340 General Rebuild Info- Cam Recommendations

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fastmerc

fastmerc

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Greetings!

New to the Pentastar world and the rest of the world has kept me from getting anything done on my 71-72 340 Demon that I acquired a couple of years back. Clutch is still bad and my shop is packed with OPS (Other People's Stuff) at the moment, plus a failed lift install! (too thin concrete!) BUTT working slowly to get thru the cow poo.....

While the clutch job is straight forward, I was considering a boost to the 340-4V. I was watching a recent-ish episode of Graveyard Cars (I know....many of you are haters..... but I also like the cars and info....not the BS! I wear my boots when I watch the show....) where they fired up a black Cuda (I believe) without mufflers and it sounded a bit more than a stock engine (aside from the obvious noise!). I doubt that anyone there publishes the specs for their rebuilds and I know Worman "talks stock" all the time.....but I'm guessing a little more lift and duration on a cam isn't too much of a crime...! My car runs more like a hand-vac and I'm thinking more Hoover.....not exactly a shop vac.....but I need it to be streetable without massive valve train/mechanical mods.

BUTT, I have no knowledge of the 340 class of engines and was wondering if there are any reference books that I can look for that outline the details of these engines, good, bad, recommended fixes etc. Good general rebuild/maintenance information. I don't have a factory shop manual yet......so references there would be good. I do know that Mopar does their manuals a bit different than the Ford stuff I've been working in for years.

Just trying to line up some ducks.....
Thanks for the forum!
Steve
 
Welcome Steve! Is your 340 a 10.5 or 8.5 to 1 comp engine? Headers? What carb and intake? Rear gear ratio?
My combo was a 484/284 hyd cam and GOOD valve springs, aluminum dual plane intake with 750 vac secondary Holley, electronic ignition and 1-3/4" headers with 2-1/2" exhaust to the rear axle. It was a 10.5-1 comp and maybe a bit more because the heads were "shaved" everytime they came off. It was a 4-speed with 3.23 gear and 27" rear dia. tire. Ran well, rumbled nicely. I thought it lacked low end until 3500 rpm. Best ET was 13.18 with slicks and open exhaust and MPH was 108. The cam was in the MP guide, recommended for an automatic. I figured it would work well with the 4-speed because of the 3.23 gear. Hope this helps and doesn't muddy the issue.
Fords,eh? Always thought a V8 Maverick would be fun. Either a 347 or there abouts or a Cleveland.
 
abdywgn,
Greetings!
I have yet to discern all the detail of this Demon. It is a 71 model, plain as Jane 4spd car! Bench seat to boot! It appears to have been rebuilt back in the early to mid 70's when the prev owner bought the car to drive in high school......and it hasn't been touched mechanically since! Still has stock carb, valve covers and air cleaner! No headers. The clutch is absolute toast and is awaiting replacement after I can get my lift installed. I've decided against changing cast iron gear boxes on my back......used to do Ford toploaders that way, but now T-5's are as much as I want to try and hurt myself with!!!! Getting old is a bugger! It has a 3.23 posi I believe....will confirm it all once it is up in the air! Can hardly wait.

What bothers me about the last post I was reading, which was a 318 cam test with extrapolation to a 340 suggested.... but the numbers, HP and TQ, which I presume were crank numbers, were much less than what I experienced with a 331 SBF build that I did for a mid engined car. Roller cam, .530ish lift max, alloy Ford Racing heads (65ish cc chambers on flat tops), about 10.5cr, ported heads to match a Performer RPM and headers, with a puny 570CFM Avenger carb. I was getting about 320HP at 3500 or so, and 305TQ at 4500 or so..... A good low RPM fun to drive power plant! It had manners.

Your engine sounds more like what this SBF was..........so I was glad to read your experience! It surely seems like the intake ports are more than capable, exhaust, not sure yet, but everything else I've read said that the intake lacked nothing! Except a diet! :) I was looking to find some apples and apples to compare!

MP Guide???? Not familiar with this yet.....

Funny you should mention a 351C....that could be one of my next projects if it isn't worn out.....working on swapping some projects. I don't like the 347's so much due to the shortness of the pistons and the rings in the wrist pins...... 331 had a little of the latter but taller slugs for more stability. If I could get the heads (may actually be Edelbrocks....) again, and a similar cam, I could be persuaded to put it in place of the Cleveland! It was that sweet!!!! Or maybe a roller 351W....... SO many engines so little time!

Thanks again!
STeve
 
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Oregon Cam Grinders has the 68 340 4 speed cam on file and can grind you one. It's a pretty good grind.
 
fastmerc said:
Greetings!

New to the Pentastar world and the rest of the world has kept me from getting anything done on my 71-72 340 Demon that I acquired a couple of years back. Clutch is still bad and my shop is packed with OPS (Other People's Stuff) at the moment, plus a failed lift install! (too thin concrete!) BUTT working slowly to get thru the cow poo.....

While the clutch job is straight forward, I was considering a boost to the 340-4V. I was watching a recent-ish episode of Graveyard Cars (I know....many of you are haters..... but I also like the cars and info....not the BS! I wear my boots when I watch the show....) where they fired up a black Cuda (I believe) without mufflers and it sounded a bit more than a stock engine (aside from the obvious noise!). I doubt that anyone there publishes the specs for their rebuilds and I know Worman "talks stock" all the time.....but I'm guessing a little more lift and duration on a cam isn't too much of a crime...! My car runs more like a hand-vac and I'm thinking more Hoover.....not exactly a shop vac.....but I need it to be streetable without massive valve train/mechanical mods.

BUTT, I have no knowledge of the 340 class of engines and was wondering if there are any reference books that I can look for that outline the details of these engines, good, bad, recommended fixes etc. Good general rebuild/maintenance information. I don't have a factory shop manual yet......so references there would be good. I do know that Mopar does their manuals a bit different than the Ford stuff I've been working in for years.

Just trying to line up some ducks.....
Thanks for the forum!
Steve
Click to expand...
What do you expect from the engine? What type of induction and exhaust does it have, it's a 4-speed so what gear does it have in the rear end? It's true an old grind will work pretty good, but if you're going to modify this in any way as you put it together or build it you're probably going to want a custom ground cam which isn't a big deal. I'm thinking something like .495 .510 lift / 220/[email protected] 109 if you're using stock heads and definitely a solid.. then let's get modified those heads beyond about job and minor casket matching and cleaning up and things like that then you can push that lift more and depending on what you want to do with the rear end of course. An easy 375-410 horsepower
 
hey RRR ... quick question, does Ken have a lifter package that he sells with that cam or can you recommend quality lifters for that particular 68 4-speed cam..Rich
 
New lifters have been a deal, most are reman and prone to fail from what I hear. Some guys are cleaning up the old lifters checking the crown and reusing them instead. 340 is a good engine easy hp I think, due to the larger bore and shorter stroke. Depending on how extensive of a build you want to do. A lot of opinions here, and a lot of good information. What heads are on the 340? You can look by the spark plugs next to the head bolt you should find a letter. Most likely an x or a j. The x heads will have 2.02 intake valves and the j heads could have those or the smaller 1.88 valves both sets of heads are good to .500 lift with factory set up. To much of a cam will require be valve springs of course. A lot of the guys don’t like comp cams, I think there a pretty good cam. And a good value. The 268 cam is slightly over the stock cam, and the 280 is a really nice street cam that you can run with the factory valve train. The 110 separation I think keeps a little more vacuum at lower rpms. Wich I think would work well o. The 4 speed. The factory carbs are pretty good flowing up ware of 700 already. A set of headers would definitely help. Just my opinion on a quick easy rebuild for street use. You bring a ford guy could probly compare the 340 to the 351w for reference as far as cam and intake combination. He ope that helps you scratch the surface
 
fastmerc said:
RRR,
Good to know! Will see if I can't dig up the specs on it for reference.

Thanks!
Steve
Click to expand...
Here's the catch. Chrysler's published cam specs are unique to Chrysler.
A '71 340 will still have the 340 valves regardles of head casting, and should have the higher compression pistons.
There's engine decoding info in the 'articles' section of the forum.

Unless you have a particular goal and plan, I'd get it running and shake out the issues. Then make whatever mods float your boat.

Depending on what can be done under Calif. smog rules, it will run a little better with a distributor advance curve similar to those that came from Mopar Performance. Basically it allows using a pre-CAP initial timing without jacking up the timing above idle.

Headers will make a noticible difference, but are a royal PIA. Compared to a maverick engine bay, the Demon will seem roomy. However the T-bars make snaking the exhaust relatively challenging. Off the shelf there's really just two choices of manufacture, Dougs or TTI.
 
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Mattax said:
Here's the catch. Chrysler's published cam specs are unique to Chrysler.
A '71 340 will still have the 340 valves regardles of head casting, and should have the higher compression pistons.
There's engine decoding info in the 'articles' section of the forum.

Unless you have a particular goal and plan, I'd get it running and shake out the issues. Then make whatever mods float your boat.

Depending on what can be done under Calif. smog rules, it will run a little better with a distributor advance curve similar to those that came from Mopar Performance. Basically it allows using a pre-CAP initial timing without jacking up the timing above idle.

Headers will make a noticible difference, but are a royal PIA. Compared to a maverick engine bay, the Demon will seem roomy. However the T-bars make snaking the exhaust relatively challenging. Off the shelf there's really just two choices of manufacture, Dougs or TTI.
Click to expand...
I couldn't agree more.

We spend lots of time talking about cams, heads, cabs, etc., and then just throw a distributor into the engine and run it. The distributor advance curve is critical to a good running engine. The exact same engine can run like a pig or a scared ape, depending on carb and distributor tuning.

I totally agree with getting the engine running and then really tune it. Don't just turn a couple idle screws on the carb and be done with it. The 340 is an awesome engine and tuned properly, you may be happy with it as is. From there, you can start to think about cam, head or carb changes. But getting a good baseline first is great place to start.

(By the way, I have 73 Road Runner with a 340 - now a 416 stroker. I've had it for 42 years and the engine has been through multiple changes.)
 
Guys, ALL great responses, just what I was looking for....little bits of goodness.
The head info was new to me, I can check for casting numbers to confirm, but suspect that the 71 should have the bigger valves....BUTT, confirm confirm confirm!
Lifters: yah that is a crazy subject!!! I guess the idea of just tossing out the old and tossing in the new is sort of old hat now! SO, who's got a lifter crowning setup???? :)

The idea of cruising into this vs tossing stuff at it......that always makes sense and I try to preach the same things with guys that I know, including my son, who simply wants to toss stuff at a project rather than work a little bit...... The magazines also preach one thing at a time...vs change everything and then wonder why you lost 75 HP....(!)....or "now it runs like a dog...."!

CA Smog: THANKFULLY, that only kicks in at 1975. I have a 1974 vehicle that THANKFULLY does not reward me every two years with the "SMOG CHECK REQUIRED" notice in my renewal regs!!! Let the horses run!!!!

The notes on the heads (x & j) and valves is great! I understand the need for headers at some point but depending on the actual design, they may not really contribute all that much to the street game....maybe 10-20HP or some more torque.....but below 5K rpm's they are fine! What I would do, which is what some of the sneaky Ford guys are doing, is using 351W exhaust manifolds which are port matched to ported exhaust ports AND either extrude honed to finish off the insides of the manifolds, or they are simply ported further into the manifold to allow for more flow! Ford SB's typically have a TINY exhaust port that begs for a roto-grinder to be applied! That and a better cam is much more fun! I always ran headers on my 351W but had to weld up the chassis once for ripping the power steering ram out of the frame due to header clearance, multiple exhaust leaks with long tube, short tube...didn't make a difference..... They all REALLY needed a "ball joint" at the header to pipes flange....but never quite go there before son grabbed the car from me....! But still a pain in the BUTT! Peeling paint.....burnt wires.....pffft pffft pffft again.....! Manifolds would be quiet!!!!

IF and that is a BIG if.....I was gonna do anything based upon what I learned with my (fun driver!) 331, is basics. Goal of 300HP+ at rear wheels, which I think is doable with stock basic parts..just a bigger cam and port cleanups...but this is a what if.... Alloy heads, to allow up to a mechanical 10.5:1 CR, with nothing larger than a 2.02 intake 1.6 exhaust, RPM or Air Gap intake, 600-630 Vac Secondary carb (or original!), solid state ignition of some OEM sort (hate Mallory and MSD....seen too many buddies on side of road....) and a cam with no more than a .530 lift, pattern to match what guys have seen work..... 110 separation angle would have good vacuum and smooth idle, although I do not have a brake booster on the car with front discs........ (Not sure how these came to be as they are not on the build tag....) and it is a manual trans car so "could" push that number down to 108 and not feel to bad about it.

I've enjoyed watching "some" episodes of Engine Masters when basics are put to the test..... Engines are simply an air pump and no matter the OEM version, they all answer to the same laws of physics! HP engine building class drilled that into me!!! Take one if you can get it at a local JC etc! Good basic info!

Cheers and thanks again! Much to digest and go check out! Now to get that danged messed up clutch out.......!!!! Priorities priorities......too many ground squirrels, gophers, and trees......ugh!

Steve
 
mad dog said:
hey RRR ... quick question, does Ken have a lifter package that he sells with that cam or can you recommend quality lifters for that particular 68 4-speed cam..Rich
Click to expand...
He will sell lifters too.
 
I'm running the .484 cam , but w/ a 727 and 4:10s. Now they killed Mopar performance so I don't know if you can get one but they had one called a radical resto cam it was like the 340 cam but it was a little bit hotter had one in a 318 and a club cab Ram from the '70s that truck would blow the tires off whenever you nailed it. And it had good size tires on it
 
While you are waiting to do your clutch, I'd suggest you pull your distributor. Have the mechanical advance checked by an old school speed shop that can run it on a distributor machine. For your engine, I'd say you want the timing to start coming in around 1000 RPM. I will also assume you will put 15* of static (base) timing into your car. You want 36 to 38 total degrees of timing, so that means your distributor should add about 22* of crank timing (15* + 22* = 37*). 22* of crank timing is 11* of distributor timing. You want this timing to come in fully by around 3000 RPM. These are rough numbers but should get your distributor to work pretty well.

So bottom line: bring your distributor in to someone that knows how to test and modify it. Have it set up so it has 11* of (distributor) advance (or 22* of crank advance), starting at 1000 RPM and "all in" by 3000 RPM. This should give you a pretty peppy and responsive distributor.

Good Luck!
 
HSorman,
All good stuff!!!! Basic target numbers are good to know!

Since I am "olds cool" by being, I'll fire up my stand alone tach and my timing gun and see what I've got.... Plot out a crude curve up to 3K and see where we're at! Adjust as neeeded!

Any advice on creating better spark with the original OEM units? I know buddies were always replacing the box on the firewall with the big transistor case on it..... not sure if that is ignition or voltage regulator.....

But words of wisdom for triggering the coil other than points, prefer to use hot rod OEM if it's an option???

(I am a large DuraSpark II fan for my "other" motors..... 10 degrees of retard at cranking feature (Blue strain relief boxes) lets you run 24 degrees of static initital advance, no vacuum, and fixed 10-12 at the distributor weights for a total of 34-36 which is what the SBF's love! Lets you run LOTS of static CR and piss for gas.....until things get too hot....that's where the alloy heads reign! ) I'm sure that the CARB boyz would be outraged.....! These things also work at "bad battery" voltages where MSD and Mallory start puking and non-performing at 9V. :)

Thanks!
Steve
 
fastmerc said:
HSorman,
All good stuff!!!! Basic target numbers are good to know!

Since I am "olds cool" by being, I'll fire up my stand alone tach and my timing gun and see what I've got.... Plot out a crude curve up to 3K and see where we're at! Adjust as neeeded!

Any advice on creating better spark with the original OEM units? I know buddies were always replacing the box on the firewall with the big transistor case on it..... not sure if that is ignition or voltage regulator.....

But words of wisdom for triggering the coil other than points, prefer to use hot rod OEM if it's an option???

(I am a large DuraSpark II fan for my "other" motors..... 10 degrees of retard at cranking feature (Blue strain relief boxes) lets you run 24 degrees of static initital advance, no vacuum, and fixed 10-12 at the distributor weights for a total of 34-36 which is what the SBF's love! Lets you run LOTS of static CR and piss for gas.....until things get too hot....that's where the alloy heads reign! ) I'm sure that the CARB boyz would be outraged.....! These things also work at "bad battery" voltages where MSD and Mallory start puking and non-performing at 9V. :)

Thanks!
Steve
Click to expand...
My approach is somewhat different.
Assuming its the factory distributor, weld up the inside of the slots, file and your mostly done.
If the tag is gone you'll have to check with the timing light, tape, and the tach. But best to do that regardless.
With the first portion of the advance shortened, you may want to reduce the initial tension a bit so the advance still begins just above idle rpm.
The factory settings were usually a bit conservative to insure cover worst case scenarios but the general shape of the curve was well tested. Service techs were expected to make small adjustments to initial timing depending on local situation including fuels available, as well as engine idiocincrities and customer.
 
The two stage advance important. More so with electronic ignition and always when using vacuum advance - which other than drag racing is very helpful for all off idle part throttle efficiency and power.

Two stage advance has the timing advance very quickly from idle to 1400-1800 rpm. Then advances slowly with increasing rpm.
The Chrysler design does this well.
An example here 360 Tune Up
Its important to make measure the actual timing like Rockable did before deciding this is the modification needed.

This thread has a good example of making other adjustments. Also shows both types of spring perches Chrysler used.
www.forabodiesonly.com

Distributor curve help needed

I just checked the curve of my stock distributor (ported vacuum blocked) and need some help to optimize. Car is a 70 Duster with a stock 360, stock converter, 3.23 gears, 28" tires. Distributor currently has FBO black & gold springs with no limiter plate. 500-24* 1000-24* 1500-25* 2000-27*...
www.forabodiesonly.com www.forabodiesonly.com

Examples of how Chrysler changed the timing, in particular the initial timing and rpm, to improve emissions at idle in this post.

The secret advantage of the heavy spring for high rpm when using electronic ignition.
 
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Mattax,
Wow! Great bits to know about dist!
Hopefully I can get some time later today or tomorrow to verify some physical stuff first, before actually firing things up! .....just noticed air is missing from one of the tires..... damned cats probably stole it......

Cheers!
Steve
 
OK, take 2.....website difficulties!
Had time to snap a few pics of the engine and bits. Guessing these are the "J" markings although they look like big "U"s..... Sooooo, actual valve size remains TBD!

Appears to be original carb, but not sure where numbers are and not worried at the moment...I know it needs an accel pump. Dist also appears to be orig. I can see tag on front of it, but can't get in to read what the numbers are.

It has this dual inlet "no snorkle" air cleaner on it. I would expect 71 to have heated air to the carb in CA??? So guessing that this is something that the prev owner swapped in?? I have more pic's of mystery items that I will ask about in the engine compartment but will save that for next post. Gotta go finish cleaning up a wheel rim....ugh!

Decal in trunk "says" Sure-Grip......but stickers only cost pennies to install..... Can't get under car easily at the moment.....cats let the air out of one rear tire.....and I can't put my hands on the other set of rear gears that "I think" came with the car.

Since this was a rare 8 speed car...... I checked out the second trans in the trunk. Hand written tag says that "he hope that the next owner chooses to install the stock scissors linkage" when the car is restored..... Any one have an idea of what Mopar may have called a scissors linkage? It's not in the trunk.....but could be in other milk crates that I put up above the office of my shop......so not really easy to get to either.....hate that....!!!

More later! Thanks in advance!
Steve

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fastmerc said:
I don't have a factory shop manual yet......so references there would be good.
Click to expand...

I very much prefer a physical printed FSM over anything available on line, but some of that's just me. I use Faxon for reprinted manuals, they are fairly priced and of excellent quality.
 
RustyRatRod said:
Oregon Cam Grinders has the 68 340 4 speed cam on file and can grind you one. It's a pretty good grind.
Click to expand...
Oh, cool. That actually happened. I read something about that on here that they might be doing that. Didn't know they actually went through with it.
 
Wow..original 340 cars are so hard to find now. You have a pretty nice and valuable project that
appears to have all of it's expensive hard to find pieces. What are your long term plans, proper
restoration?
 
lilcuda said:
Oh, cool. That actually happened. I read something about that on here that they might be doing that. Didn't know they actually went through with it.
Click to expand...
Yup. They sure did. Because of "whatever" constraints they have, their version was like 1 degree different, yet people on here argue and say they gotta have "the real thing". LOL

But yes, they have it on file and you can call up and order one.
 
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