Compression test numbers - Low?
#1
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Compression test numbers - Low?
73 914 - estimated 85k miles.
Did a compression test today. 112 -118 in all 4. Seems low. The car doesn't seem to have a lot of power, but it's only running the little carbs. It's still popping when you back off the throttle and at higher RPMs.
Timing was off. Speaking of that. This engine doen't have a vaccum advance unit on the distributor. Do you just set the timing at idle? I found a red mark on the flywheel that I suspect is the timing mark for 28 degrees. Anyway, it runs ok. Funny, we removed the cap and put it back on, then it would hardly crank because of the severe advance. It's ok now.
Our goal is to figure out the engine before we pull it out to fix the clutch. (won't disengage completely).
Thanks,
Dan and Andrew
73 914 2.0
Did a compression test today. 112 -118 in all 4. Seems low. The car doesn't seem to have a lot of power, but it's only running the little carbs. It's still popping when you back off the throttle and at higher RPMs.
Timing was off. Speaking of that. This engine doen't have a vaccum advance unit on the distributor. Do you just set the timing at idle? I found a red mark on the flywheel that I suspect is the timing mark for 28 degrees. Anyway, it runs ok. Funny, we removed the cap and put it back on, then it would hardly crank because of the severe advance. It's ok now.
Our goal is to figure out the engine before we pull it out to fix the clutch. (won't disengage completely).
Thanks,
Dan and Andrew
73 914 2.0
#2
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While your compression readings are a little on the low side, take solice in the fact that they are so close to each other. You would need to make a comparative test of the gauge on another "known good" compression engine or use a "known good" gauge before accepting the results as gospel. Even so, the readings are not low enough that I would recommend repair to a customer as long as they can accept the fact that the engine is not what it once was or could be. It will not cause more than an even loss of power. As to the timing, use a good advance timing light and set total timing to something in the neighborhood of 30 degrees +/- 2 total advance, adjust for local temp and humidity and run it.
#4
Well I wouldn't pull the motor just yet either. Get it running and sorted out. Identify ALL the oil leaks and then start making the repair list. My son pulled the motor/trans in 3 hours on his own. Just needed help driving one of the jacks to lower assembly out. PP has great step by step procedure with pictures. Also look at setting timing with carbs. It will all be clear.
I think we are going to put the "M" calipers 19MM Master cylinder and "T" fitting on this weekend <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
I think we are going to put the "M" calipers 19MM Master cylinder and "T" fitting on this weekend <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
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Bryan
I was very happy to see the numbers consistant. At least there's hope. I just remember seeing someone with readings near 140 so I was concerned.
Art,
Didn't open the throttle. I'll try it on a couple cylinders and see if it makes a difference. Need to do the oil shot and check rings. Probably won't make much difference, we'll probably just drive it.
Joe,
I definatly want to make sure the motor is ok before we pull it out. Huge valve cover leak on the right side. Fixing that seemed to dry up the engine. Let's hope. I'm more concerned with the popping. The suggestion on PP tech articles helped. I think now we can set the timing correctly. I have to keep saying "We" cause, he's suppose to be doing all the work, at least in theory.
DanD and Andrew.
I was very happy to see the numbers consistant. At least there's hope. I just remember seeing someone with readings near 140 so I was concerned.
Art,
Didn't open the throttle. I'll try it on a couple cylinders and see if it makes a difference. Need to do the oil shot and check rings. Probably won't make much difference, we'll probably just drive it.
Joe,
I definatly want to make sure the motor is ok before we pull it out. Huge valve cover leak on the right side. Fixing that seemed to dry up the engine. Let's hope. I'm more concerned with the popping. The suggestion on PP tech articles helped. I think now we can set the timing correctly. I have to keep saying "We" cause, he's suppose to be doing all the work, at least in theory.
DanD and Andrew.
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Tried the carb open, no change. Then we did an oil test. Slight increase of about 10 psi. Probably about right for an 80k miles car. Put it back together. Fired up and ran good. Decided to go for a test run. Ran quite good without the high rpm popping we were getting before. Apparently the timing was the culprit. Power was better too. Looks like we'll run it like this once we get the clutch fixed. It's getting to be a pain to turn it off to put it into 1st or R.
Thanks all for the help.
DanD and Andrew
Thanks all for the help.
DanD and Andrew
#7
So do you think it is the clutch or transmisson keeping you out of 1st or Rev.
I have problems with 1st if I take it out of gear at a long stop light. I need to make a mental note to push in clutch count to 5 and select 1st.
Real tough to train brain switching from my 928 to my boys 914.
"WE" worked on his brakes all day yesterday. Figuring out why it did'nt stop so good. most of the pads were rusted into the caliper. I think we were only stopping with maybe three and a half pads.
We are playing with the "M' calipers need to rebuild em.
I have problems with 1st if I take it out of gear at a long stop light. I need to make a mental note to push in clutch count to 5 and select 1st.
Real tough to train brain switching from my 928 to my boys 914.
"WE" worked on his brakes all day yesterday. Figuring out why it did'nt stop so good. most of the pads were rusted into the caliper. I think we were only stopping with maybe three and a half pads.
We are playing with the "M' calipers need to rebuild em.
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#8
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Actually, I'm pretty sure it is the clutch. It's adjusted as tight I it will go and yet, in first or second with the clutch all the way to the floor, it will try to move the car unless you hold the brake down.
So, for "us" it's clutch time. Your problem could be the same or it could be syncros going out. Try adjusting the clutch cable, and if not, well... <img src="graemlins/crying.gif" border="0" alt="[crying]" /> Either clutch or syncros. On rare occasions, new or different gear fuid can help.
> "WE" worked on his brakes
I do know what you mean
So, for "us" it's clutch time. Your problem could be the same or it could be syncros going out. Try adjusting the clutch cable, and if not, well... <img src="graemlins/crying.gif" border="0" alt="[crying]" /> Either clutch or syncros. On rare occasions, new or different gear fuid can help.
> "WE" worked on his brakes
I do know what you mean