Mopar Small Block Head info:

[66fs]

1971 was the first year for 360s. They used J heads in cars and trucks. I assume J heads were revised for emissions. The performance X heads were gone and J heads were used for some 70 and 71 340's, with 2.02 intake valves. 71 up 360s, and 72 340's all use 1.88 intake valves. HP heads, 340s and 360s use 4 groove keeper intake valves with .0005 smaller stems. Standard 360 heads used 2 groove keepers and trucks used rotating retainers which move the keeper grooves down on the stem. Stay away from castings with excessive core shift. They are more prone to cracking and thicknesses less uniform. The more time went on the more the castings were compromised for emissions reasons and performance took a back seat, until the 302 and 308 heads which got some of the advanced design from W2 heads. But these are very prone to cracking between the seats.

 

[MOPAROFFICIAL]

308 head was the only head to barrow design enhancements from the prior development of the w2.. Because the 302 has the same exhaust port variety it always had from the intro of the 318la.
The 302 and all 318 heads have basically 3 intake port designs and 3 exh ports before the magnum predecessor.

#315 1964-65 is laid back and ramps up 'as cast' with varying casting/core shift lending med to short exh short turns, slightly diff exh port window size and core thickness. They list a specific header gasket you can port match too on those and 920's. They are a closed heart'ish shape chamber.
#920 1966-67 'dice heads' by the 4 dot squares cast on the outside...very much the same as the early heads with but a slightly different closed chamber that was more or less edited from the previous.
#234 1967 truck/indst. These heads fearure very the 1st version of the 675 style int/exh ports and the same closed chamber as the 920 . The big difference with these heads is they have no exh heat cross over and instead flow water through a passage in the same location as the exhaust cross over would be that flows through the intake=water heated intake.
#675 1968 the brand new official passenger car head intake port, more blunt & bull nosed. Taller exhaust floors than previous 273 heads and were open chamber.
#593/163 air injection heads , they brought back the early laid back intake port from the 273 era, but even taller exhaust port floors. They were open chamber.
#302 closed chambers, 675 intake port and late #163 exhaust ports with air injection. The 163/593 is the open chamber twin to the 302 head and flows a hair better as cast without the chamber in the way.

Basically..Chrysler had a few port designs that differed in the intake short turns and exhaust ports. The early versions tended to peak higher but also mostly in the higher lift 'given the exact same work is done'.

 

[Garrett Ellison]

Do the 234 heads need the same degree of extra radius and chamber blending on the short side as the 302 fast burn heads? What intake port volume do they have and what intake port volume do the pre 974 (155cc) heads have?

 

[MOPAROFFICIAL]

Do the 234 heads need the same degree of extra radius and chamber blending on the short side as the 302 fast burn heads? What intake port volume do they have and what intake port volume do the pre 974 (155cc) heads have?

I have a set of STOCK 2.02 915 j heads that are 155cc int port.
The 974 in the pic cc'd with 1.88 int @160cc
The 2.02 tulip chrysler used takes up more bowl volume was always my assumption of the diff...compare them sometime.The differing port volumes.. 'after the 894 x and 915 J'.. i also , in retrospect , attribute to the port window area being bigger or smaller cast. Some were really sloppy..and some have more cast slop in the bowl 'smaller bowl due to more material Whether intensional or just a sloppy fashion of calculated casting for app 'trucks n vans'..there are measurable differences...that all is aside from the X and J which was an intake port floor revision of course.

 

[John Collins]

273/318 are pretty well known, but reasoning behind him now parroting me about the 302 is obviously not understood by him. Its the chamber, the very thing everyone gushes about is the achilles heel to its air flow. It can be made to work very well...but just like the speedmaster heads it is work and you really need to be able to test and know how much is really enough for it to work like it should. Aka you need to be able to drop a big stone down/cutter and hand blend the chamber below the short turn. The valves that come in those heads are also truck valves, they are big stem to head and heavy af. You want passenger car valves for a 1970 dart/valiant/demon/duster etc..
All the guys who just homeported the 302s on this site and didn't have a lot of chamber unshrouding done and I mean a lot ..and a flowbench test...their heads might only do as good as stock 675 heads. Closed chambers are work to implement and not hinder the ultimate power maker=airflow.
The x is its own, came 70cc, has a different intake port floor with a flatter peak to straight wall ssr. The average eye doesn't see it at a glance. The machining of those heads p.r holes are a minute amount wider on the set i have when compared to the sets of 1970 j heads i also own, full ported and the other bone stock. There's probably like 6 versions of the of the 360 J head design.. of which mostly revolved around the exhaust port with the exception of a couple intake port volume revisions. The 3418915, 587, 974, 596, 1978/79 recast 915 full number of '341915 smog version 'notice the 8 is missing' with air injection exh floor. Heck.. even the 308 is a J head intake port... with the 6th or so revision of the exhaust port. There are a handful of casting numbers mixed in between as extension/alternative part numbers of the those revision/changes but we'll focus on the mostly common ones that feature those same characteristics.
The 1st version '915' were used in both the 340 cars and in vans/trucks and came both 1.88/2.02. Cast in 1970 for 71.
The 1st j exh revision came with the 587 with small air injection boss..not an advantage though. In that casting the boss is not big enough or close enough to the seat to really aid in flow and the airhole if not plugged flush to the port floor actually creates reverse Eddie's and hurts the flow numbers on the flow bench when tested.
The #974, really good head. 155 cc J intake port, exh port a hair smaller than previous w/bigger air injection bosses right to the seat, tall exhaust ssr floor. Theres more material removed to get to a ported 915 peak int flow due to the slightly smaller port volume... but great head. The 974 were 72-74cc chambers. After the 974 they went back to an exh port floor design that carried air injection bosses that were cast right between the 587 and 974 in the port floor...in other words..they down graded again where you won'tgain from it incorporating it into the ssr for an increase because they pushed it back from the seat so it's a tease and is marginal in any shaping potential.
The late 70's and the oddities of truck heads where they re introduced the j 915 casting minus 1 digit... a meaty casting... air injection, induction hardened with very wide margin seats small bowls and truck valves...intake port on the small side. Chrysler really started getting sloppy on the castings though the shape was mostly uniform...port windows were not sized well as they were in previous years... tapered.. somewhat smaller... extra thick intake decks.. and big 72cc chambers which if you put early passenger car valves in would be 74cc. Truck valves have flat exh valves fwiw and eat up a lil chamber volume.
There a couple versions/casting of the 302 and 308. 714 for the 302 and some weird one i have lost in my mind atm for the alternative 308.
Many can take and emphasize a unique feature over another quite easily and build upon all that.

Here is a pic of #974 exh port ,ported.
Its WAY taller than any 915,587,596,894 etc and easy to get great exh numbers low to high lift.
I have had all of them at some point, still have most. When i get my hair cut and some time ill post my youtube vid up and show some of that stuff.

View attachment 1715667873

Sorry to hi-jack, but I have a set of the 974’s. What would you suggest as a good intake manifold and carb combo for them? It’s a mild 360. Uncertain to cam. Currently has a 318/360 Edlebrock and Carter 625. I’m thinking about building another engine and I wanted to upgrade my current setup while building the new engine and would like to get a combo I can use now and then use down the road for the bed build. Thank your for any help!

 

[MOPAROFFICIAL]

Sorry to hi-jack, but I have a set of the 974’s. What would you suggest as a good intake manifold and carb combo for them? It’s a mild 360. Uncertain to cam. Currently has a 318/360 Edlebrock and Carter 625. I’m thinking about building another engine and I wanted to upgrade my current setup while building the new engine and would like to get a combo I can use now and then use down the road for the bed build. Thank your for any help!

Cam choice and then gearing would be needed to help in that decision.
See ..you could end up choosing a cam that would require a single plane and/or you could end up with a requirement for deeper gears ...and say you don't have those deeper gears 3.91-4.57 in there ?
You would want to go with a dual-plane 'LD340,RPM, and not a manifold better suited for that big cam 'Victor/SP ..because you will need some now make up for some missing torque to get moving quicker.

Most cams stock to 240's dur @.050 will like a dual plane. Even more can work but you'll be limiting the availability of the cams upper rpm power. What are you doing for gears and will you be using headers?
That alone can aid in choice.

 

[John Collins]

Cam choice and then gearing would be needed to help in that decision.
See ..you could end up choosing a cam that would require a single plane and/or you could end up with a requirement for deeper gears ...and say you don't have those deeper gears 3.91-4.57 in there ?
You would want to go with a dual-plane 'LD340,RPM, and not a manifold better suited for that big cam 'Victor/SP ..because you will need some now make up for some missing torque to get moving quicker.

Most cams stock to 240's dur @.050 will like a dual plane. Even more can work but you'll be limiting the availability of the cams upper rpm power. What are you doing for gears and will you be using headers?
That alone can aid in choice.

Thank you for your time, first off!

I’ll be running with an 8 3/4 with 3.23 gears and TTI headers. I want a fairly “mild” build and would be happy with one HP per cubic inch. I’m just learning the intricacies of cam’s and don’t yet have a full understanding of them. My thought on my next engine was to have a stock LA360 short block with either the 2.02/1.60 J heads with an LD340 or Performer RPM heads and RPM intake and a 750 CFM carb and whatever CAM makes sense with that combo. I’m at the beginning of this journey and in no hurry to build. Depending on the advice I get here and elsewhere, I’ll start trying to track down the components necessary for a build. My honest to goodness hope is to go the J head/LD340 route and find deals on pieces that’ll need a little TLC, but no machine shop work. I have the time right now to put the work in to rehab and lack the dinero necessary to buy new at the moment. Either way, I know it’ll be more money then I budget for and in the long run will take the route that makes the most sense.

 

[Captainkirk]

Just my .02, John...but by the time you pay for a decent set of J's (most likely you would end up with the 1.88's as they only made the 2.02's through '71) and have them upgraded to 2.02 intakes and have the bowls and ports massaged...you'll likely be close to, or exceeding the cost of a set of Edelbrocks. Summit has them for around $750 each now. They come ready to run with 2.02's, flow better than cast heads out of the box, and weigh about half. They also have the 63cc chambers, which would boost your compression a smidge over the 65cc J chambers. They would top your 360 very well and tend to cool faster than cast iron heads as well. Again, just my .02...

 

[John Collins]

Just my .02, John...but by the time you pay for a decent set of J's (most likely you would end up with the 1.88's as they only made the 2.02's through '71) and have them upgraded to 2.02 intakes and have the bowls and ports massaged...you'll likely be close to, or exceeding the cost of a set of Edelbrocks. Summit has them for around $750 each now. They come ready to run with 2.02's, flow better than cast heads out of the box, and weigh about half. They also have the 63cc chambers, which would boost your compression a smidge over the 65cc J chambers. They would top your 360 very well and tend to cool faster than cast iron heads as well. Again, just my .02...

That’s about what I’ve been seeing. Unless I take the risk of doing the machine work myself, like you said, it’ll be similar costs or more for the J heads. I found a .40 over 360 core with original crank and heads on here for $500 plus shipping though... Found it in the archives from last year. It’s an LA360 from ‘75. Uncertain to the heads, but I’m hoping they’re 974’s. The block and heads look to be in great condition, uncertain to the condition of the crank, but I assume it’s fine... All will go to the machine shop to get a once over at the least. It’s the same engine/head combo I have now, actually. There’s a set of .40 over coated pistons I can get for a decent price as well. I like the idea of the Eddlebrocks, but if I can get this engine and heads, I’ll probably try my hand at doing the machine work myself. At the least, do a clean up and then eventually buy the Edlebrock heads and add some cheap Harbor Freight tools to my arsenal. Lol. It’s a fairly “cheap” way to get the ball rolling at least and I only see positives coming from the four scenarios. 1) machine myself and fail... gain experience on the cheap and buy the Edlebrock or get lucky on the way with big valve J heads in good condition(most likely scenario). 2) machine myself and succeed... best case and least likely scenario. 3) put the iron heads on the shelf and save them for a later project/when rebuilding my current engine in my car now and buy Eddlebrocks. 4) machine myself and succeed and save them for when I rebuild my current engine that’s in my car now and buy Eddlebrocks. I won’t get into Cam selection until I have an actual build plan. I also have some more lines in the water for other engines that are complete with transmissions, but I like the idea of starting with a somewhat clean slate... Less chance for surprises and literally much cleaner to start. Lol.

I appreciate the input!

 

[Captainkirk]

That’s about what I’ve been seeing. Unless I take the risk of doing the machine work myself, like you said, it’ll be similar costs or more for the J heads. I found a .40 over 360 core with original crank and heads on here for $500 plus shipping though... Found it in the archives from last year. It’s an LA360 from ‘75. Uncertain to the heads, but I’m hoping they’re 974’s. The block and heads look to be in great condition, uncertain to the condition of the crank, but I assume it’s fine... All will go to the machine shop to get a once over at the least. It’s the same engine/head combo I have now, actually. There’s a set of .40 over coated pistons I can get for a decent price as well. I like the idea of the Eddlebrocks, but if I can get this engine and heads, I’ll probably try my hand at doing the machine work myself. At the least, do a clean up and then eventually buy the Edlebrock heads and add some cheap Harbor Freight tools to my arsenal. Lol. It’s a fairly “cheap” way to get the ball rolling at least and I only see positives coming from the four scenarios. 1) machine myself and fail... gain experience on the cheap and buy the Edlebrock or get lucky on the way with big valve J heads in good condition(most likely scenario). 2) machine myself and succeed... best case and least likely scenario. 3) put the iron heads on the shelf and save them for a later project/when rebuilding my current engine in my car now and buy Eddlebrocks. 4) machine myself and succeed and save them for when I rebuild my current engine that’s in my car now and buy Eddlebrocks. I won’t get into Cam selection until I have an actual build plan. I also have some more lines in the water for other engines that are complete with transmissions, but I like the idea of starting with a somewhat clean slate... Less chance for surprises and literally much cleaner to start. Lol.

I appreciate the input!

I have a set of 1.88 J heads at the machine shop as we speak. I'll let you know what sort of pricing they quote me to go through them as a comparison for you.

 

[Dartswinger70]

Guess you haven't been to Fremont St.????

They must have those everywhere. In my neck of the woods growing up it was "Front Street" the street starts with an "F" I dunno why...

 

[John Collins]

I have a set of 1.88 J heads at the machine shop as we speak. I'll let you know what sort of pricing they quote me to go through them as a comparison for you.

Thank you sir! It’ll be interesting to see what you’re quoted... What all are you getting done to them?

 

[Captainkirk]

Thank you sir! It’ll be interesting to see what you’re quoted... What all are you getting done to them?

Depends on the quote. Valves, guides, springs at the minimum. We discussed hardened exhaust seats. He suggested I replace valves and I asked him about upgrading to 2.02s if we do. He said the cost would be the same as 1.88s but some bowl blending would be needed. So I'm awaiting the quote...if it comes within 200 bucks of Eddies I'll likely go that route. Keep ya in the loop.