66-73 stock small block heads?????

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Bucky Jones

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Where can one find scripture and verse on specifications, fitment, interchangibilty and cannibalization of 273/318/340 heads, blocks and exhaust manifolds/ headers???
Ex: X vs J?
273 vs 318 vs 340 exhaust ports/ header fitment?
valve/cam differences?
optimum cams/heads/exhaust vice 273/318/340?
Is there a matrix chart or computer program in captivity somewhere?
I had a new, STOCK, 1970, 340, 4spd Duster in Germany and it would fly up and down the autobahn. It would go from 0-130 mph in no time and would purr like a kitten at idle. Perfect setup although a Thermoquad and 1 or 2 more gears would have been cool! Mopar had that engine right. I put headers on it when I got it home but did not make much difference. I do not know the specs on that engine but I would love to build one just like it or a 275+HP 273 to put in my 67 Formula S. I just need that scripture and verse.
1972 was the beginning of the end of the powerful stock small block Mopars.
Comments? Suggestions?
Thanx
 
If you think the 340 was sweet, wait til you build a 360!
But I have to agree, 2 more gears would have been nice. Bring them all together a bit, and a deep o/d.

As to the matrix, most of it is already in your head, at least the stuff that matters.

I doubt you would be happy with a NA 273. Of any output.

A large bore stroker though?!Yeah, that'll fly.Just dont choke it with a too-small head.

If I had money, I'd build a turbo SBM. A small SBM, with a long stroke.
 
Everyone is gonna chime in and tell ya that eddy or other aluminum heads are better than any stock cast iron head, and much lighter. Porting helps any stock head.
 
Holy cow, how are we going to answer all those questions? Watch this! lol
 
The 340 cam's specs are readily available on the internets.

The 340s and 360s use larger intake ports- think the exhausts are larger as well. The manifold outlets are larger also. '70s had around 10.5:1 CR, while '71 dropped to ~10.2/10.3. Some early 360s had flat top pistons but I don't know the CR on that.

Where the '68-71 340s were rated to 275, their successor cast crank motors were rated to 240hp. Right around what a stock '92-'02 318 truck motor was rated for. The 360s picked up a little over the last American car 340s and matched that '93-'03 360 truck motor ratings at 250hp. The old motors had larger cams to achieve the power than the newer ones.

The bump in performance in Xs isn't worth the bump in pricetag. Now, for the same price as a set of Xs you can get aftermarket heads that are superior. For the same tag as fixing those Xs up, your aftermarket heads can be ready to run. Unless you have a car they're correct in- you're best off not buying them or selling them and getting something cheaper or better to run on it.

AJ/FormS said:
If I had money, I'd build a turbo SBM. A small SBM, with a long stroke.
Click to expand...
I think that'd definitely end up pretty wicked with a crude EFI conversion on it.

What I've thought would be real neat for a while now would be picking up a very nice 318 Mag with good bores and stroking it and upgrading to aftermarket replacement heads with big valves and stepping up in the cam department dependent on what it'd actually go into.
 
ahhhhh....the Age Old Question.


It is BASIC and SIMPLE if you think about it.

273-2bbl, and 318-2bbl.....have the smallest valves 1.78/1.50, lightest duty springs (.450"), smallest ports.

68-70 (X,O,U castings) 340's have 2.02/1.60 valves.... .500" springs, no rotators, and monster ports.

71-73 ( J castings ) 340 heads have 1.88/1.60 valves, .500" springs, no rotators, and very good ports.

587' castings that came on 360's after 1973, and 318-4bbls.....have 1.88/1.60 valves....and not all of them had .500" springs, and some had valve rotators....and eventually got SMOG Air Injection ports phased into production.

302' casting 318 heads......1.78/1.50 valves, weak springs, small ports, small combustion chambers, air injection ports

308' casting 360 heads.....1.88/1.60 valves, .450" springs, enlarged pushrod holes, 340-360 sized ports, air injection ports


^ right there.....
 
Do not build a 273! Build your 340.
For a cam, it depends on what you want to do with the car. The larger the duration the higher the operating RPM of the engine.
There is no matrix.

EDIT;

The stock 340 was 275HP as per the factory. A set of headers add 25Hp.
 
Bucky Jones said:
Where can one find scripture and verse on specifications, fitment, interchangibilty and cannibalization of 273/318/340 heads, blocks and exhaust manifolds/ headers???
Is there a matrix chart or computer program in captivity somewhere?
Click to expand...
No that I have found.

Suggestion: Read a lot of posts here on question about builds and gather a lot of that info. An example is the post from prine on the OEM head summary. But that leaves out all the after market heads, AL and iron. I have been going down that road of 'catching up' on all the mopar small block info and it's taken a couple of months to get a good framework of info to work from.

So the first and most important questions for the OP are:
- Are you trying to duplicate the 340 performance you had, or go further in terms of HP and torque?
- What is the primary use of the car and engine? Street cruise, street performance, drag racing? What aspects are important to you? Max high RPM HP? Trailer towing? A 'wild and hairy' ride that you can barely hold on to when you just touch the throttle? Good fuel mileage? Just be realistic: some things are mutually exclusive.... the usefulness of the suggestions is very dependent on hwo well you tell people waht you really want to achieve. It sounds like you want an OEM 340 clone: 300+ HP and decent street manners, but let's be sure.
 
Bucky Jones said:
Where can one find scripture and verse on specifications, fitment, interchangibilty and cannibalization of 273/318/340 heads, blocks and exhaust manifolds/ headers???
Ex: X vs J?
273 vs 318 vs 340 exhaust ports/ header fitment?
valve/cam differences?
optimum cams/heads/exhaust vice 273/318/340?
Is there a matrix chart or computer program in captivity somewhere?
I had a new, STOCK, 1970, 340, 4spd Duster in Germany and it would fly up and down the autobahn. It would go from 0-130 mph in no time and would purr like a kitten at idle. Perfect setup although a Thermoquad and 1 or 2 more gears would have been cool! Mopar had that engine right. I put headers on it when I got it home but did not make much difference. I do not know the specs on that engine but I would love to build one just like it or a 275+HP 273 to put in my 67 Formula S. I just need that scripture and verse.
1972 was the beginning of the end of the powerful stock small block Mopars.
Comments? Suggestions?
Thanx
Click to expand...

The old Chrysler Racing manual had an untouched head pecking order, when you could not port for Stock and Super Stock Class racing. Prine is pretty much right in general, except the 70-71 340 J heads had 2.02 intake valves. The best heads were X heads, then J / O / U, then the next in line etc. They got progressively worse till the 308 castings. However once you start porting there is not much difference, not that I'm a porter, I just clean up the bowls, gasket match the ports but leave the bottoms untouched, equalize the chambers within .2 cc and go. Early heads rarely crack, smog heads should always be magged. I've given up on finding uncracked 308's and I'll never run aluminum heads. X's, J's, and 587's are fine with me. The 587's and up had hard exhaust seats. The general pecking order is the same for the small port 273 / 318 heads. The older the better. Personally 340 engines were pretty much perfect, HP 273's next. 360's and 318's last although the 74 HP 360 was pretty good. They all have pluse's and minus's TQ carbs and manifolds are the best street induction, the trick is to find a good one now. I guess the good ones are all about 40 years old. I still like the 340 cam, but I drop the compression from the 68 to 71 340's. All Chrysler small blocks can be made to run very well. Some have all the good parts to begin with.
 
Thanks...I try to post relevant info....and I HAVE browsed thousands of threads, and been messing with Mopars for the last 20 years.

IMHO....if you wanted to stay with Cast Iron heads and make everyday NA 500hp.....I think it would be Hard to beat a set of INDY LA-X heads....for $1050.00 assembled.....then throwing in a NASTY Hughes Camshaft....

[ame]http://www.indyheads.com/images/laxmaxtaprice.pdf[/ame]

http://www.hughesengines.com/Index/...nQ=&searchmode=partnumber&page=1&partid=30245

:happy1:
 
66fs said:
The old Chrysler Racing manual had an untouched head pecking order, when you could not port for Stock and Super Stock Class racing. Prine is pretty much right in general, except the 70-71 340 J heads had 2.02 intake valves. The best heads were X heads, then J / O / U, then the next in line etc. They got progressively worse till the 308 castings. However once you start porting there is not much difference, not that I'm a porter, I just clean up the bowls, gasket match the ports but leave the bottons untouched, equalize the chambers within .2 cc and go. Early heads rarely crack, smog heads should always be magged. I've given up on finding uncracked 308's and I'll never run aluminum heads. X's, J's, and 587's are fine with me. The 587's and up had hard exhaust seats. The general pecking order is the same for the small port 273 / 318 heads. The older the better. Personally 340 engines were pretty much perfect, HP 273's next. 360's and 318's last although the 74 HP 360 was pretty good. They all have pluse's and minus's TQ carbs and manifolds are the best street induction, the trick is to find a good one now. I guess the good ones are all about 40 years old. I still like the 340 cam, but I drop the compression from the 68 to 71 340's. All Chrysler small blocks can be made to run very well. Some have all the good parts to begin with.
Click to expand...

^ Well Said.
 
66fs said:
The old Chrysler Racing manual had an untouched head pecking order, when you could not port for Stock and Super Stock Class racing. Prine is pretty much right in general, except the 70-71 340 J heads had 2.02 intake valves. The best heads were X heads, then J / O / U, then the next in line etc. They got progressively worse till the 308 castings. However once you start porting there is not much difference, not that I'm a porter, I just clean up the bowls, gasket match the ports but leave the bottons untouched, equalize the chambers within .2 cc and go. Early heads rarely crack, smog heads should always be magged. I've given up on finding uncracked 308's and I'll never run aluminum heads. X's, J's, and 587's are fine with me. The 587's and up had hard exhaust seats. The general pecking order is the same for the small port 273 / 318 heads. The older the better. Personally 340 engines were pretty much perfect, HP 273's next. 360's and 318's last although the 74 HP 360 was pretty good. They all have pluse's and minus's TQ carbs and manifolds are the best street induction, the trick is to find a good one now. I guess the good ones are all about 40 years old. I still like the 340 cam, but I drop the compression from the 68 to 71 340's. All Chrysler small blocks can be made to run very well. Some have all the good parts to begin with.
Click to expand...
Another correction to prine is that the .500 lift springs don't seem to have come stock on any of the heads. It's just that they're at the top of the attainable pre-Mag head pecking order so they tend to keep the .500 lift springs when they're passed on. Stock springs are typically very closely matched to the lift which means 340 heads and E58 (and I think E55 360) heads should have better springs on them than low-performance 360s even though cast numbers are the same. So 273 and 318 springs stock wouldn't be good over .400 lift, the 360 springs should be alright for .410 to .430 lift depending on which motor it was, etc. From what I gather- I don't think many 587s had hardened seats if any did- pretty sure they were phased out prior to the leaded cars/trucks being phased out. What I've seen of the factory information leads me to believe hardened seats were phased in on 318s before going to 360s and didn't go to 340s. It's seemed to me so far that 587s were tapped for the smog ports and typically were plugged with weld- that's how the sets I've seen thus far have looked.

Those small cam differences can make a very big difference in the way they run.
 
Correct this then.....:finga:

:wack:

.500" springs.... = springs for .430" - .480" lift (340 spec) and 6500rpm.

tell a newbie that OE Orange Stripe 340 Valve Springs came in anything performance SB then.....

Single Springs with Dampeners...No Valve Rotators....good to ANYTHING Under .500"

:violent2: :banghead:
 
Infecteddog said:
...I don't think many 587s had hardened seats if any did- pretty sure they were phased out prior to the leaded cars/trucks being phased out. What I've seen of the factory information leads me to believe hardened seats were phased in on 318s before going to 360s and didn't go to 340s. It's seemed to me so far that 587s were tapped for the smog ports and typically were plugged with weld- that's how the sets I've seen thus far have looked...
Click to expand...

Hard seats started about late 73 across the board, 587's are in that range. I have a set, no smog holes, ever. When you grind valves you know right away if the seats are hardened or not. You can also tell by the bluish color if they have'nt been blasted.
 
Prine said:
Correct this then.....:finga:

:wack:

.500" springs.... = springs for .430" - .480" lift (340 spec) and 6500rpm.

tell a newbie that OE Orange Stripe 340 Valve Springs came in anything performance SB then.....

Single Springs with Dampeners...No Valve Rotators....good to ANYTHING Under .500"

:violent2: :banghead:
Click to expand...



Correction... :finga:
Good for a STOCK 340 camshaft with lobes from the 60s. Spring use is based on spring pressures, of which, a factory spring has very little of - performance or not. I've been doing this a bit longer than you, and I can tell you most of anything technical you know older then 10 years means jack ****...lol.
 
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