Something Doesn't Seem Quite Right...

[Don G 1947]

There is a wall somewhere that should have an indent of my face on it,

All I have to say is, stupid oil bath air cleaner...

Oil bath air cleaners require 50 weight oil.  Anything less than that and it will slosh around and cause facial indentations on walls.

 

Don

[41/53dodges]

So I was filling up the truck yesterday, it got less than 8 MPG now! what the heck is going on here? valves were all adjusted and the distributor was timed recently.

Why would the mileage still be not good?

[Don Coatney]

So I was filling up the truck yesterday, it got less than 8 MPG now! what the heck is going on here? valves were all adjusted and the distributor was timed recently.

Why would the mileage still be not good?

 

 

Did you read your spark plugs?

[41/53dodges]

Last I checked they were a nice golden brown color,

The brakes aren't hanging up, went through them last week to find a leaky wheel cylinder, cracked union, and plugged up master cylinder (causing a slight hangup)

Like usual the truck spent some time idling around, plus idling while doing the adjustments, so probably round 2 hours of total idling. would that be enough to chug 2 gallons of fuel? actually that makes sense...

[TodFitch]

Last I checked they were a nice golden brown color,

The brakes aren't hanging up, went through them last week to find a leaky wheel cylinder, cracked union, and plugged up master cylinder (causing a slight hangup)

Like usual the truck spent some time idling around, plus idling while doing the adjustments, so probably round 2 hours of total idling. would that be enough to chug 2 gallons of fuel? actually that makes sense...

I'm getting confused on the math, old age. But maybe I've got it:

My '33 Plymouth gets about 17 miles/gal on the road. It is geared such that at 60 MPH (1 mile/minute) it is running about 3000 RPM.

 

So in 3000 revolutions of the engine it goes through 1/17 of a gallon of gas. Or to reverse things it uses about 1 gallon every 51000 revolutions.

 

If you idle at 600 RPM for 120 minutes, that would be 72000 revolutions which, if it uses gas at approximately the same rate as when driving, would be a bit under 1.5 gallons.

[Don Coatney]

I'm getting confused on the math, old age. But maybe I've got it:

My '33 Plymouth gets about 17 miles/gal on the road. It is geared such that at 60 MPH (1 mile/minute) it is running about 3000 RPM.

 

So in 3000 revolutions of the engine it goes through 1/17 of a gallon of gas. Or to reverse things it uses about 1 gallon every 51000 revolutions.

 

If you idle at 600 RPM for 120 minutes, that would be 72000 revolutions which, if it uses gas at approximately the same rate as when driving, would be a bit under 1.5 gallons.

Interesting concept. Is fuel consumption per revoloution the same at idle as at speed? Everytime you push the foot feed the accelerator pump squirts, the throttle plate opens, spark advance changes, a different carburetor jet comes into play, and the engine is working harder pushing the car that is resisting every move. Lots of things to consider. My confused thoughts are that more fuel is consumed at speed as more work is being done.

[TodFitch]

Interesting concept. Is fuel consumption per revoloution the same at idle as at speed? Everytime you push the foot feed the accelerator pump squirts, the throttle plate opens, spark advance changes, a different carburetor jet comes into play, and the engine is working harder pushing the car that is resisting every move. Lots of things to consider. My confused thoughts are that more fuel is consumed at speed as more work is being done.

Yes, I would expect more fuel to be used at speed. . . But for the first approximation that ought to set an upper limit.

 

Forgetting all the nasty details about the internals of a carburetor and just assuming that it does a perfect job, make the assumption that it is getting the theoretical best fuel/air mixture of 14.7:1 by weight at all times. The amount of fuel/air being sucked into the engine depends on displacement, RPM and absolute manifold pressure (atmospheric - measured vacuum). Displacement is constant for any given engine and RPM is the first approximation dealt with above so we are left with fuel consumption being proportional to the inverse of the manifold vacuum (high vacuum => low consumption). (Thus the reason they used vacuum gauges on the dashes of some cars in the 1970s that were labeled in MPG to assist the driver in being economical.)

 

Since the vacuum is, or at least should be, higher at idle than under load the fuel consumption per revolution will be lower at idle.

[41/53dodges]

So I think I figured out the fuel issue, the float was almost 1/8" too high, allowing fuel to seep down the sides of the carb, plus Ive noticed that even though the tank was full, fuel is sloshing in it. so that means it really never is full due to the lack of a vent!

Now the real issue I need to address, I'm sure youve seen the picture of my radiator, so I ordered a new one and while I wait I'm going through everything to prevent this, but i still need to adapt the radiator. The top inlet is 1.5" and points straight back, which calls for a straight thermostat housing too. I read that a 64 and up mopar v8 housing (like the one below) as a similar bolt pattern and thermostat diameter, but the correct hose placement and size. Can anybody confirm this? Also, the old style thermostat likely wouldnt work here, so a new style would be needed. any issue there?

Thanks,

Josh

 

http://www.ebay.com/itm/Spectre-4739-Straight-Chrome-Thermostat-Housing-/400472731516?pt=Motors_Car_Truck_Parts_Accessories&hash=item5d3e08ef7c&vxp=mtr

[Jeff Balazs]

Josh;

I sourced a straight new style thermostat housing from VPW.

 

Jeff

[Merle Coggins]

Does your engine have the external bypass type thermostat? If so, I would suggest drilling a small hole in the center plate of the new thermostat to create a slight bypass. This helps to allow a little bit of circulation to bring the hotter coolant up to the thermostat so that it will open.

 

Merle

[41/53dodges]

Thanks Jeff, but this is not a stock replacement. this is for a different size hose for an aftermarket radiator.

And Merle, luckily this is an internal bypass motor, so no issues there!

[Plymouthy Adams]

on the Radiator...Summit Racing has a various style and sizes of after market radiator you would be able to adapt to your build.  Ihave always been successful grabbing one of these.  I will admit that on two of my builds the lower outlet I had cut and welded to meet the requirements of the Mopar lower hose as they are a bit different than Ford or Chev applications...this is not a hard or expensive task to have done and given the very cost of these radiators compared to a custom build..you dollars ahead..the aluminum built units are great heat exchangers also. Summit radiator are available by picture on dimension on their website and can be bought by size of unit, size and position of inlet/outlet and with or w/o automatic trans oil cooler

[41/53dodges]

Ive got the radiator, a pretty nice griffin aluminum job (if the stupid thing ever ships!) And it just seems to me that adapting on the engine end would be better than the expensive new radiator end, hence the new thermostat housing.

[Plymouthy Adams]

as a note to you and not stated on the box of any Griffin at the time and I have not followed up since talking to the president of the company, the rads are only warranted to 16 lbs of pressure...he stated to me on the phone that all modern advertising and shipping instruction will point out this lack of information and state the 16 max application...

[41/53dodges]

hmmm... Thats pretty odd. Nowhere have I seen this information! Good thing I am only going to run a 6 lb cap, for the heater cores sake. So it sounds like you have experience with griffin, other than that is there anything wrong with them?

[Plymouthy Adams]

not to my knowledge...just as a matter of information, lots of circle tracker use these extensively and they report running to 22 lbs with no adverse effect...I just stated the limited warranty pressure as this is not an addressed item in their paperwork that comes with the product in the past...

Edited August 3, 2013 by Plymouthy Adams

[41/53dodges]

Well thanks for the tip!

Now my biggest question is still, does a normal new style thermostat work on our engines? I though there was something awhile back about it interfering when it tries to open

Edited August 3, 2013 by 41/53dodges

[Plymouthy Adams]

there are adapters available that does use the later style thermostats...as long as you use this in conjunction with the newer item you should well be set to go...dependent on the style thermostat housing this may not be a needed item and a late model thermostat will fit without any need to adapt..

Edited August 3, 2013 by Plymouthy Adams

[41/53dodges]

there are adapters available that does use the later style thermostats...as long as you use this in conjunction with the newer item you should well be set to go...dependent on the style thermostat housing this may not be a needed item and a late model thermostat will fit without any need to adapt..

Thats what I needed, Thank you sir!