Porting Question

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64 SRT8 Dart

64 SRT8 Dart

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I'm gonna be doing some port cleanup on a pair of smog heads (973's) and have a question about the exhaust ports.

Can you get rid of the hump that's in the bottom of the port from the smog ports? Grind them down all the way without hitting water or just massage them a little bit? The ports have been plugged on the outside by p/o. Valves are 1.78/1.5.

Will be going on a very mild 318, bored .030, cast piston, performer intake, 600 or 650 Holley, prob around 9-9.5:1, and .454/.454 [email protected] cam, 273 adjustable rockers.

Just want this little teen to surprise some people as some friends at work are already pokin some fun at me for even having the 318 block machined. So wanna get as much out of it for the parts I have. lol


Oh, I do have some 1.88 J heads that I can put together, if that would help, but I read the 318 head porting thread and wanted to give it a shot.

Any advice is greatly appreciated!!
 
I've done a few sets of 360 heads with that bump, ground them down, and I've never ran into any trouble. But, I've never done 318 heads, although I'd like to just out of curiousity lol. Although, I do have a set of clean magnum heads/rockers/etc lying here, they would look good on your 318....
 
you can grind them down flush with the floor, but I've never found it to do much if anything for flow on the bench
 
That cam,P.M Rumblefish.He has some history,whith that cam's characteristics.Different heads,318/360 .He knowes how Crane cams work.
 
Grind them flush with the window side of the port then just blend them to the bowl side/short turn...aside from bowl work..work the the kink in the roof if u wanna pick up flow with working the runner.
 
Thanks everyone!!

1wild&crazyguy, how much can I get the kink out without hitting water?
Is that a water passage that is in that area, well it looks that way if I eyeball it, like it goes to the freeze plugs at the end of the heads.
But what do I know, this will be my first attempt, lol.
I guess I'll just do what I've read and try not to be too greedy, lol.
Thanks again!!
 
there's water under the roof kink, usualy the roof kink doesn't hurt the flow much (2-3 cfm in my testing). The best gains are a good multi angle valve job, an aftermarket tulip shape stainless valve, blending the bowls, and radiusing what little shortside there is.
 
72 c +or- 2cc's unmilled.

I want to
Know gear ratio tire size and if your running a stock converter. Dependent of these factors would sway me in what head I would use and how to work it or not.

Truth be told, a decent gear ratio and wide tires with the stock head will get you low 15's.
A bo blending and the 360's valves in the 318 head is a real nice upgrade and out power the J head as cast. The problem with the J head is it is a compression dropper. Not that the cam needs much to begin with.

How many cc's in the slug?
 
skrews said:
there's water under the roof kink, usualy the roof kink doesn't hurt the flow much (2-3 cfm in my testing). The best gains are a good multi angle valve job, an aftermarket tulip shape stainless valve, blending the bowls, and radiusing what little shortside there is.
Click to expand...

There's water around the whole port,so what.
After bowl and short turn work...the flow numbers jump with straightening the roof..they can go from 145/155 to 175 or more.Thats what happens on my bench
 
64 SRT8 Dart said:
Thanks everyone!!

1wild&crazyguy, how much can I get the kink out without hitting water?
Is that a water passage that is in that area, well it looks that way if I eyeball it, like it goes to the freeze plugs at the end of the heads.
But what do I know, this will be my first attempt, lol.
I guess I'll just do what I've read and try not to be too greedy, lol.
Thanks again!!
Click to expand...

Pop the freeze plugs out of the ends of the heads and u can pinch to feel the roofs thickness and know when enough is enough....but in reality, u can completely straighten the roof ' after the bowl'
 
1wild&crazyguy said:
There's water around the whole port,so what.
After bowl and short turn work...the flow numbers jump with straightening the roof..they can go from 145/155 to 175 or more.Thats what happens on my bench
Click to expand...
The roof kink is there to accommodate the water jacket. Grind too much you'll find water. I've cut these heads up with a band saw, some castings are thinker than others through that area. I've worked over these ports to 170ish cfm with out touching the roof kink then blended it in with only 3-4 cfm gains, not worth the risk IMO.
 
Well ur working the port different than I am, with the way I do it the roof work makes a considerable diff and I keep the port small and velocity up at the same time. Different pokes for different yolks lol
 
skrews said:
there's water under the roof kink, usualy the roof kink doesn't hurt the flow much (2-3 cfm in my testing). The best gains are a good multi angle valve job, an aftermarket tulip shape stainless valve, blending the bowls, and radiusing what little shortside there is.
Click to expand...


Nice and simple and no risk of messing up and hitting water
 
Btw skrews, are u using a stock 1.50 valve and performance valve job?

Dodgefreak, the only way u would hit water I'd if u went well beyond straightening it, the roof is pretty thick and Ive used this practice with all factory sb mopar heads and its worked nicely.
 
1wild&crazyguy said:
Btw skrews, are u using a stock 1.50 valve and performance valve job?

Dodgefreak, the only way u would hit water I'd if u went well beyond straightening it, the roof is pretty thick and Ive used this practice with all factory sb mopar heads and its worked nicely.
Click to expand...

I'm using 1.6 valves that are sb Chevy circle track take outs that I cut down to 1.55, 15* back angle with 11/32 stems, and 5.01" length. Got lots of them on the shelf as the circle jerker crowd replaces them every season. Using a 608 profile Serdi valve job (32* top cut, 45* .050 seat width, and a radius bottom cut) if I recall properly, along with a deshrouding cut and 75* bowl cut. Don't mind the 11/32" stems cause the guides will be getting replaced with bronze guides anyway, facilitating the use of 11/32 stems. The 1.55 dia. widens out the seat so that I get the full cutter form all the way down the bowl. Once the guides are drilled out to .5 for the bronze guides I go in and grind whats left of the guide flush with the roof and streamline the throat in to the port. Once the guides are in, and the valve job and bowl cuts are done I blend it all in. Its cheap, quick, and works good for me. : )
 
When I first started porting I was told to remove the kink because there was power there. I did it and never hit water. But since then I've had more heads flowed and found similar to skrews. Unless the exh valve and associated volumes are increased a bit there's no reason to touch it. Even when I use the 1.65 valves it's still visible although it's smoothed. I've seen as thin as .080" as cast with my sonic tester there and I'd imagine with core shifting some ports could be less than that.
 
Cool, I'm doing an 11/32 stem 1.60 valve in some 974 heads with the better port floors, look at the 360 head trip thread for numbers, I also lay the bowl roof flat but still straighten the kink and leave the wall alone all together, just bowl,ssr,roof work.
 
For what its worth I straighten the roof on mine and open up the roof at the "lip"/top of the exhaust port,my last set of 915 smog heads flowed
.400 .450 .500 .550
163 177 187 195
This was with stock type 3/8 stem 1.6 stainless tulip type valves.
 
i have a v nice set 71 of j heads cut to 2.02 and stock 160 exhaust if any 1 interested pm me they are all metall beaded and and pressure tested , ready to build theve been magnafluxed and bead cleaned and all holes checked all good u can call my machinist and have verified or built by him jon bailey, bailey motors he's the 1 the builders call bailey motors ,cottage grove wisc.
 
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