Engine question...

K

kqa3637

Junior Member
I have a question for the Model A owners about my engine...
I have a 1930 Fordor Town Sedan... All stock... Stock engine with a stock head, stock transmission, and a stock rear end... I am getting 11 miles per gallon...

Cylinder compression is 1-58, 2-56, 3-58, 4-56 lbs ... When I add oil to the top of the pistons and redo the compression test I get 1-60, 2-57.5, 3-60, 4-57 lbs... Not being an engine guru, could someone tell me if the rings are ok, or do I have something more serious going on here...

I have read several places here that the Town sedans should be getting around 15 miles per gallon, and I’m trying to see what I could do to get my mpg’s a little higher... I do use Ethanol free gas, it is well timed, the car runs well and burns No oil...

One more question... If I changed over to a high compression head (like a 5.5 to 1) would that increase the mpg or not?

Many thanks ahead of time...
 
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I say yes and yes. A "wet" compression increase of only 2 lbs. indicates that the rings are good. a higher compression head should give at least 2 mpg. increase in my experience.
 
How are your plugs burning? What are the tire air pressures? What are your driving conditions, hilly, town driving with stop and go,etc! There are way to many variables that determine fuel mileage. Yes a higher compression head should help! Running a coolant thermostat will help! Dragging brakes will not help! Driving with the windows down will not help! How fast or slow your driving will cause mileage to vary! Good luck getting your fuel mileage up and have fun! :-)
 
Big hammer said:
How are your plugs burning? What are the tire air pressures? What are your driving conditions, hilly, town driving with stop and go,etc! There are way to many variables that determine fuel mileage. Yes a higher compression head should help! Running a coolant thermostat will help! Dragging brakes will not help! Driving with the windows down will not help! How fast or slow your driving will cause mileage to vary! Good luck getting your fuel mileage up and have fun! :-)
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all the above in addition to: alignment, rear end ratio, intake leaks, fuel leaks, carb clean and properly setup, idle adjustment is set correctly, Gav set correctly, using spark lever as you should, spark properly setup, timing dead on, etc...

but yes your engine is good.
 
Is ur arithmetic Correct?

Ck your Stoichiometric / A/F ratio on a gas analyzer this will tell ya everything u need
 
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Try a different carb. if you can. Look for fuel leaks. Check Toe in, dragging brakes, and tire pressure. Before you start changing anything other than the carb., double check your mileage. I have a t/sedan. You should get close to 20 mpg. They are heavy cars
 
What sort of driving do you do? Long runs on the open road? Short runs? Stop/start in town? Some or all of the above? Without that detail mpg figures mean very little.
 
myself I don't worry about gas mpg I just love to drive it and add fuel when needed
kevin
1930 tudor
1923 model t roadster p/u
 
I used to get 15 or so, then I replaced the worn cam with a used but not worn "B"cam, put in valve seats because of too many seat grindings, and a thermostat-- top speed went from 52to 67, and fuel mileage over20, on a long trip I averaged 23 at speeds over 60,-- stock head, gear ratio, same untouched carb and dist--- with the old cam I could get spark knock, after never even with full advance in any conditions, both ways the plugs (repro 3X)would burn light tan--- the valves sunk in the block and the cam not lifting the valve out of the hole as much as it should restricts flow
Adding the thermostat was good for 1.5 mpg

The jets in my carb are original, have never been flow tested, but I have done loaded emission testing when it was done for NJ inspections--- both before and after the addition of ethonal, and the ethonal dies lower emissions. My carb is a little rich on regular gas, a little lean on 10%ethonal--- with ethonal the car would have passed emissions as a 2002 Honda Civic--- I had to run it as a later car, no old cars in the database
 
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A cold engine needs a richer mixture, i could close the GAV sooner, ---before the thermostat I had to have 1/4 turn, after I could close it, and the oil stayed cleaner longer because it got up to temp quicker too---thinner oil less friction moving the oil
 
My 1999 Olds 88 runs in the 195* to 205* range because that's where the engine gets it best fuel economy. I use a 180* in my Model A.
 
kwisor said:
myself I don't worry about gas mpg I just love to drive it and add fuel when needed
kevin
1930 tudor
1923 model t roadster p/u
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This exactly. As noted there are too many variables to accurate.
Old timers used to fill up early in the morning when the air and the gas in the ground was cooler. My Grandad said it improved mileage.
 
Do you know the actual rear end ratio? Simple things first. As mentioned, what color are your plugs after warmed up and ran at speed?
 
Another thing to look at is --are the brakes dragging, how easy is the car to push, fuel economy is not just the engine

For the people that say --fuel mileage doesn't matter, it does, running too rich dilutes the oil, increases cylinder wear, carbons the rings,valves, pistons
 
It sounds like your engine is in good shape with all compression numbers within ten lbs of each other. I would not be happy with the stock HP of a mod A, but then I live in a very Hilly area. Myself, I would want to put a high Comp head on it and port and polish the manifolds.
This probably increases the HP about 8-10 or some 20- 25% with out putting more gas in the cyls.
Terry
 
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