Hey guys. So my F22B dohc head was bad after i spun a bearing in that motor. (dont' put a head in with warn cam journals...just a waste of time...the head whines when cold).
Soo, i'm rebuilding an SOHC i had (from ALeks on here...mine had molten cast on it from when i melted a piston on a boost spike on my original motor).
I've done some porting on my own and it's coming out pretty good i think.
I'm not touching the intake runners as there is too much geometry and math in that. I am however doing the "bowls" this is where the machinining edge meets the cast port. there are lips and ledges that can be smoothed. For all heavy cutting i just used a die grinder and carbine oval bit...did all the bowling. The Exhaust was COVERED in tough carbon...soaked in engine gunk stuff, and scraped a lot away with screw driver. rest came off later.
Ok, so after the lips were all gone, i then started with the flap wheel. The carbide leaves a ripply chunky surface. For the intake you want it a bit rough, but not that bad, so i smoothed it out briefly with a small flap wheel. on the intake, i had to lay into the flap wheel to get all the little chunks out.
It's now silky smooth on the exhaust and i'm awaiting picking up a small cotton wheel and some aluminum polish. You want the exhaust as smooth as possible to avoid carbon build up. i'll also heavily polish the combustion chamber. Same logic applies here...avoid carbon build up spots as well as limit hot spots that can cause detonation.
All the while, be very careful not to hit the valve seals with the die grinder anytime, if you dont' trust yourself, put a ring of duct tape or masking tape on that edge. I left my exhaust ones really dirty so if the Flap wheel ever grazed it, it would be no biggie...but the intakes are already perfectly clean and you can't make the same mistake.
After polishing i'll resinstall the valves. Also do valve "lapping" where you put compound on the valve seal face and turn it many times while pressing into the head...this cleans and trues to seal as good as you'll get without machining.
I may also port match the exhaust to my 2g DSM exhaust manifold...they are off by like 1/8"...good if i stay turbo, bad if i'll go back to NA.
head will get a resurface and then new valve seals. hopefully i'll have some pics up sometime.
Anyone else ever do any DIY porting? Doing the bowls and other problem areas can net about 5% HP sometimes. After cleaning all the raggedness in the exhaust i wouldnt' be surprized if it did.
mark
Soo, i'm rebuilding an SOHC i had (from ALeks on here...mine had molten cast on it from when i melted a piston on a boost spike on my original motor).
I've done some porting on my own and it's coming out pretty good i think.
I'm not touching the intake runners as there is too much geometry and math in that. I am however doing the "bowls" this is where the machinining edge meets the cast port. there are lips and ledges that can be smoothed. For all heavy cutting i just used a die grinder and carbine oval bit...did all the bowling. The Exhaust was COVERED in tough carbon...soaked in engine gunk stuff, and scraped a lot away with screw driver. rest came off later.
Ok, so after the lips were all gone, i then started with the flap wheel. The carbide leaves a ripply chunky surface. For the intake you want it a bit rough, but not that bad, so i smoothed it out briefly with a small flap wheel. on the intake, i had to lay into the flap wheel to get all the little chunks out.
It's now silky smooth on the exhaust and i'm awaiting picking up a small cotton wheel and some aluminum polish. You want the exhaust as smooth as possible to avoid carbon build up. i'll also heavily polish the combustion chamber. Same logic applies here...avoid carbon build up spots as well as limit hot spots that can cause detonation.
All the while, be very careful not to hit the valve seals with the die grinder anytime, if you dont' trust yourself, put a ring of duct tape or masking tape on that edge. I left my exhaust ones really dirty so if the Flap wheel ever grazed it, it would be no biggie...but the intakes are already perfectly clean and you can't make the same mistake.
After polishing i'll resinstall the valves. Also do valve "lapping" where you put compound on the valve seal face and turn it many times while pressing into the head...this cleans and trues to seal as good as you'll get without machining.
I may also port match the exhaust to my 2g DSM exhaust manifold...they are off by like 1/8"...good if i stay turbo, bad if i'll go back to NA.
head will get a resurface and then new valve seals. hopefully i'll have some pics up sometime.
Anyone else ever do any DIY porting? Doing the bowls and other problem areas can net about 5% HP sometimes. After cleaning all the raggedness in the exhaust i wouldnt' be surprized if it did.
mark
Comment