I am in the middle of putting back together a 150 crossflow motor that I had bought from a dealer in Florida. This block cost me 2300 plus shipping etc. This is the 4th block I got from them and this one had a leak that I could not find/fix. In an attempt to fix it, I pulled the p-head and went to fix a stripped hole that I knew was there from the past(this motor has been sitting for a year or more because of the leak). It has about 6 hours on the motor. I had pulled the front crank case cover off so I could pull the lower head bearing cap. That's where I had to fix a stripped hole. I had gel seal on the block(ready to put back together after re-tapping and a heli-coil) when my son pointed out to me that the lowest sealing ring on the crank was cracked/broken..........I found the leak. I tore it down and found out that the company had put 5 forged pistons and one cast piston in this motor.........and they were not new pistons. Even though the warranty is out, the company is sending me 6 new pistons and more stuff(gaskets etc). I think at this point that I'd rather build it myself anyways. Now for the topic of discussion, on this block, I just discovered that the exhaust ports are not stock....at all. They have been raised to a top/bottom height of 7/8 versus a 3/4 stock opening. They have also been widened. Actually they look like 235 exhaust ports. They are not squared off however. This was done by a machine. It's got the bump in the middle like a normal port. I compared the ports to a dead 150 that I have that needs machine work done. The intakes appear identical, but the exhaust........major difference! I have ported my 150's before..........but just not the exhaust and I have never raised the ports either. What can I expect from the exhaust ports being raised 1/8 inch? I had this motor running last year(leak included) and it ran great on the top end. This is my first time ever seeing just the exhaust ported. I welcome other's insights. I didn't seem to see a problem with the factory jetting (gt 150 carbs). Does this port raising let the motor breathe more on the top end?
