Motor help

[jchalk1949]

I have a 52 Dodge Coronet running a 1949 218 Dodge truck motor with the three speed trans. Car trans., not truck. I didn't do this swap, it came this way. I rebuilt the motor, and find that top speed is around 45 mph. Compression is around 90 psi across all cylinders, and vacuum is around -24 psi at intake manifold. I have heard that trucks of this era were under powered and maybe this is all I can get out of it. ANY ideas? Any upgrades, like in cheap? I am looking into getting a drive shaft made, so should I swap? And to what. I do like the flathead though, and it was my first rebuild. Though it is 80 over, and leaks oil on the floor. One last question. do these motors make a tapping noise? I know that the lifters make noise, but this sounds pretty loud.

Sorry for the long post, but if anyone can help, it is the people on this site.

[greg g]

90 is low for a fresh rebuild, what rear end is nthe car? does the engine rev ok when not in gear? Is the fluid drive still inplace? No it should not be making a loud tapping sound. Can you isolate where the sound is located? Up high like valves or down low like bearings.

When you say rebuilt, did you mess with the timing chain and gears? did you get it aligned forrectly for proper valve timing?

Truck and car engines were pretty much alike as far and power and torque ratings are concered.

[Dodgeb4ya]

That car should have plenty of power for a six and be able to drive at 60 MPH. Rear end ratio is stamped on a small flat pad on the underside of the differential-probably a 3.9 or worse a 4.11. Too low for 60 MPH !

[jchalk1949]

No fluid drive. Cylinder pressure taken with a questionable gauge. But all are equal. Engine just seems to wind out at 45. I will check the gear ratio of the rear when I get a chance, but that seems like a possible.

[jchalk1949]

Yes it was a complete rebuild. New timing chain. Sound, sounds like lifter noise.

[greg g]

what size tires?

[jchalk1949]

The number of thr rear axle is 1141544-44. there is a 241 above this number. Closest I can come up with, and this is with a mirror looking upside down is 3.91 or 3.61. Tag is on the top of the carrier. Tire size is 235/75R15.

[Big_John]

Yes it was a complete rebuild. New timing chain. Sound, sounds like lifter noise.

Have you checked the valve lash?

[jchalk1949]

Twice. Just like it says in theP15-D24 technical tips.

[jchalk1949]

That sounds right. NOW the million dollar question. Could the gears be to high? Just to set the record straight, i reviewed my first post and it should read 1950 coronet.

[greg g]

With your tires and gears your car should easily cruise at 60 mph at about 2800 RPM give or take.

I run 225 75 15 with 4.11 in my plymouth coupe 62 is 3120 on various calculators.

45mph would be around 2200 rpm. with your set up

Edited July 7, 2011 by greg g

[jchalk1949]

Great. I guess I need to hook up a tach. while driving to see. Seems like I upshift from 2nd. to 3rd. around 25 mph. Is it possible with all things being right ( like no slipping clutch, no dragging brakes ) , for the engine to wind up and the car not go over 45 in third gear?

[55 Fargo]

Great. I guess I need to hook up a tach. while driving to see. Seems like I upshift from 2nd. to 3rd. around 25 mph. Is it possible with all things being right ( like no slipping clutch, no dragging brakes ) , for the engine to wind up and the car not go over 45 in third gear?

This car should wind up at 85 mph, never mind 45 mph.

How does it sound at 45 mph, is it revving high, or is it running quietly down the road.

You state your running it with the gas paeadl to the floor, correct?

Is the throttle linkage working correctly or is it not opening the carb all the way?

Timing, valve adjustment, coil plugs wires,are all ignition, and fuel systems functioning and verified to be correct.

Shifting from 2nd to 3rd at 25 mph sounds about right. At 45 mph, is your gas pedal right to the floor?..........

[jchalk1949]

I am not sure, but I think the peddle has a little more room to go. As I stated in the first post, the car shakes from a bad u-joint. The machine shop did not get it right. So the car shakes at higher speed. But it does seem to me to be revving quite a lot. Kind of like a "if I give it more gas I may blow the motor" feeling. I will take it out this weekend and try again. Thanks to all. Will keep you Posted.

[55 Fargo]

I am not sure, but I think the peddle has a little more room to go. As I stated in the first post, the car shakes from a bad u-joint. The machine shop did not get it right. So the car shakes at higher speed. But it does seem to me to be revving quite a lot. Kind of like a "if I give it more gas I may blow the motor" feeling. I will take it out this weekend and try again. Thanks to all. Will keep you Posted.

Clutch slipping, or 4.56 ratio diff. Okay revving high at 45 mph with 3.91 gears does not add up.

Even with 4.11 gears, it would sound busy at 50 mph, but would certainly go faster.

[55 Fargo]

I am not sure, but I think the peddle has a little more room to go. As I stated in the first post, the car shakes from a bad u-joint. The machine shop did not get it right. So the car shakes at higher speed. But it does seem to me to be revving quite a lot. Kind of like a "if I give it more gas I may blow the motor" feeling. I will take it out this weekend and try again. Thanks to all. Will keep you Posted.

Okay, this is new info, but should not allow your car to tap out at 45 mph, with the gas peddle floored.

Are your valves adjusted correctly?

If you have driveline vibration, you need to determine the cause and correct it.

I suggest you contact your "machine shop", and have them work with you on this.

How do the spark plugs look?............

[Niel Hoback]

I think you should check your throttle linkage. It sounds like the pedal doesn't pull the throttle open far enough. Have someone hold the pedal down whike you look down the throat to see if it is actually wide open. the throttle linkage length is adjustable across the top of the head.

Do you have a thick carpet under the pedal?

[jchalk1949]

No carpet and the throttle opens.

[55 Fargo]

No carpet and the throttle opens.

Okay well thats good news, so what have you done in the last few days to diagnose the problem?

Did you speak with your "machine shop" about it?

[Don Coatney]

Have you checked the accuracy of your speedometer?

[jchalk1949]

After almost two months, and $200 the problem is solved. It seems that the replacement points from Autozone did not have a strong enough spring. The points would float at higher speeds. I have noticed a better idle now also. The mechanic I took it to works on older cars, and it still took him awhile, though he did seem to think it was in the ignition system. I think he got the replacement points from NAPA.

[greg g]

That seems to be par for the course these days with points being made in china. Probably with mexican parts. Your problem has been reported several times here.

Also I would doubt they will hold thier gap for very long and you probably willneed to check them after about 1000 miles. The rubbing block, is made out of recycled milk cartons, and they are no longer equiped with the little felt lubricating wick.

I looked at sets from NAPA, Auto Zone, and one or two other before finally getting 2 American sets from Car Quest with built in spring hard plastic rubbing block and the lubricating wick.