Hi all

Can you please help me I have obtianed a 1500cc datsan motor Yes I know it's not a 1200 I have two of these also. However what I'm wanting to know is the 1500 I have has 120lbs in each cyinder which seems a bit low to me do they make a low compression motor or should it be around the 170lb mark all suggestions wellcome thanks.

Noel

Hi Noel,

Datsun made several totally different 1500cc engines, including but not limited to E15, J15, A15.

Which one do you have?

120 lbs sounds good, especially if they all four cylinders read the same.

Most engines I've worked on have around 145 psi, it all depends on the cam -- as well as the static compression ration. Most engines from 70s and 80s used 8:5:1 ratio. Most Datsun engines were around 9:1.

Hi thanks for that it is an A15 motor and yes all four are at the same compression. I have not run this motor yet. However I was told it was a bit sluggish. if 120lbs is allright could you think of what could corse it to run sluggish and what I can check for thanks.

Noel

cheak the cam timing and the advance in the dizzy

these are the two most common reason's for a good engine to run slugish

that sounds low to me, i think spec is supposed to be 170lbs
if they are all low and even, definetly check cam timing

Yes there's a quoted spec, but I've never measure it that high.

Most mechanic's books say don't worry about the number, unless the cylinders vary.

Anyways, if you want to be sure, re-rest it:
1. Remove all four spark plugs, block throttle open
measure compression
2. Squirt a little engine oil in each plug hole
measure compression

If it goes up significantly after oiling, that indicates the rings are worn out.

good to see someones been listening at tech lol

really?!
mine's always been right at 175lbs, never bothered with the wet test....
hell when i first built my corolla, i had almost 250lbs per cyl!!!!! i had to scrap THAT head

Really.

But I don't doubt you saw 175+ psi.

Maybe it depends on the guage. The last thing you want is to rebuild an engine that doesn't need rebuilding. In the end guys say "see, it works good now" but it worked good before too. If the engine is not smoking from the rocker cover or tailpipe there is no need to put new rings in it. However most people can't see the tailpipe when they are driving.

Hi thanks for all the info will have a look at the timing etc etc once again thanks


Noel