Continental L-head Gas Compression numbers

[stevieb49829]

Is 120 PSI after 3-4 cold revolutions good enough for an F 124 Continental (out of a forklift)? It had that in 2 of the 4, but there was probably crud in the valves on the other two at 95 PSI. I didn't do it!! Someone pulled the plugs with dirt around their bases. It's all cleaned up now, and I'll run the test again when it's all back together and has a starter hanging on it. I know about the 10% difference between them. steve

 

[NDIHC]

I don't know about your particular engine, but the old timers that I started out working with in the 80s always said that you should have a minimum of 90 psi on old engines. Now our manufacturer says 170 minimum. Times have changed!

 

[stevieb49829]

I don't know about your particular engine, but the old timers that I started out working with in the 80s always said that you should have a minimum of 90 psi on old engines. Now our manufacturer says 170 minimum. Times have changed!

These old Continentals have 6-7 to 1 compression, some lower than that. Most automotive engines run at least 9-1, and some a lot higher. I can see why the 170 would be desireable nowadays, with variable timing and computer-controlled ignitions to keep the spark where it does the most good.

 

[NDIHC]

These old Continentals have 6-7 to 1 compression, some lower than that. Most automotive engines run at least 9-1, and some a lot higher. I can see why the 170 would be desireable nowadays, with variable timing and computer-controlled ignitions to keep the spark where it does the most good.

Ours are in the 10 to 11.5 to1 range with with variable valve timing, variable valve duration and either direct or both direct and port injection. Our turbo engines are in the 9 to 1 ratio range. Some a little higher. We also have the Atkinson cycle engines with variable compression ratios. They make for a lot of power from small engines and clean burning. But those old low compression, slow running engines sure are smooth and quiet running. My 1940s Chevy 216, 50s 235 and old tractors with 5.5 or 6 to 1 compression would run happily at 90 psi. These new ones misfire at 160 psi.

 

[dhermesc]

There is a reason seeing an old Farmall or Ford that is 70+ years old still running and being used as an everyday event - but to see someone driving a 1949 Ford or Chevy in traffic in a daily commute would be rare event that most would record.

 

[Richard G.]

There is a reason seeing an old Farmall or Ford that is 70+ years old still running and being used as an everyday event - but to see someone driving a 1949 Ford or Chevy in traffic in a daily commute would be rare event that most would record.

I know it's been a while, but I drove my 51 Chevy PU 30 miles round trip to work all through the 80's.
Original engine and 3 on the tree.
Hauled a lot of firewood in the winters and sold it to students at Clemson where I worked.

 

[Butch(OH)]

Start it up and see how it runs. If it runs OK then forget what the compression guage read, or is it going in a race car? LOL

 

[Dean]

There is a reason seeing an old Farmall or Ford that is 70+ years old still running and being used as an everyday event - but to see someone driving a 1949 Ford or Chevy in traffic in a daily commute would be rare event that most would record.

On the way home from my doctor's office, yesterday, I noticed a seemingly stock Model A in my rear view mirror.

 

[stevieb49829]

Start it up and see how it runs. If it runs OK then forget what the compression guage read, or is it going in a race car? LOL

My fingers are crossed, Butch. I looked it over good with the head off (while cleaning the spark plug dirt out of the cylinders) and it's in really good shape. Valves and seats are very clean, and matching good, and it looks darn near brand new in there. .040 over and no ridge. I think I found a keeper, in spite of having to do a bit of work to change it from being in a forklift. For $200 scrap price I think it was a really good bargain. I'll be back when I have a video of it starting and running - maybe next week. steve

 

[Blackhole49]

Is 120 PSI after 3-4 cold revolutions good enough for an F 124 Continental (out of a forklift)? It had that in 2 of the 4, but there was probably crud in the valves on the other two at 95 PSI. I didn't do it!! Someone pulled the plugs with dirt around their bases. It's all cleaned up now, and I'll run the test again when it's all back together and has a starter hanging on it. I know about the 10% difference between them. steve

This tractor runs fine pulling the attached mower with 95 in all 4, albeit with smoke and burning a qt of oil every 5 hrs. Been doing that for the 20 years I've owned it.