Compression question.

P

packrat6

Member
The engine in my '30 Fordor was rebuilt some while before I bought the car. I tracked down the son of the man who had had the engine work done but he did not know much about it.
In doing a compression check, I find the readings at about 110# across all four cylinders. What would have been done to this engine to achieve that kind of head compression??
 
I would think that monster has one heck of a cylinder head on it, maybe two.m[smiley face]. The deck may have been cut quite a bit too. It could make a difference what pistons it has in it.

But, as long as the starter is working,,,,,,,
 
FWIW, I am running a new Snyder's 6.0 head, .060 over pistons and have ~ 105 psi. across all 4.
 
One of my touring engines has a 5.5:1 head on it but it has been off a few times. I have it machined for flatness each time so who knows where it is now. That engine gives me about the same figures as the OP and it's done about 45,000 miles towing a camper that weighs about the same as the car at 50 mph and it's still going.
Your car will have more zip than most with that compression so I suggest you enjoy the heck out of it as it is. Just don't over advance to timing. I'm sure someone will advise what the maximum advance should be but my guess is about 20°.
 
A higher compression also runs a little bit cooler too. Seems odd, but it works that way...
 
Gene F said:
A higher compression also runs a little bit cooler too. Seems odd, but it works that way...
Click to expand...

Yup, combustion is more efficient. More go for less $.
My Burtz engine is running a 6:1 head, cam shaft from a local regrinder - 0.308" lift (I don't have the timing with me at the moment) and a Webber carburettor. At 85-100 kph (53 - 62 mph), it turns in 27 mpg. That's imperial gallons (about 23.7 miles per US gallon). I'm very happy with that. I made a stop on the side of the distributor to limit the advance to 22° - perfect. I'm considering a thermostat for it but so far, over my 4 Model As and several attempts, I have not found one that works anywhere near the way it is supposed to. The worst was a 180° T/stat that opened at 145°. Does anybody make a decent one?
 
Synchro, If you do use the thermostat that is mounted in the output hose, drill some holes in the flange so that there is some circulation when it is closed. The thermostat will operate better. Otherwise it will open in bursts causing the engine temperature to fluctuate and the coolant to escape out the overflow pipe when the slug of hot coolant gets into the radiator. Plus it keeps the head temperature more uniform.
 
Increasing volumetric efficiency through performance upgrades results in an engine that runs cooler and doesn’t have the common failures that stock engines do…burned exh gaskets, warped manifolds and failed condensers (from heat) to name a few..

Vintage precisions thermostat housing support the thermostat correctly, instead of lodging it in the hose. This stability decreases binding and warping during heat cycles, insuring accurate opening temps.
 
jack backer said:
Increasing volumetric efficiency through performance upgrades results in an engine that runs cooler and doesn’t have the common failures that stock engines do…burned exh gaskets, warped manifolds and failed condensers (from heat) to name a few..

Vintage precisions thermostat housing support the thermostat correctly, instead of lodging it in the hose. This stability decreases binding and warping during heat cycles, insuring accurate opening temps.
Click to expand...

Why install a thermostat on a motor that comes to operating temperature so quickly and wasn't designed to operate with one? I'm new to the A, trying to soak up all the info I can.
 
Because if you have a radiator that cools well and you drive at temperature below 60*F the engine will not get up to operating temperature
 
And when an engine doesn’t get to proper operating temperature increased engine wear is the result, along with inefficient combustion, the two issues work together to shorten engine life. It’s why every modern engine one.
 
nkaminar said:
Synchro, If you do use the thermostat that is mounted in the output hose, drill some holes in the flange so that there is some circulation when it is closed. The thermostat will operate better. Otherwise it will open in bursts causing the engine temperature to fluctuate and the coolant to escape out the overflow pipe when the slug of hot coolant gets into the radiator. Plus it keeps the head temperature more uniform.
Click to expand...

Perhaps I should have mentioned that I have always drilled 3 x 1/8" holes in the T/stat, even before it was mentioned here.
 
Get a modern t/stat, tig weld it to a short length of SS tube that will fit in the top hose,Hey presto a modern t/stat that works. All my old rockets have them in , take a look on the v8 side and see how the 33 went out west this last month.
Lawrie
 
Lawrie said:
Get a modern t/stat, tig weld it to a short length of SS tube that will fit in the top hose,Hey presto a modern t/stat that works. All my old rockets have them in , take a look on the v8 side and see how the 33 went out west this last month.
Lawrie
Click to expand...

I agree with the thermostat in the hose with the sleeve (AND a clamp) to keep it from moving up the hose or turning around "Bass Aackwards" like a stat without the sleeve will do..

Berts has been selling these sleeved stats for at least 20 years.

I used a version of this setup since 1963.

It was a tractor thermostat inside a housing which I installed in upper hose after cutting 3 or 3 1/2 inches out of the hose. Was made in Holland ... I still have it in the garage.

After 50,000 miles it finally gave up the ghost.

I now have the Vintage Precision housing since whenever they introduced them.
 
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