different heads

[lee37vernon]

few questions ..

1) are there two versions of cool head , whatever make , for like big bore and standard bore ??

2) i have just noticed on 2 STANDARD heads that one has a larger dome than the other , its not been machined so i presume the 89 one off my engine is different to the earlier year one on the 265 barrell i intend to use . would this be correct ? and are there any benefits to either cylinder head design ?

3) the cylinder i'm gonna use is all ported and o ringed , so uses NO head gasket. the head on it after further inspection has no machining either .. so what about the squish ?be like non existent ......?!! i cant put it on to check yet as i'm waiting on stuff before the bottom end goes together .maybe someone sold me it but kept back a coolhead or something ??

4) the barrel is using an 86 style piston with spacer , if i find my squish to be too small can i add an extra base gasket to the spacer plate to up the squish to acceptable level ? would this then throw out all the port timing ? should the spacer plate + two gaskets = extra length of the 89long rod crank precisely ?

i know theres a lot there but forwarned is fore armed .. :eek2:

[lee37vernon]

bump

[punker69q]

1) Yes, their is different versions to match different cylinder sizes

2) 89 or earlier, there is no significant changes in stock heads that I am aware of, however since they are cool heads they could have been made for gasket or o-ring heads, which would change the shape and size of the domes. The key is to have the head that will provide the correct volume, squish clearance, squish height etc etc for the given engine size

3) Depending on how far from top the piston come at tdc (or how far out, I have seen some cylinders decked like that) you may have a correct squish clearance. You will need to make precise measurements for this to make sure that everything is ok. You can also use some type of clay and make the motor turn with the kickstarter then measure the thickness left for the squish band, don't know what kind of clay though, never used that.

4) Don't use 2 base gaskets to correct the squish band, that would change the port timing, which is bad, specially for a cylinder that already have been decked and ported. Get the dome machined to get the correct squish clearance and keep your precious port timing like it is supposed to be, a small error here will cost you hp and torque. Machining the dome is a 30 min job, it's what it took me to modify mine, and this is including the time to digitized (sp???) the head shape, calculate the volume needed to get the correct compression, program the correct head shape and modify the head in a cnc lathe.

[lee37vernon]

the 2 heads in question are STANDARD HONDA HEADS .. with definately no machining i'm sure . one has a visibly larger dome , this will be what i'm assuming is the earlier one .
thats why i was concerned about squish , run a normal engine with no head gasket and it would be tight so this should be same unless its a custom spacer but then , unless the cylinder was ported accordingly the timing would be out ..

ahh , the pleasures of buying from e bay .. :ermm:

[lee37vernon]

bump ..