• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

RAD's 3L build

Well I have decided against milling the heads because the surface looks like it may be too thin and I don't want to hav to be worried about warping or blown head gaskets or anything of that nature. Now my problem is I am grinding my exhaust valves (and maybe my intakes) and after grinding the face of the valve down to get rid of the pitting there is a lip that I need to know the specs for but I have no idea what it is called. The lip is on the valve face where the face would seat with the valve. My chilton said something about the "margin" but doesn't give specs for it. Anybody know what this is?
 
Yesterday I dropped my heads off at a shop to have them cleaned up because after I matched them to the bugzuki plates well... lets just say it wasn't the greatest looking thing ever. So I should be getting those back next week. I just finished grinding my valves too and I think they came out pretty well. I took a 26* angle cut on the exhaust valves to take that lip off and took about .002-.003 off the face to get rid of the pitting. My machine friend said don't take off more than .006 and the margin should be fine. The intakes were fine so they weren't touched.
 
im planning on doing the ol grease grind and flip method. but DOOOd i was also thinking of porting the exhaust as well on my build cuz im goin headers but just sayin thats awesome you did that im gonna do it now too
 
Haha thank you for the support guys I actually think I did pretty well seeing it was my first time. I'm just having the shop make everything smooth and pretty. And csvtguy I would reccomend not doing the exhaust ports mine are barely being touched up. When you hold the exhaust gasket up to the ports, the gasket is a bigger opening then the ports on the heads and when you hold the gasket up to the headers (MSDS) they are the same size. Thi difference in size with the air moving from a smaller port to a bigger port is going to prevent the air pulses from trying to turn around and head back the wrong way on a one way street. I can't recall what this effect is called but I wouldn't worry about the exhaust ports.
 
RAD Merc SVT said:
Haha thank you for the support guys I actually think I did pretty well seeing it was my first time. I'm just having the shop make everything smooth and pretty. And csvtguy I would reccomend not doing the exhaust ports mine are barely being touched up. When you hold the exhaust gasket up to the ports, the gasket is a bigger opening then the ports on the heads and when you hold the gasket up to the headers (MSDS) they are the same size. Thi difference in size with the air moving from a smaller port to a bigger port is going to prevent the air pulses from trying to turn around and head back the wrong way on a one way street. I can't recall what this effect is called but I wouldn't worry about the exhaust ports.
Click to expand...

But if the ports on the gaskets and the headers are slightly larger wouldn't there be a slight gain with matchin the port size on the exhaust ports?? At least polish them?
 
Personally I wouldn't bother with it. My opinion is if your going to do anything to the heads for performance leave it to the pros and let them go all the way with it. Just my input.
 
Basically what you would gain from more flow because the ports are the same size you would lose because the low pressure area behind each pulse is trying to force the air back up into the engine instead of pull the next pulse through this is what the smaller port into bigger port prevents because the pulse juse hits the wall where the difference is. Get it? what you are doing to put a port match 3L into your car is what you should stick to. I am porting my heads based on flow rates and science to get some more performance out of them and I looked at them saw where I could get gains and am now paying a proffesional to get the gains
 
Well I just finished grinding my valves today and I think they came out really nice. No more pitting but I hope they still have a thick enough margin I only took like .003" off. Also Reversion is the effect I've been trying to explain. After combustion and the gases are exiting the chamber there is a pulse following it out. When this pulse crosses into a new area like from the head to the manifold it creates a reversion wave. (I don't know why but it does) This reversion wave tries to push back the other way therefore slowing down the rest of the gasses trying to exit. If there is a difference in the size between these it will create a wall for the wave to run into so it does not effect the gasses coming out as much.

Here is a crappy picture... it may be hard to read
598540590_2132564503_0.jpg
 
RAD Merc SVT said:
Haha thanks for that I was having a hard time explaining it and thats the best pictue I could come up with. Thank you for the help
Click to expand...

NP. You had me wondering. I studied intake/exhaust manifold design as a independent study in college as part of my BSME and I never remembered seeing anything about reversion flow. So naturally the subject sparked my interest.
 
Thats cool I hope I helped you learn something. I spend alot of time trying to learn as much as I can. Also my auto teacher in high school is one of the smartest guys I've ever met so he teaches me and shows me where I can get gains on my engines.
 
since there is always going to be some gas thats wants to revert, having the step from the port to the header actually hurts and is part of what causes reversion in the first place. this is because the gas will expand into the larger tube and some will revert in the process. the reverting gas will hit the step and turn towards the middle, making it harder for the next exhaust pulse to exit the head. A reversion tube works because it allows a place for the little bit of gas to revert to without allowing it to push back into the center of the tube (i believe a proper reversion tube also has angled slits in it so that the passing exhaust pulses can pull out any gas that has reverted in the open area). if you are not going to use a proper reversion tube then you need to make the transition between head and manifold (and manifold to exhaust as well) as smooth as possible to help prevent reversion.
 
crap I never win. Ok I got some more research to do. I'm heading to phoenix for the week and I will get my heads back after that. based on some more research and talking to my machinest I'll figure out if I'm gonna have them port matched or not. Thank you for the help guys and I will talk to you when I get back and that is when the assembly of the engine begins
 
Hey everybody It's been a while I've been really busy lately. I got my heads back awhile ago and finally got some pictures. They came out 10 times better than if I had done them myself.
DSC04873.jpg


DSC04877.jpg


DSC04876.jpg


DSC04878.jpg

He took out a lip on the inside of the runner by where the valve goes (right where the grind is) and when I get my valve job done I'm going to have him run the cutter down the exhaust runner from the chamber side to clean that up a little bit.
 
You must log in or register to reply here.
Back
Top