318 head porting for the average joe

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Be sure to post pics as you go marcelo. My heads already had 1.88's in them when I got them. So I'd like to see how you go about blending the throats into the bowls. My kit arrived yesterday. So I'm hoping to spend part of my xmas break sitting at the bbq table chipping away at my heads too.
 
The guy at the shop suggested me doing like a straight shot from the throat (where the diameter is ~1.65") down to the bowl. What do you think?
 
Update

I did some more work today -straight wall, roof raise/widen between guide and straight wall and shortened the guide height about 3/8=210 cfm
Up to .500 the ratio is now around the accepted 75% standard
will post pics later
 
ok ok ...lol...i need a new mem card, kids got ahold of the cannon ...so it's probably in couch cushion or something.
But Ill get'em up so you guys have something to look at/copy or whatever..lol
 
Justin would it really be worth it to clean up the runners, valve guide boss and bowl area on these 318 heads in my other thread if I use the factory 273 exhaust manifolds. It does have duals running all of the way back. Would the increase in flow help make up for the compression that I will be losing by swapping to the open chamber heads?

The only reason why I would run them is because they are fresh, super cheap and have hardened valve seats. I have to tear them down anyway and install new valve stem seals anyway.
 
Badart said:
Justin would it really be worth it to clean up the runners, valve guide boss and bowl area on these 318 heads in my other thread if I use the factory 273 exhaust manifolds. It does have duals running all of the way back. Would the increase in flow help make up for the compression that I will be losing by swapping to the open chamber heads?

The only reason why I would run them is because they are fresh, super cheap and have hardened valve seats. I have to tear them down anyway and install new valve stem seals anyway.
Click to expand...

Well of corse it'd help, manifolds or not, do the angle smoothing and guide shape, it's safe, u cant really screw up if you take you're time at slower grinder speed. look at the 1st page of this thread.

At the very least...
cc them heads, then just have them milled=60 bucks.. and u wont be losing any cylinder pressure and it will be a win by virtue of good sealing valves.

as for the last question..lol...you gotta consider the rings, if they are not sealing 'more blowby from more cyl pressure' and say the the cyl pressure is way down already=110'lbs....dont expect a lil more flow to cure the loss of power once u start burning oil ...and again, measure both chambers of the 2 heads...and u can figure the diff and get a rough idea

if it were me, i would have done a leak down test before the old heads came off.

every 5 cfm is said to give 10 hp increase, that is if the cam works at the lifts flow increase.

what do u think? ;)
 
Great thread Justin. You are telling us how to do a little or a lot and that's good because lots of us don't need full blown, max flow, race heads. Heads are a science as is camshaft selection and putting together a total package that runs better than the same parts in a similar car. Keep up the good work. Mike
 
1wild&crazyguy said:
Well of corse it'd help, manifolds or not, do the angle smoothing and guide shape, it's safe, u cant really screw up if you take you're time at slower grinder speed. look at the 1st page of this thread.

At the very least...
cc them heads, then just have them milled=60 bucks.. and u wont be losing any cylinder pressure and it will be a win by virtue of good sealing valves.

as for the last question..lol...you gotta consider the rings, if they are not sealing 'more blowby from more cyl pressure' and say the the cyl pressure is way down already=110'lbs....dont expect a lil more flow to cure the loss of power once u start burning oil ...and again, measure both chambers of the 2 heads...and u can figure the diff and get a rough idea

if it were me, i would have done a leak down test before the old heads came off.

every 5 cfm is said to give 10 hp increase, that is if the cam works at the lifts flow increase.

what do u think? ;)
Click to expand...

I do have the stuff and plan on doing a leak down test before I tear into anything. I will post the results. Thanks again Justin. :prayer:
 
CC'd mine today twice each and came up with 67-68cc for each side. This as accurate as I could get for what I had to work with. :thumrigh:

318 Head Porting 88-1.JPG
 
I don't see a plug in there....

For certainly cc the head with a spark plug in there.
 
You say it's there. OK by me. No need for a picture. I just do not see it in that picture.
 
Will these porting tips work for any SBM head like the 273/340/360s? Or is this strictly 318 head porting tips?
 
I am building a set of 675's myself now. I bought them off craigslist, and they were part of someones unfinished project. The interesting thing about them is that they have 2.02/1.60 stainless valves and lunati springs and retainers.

I've started the porting and feel pretty good about it, taking the flashing and lumps out of the ports, and smoothing around the valve guides. I have not done any cleaning up in the combustion chambers, and I'm trying to figure out how important that is, and there is also the issue of my fairly high lift cam. It looks like I need to grind down my guide boss's to accommodate the higher lift and the taller retainers. I called a shop and they wanted $100, but I'm thinking that I could possible grind these down myself with a simple grinder. Am I crazy to try this? I've looked at buying the boss cutting tools and I can't really figure out which one will work for me (I don't need to narrow them or anything, just cut them down). Any input on this? The cam is a lunati 60403 grind (.514 lift on exhaust side) stock rockers.
 
Badart said:
CC'd mine today twice each and came up with 67-68cc for each side. This as accurate as I could get for what I had to work with. :thumrigh:
Click to expand...

Probably close an anything can get. Nice work.
 
I was reading the OP and Shady Dell's site the stock heads flowed 175 cfm untouched but everything I've read so far say they flow 135 cfm stock which I always thought was low even with small port and valves. I'm guessing the low number is from a old test done at a lower "inches of water" or some Old Wives Tale that keeps getting passed on. So if a 318 flows 175 cfm than there not the dog head everyone makes them out to be.
 
need your help wild and crazy guy ! duplicating this question from my restoration thread

Working a freshening up my 318 646 heads, motor has 14 thousand KM's on it.. built by an engine shop 10 years ago.

Motor is apart and I pulled the valves from 1 cylinder to look them and the ports over.


On The exhaust valve, the seal had ridden up inside the valve spring.. not on tight on the base as the intake size was.. Is that wrong?

2nd question I had to use a center punch to push the exhaust valve out of the head, really had to use a lot of force to remove it. small bits of brass left in the valve lock grooves when it came out.

Is that normal ?.. Intake valve popped out no problem.??

3rd and final for today What do you think caused the build up on this intake valve.. This motor has 14 thousand KM's on it. I know it was running rich for many of those miles prior to dialing it in with wideband air/fuel setp.

Thanks ! Ken
Attached Images

318 Head Porting 100-1.JPG


318 Head Porting 100-2.JPG
 
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