Some 340 Questions

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Fstforward

Fstforward

Barracuda Freak
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Ok, excuse me if I rehash anything said long ago, BUT, I have this 1964 Barracuda, and the 273 that originally graced the engine compartment is long gone, a few owners back, and in it's place now sits a relatively strong 340, from a 1970 Duster.

I plan on freshening up the engine, the freeze plugs seep right now, and there's no room to get to them, so the engine has to come out, and as long as it's out, might as well give it a once over(rings, bearings, cam, yeah cam, nice lobey cam).

My question, where on the heads do I find out which kind of heads it has, and what are the advantages/disadvantages of the j heads and x heads?? Shoudl I junk these heads and go for nice higher flowing aftermarket heads(as long as they are available) or sit down with a die grinder and open up the passages on these?? Also, roller lifters/rockers or flat tappet, which is a better choice??

This vehicle WILL NOT be raced, just want a nice strong engine, something decent to go to shows and cruises.

Oh well, for my first question, be gentle with me.....(8^)*
 
Fstforward said:
My question, where on the heads do I find out which kind of heads it has, and what are the advantages/disadvantages of the j heads and x heads?? Shoudl I junk these heads and go for nice higher flowing aftermarket heads(as long as they are available) or sit down with a die grinder and open up the passages on these?? Also, roller lifters/rockers or flat tappet, which is a better choice??

This vehicle WILL NOT be raced, just want a nice strong engine, something decent to go to shows and cruises.

Oh well, for my first question, be gentle with me.....(8^)*
Click to expand...

I'm sorry, that was a multi question post, you'll have to be spanked by a local Hooters girl. This will be a public floggging with a wet noodle and ladel. A wooded soup spoon may be subed in incase lental soup is being served....now on to answer your questions.

The head question. The letter series heads have there letter cast into them, one on each end by the spark plug holes.
X heads have 2.02-1.60 valves while all other heads have the 1.88 intake vale. I've been told the J's did indeed come with 2.02 valve but I have never seen it myself. Ethier way, they can be added in without issue since there the same head, just with smaller valves.

The OE iron is a good head and can do/go very far for a generally cheaper price than aluminum heads can though most aluminum heads are ment to be ported for serious power.

What is it you want to do with the engine/car and amount of power output?

On cam choice, a roller offers more. The solid cams, if choosen wisely, can stand toe to toe with a roller cam if your willing to live with a bit more spring pressure and change them out after awhile.

On rockers, I like rollers with my Hyd. cams. I'm not so keen on the noise otherwise with solid cams.
 
Well, I am bending over waiting for the hooters girls to spank me!!! (8^)*

As far as the engine goes, I want a nice, strong street machine, with a nice, lobey sound, and I will end up with, probably, Flowmasters on it, and i want the car to "announce" it's arrival and turn heads based on sound, first!!

Does that make sense??

FF
 
on the cast iron heads...you need to do an assessment on how much it is going to cost ...do you need new valves..springs, harden seats..guides?

not knowing your budget....price the hydraulic roller cam...lifters...and new springs of course...along with adjustable rockers... and a flat tappet hydraulic cam will look pretty good.
 
Yes sir. Junk trhe heads. I'm giving $50 for junk 340 heads these days. Get you some really good aluminum heads for that motor. Tell me when you want my address and i'll need an address where to send the $50 and of course the shipping.
Small Block
 
LOL @ S/B.

FstFoward, yes, that makes sense. Before anybody goes any further, what tranny do you have and what is the rear end's gear ratio... or what it'll be when done.

70aar, budget, BUDGET! We don't need no stink budget. We have monoploy moey to spend first! Ha ha ha ha.
But seriously, your right. He did mention and I assumed that he can port heads himself there by making a iron head cost effective. The Iron head can flow very nicely.

For the most part, I don't have it in my pocket to purchase aluminum heads and then port them. This is even more so with Edelbrock heads. I'd rather Brodix, Indy or MP heads for this venue.
 
FF.

You can achieve a lopey sound through a lower centerline cam shaft. 110 has the standard chopy idle while a 108 chops a bit more and a 106 is a chop that sounds much like a high a a kite crackhead choping for his life....aka next fix or be burned alive.

A chopy idle is nice, the ones that have a pernounced idle are of a higher compresion.

Then the sound itself is the muffler.
 
Ok, what I am taking so far from this is the 340 heads are pretty decent on their own.

As far as transmission goes, I haven't explored underneath that far yet(some personal stuff going on), but plan on getting underneath real soon. What should I look for on the tranny for identification? It's a 4 speed, and as far as I know, it's the original.

Rear end gears, not sure what's in it, but would like something nice and streetable, like mid 3's(3.53??)

FF
 
pettybludart said:
Through a 360 crank in it ,work over the heads!It,ll perform,just better!340,s already perform!
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I did the math and a 360 crank adds about .27" of stroke, but what other mods need to be done if a .360 crank is put into a 340?? I know effective displacement is raised to ~367 with the 360 crank/340 block, but would I need different pistons or rods because of the longer stroke???

I appreciate all the input, this way I can do all the research, come up with the plan, and move forward and be ready when I do pull the engine and start the build.

FF
 
Just use teh heads you have, odds are they are 2.02 heads anyway (unless it is a cast crank external balance 340).

The easiest way to tell if they are "X" or "J" heads is to look around where the spark plug holes machined in the heads. If they have an X cast into them they are X heads, if it is a J (or an O with a portion machined away by the spark plug hole) they are J heads. If it has an O they are "O" heads.

Either way they should work fine for what you want , maybe even with 1.88 intake valves. Unless you are racing or really worried about how it pulls above 3500 RPM, the low performance heads with 1.88" intake valves will work fine and sound just as nasty when idling around the drive in.

I have a 340 in a 3360 pound car that runs low mid 12's . it has 2.02 valve "O" heads on a .030 over 340 engine. Might have a very little porting, but not much past a bowl blend and gasket match.

Bob
 
Fstforward, the 340block/360 crank deal are the same mods as putting 340 pistons in a 360, the top of the 340 piston needs to be stepped to clear the bottoms of the heads, plus the wrist pin boss needs trimmed a little to clear the counterweights.
Why do all that when the A/M makes good pistons for the 360, now?

If you're going to stroke a 340, do a 416 and be done with it.

Mark.
 
Fstforward -
Everybody so far has focused on the engine and rear end gearing. My concern is the rear end itself (the cars, not yours - you're just waiting for your Hooter girl spanking).
You're gonna need a 8.75 behind a stout 340/4-speed combo. Nothing's been said so far about what is in the car so I assume it's the original rear end that was behind the 273/4-speed combo.
Something else to consider.
 
Ok, I'll bite, what is involved in going from 340 to 416???

Beginning to think that just warming over the 340 is a good enuf idea, at least for now!!

And excuse my ignorance, but what is a "bowl blend"

FF
 
I've been away from these cars for so long that I seem quite naive! My origianl Barracuda was a 65, 273 bored .060, heads ported, full race cam, and I did race it, 12 flats on pump gas. had a 9" rear with 4.11's.

Now, for my NEXT question, how do I know zactly which rear end is in this beast?? Casting numbers, measurements, any help would be appreciated.

FF
 
rumblefish360 said:
LOL @ S/B.

FstFoward, yes, that makes sense. Before anybody goes any further, what tranny do you have and what is the rear end's gear ratio... or what it'll be when done..
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Well, got under the car today, only numbers I could find on it were C95664J on the side plate, and C95639U on the case. Other than those, couldn't see any others.

Rear end wise, only found one set of numbers and they were unreadable, but the whole thing looks like it was installed not horribly long ago. Real clean(cept for the leak on the rear cover) paint is beautiful, not like a brushed and painted unit.

Engine # is 2780930-340-1

Heads, passenger side is a J, crivers side just has a blank pad, no O, X, or J, so, now what am I looking at???

Thanks again

FF
 
Since the rearend cover is leaking like you stated it is probably an 81/4 rear which should be good enough for the street. The 8 3/4 has no rear cover, it is solid and round and the center chunk is removed through the front!
 
The last '66 273 4bbl stick car I had came with the 7 1/4 from the factory. I would plan for an 8 3/4 if you want to build the engine. IMO, rebuild the 340 and go with it. It will be a snappy car with the stick and some gear. If you plan to rebuild it completely, build the 416 and as Mark says, be done with it.
 
moper said:
The last '66 273 4bbl stick car I had came with the 7 1/4 from the factory. I would plan for an 8 3/4 if you want to build the engine. IMO, rebuild the 340 and go with it. It will be a snappy car with the stick and some gear. If you plan to rebuild it completely, build the 416 and as Mark says, be done with it.
Click to expand...


Where can I find info on what the 416 build takes, both in parts AND work???

Thanks in advance

FF
 
Fstforward said:
Ok, I'll bite, what is involved in going from 340 to 416???
Click to expand...
I regret mentioning this, truthfully.
There are stroker component kits out there which are basically a 4.00 inch stroke crank, aftermarket rods and pistons, all of which bring a .030 over 340 up to 416 cubes, some kits are reasonable, others are outrageous in price.

Fstforward said:
Beginning to think that just warming over the 340 is a good enuf idea, at least for now!!
Click to expand...

In your case, especially with something that already runs, this is the best course and, with that little Barracuda, plenty for street performance and that kick in the *** for a bit of fun.

Fstforward said:
And excuse my ignorance, but what is a "bowl blend"

FF
Click to expand...

A "Bowl Blend" is NOT some special weed/narco combination! :D

This term refers to removal of material from the area directly below the valve, up to where the intake port enters the area below the valve.
This area is called the "bowl" (or "pocket"), which is probably the best place to do minor grinding and can get you some notable performance gains with a minimal amount of work.
DO NOT grind on heads you want to save, or use, if you don't have any experience doing this, as you will likely destroy one or 2 in the process.

Mark.
 
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