302 heads

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cudadreamer

cudadreamer

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Hi,
I`m new and my son has a 72 Dart were rebuilding together.We are building a 72 318 on a budget.We`ve been reading alot about using
302 (86-91)with 86-87 being the best years.His bottom end is stock
`72 318 in good shape.Cam is Mopar Performance purple .484 lift. We were told 1.88 and 1.6 valves at minimum to use.But I talked to a machine
shop in florida and they told me when we replace the valves with bigger it would drop cc. in chamber.They said to open them up to get back to range we want we would be defeating our purpose to gaine flow.What is best thing to do here.We read how easy the heads are to find for cheap but have had no luck locally.We saw some on craigs list but no one wants to ship them.E bay has some but there new with 1.78 valves.We would like bare heads or ones some one has reworked and moved on and wants to sell.Son has minimum wage job and hours are low due to going to high school.We need advise and help finding 302`s at a good price.He has loved Darts since he was a kid.PLEASE HELP IF YOU CAN.

Out of ideas Dad
 
I'm not with that to the degree he states. Though, when you install the 1.88 - 1.60 valves, IMO (And with that cam) a bowl porting to open up under the valve is the min. amount of work to be done.

On the flip side, another cheap way to go is get a set of 360 heads and mill them down on both sides to regain the amount of cc's in the chamber. Milling the head down is a lot cheaper than porting.

The 360 head will flow around 180 - 200 cfm. This amount of flow from a 318 head will require a fair amount of porting and at a expense that may not be in the pocket. Most will note that I like a 318 head on a 318. And to a point, I do. The cam you have selected, IMO, would probably like the 360 head better since the cam's RPM range is a bit higher up the scale and into the 360's head more useable range for the port size and power potential.

Your biggest issue, IMO, is compression. The MoPar cams do like a fair bit of it.

Also, milling the head on the deck surface is one thing. To get the intake to fit, the heads surface that mates to the intake should also be milled. This can only be milled so much since it will cut into the valve cover rail. To much and sealing the valve cover is hard or impossible to do. To get around this, mill the intake surface to fit. Get this amount and mark it down some where so it is a guide for the next intake, if need be.
 
I agree with Rumble. The 360 heads already have bigger ports and valves. They just need a smaller chamber to up the compression. That can be done by milling. The 302's are a good head but to get more performance out of them they need bigger valves and some porting. They will increase performance over the stock heads just by raising compression but they flow about the same as the stockers.
I can't see why increasing the valve size would lose compression. You have to machine the valve seat bigger not deeper. tmm
 
thanks as I stated in above reply he just wants these heads so I guess were going to
do 302`s with big valves and he`ll spend money on bowl work and seat work.
Thanks for the imformation.

Alan
 
Chrysler musta thought more flow was more important than compression. In the same era as the 302 heads, ALL of the police 318s got the 360 heads. All of them.
 
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