Low power, low vacum
 

Some of you may remember I wrote in a few months ago and had just purchased the 38 sedan that was rebuilt from ground up. Looks fantastic but have been chasing a few gremlins, mostly low power. I started with pulling the distributor to advance it cause I could not see the hash mark scale on the side.
Set points, timed it and reinstalled. Ran crappy. Pulled distributor again and found I had set wrong points for timing. Adjusted everything and reinstalled, started and ran okay. Not much power tho. Advanced timing 4 degrees and ran a bit better but overheated. Backed timing off back to standard and runs okay at cold idle.
Adjust idle speed cold and when it gets hot idle goes way up. At highway speed it runs rough. Checked plugs and were sooty. Checked idle vacum and only 5-6 inches.
I feel like I am chasing more than one gremlin? What should I concentrate on first. I know the old rule: only change one thing at a time.
Why is my vacum so low? Is that causing the low power problem?
Thanks in advance for your help. This flathead thing seems to be a bit fussy, or it may be the operator is not a flathead wrench!!!!

Re: Low power, low vacum
 

first define low vacuum--check for leak on windshield wiper motor
2nd year engine--possible adjustable lifters?
3rd pull carb and check for trash in float bowl and jet size--also tell us carb type and numbers 38 should have stromberg

Re: Low power, low vacum
 

Don't remember seeing your prior posts, so I have no history. Has the car run this way since you bought it? I would do a compression check to see if the hardware is healthy. If compression is good, that eliminates a lot of things. If its bad you can give each cylinder a squirt of oil to check for bad rings. If still bad the valves need checking. Do a leakdown test. If it all checks good, it has to be spark or fuel.

Re: Low power, low vacum
 

Distributor needs to be checked on a distributor machine to be sure it’s operating correctly.

Re: Low power, low vacum
 

You are at 4,692 altitude (I am at 8,300 ft so there is definite a reduction in vacuum). Your vacuum will be lower, but not 5-6 inches. But that having been said, you might want to have a vacuum gauge on the engine and then adjust the distributor, while the engine is running, to see if the vacuum increases.

Re: Low power, low vacum
 

I never thought of the vacuum wiper system!!! Thanks for the tip allanwoodie!!
I still have the vacuum gauge attached so I can check that and move the timing also.
I will also get compression readings to see if the 900 miles on the supposedly rebuilt engine give good numbers.
Thanks guys. Will report back when or if I find any smoking gun.

Re: Low power, low vacum
 

Have you done a compression check on each cylinder? ....Oops Russ mentioned compression already. :)

You won't make a lot of engine vacuum without cylinder compression. The combustion engine is essentially an air pump with fuel/spark added. Why superchargers and turbos are popular.


Funny thing is the more you run an "old not run in a while" motor, sometimes the numbers get better. Best of luck.

Re: Low power, low vacum
 

Okay. Ran some tests this morning. Cannot find any source of vacum leak. Wipers not hooked up and distributor vacum line is missing and plugged at carb.
Pulled all plugs and all are sooty except front drivers side. Don't know what number plug that is. That plug is nice and clean, not soot. Too clean. Checked compression and all are 70-72 one at 75. Front drivers side reads 50psi. Squirted oil in the hole, waited a few minutes, and tried again. Now reads 72psi.
Rings or valve? A dose of Marvel?
Still cannot figure why such low vacum. Don't know the reason for the low power???
Don't know where to go from here. Suggestions??
Thanks

Re: Low power, low vacum
 

low compression numbers, should be over 90lbs. did you remember to remove all plugs, block the throttle wide open?

Re: Low power, low vacum
 

Sounds like rings. 50 is awful low. Was the engine rebuilt? Front cylinder on driver's side is 5.

Re: Low power, low vacum
 

Yes, removed all spark plugs and blocked throttle open.
Yes, the engine and entire car was rebuilt in 2010. Underside looks as good as the rest with obvious mostly new parts under there. Car only has less than 1000 miles since restoration. Did set for 10 years after previous owner finished it.

Re: Low power, low vacum
 

Oh yea. Forgot to tell you I did pull the carb and it is a Stromberg and the main jets do not have any markings on them at all. Looked them over good with a magnifying glass after getting them out, but no marks. Do the stock jets not have markings, but bigger or smaller ones do?

Re: Low power, low vacum
 

Evidently I can only think of these things one at a a time.
When advancing the timing, which way do you move the screw on the crab distributor? Up or down?
If the distributor rotates ccw when viewed from front, wouldn't you move the adjusting screw opposite direction of rotation to advance? That would mean moving the adjusting screw down?

Re: Low power, low vacum
 

Boy, that sounds like real bad numbers for a 1000 mile engine. After sitting 10 years, you could have a bunch of stuck rings and valves. I would get the distributor set up properly and installed, adjust the carburetor so it runs the best, nd change the oil and add a bottle of Marvel Mystery Oil and see if you can put a few miles on iy. Maybe some things will free up. As long as you have decent oil pressure and no funny noises, I don't think you can hurt anything.

In 1994, I bought a '50 ford that had been wrecked in 1954, and had sat for 40 years. It would hardly run, as it had a couple of stuck valves. After getting everything loose, the engine turned out to be an excellent runner.

Re: Low power, low vacum
 

I agree with tubman do what he suggests and i’ll only ad one thing also put 5 oz of marvel mystery oil in the gas had quite a few of the old flatheads in my time with sticky valves may take a few tank fulls but that stuff works good luck

Re: Low power, low vacum
 

it's a 38 but what engine is it?
You say crab distributor. A crab won't fit a 38 motor. Is the motor later or an adaptor used on the 38 motor?
You say the vac line dizzy to carb is disconnected.
If crab type dizzy, it will not advance properly if vac not connected to release the vac brake. Is the vac brake wound fully out or not fitted?
Lots of things that can be wrong.
Low miles motor. Could have glazed bores. Could have stuck rings.
On a crab if the screw is on the driver's side, you move it down to advance. You have to imagine the dizzy rotating anti-clockwise.

Mart.

Re: Low power, low vacum
 

Well, call me stupid.!!! All this time messing with the distributor, I now find out I have been retarding the timing substantially. I set it in the car at factory setting and then thought I was advancing it by moving the screw and plate UP.
After reading several articles and Van Pelts directions and pics I now know that to advance it, I have to move to screw and scale DOWN. I have been running it almost fully retarded and complaining about no power. DUH!!!
SOOOO, tomorrow I will reset the distributor, pour some MMO down the #5 plug hole and in the tank, find some #52 jets, put it back together, test for vacum, and take it out and run the dickens out of it.
If I haven't hurt it by now doing everything wrong, I probably can't hurt it by setting a few things right!!!!!
Thanks guys for your advice and patience.

Re: Low power, low vacum
 

You said the carburetor was a Stromberg. If so, I thought the standard jet is a #45.
When you said you will put in #52 jets, it makes me think you have Holley/Ford carburetor. Plus, if You're at almost 5,000 foot altitude, going bigger on jets is the wrong direction.

Sal

Re: Low power, low vacum
 

Yup, you are right. I spoke before I knew what I was talking about. Looking in the old service manual I have, it showed a picture of a carb and I thought it said Stromberg. Wrong, you are right it is a Ford with 94 cast into the body. The main jets did not have any number on them but using drill gauges a 55 just fits. So, figured 8-10 % because of elevation should put me at 50-52. Old buddy across town has some 50's I am gonna try.

Re: Low power, low vacum
 

Yes I'd try the 50s.