How hot is too hot?

[Ritzy1]

Thanks again for all the feedback. As many of you know, these carbs come with .045 jets. Since I'm a rookie with flatheads, I consumed Vern Tardel's book How to Rebuild and Modify Ford Flathead V-8 Engines. That became my bible. In there, he recommended starting with .041 jets with a dual carb setup at sea level, which is what I did. When I first started it up, it went way hot, so I changed back to the .045 jets. After some tuning by John Freeman at Freeman's Garage (authorized Stromberg distributor), we decided to put the .041s back in. There may indeed be a happy medium (.043). Again, it's only been on the road for two weeks, so I'm still sorting. I do love how it cruises along effortlessly on a flat highway at low RPM in 5th, but I realize I've got to raise the RPM up for when I come to a hill. So far, I've just been dropping it down a gear if it starts to lug. I think I've yet to get it above 3,500 RPM in any gear.


40cpe, I'll test your equation when I take it for a spin later this week, and let you know the result.

[qmdv]

Originally Posted by flatjack9

i'm running about 2300 rpm at 70 mph. Get around 20 mpg on the highway.

I have no overheating problem cus I just got the engine fired up. But in a 32 Roadster with 281cu in 59AB and 3.27 rear end gears I calculate 2700 RPM at 70. Is that to many RPMs. Tires are 28 1/2 diameter

[JSeery]

Originally Posted by qmdv

I have no overheating problem cus I just got the engine fired up. But in a 32 Roadster with 281cu in 59AB and 3.27 rear end gears I calculate 2700 RPM at 70. Is that to many RPMs. Tires are 28 1/2 diameter

Just depends on the rpm range you are comfortable with. I like to keep the engine in a bit higher rpm range myself, other do not. It also depends on the cam you are running. I like a longer duration higher lift cam, there for the higher rpm range.

[big job]

Thats why Model Ts have no temp gauge !!! LOL

[Ol' Ron]

I don't think it's too hot, YET! like tosee cruise RPM around 2400 with a Max#1 cam. Enjoy the ride.

[Sid]

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Running that trans./rear end gearing you may be lugging. I'm running the same overdrive trans. with 3.25 gearing and 235/70/15 tires and at 65ish in 5th gear i'm at about 1900 +- rpm and I almost feel 3.40 gears are possibly more suited. With your gearing you may consider running in 4th gear. I am running the V8 Camaro 5 speed that has the 2.95 first gear so you may have to consider your first gear ratio for your decisions. As far as a final rpm probably 2100 to 2500 rpm is a good safe range. Some folks may dis agree.

[Ritzy1]

Originally Posted by Ol' Ron

I don't think it's too hot, YET! like tosee cruise RPM around 2400 with a Max#1 cam. Enjoy the ride.

Interesting to see you recommending 2,400, Ron. Putting this thing together, my mind was thinking low RPM at highway speeds like a modern car (1,800-2,200).

I was also surprised to see flatjack9 getting 20 MPG running 2,300 RPM.

This is how I learn. Great resources here! Thank you!

Tomorrow night when I get home I'll see what the RPM is in 4th @ 70 MPH.

[Ol' Ron]

I also think the water pumps have allot to do with the temp. along with the radiator and condition of the block water jackets. Most modern radiators have a 7 LB cap. Yet some engines overheat. Flatheads do that????

[Tinker]

Just to keep this in this thread and not start another.


rpms.


Idle about 1000-1200
Running/cruising 2000 -2400
Max on a hop up 3,500-4,000


???


.

[Liam]

Do not pay attention until it starts to boil.

[tubman]

Originally Posted by Tinker

Just to keep this in this thread and not start another.


rpms.


Idle about 1000-1200
Running/cruising 2000 -2400
Max on a hop up 3,500-4,000


???


.

This seems high. What cam are you running?

[JSeery]

Originally Posted by Tinker

Just to keep this in this thread and not start another.


rpms.


Idle about 1000-1200
Running/cruising 2000 -2400
Max on a hop up 3,500-4,000


???
.

I like a fast idle, but that's way beyond a fast idle! Your halfway through the advance curve.

[flatjack9]

I idle at 800 with my 39. I like the speed up a little because of the cam and the crank mounted fan.

[Ritzy1]

Mine seems to idle all over the place. It certainly doesn't like to idle when it's cold. If I try to hit the road too fast, it'll die when I come to a stop. Once it's warmed up it can range from 750-900. I need to check to make sure the throttle's not sticking somewhere.

[Charlie Stephens]

Is your temperature gauge accurate? You can boil a pot of water at sea level and it will be 212 degrees.

Charlie Stephens

[Ritzy1]

Originally Posted by Charlie Stephens

Is your temperature gauge accurate? You can boil a pot of water at sea level and it will be 212 degrees.

Charlie Stephens

Haven't tested it Charlie, but I also don't feel the need to. It's brand new Dakota Digital stuff, and when the fan kicks on using a separate thermostat control, the gauge is reading 185.

[Ritzy1]

Originally Posted by 40cpe

Assuming 27" rear tires, the RPM calculator says that Ritzy1 should be turning about 2378rpm at 70 in 4th gear (1:1 ratio). That would be an option to check the operation and temperature at normal RPMs.

Yup, 2,380 RPM @ 70 MPH in 4th. Right on. It did tick up to 205 on both heads again, but dropped fairly quickly when I slowed a bit. May need to fatten it up.

[qmdv]

Originally Posted by Ritzy1

Yup, 2,380 RPM @ 70 MPH in 4th. Right on. It did tick up to 205 on both heads again, but dropped fairly quickly when I slowed a bit. May need to fatten it up.

What is your rear end ratio

[Tinker]

Originally Posted by JSeery

I like a fast idle, but that's way beyond a fast idle! Your halfway through the advance curve.

I probably idle at about 600-700, I'm guessing... Don't have a rpm on the car but have a rpm tester, never really tested, just by ear (guess I'll test it, i tune with vacuum). I do have a reground cam, it's a bit lumpy. Could use a bit more idle so it doesn't load up idling. I do run a vacuum gauge in my 36 full time, no rpm.


It was just a topic suggestion I made for discussion. Not what I run.

[Tinker]

Originally Posted by Ritzy1

Mine seems to idle all over the place. It certainly doesn't like to idle when it's cold. If I try to hit the road too fast, it'll die when I come to a stop. Once it's warmed up it can range from 750-900. I need to check to make sure the throttle's not sticking somewhere.

Have you put a vacuum gauge on the car? How are the plug reads? Sounds to be too lean from that description. Possible float or fuel pressure. Just from your post above.