4mm stroker porting vs Spacer plate

[Alex29573]

Hey everyone, i will be buying a 4mm crank soon and wanted to know if anyone knows or can tell me how big of a difference it would be to use a spacer plate VS get my porting updated for the 4mm stroke...

 

i currently have stock cylinders that have something close to a drag port done to them. Should i do the spacer plate or get everything opened up more for the bigger stroke?

 

 

thanks

[kodie]

Are you talking about spacer plate for the head? If so if you have an aftermarket head get some 4mil cut domes they are more reliable. If you have a stock head then you can run the spacer plate.

 

As for the cylinders if they are already ported for a standard stroke crank. Then I am certain you will need new cylinders to have them ported for a 4 mill crank.

[Damnit Bob]

I am pretty sure that the spacer plate is designed more for cylinder head clearance than to match up the port job. Could be wrong but thats my take.

[Alex29573]

Are you talking about spacer plate for the head? If so if you have an aftermarket head get some 4mil cut domes they are more reliable. If you have a stock head then you can run the spacer plate.

 

As for the cylinders if they are already ported for a standard stroke crank. Then I am certain you will need new cylinders to have them ported for a 4 mill crank.

 

 

im talking about a base spacer plate which will raise all windows by 2mm. i run a milled stock head.

 

 

my portsmith says i can keep my current cylinders and report them to work with the 4 mil

[AKheathen]

well, i was going to say you have to have your transfers checked to see if there is enough material, but it looks like you already did. now, the 1.5mm spacer will make it run, but reporting it and clearancing the domes, or using a head spacer will make it run right. just running a base spacer and stock drag port will likely make it run like crap for power.

[BigRed350x]

Don't waste your time with the spacer plate. Just get it ported for the stroke. Spacer plates are only used to accomodate longer rods on cylinders that weren't originally set up for the longer rods. On the smaller setups they have pistons with offset wristpins to accomodate the longer rods.

[jbooker82]

You have to ethire run a spacer plate, or run a cool head with stroker domes.

 

The piston falls 2mm farther down in to the cylinder, it also comes up out of the bore 2mm for a total of +4 mm stroke. You then need to have the cylinders reported. The spacer plate isnt designed to correct port timings. It just required to keep the piston from hitting the head.