Poor cylinder casting?

[theguy2024]

Every kit I buy the cylinder ports always look like this so i’m starting to wonder, are these specifically casted like this with the port timings worked out or is this just bad casting? I usually port out all that inner material. I am planning on properly opening up these ports this time hopefully I don’t screw up the timing!

Also I wanna deck the head this time, what is a good amount to sand off for squish?

 

[Greg58]

The iron sleeve cylinders I’ve bought looked like that, I cleaned mine down flush with the port with a slight taper, you need a degree wheel to check timing and make Adjustment’s as you go. I didn’t and mine has very little bottom end torque but flys at top end, you need a base line timing goal, I got the numbers from my best running engines and will use that to start on the next one.

 

[2stroker412]

Where did you get that one? What was the price?

 

[Mossy]

Every kit I buy the cylinder ports always look like this so i’m starting to wonder, are these specifically casted like this with the port timings worked out or is this just bad casting? I usually port out all that inner material. I am planning on properly opening up these ports this time hopefully I don’t screw up the timing!

Also I wanna deck the head this time, what is a good amount to sand off for squish?

Every kit you buy from the same place isn't going to be the same as every kit... And even if you buy 100 at a time there all going to be slightly different... A degree wheel will tell you the timing of the particular cylinder you have in hand... I have several cylinders that ported for pk 80 or grubee and a falcon 911 that recommend the pk 80 bottom end... Given the various cylinders and the bottom end difference and the poor quality control... And the number of parts available now compared to 10 years ago... Any way there is 2 ways to smooth out the ports one is too remove the casting flash the other is to fill in with tank weld jb weld... If the port timing is off you don't want to make it worse and you can add or subtract base gasket or make a shim out of dead soft copper... Then when everything is set and with the timing the squish is something else... Matching the squish band to the dome of the piston then measure the squish with a piece of sodder... .7 mm is what I've heard on the Chinese cylinder... I've seen a few posts where people assume every motor is the exact same and quality and skip past the measurements to whatever someone else did to another motor and whoever did the porting may not know what they did or got lucky and got a runner... On another note I buy 6 at a time so I can get some consistency and when I get around to it be able to mix and match the parts together from the same batch... Even then I wouldn't assume all 6 are going to be the same... close mabe but I'm taking a different approach than most by having a stock of basically everything... That said I could answer your question if you happen to have an engine from the same place at the same time I do but it wouldn't be 100% and easier to measure the timing for each and every kit... To go further it doesn't account for wobbly cranks and bearings that are pressed in improperly and cases that may have differences so I would start there otherwise it makes no point to have perfect port timing if it's going to shake the seals loose and have problems a few miles down the road... Same difference with the clutch side of it... A balanced and trued crank with the clutch set up right bottom end first then map the port timing and do your corrections and then squish is how I see it so I'm not taking it apart more times than I have to enorder to get to where I want to be... Like Greg58 posted above lost some bottom end for some top end... I'm all about the bottom end and don't mind losing some top end for it... So when I see what he's doing I'm making careful notes to that because it's good to know how far to go with it... Moving the cylinder around with different thickness of gaskets or no gaskets and then cut the ports would be the best way to take the least amount of material away from the cylinder... Another example is a pk80 low hole cylinder short rod with a zeda hi hole long rod crank would have some potential for bottom end grunt but nothing is consistent like a Chevy 350 or 318 Mopar I'm used to...

 

[Larry Trotter]

The head design has far more to do with squish than anything you can do with decking the cylinder. Take a look at this head designed for a large squish band. If the head isn’t designed for squish there’s really nothing much you can do.

 

[Larry Trotter]

The head design has far more to do with squish than anything you can do with decking the cylinder. Take a look at this head designed for a large squish band. If the head isn’t designed for squish there’s really nothing much you can do. View attachment 111695

The head design has far more to do with squish than anything you can do with decking the cylinder. Take a look at this head designed for a large squish band. If the head isn’t designed for squish there’s really nothing much you can do. View attachment 111695

sorry don’t know how the other pictures got there. Haha