1948 B1D compression question

[tomater48]

Have 1948 that starts and runs quite well - but seems to strain going up hills.

Did compression test which resulted in the following (dry/wet)

Dry Wet(30w)

105 112

100 110

98 110

90 105

65 78

100 108

Any thoughts on if

1) the one cylinder could be cause of low power

2) What first jumps out at members that might be causing the problem

3) Truck starts and runs really well - should I fix or leave?

Thank you!

[Merle Coggins]

You might want to check your valve adjustments. One low cylinder could indicate a valve not seating properly. You may have one too tight. Or it could be bad rings on that one piston. Do you get a lot of blow-by or smoke?

I'd also recheck the points gap and timing. I had my points get out of adjustment due to a rapidly wearing rub block. When the gap got too small I lost coil performance. It also make the timing retarded which robbed engine power. A quick readjustment made it a whole different truck.

Merle

[Dave72dt]

The one thing to remember is these engines didn't make the horsepower we're used to in more modern vehicles so they aren't going to top hills the way you're used to. Check out the low cylnder and if you're not smoking, drive it.

[stevenelle]

When I first got my B2b and got it running, all cylinders had poor compression. Yet it ran fine (and sure was easy to start with hand crank). Never had an excess of power but more than I would have thought possible from an old worn out 1950 engine. I drove it that way for about a year or two.

I suspect it might be what has already been suggested (point gap and/or ignition timing). You may need to advance the spark way more than what the book says. May want to use a vacuum gauge to help set.

That original engine ran well enough, although it smoked a bit too much. Rebuilding the engine was very satisfying for me and it was the first engine I had ever done. The guys on this forum will provide you with all the help and encouragement you need to tackle just about any job.

I like your forum knickname. The kids in my neighborhood call me Tomater when they see my truck parked out front. For those of you who do not know who Tomater is - a talking, old, beat-up, buck-tooth tow truck cartoon character from a kids movie "Toystory". If you have young grandkids ask them about it.

[Merle Coggins]

For those of you who do not know who Tomater is - a talking, old, beat-up, buck-tooth tow truck cartoon character from a kids movie "Toystory". If you have young grandkids ask them about it.

Actually TowMater is from the movie "Cars". You don't have to be a kid to love it.

[41/53dodges]

nope, but the sequels are always crappier. BTW merle, i need to convince my father that about 60 LBS compression out of an engine sitting awhile is normal, otherwise he is all thats holding me up right now. he thinks in terms of 180 being low compression, as he is a 2-stroke engineer. any ideas to convince him?

[tomater48]

Hi Merel -

Thank you for the sage advice.

I was not thinking timing - but can see how that would do it.

I do not get much blow-by at all and it does not smoke.

Will check out timing and points.

[tomater48]

Stevenelle -

WIll be checking the timing and advancing the spark.

I think you and Merle may be on the mark.

It is curious that it seems to have plenty of low end torque - the advanced spark may just do trick.

Thanks again.

[Merle Coggins]

BTW merle, i need to convince my father that about 60 LBS compression out of an engine sitting awhile is normal, otherwise he is all thats holding me up right now. he thinks in terms of 180 being low compression, as he is a 2-stroke engineer. any ideas to convince him?

Well, I'm not going to try to advise how to convince your father to let you buy stuff that will add clutter to his garage. That's between you and him. However, the lower compression numbers from the engine in question is partly do to it sitting and not running for some time. Also, I don't believe the cranking speed was up to where it should have been. I may need to go through the starter as well, or get a better jumper pack to crank it with. My shop manual specifies 110-140 PSI @ a minimum 150 RPM. It also specs 80 PSI minimum and 20 PSI maximum variance between cylinders.

In the mean time, since it's not in my way, it'll sit there until you come get it or tell me otherwise. If I get time I may tinker with it some more and get it running. Your father might be more convinced if it starts and runs good, but that will also raise the price.

Merle

[Dave72dt]

nope, but the sequels are always crappier. BTW merle, i need to convince my father that about 60 LBS compression out of an engine sitting awhile is normal, otherwise he is all thats holding me up right now. he thinks in terms of 180 being low compression, as he is a 2-stroke engineer. any ideas to convince him?

Pull the plugs out of a daily driver and run a compression test on it for comparison? He may only see 140 or 150 out of it. You may want to do this without him around first and if you leave the lights on and run the battery down so it goesn't spin too fast, that'll help.

Unless you have some broken rings on that piston, compression will come up as the rings loosen up in the piston.