Uneven compression on Nash's block
 

Mug and I have been building his car for exactly a year now. (90 TSi AWD, 2.4/GT3582/ALL Supporting Mods)

We are using Nash's 2.4 block (yeah, I know.....)

We broke it in tonight, 20 miles. Vacuum pulls

JET told us that Nash put 8.8:1 pistons in the block

the numbers are 185-165-165-185.

I had spark plug wires 1 & 4 crossed at the coils

On a new motor, how bad is it that excess gasoline was pooling in 1 & 4?

It makes sense that the rings seated really well with all that gasoline causing the rings to file themselves against the honing.

what do you think? am I stuck with un-even compression? or will it even out eventually.

Re: Uneven compression on Nash's block
 

We had the car running probably 5 times, each time under 60 seconds with the crossed wires.

We put the 20 miles on the car with all 4 firing properly

Re: Uneven compression on Nash's block
 

I'd put some more miles on it, and do more vacuum pulls, then re-check it.

-A. Swift

Re: Uneven compression on Nash's block
 

It doesn't matter if 1 & 4 are backwards. There is no backwards, 1 & 4 are on the same coil, when it fires, they both fire.

Why do you think there was excess gas pooling? Way too much fuel is usually a bad thing for ring seal.

Re: Uneven compression on Nash's block
 

ecoli, you are right, what I was trying to say was I had two spark plug wires switched and the car wasnt running right.

it ran, it idled really high, it was hard to start, so I started to check cylinders for fuel and number 4 spark plug was saturated. so I unplugged everything and started over. after I plugged them in correctly it ran great.

So yeah, I guess 1 and 4 couldnt have been misfiring, more like 4 and 2 or something.

That throws my theory out the window I guess.

I will put some more miles on the car and see what happens.

Re: Uneven compression on Nash's block
 

Are you sure it isn't a compression test or battery cranking problem during the test or anything? 20 psi differences like that are common on a high mileage 4G63 motor, expecially the center cylinders, but it is very rare to see more than a 5psi difference on a new motor.

Any possibility it is actually a head, valve, or cam problem?

Re: Uneven compression on Nash's block
 

A leak down test would tell you where the compression is going. For the most part compression problems are head related unless there is a lot of mile on the motor, then it could be just about anything. What compression tester are you using and how did you do the compression test?

~John

Re: Uneven compression on Nash's block
 

sounds like leaky head gasket bt/wn 2nd and 3rd cylinders.

Re: Uneven compression on Nash's block
 

I would get some more miles on the engine first. The rings might be more seated on 1&4 than the other 2. Go out and get on it some to start seating the rings, don't be real nice to it. After you get 200 miles on it, check it again. If they are still off, then do like John said and do a leak down test.