking lot to test and tune before it became incorporated and patrolled. It was about a mile between my shop and the parking lot. Perfect to adjust, test, adjust, test, etc...
Agreed.
A good vacuum gauge might give him some clues.
Even the old "spray some carb cleaner around the carbs while running" might yield results...
If it sat for a really long time then he's got some work to do (carb floats/gaskets/pump assembly).

On a side note, here's what paragraph 2 says on this website: 600-cfm Holley 1850 - Applications - Tuning - Tech - Hot Rod Magazine
"Because the 1850 is designed with a somewhat lean idle circuit, driveability problems occur when it is used on an engine with a big camshaft and low manifold vacuum because the idle circuit cannot supply sufficient fuel to run at light throttle."
Might be worth checking out...

I will admit some prejudice in this area, as I am an Edelbrock fan...
 

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