318 head porting for the average joe

[66fs]

It runs good but it's just a dog. Starts easy, even though it still has its lean burn it had since new. THAT WILL be going away.
It loves cruising 70 down the highway, it just don't have any balls, can't hardly pass anyone if I need to. I rarely try to get it to much over 70, (it definitely will) but I am in town at lesser speed just as much as on the highway, and it needs help getting out of it's own way.
In addition to waking up the engine I'd like to swap to something around 3.08 gears.

If you want more, the factory performance gear was 3.23's. Assuming you have an 8 1/4 rear that would be 3.21's. I can't remember what is in between. A Sure Grip would be nice. Next would be to swap a performance electronic distributor setup similar to a 73 340 so you could set and vary your timing. See Hailifaxhops. You could also swap to a 73-75 Carter 318 2 barrel carb and ditch the lean burn stuff. Sounds like a real nice highway car. Next would be a cam and double roller ting set. and a 360 intake and TQ. See, it gets crazy fast... Good Luck.

 

[66fs]

As far as getting smaller chambers on a 360 head I don't want to have to shave enough off to introduce manifold sealing and fitment issues. At one point I had 2 ex squad diplomats. One 2 bbl the other a 4 bbl engine. I never had the heads off of either but the 2 bbl one had the 302 heads, the 4 bbl one had "360" heads, as it had "360" cast into the heads (besides the casting number which was elsewhere on the head) both had 904s (probably actually the 998 version of the 904, being mid 80s cars) and both had 2.94 gears. The 2 bbl one ran better than the 4 bbl one, it would run circles around the 4 bbl car. Even my 87 3/4 ton van, also a 2 bbl 318 with 302 heads, would outrun the 89 (the diplomat that had the 4 bbl) and strangely the van also had the same 2.94 gearing.

You do have those 302 heads... It is only time and money. Most of my playing was when I had no money and plenty of time. I personally have not run 302 heads. I have 2 or 3 sets, but when I looked at the flow numbers I decided to keep the 273 heads. Milling 360 heads is a no brainer. .040 and .038 off the intake side. Must have done it 100 times, never a problem. And I'm still not telling you to do that with your car unless you change everything.

 

[volaredon]

I have a distributor already for the lean burn ectomy. And, I have an NOS BBD that was destined for my slant 6 build for something else. I also have a 500 and a 625 edelbrock afb that could work on that Fury or a couple of fresh ready to go TQs to boot. It is a nice highway car now... I want to make it better.
On gears for an 8-1/4 they used the 8-1/4 in cherokees too some of which came with 3.07/. 3.08s. so they are available. If I do the ring and pinion swap I'd go either 3.08 or 3.21/3.23.
Now on keeping with the thread, can I do anything with my 302 heads to make them worth swapping? I do still plan on swapping in a small cam at the same time whether it be something along the lines of a 252 or the 260 that I already have.

 

[66fs]

Something is wrong with the 318 in your car, it should run fine as is. Maybe the Lean Burn stuff. Have you played with the carb and timing at all? Back to your question. See post #260 and thank Justin. If that gets you to 190 cfm, that is where 360 heads flow stock. If you are sure they are not cracked, I'd mill them .020 and .019 on the intake side while you are at the machine shop. Use viton positive seals and 340 or equivalent valve springs. Find true TDC while the heads are off and degree in your cam. I'd run the 260 duration cam over a stock 360 2 barrel cam. Use a double true roller timing set. I put 4 barrel carbs on everything and a good TQ is the best, but the others you have will work nicely.

 

[volaredon]

well they shouldn't be cracked, they just came from the machine shop with 16 new valves and a fresh valve job about 6 months ago, then to the spot they occupy on the shelf. they have new viton seals too. but they have not been ported. I was told they were shaved, "just enough to make sure they are square and not warped". I think only like 0.007-0,010 was the numbers they mentioned.
I got the 302 heads at a garage sale, from a guy who had a couple of late 80s trucks sitting along the fence line, the seller told me that the engine they came from "ran good "but that he had "built" a 360 to put in in that engine's place". Don't ask, why but I have always been a huge fan of the 318. have had many. I've done more 360>318 swaps than 318>360 swaps over the years, but have gone both ways based on "what I could get my hands on" at the time. Ive had some 360s that have been real dogs. the TBI one in my son's 89 Ramcharger had to have been the worst of them/ That truck now has a carbd 408.
most vehicles I have had, I have seen no appreciable difference in how a 318 pushes it down the road vs how it moved w/a 360 except at the gas pump. The 360s (that I have had) have had a much harder time passing a gas pump than any 318 I have had, except 1. the 88 TBI one I had in a shortbed D100.

on the "something is wrong" with my 318 in my Fury, I have had 318s in damn similar cars before, side by side, same gearing same size tires, etc and all stock/ but yet they don't run the same.
Yes, I have played with carb and timing on this one. it does "run fine" starts easy, runs smooth, 20" on vacuum gauge, steady needle, etc....and will happily cruise 70 all day, that seems like its happy spot. but it just seems to struggle a bit in getting there..... and yeah, alot of that could be the timing advance (or lack of?) from the Lean Burn. It still has its original Holley 2280 2 barrel in place. that "struggle getting there" is what I want to improve on.
It does have a true roller, double roller Edelbrock timing chain on it, already, I put it in about 10k ago, because "I was in there"// as in I had to replace the water pump and as most here know, from water pump to timing chain on a small block, is a difference of 4 more bolts. Did the chain while I was that close, was afraid of the age factor on the nylon cam gear that was original/stock to the car. I wouldn't think that timing set would be that badly worn yet. Whatever cam I put in, I plan to reuse that Edelbrock double roller set.

 

[66fs]

It is not the 318 part that is wrong. I will take a 318 over a 360 any day. Sounds like you have been chasing this down for a while. I was working for a small Chrysler Plymouth dealership till about 75-76. I remember when the Chrysler Cordobas came out. What a sweet cruising car that was. A 318 would run down the road, no sweat. Your problem is probably the Lean Burn system. My only suggestion would be to richen the jets in the carb a couple thousandths. I much prefer the carter 2 barrel carb from about 1973, https://www.allpar.com/attachments/bbd-six-carburetors-jpg.74706/. You could adjust the position of the metering rods with a screw under the top plate. I would figure out what is wrong with the 318 before swapping heads. Your 302 heads sound good, not sure you will gain much without relieving the chamber. Sounds like you have a handle on the rest.

 

[volaredon]

Yup. Worked on lots of BBDs over the years.
I bought 2 NOS 318 spec BBD carbs this past summer, a guy on the/6.org site posted some for sale there, also told of his then-Ebay listing for them.
One went onto my son's/6, I bought the 2nd one for my /6. List # 6537,a "heavy duty emissions" calibration from something like a 75-ish 318 pickup truck. I have most of 3 used BBDs hanging around the garage, one of which is this same carb number. I remember playing with metering rod hanger adjustment plenty back then.
And Cordoba's? My 1st 2 cars were a 76 then a 75 right behind it. Then a Ràmcharger. I have never owned anything besides a Chrysler product ever. And I have never owned a front wheel drive vehicle in my life either.
That thought was sound of "sealed for life" when I proved to my then boss that my 87 3/4 ton B van (with a 318, surprise, surprise) and 2 barrel, was better on gas than the boss's 91 voyager wrong wheel drive POS with a 3.8 sideways v6.

 

[Bronze Barracuda]

Dont port 273/318 heads for a 360, use and port the 915 heads, 1.94/1.60 chevy valves work great for the lesser work approach to 250cfm.
If you've never ported anything, dont have a grandeurous expectation.

Thanks for the help and info.
Lucky me though I found a 1970 340 for $300 Canadian about $240 US. I'll probably put the 318 with the 714 heads into my son's 56 Custom Royal. So I'll get a lot of help from this thread afterall directly related to porting 318 heads.

It is not the 318 part that is wrong. I will take a 318 over a 360 any day. Sounds like you have been chasing this down for a while. I was working for a small Chrysler Plymouth dealership till about 75-76. I remember when the Chrysler Cordobas came out. What a sweet cruising car that was. A 318 would run down the road, no sweat. Your problem is probably the Lean Burn system. My only suggestion would be to richen the jets in the carb a couple thousandths. I much prefer the carter 2 barrel carb from about 1973, https://www.allpar.com/attachments/bbd-six-carburetors-jpg.74706/. You could adjust the position of the metering rods with a screw under the top plate. I would figure out what is wrong with the 318 before swapping heads. Your 302 heads sound good, not sure you will gain much without relieving the chamber. Sounds like you have a handle on the rest.

Curious about, "taking a 318 over a 360 any day"? How come? Just a question of curiosity. Is that for trucks as well or mainly cars that you prefer the 318 over a 360?

 

[volaredon]

He's not the only one here who would rather have the 318. Count me in that camp as well.
The 360s I have had over the years are more likely to be sludged up when the valve covers come off,
have not seemed to lose any power in the cars that I have put 318s in where 360's came out, seemed to gain nothing when I have put 360s where 318s came out of, only that the 360s have been gas sucking pigs for no benefits in those situations.
76 Charger SE, 75 cordoba vehicles that I put 318s in place of 360s and. 78 D200 that I pulled the 318 from and went 360 back in. All stock motors, none had gear swaps, etc.
Stock vs stock I never saw any advantage to the 360 in any of those vehicles.
On the charger, it wasn't mine yet it was still my dad's car at the point of the engine swap, we used the distributor and intake/carb from its original 360 on the 318 that went in. That same 318 then went into the 75 cordoba after the charger got wrecked. I had driven both cars and that truck with both engines.

 

[66fs]

For me it is the interchangeability. Internal balance and the smaller engines will rev higher with the limits I place on my small block engines. 7,000 rpm redline, .500 inch lift, solid cam, duration under 284 degrees, single valve spring with positive seals, factory heads, factory exhaust manifolds, and run on 91 octane fuel. My cars are light early A bodies, and limited to how much rubber one can fit in a stock wheel well. I don't drag race so mpg and a higher top end is more important to me. They have to be completely streetable, go any where, any time, for as long as I want, and as fast as I want. 360's are fine for trucks, heavy cars and some one else. If I go past a 340 in a later A Body, I personally would go 383 big block.

 

[18teener]

I thought I would make a start on my 318 heads. This is my first port (on a 318) so any comments/feedback would be welcome.
One question regarding the exhaust port. Can I remove the hump on the roof completely or do I risk water?

Thanks.

 

[18teener]

No one?

 

[ChargedDart75]

No one?

Create a new thread asking this question. You'll likely get an answer from some of these guys there.

 

[yellow rose]

No one?

You can take it out.

 

[Cudafever]

Ok
no on want to bite.
so here is MY! shORT answer.
The first time porting should be a focus on cleaning up the port, NOT porting aka changed the port design. (LEAVE THE SSR ALONE!!!!!!!)

3 angle valve job with the 65 degree cut, opening up the bowl area (under the valve) on the intake side.
Light clean up on the exh side. AND CALL IT GOOD!!!!

It's simple and quick and rewarding.................from there on, for a beginner, you can take away every think you just created by what i stated above.

There that should cause some opinions to flow

 

[18teener]

I'm not sure what to take from that.
I haven't changed the port design. This is very much a take on the thread OP's postings i.e. open the bowl and knock off the rough edges. I have not touched the SSR other than to blend the rough transition to the seat. The port is stock from the guide out to the flange (I did smooth the pinch but it's no wider).
The three angle job will not happen, again as the OP's posts.
This is my first 318 port NOT my first port.

 

[Cudafever]

I'm not sure what to take from that.
I haven't changed the port design. This is very much a take on the thread OP's postings i.e. open the bowl and knock off the rough edges. I have not touched the SSR other than to blend the rough transition to the seat. The port is stock from the guide out to the flange (I did smooth the pinch but it's no wider).
The three angle job will not happen, again as the OP's posts.
This is my first 318 port NOT my first port.

Well then.
Care-E on!
..............................................over and out.

 

[polyjohn]

Well then.
Care-E on!
..............................................over and out.

looks good to me 18teener!

I've been following this thread for TEN years NOW and its been very, very interesting indeed.
Justin has come and gone with 'no sign of' since???

But his knowledge and enthusiasm for the lowly 318 head has fuelled many folks into become HOME HEAD porters...
(who needs experts when you can do it yourself)...

Seen some horrors when folks try to turn a 318 head into a 360 head!
So don't put 360 heads on a 318, but you can put a 318 head on a 360 (so folks say)?



After 30 years of head porting I have finally done a set of 273/318 closed chamber 1966 heads! (thanx to Covid restrictions)
I was pleasantly surprised to see how nice the castings were for that year!!!

WELL WORTH THE EFFORT FOR A STREET DRIVEN MOPAR...

 

[18teener]

Thanks polyjohn.

 

[polyjohn]

Head porting is a lost SKILL and 'back in the day' that's all you had to GO FASTER!

Now its all 'bolt on and go'...

I have over twenty sets of heads here, some mild but mostly WILD!
I do possess Aluminum heads, Indy, MP and the B1BA Brodix heads are a work of Art indeed.
We all assumed that BIG is BEST and when you Drag-race that's pretty much the 'bottom line'.
Get the engine up to MAX rpm's and hold it there as long as possible with gearing, same goes for Nascar 'high speed tracks'.

But there is a lot of other places where you need a smooth torque curve and power band.
Most folks do NOT have access to a Flowbench or a Dyno, but that ain't the end of the story!
Many folks 'back in the day' did 'seat of the pants' experimentation, one modification at a time...

Back when we had Mopar Performance, Porting Templates, we thought we were GODS!
Porting our own iron heads and making the other guys look slow...
Better ports meant better flow and biggercams, then it just snowballs after that!

THE PROBLEM WE ALL HAVE NOW,,, IS TOO MUCH CHOICE!
Everyone's combo is better than the next guys and they have the Dyno results to prove it!

But back in the 'real world' some of us just wanna get a bit more 'on a budget'.
Street cars that are real 'grocery getters' and not 'drag cars' on the street...

 

[Cudafever]

I've been following this thread for TEN years NOW and its been very, very interesting indeed.
Justin has come and gone with 'no sign of' since???

But his knowledge and enthusiasm for the lowly 318 head has fuelled many folks into become HOME HEAD porters...
(who needs experts when you can do it yourself)...

Theirs a guy around here that has the same drive and enthusiasm as justin........you would think it was his twin Brother

 

[polyjohn]

Thanx CudaFever!

I had a twin brother, but unfortunately, God needed him for duties elsewhere...

But anyone who takes the time to port 318 heads can always be my 'Brother in Arms'.

I'm not a military man but have a great love of Mopar and the Folks who help 'fight the cause'...

MOPAR OR NO CAR, even with 318's lol...

 

[MOPAROFFICIAL]

302 head info.

They are very restrictive as cast and flow a considerable amount less than the 675, 920 etc..without modification.
The picture shows the shrouding and what a simple stone drop can do to help that.
2" nickle chrome stone cut 15 degree bottom, outer edge cut to 45 then 60 above to create a nice transition and not leave a ledge at the chamber wall. Start there if you want to make the most of this casting, followed by a nice 5 angle 75,60,45,30,15.
Doing that will bring the numbers up by 25 cfm! as well as shift the bigger flow to start earlier in the lift range.
Example
Stock cfm........deshroud and perf vj
.100-48...............50-typical closed chamber
.200-87...............106 +19
.300-131.............157 +26
.400-152.............173 +21
.500-166.............179 +13
.550 peak-175.......179

Add porting and you can see numbers jump another 25 cfm from .300 up with 200 by .400 and peaking 210-215cfm around .500-.550. They weren't intended for high lift drag/perf. They do what they do early and don't need much cam lift.

1st pic showing a 5 angle vj vs stock

2nd pic shows a 4 angle vj and was the initial test port for the stock vs vj/deshroud and port.

 

[MOPAROFFICIAL]

I thought I would make a start on my 318 heads. This is my first port (on a 318) so any comments/feedback would be welcome.
One question regarding the exhaust port. Can I remove the hump on the roof completely or do I risk water?
View attachment 1715704583
Thanks.

Shorten the guide.
Make that bowl more evenly round and think light bulb in shape, to a minor extent.
Come in from the port window and mildly work the floor on the common wall side of the port to be straighter, still ramping up a hair, but make it so its 'flat meets short turn lip'.
Go straight up from the lower 60 angle and then laid back just a hair all the way to the ssr peak. Work the common wall bowl side into the wall near the head bolt. I have some videos I'm putting together. Lost one, had to start over. Hard to find the time to play around.

 

[polyjohn]

Nice one Gold Member!

We don't see any 302 heads here in the UK.
But we do see the early closed chamber 273 head which is very similar 66-67? (possibly).
I am doing a pair for a nice 318ci (for a B-Body), oops.

My trusty phone packed up so no pics at present.

Me I have a different problem to you, so much time and no enthusiasm.
17 months lockdown and retirement...