I got my motor built have about 1300 miles on it now. Had compression checked out. All but one cylinder is close to 160. The low one is 120. Is this ok and why. I called the engine builder he said it could be a bent valve. He asked how it ran or if I could here any ticking noises. I said no ticking noises and runs good. He said I shouldn't worry about it. Any input. Got eagle crank, rods, je pistons champion ported irons and match ported intake. T@D roller rockers and a 212/212 comp roller cam. Also main caps.
New motor bad compression?
- Thread starter J_risch
- Start date
- Joined
- May 28, 2001
1. After the engine has run for the first hr, it's about as "broken in" as it's going to get.
2. Recheck the valve settings.
3. 40psi difference is waaay too much.
2. Recheck the valve settings.
3. 40psi difference is waaay too much.
Just a Six??
OK! Who Farted??
- Joined
- Jul 4, 2003
Bent valve, bad rings? Something is wrong. try a leakdown test on it. Maybe you will find something?
Just a Six??
OK! Who Farted??
- Joined
- Jul 4, 2003
Break in what?? Rings seat in first few miles. Some boost helps & other than that its broken in. If a flat tappet cam thats done in the first 20 mins of 2000-2500 rpm for 20 mins.
He has 1300 miles so its definately broken in already. I hope he didnt baby it or cruise at steady speeds all the time.
meanchicken
gallo vicioso
- Joined
- Oct 6, 2007
If you have not re-torqued the heads.....re-torque the heads...
novaderrik
Well-Known Member
- Joined
- May 12, 2004
lots of brand new cars and trucks get synthetic oil right from the factory- every Corvette built since the mid 90's, for example. i don't think there is any need to break in those engines..
with modern machining tolerances and materials, the rings are broken in by simply turning the engine over on the engine stand as you assemble it, and a flat tappet cam is broken in after about 20 minutes of run time.
turbofabricator
Well-Known Member
- Joined
- Mar 7, 2004
I disagree with this. It takes MUCH more radial tension to seat aqq set of rings than the engineered radial tension, especially with a set of performance rings. On the engine dyno, you can watch the rings actually seat by watching blow-by. They generally won't seat until a significant load is applied. Boost, as stated earlier, helps seat the rings. It is cylinder pressure behind the ring that forces them hard against the cylinder wall, creating the ring seal by "wearing" into the block. There is nowhere near enough radial load to knock down the honing ridges by turning, the engine over on the stand. I DO agree with your other statements, though.
I break an engine in by running it at 2,000 rpm for 15-20minutes while checking for leaks and any other anomoly. Then drain oil and cut the filter to check for copious amounts of debris. (There WILL be some) then add new oil/filter. Warm engine up, then put in gear, slowly bring boost up to 2-3 Psi against the converter, then slam my foot to the floor and watch the boost go to 15 or so. This is what actually seats the rings. Then hand the keys over and tell them to go ahead and race it today.
quote
<<with modern machining tolerances and materials, the rings are broken in by simply turning the engine over on the engine stand as you assemble it.>> quote
I break an engine in by running it at 2,000 rpm for 15-20minutes while checking for leaks and any other anomoly. Then drain oil and cut the filter to check for copious amounts of debris. (There WILL be some) then add new oil/filter. Warm engine up, then put in gear, slowly bring boost up to 2-3 Psi against the converter, then slam my foot to the floor and watch the boost go to 15 or so. This is what actually seats the rings. Then hand the keys over and tell them to go ahead and race it today.
quote
<<with modern machining tolerances and materials, the rings are broken in by simply turning the engine over on the engine stand as you assemble it.>> quote
haha Ken, I love that last sentence.... :biggrin:
Ok try a leak down test then what. What am I looking for with a leak down test. It should not leak down correct? If it does then something is wrong?When an engine is built do the engine builders usually do a comprission test when the motor is put together on the stand? I also heard from somone that if it is not below 100 it should not be a problem. Car runs good though just don't want to screw anything up. Got way to much in the motor.
