Head Mods for Combustion Chamber

F

FloridaMan

Active Member
How many of you guys are having the heads machined when building the larger motors? Can I get away with tapering the edge with a dremel? Or do I need to have it properly turned?
 
Dremmel did this. IMG_20211008_234629.jpg
 
well, I am not doing the work myself, we have a "head guy" for that, he does nothing but repair heads and the entire work did just cost me 30 bucks (in India). He also polished the head after having widened it so my head looks a bit more finished than Dools.
 
Going to be black and dirty now just like thisIMG_20230328_160532.jpg
Doesent stay shiny for long.
 
I find it quite therapeutic, you may end up Porting it :cool:
 
Not really, but it is mostly done by feel, run your finger from the seat and feel the irregularities and remove them, you end up with a dirty finger!
Just matching the valve seats to the ports is worthwhile.
 
Hey guys... my 477 kit with HT-b cam and Red Box is on the way... so do you guys recommend this head work as part of the install... is it necessary? What are the implications if you need to revert to stock one day?

Thanks in advance!
 
I have done it on one 500cc only - mostly because I got knocking bc of the higher compression. it worked for that, but I havnt done it for subsequent BB mods, just went with high octane fuel - 95 RON should be good enough. I only ever built one 500cc back to 411 for reselling, its not a common occurrence. However theoretically it should not matter in a built-back scenario except for minuscule power loss due to a bit less compression.
 
Hey folks,

So I've been thinking about this and the use of additional gaskets made me think - if you cnc'd an aluminium section using the gasket as a template, this could be a way to increase the overall volume and decrease the compression ratio. Assuming a stock compression ratio of 9.5, according to my calculations, you would need a 1.4mm thick section. Given you'd need to add a second gasket you could go with 1mm to err on the high side.

Would this work?

I see that there is actually a template for the base gasket:

sam2019

Thread 'Sample pattern for cutting cylinder base gaskets'

Various formats: Corel Draw 12 and 2019, pdf
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I imported the CorelDraw file into sketchup and have created a 3D model from that... will this be good enough do you think? I'm sure there would be some polishing and adjustments to make after but it should be close enough?

Thoughts?
 
Every 1mm you add will require 2mm of chain.
 
Depends on the length of the chain, like how old and stretched.
 
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