Author Topic: 340 recommendations?  (Read 1225 times)

Offline mcemond

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340 recommendations?
« on: October 02, 2017 - 03:22:39 pm »
Warning: I know enough about engines to be dangerous to myself and others...
I'm getting close to my engine rebuild date on the macninist's wait list and starting to think hard on what to do. Here's where I'm at:

I want:
Factory original look of engine bay
Long engine life (with how hard these 340 are to find, I don't want to bust it!)
Comfortable (and fun) driving highway and town - but this is not a street racer so any modifications should result in mild performance boost while maximizing drivability for years to come.
I want to run on pump gas (I can add lead additive)
To run at a lower compression (9.5-7) and lower rpm to go a little easier on the motor
To take full advantage of modern internals to make the motor as bullet proof/ efficient/ reliable as possible. Gas mileage isn't a concern though.


What I have or am in process of getting:
Roughly date correct 340 block
Stock cast J heads, intake and manifold
Stock thermoquad
4 speed 309 highway gear
2.7 rear, I forget which 2.7 ratio though.


Parts I have on the side that I'd be happy to use if they work:
Crane gold rockers 59-1.50 C -03, rods and hydraulic tappets. Apparently they are like $750 new so I'd like to use them.
Timing floating gear set - I don't mind the 'blower' noise and like the accuracy


After talking with a friend I'm leaning towards stroking it


So the questions are:
Is stroking the 340 a good idea for my goals and what I have to work with?
What is the optimal stroke size/ kit for the air/ fuel/ exhaust restrictions presented by stock components?
Will stroking a motor destabilize it? I've heard that from time to time, introducing  vibrations, harmonics, etc.
Should I add a different mild cam as well? If so what would be best for this application?
Will it in fact increase smile width while depressing accelerator?
 :burnout:

Thanks
Mike
« Last Edit: October 02, 2017 - 03:27:17 pm by mcemond »




Online 1 Wild R/T

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Re: 340 recommendations?
« Reply #1 on: October 02, 2017 - 04:11:47 pm »
JMHO but... If you are building a car that needs a 340 you should build a 340.... If you want a stroker small block why spend the $$$ for a 340 block?  build a 360... And if your gonna build a 360 I'd get a 88-92 360 roller block..... That way you run a roller cam & lifters with minimal expense...

Add a Scat   48035bi stroker kit  & your off to a great start...  Forged 4" stroke crank, depending on head choice around 10-1 C/R  If you want 12-1 order kit 48033bi

best deal I've found is through Clegg    http://www.cleggengine.com/chrysler-small-block-4340-forged-crank-360-main-365ci-408ci-competition.html
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/90,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...

Offline mcemond

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Re: 340 recommendations?
« Reply #2 on: October 02, 2017 - 04:47:59 pm »
Thanks for your response Wild. Originally I was going to go with a completely stock rebuild... but then I start thinking and that always leads to trouble.

I'd like to stick with the 340 but I get what you are saying. Maybe a 340 with modern internals but not necessarily stroked. Its definitely something I've considered. I was just thinking lower rpm's may be better for the engine and a timing gear.

Thanks again for your suggestion.
Mike

Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #3 on: October 02, 2017 - 06:34:06 pm »
1 Wild is spot on, but I also understand your wanting the 340 to come alive as is...

If you are updating internals anyway, go similar to what 1 Wild suggests, just pick your poison here...

http://www.cleggengine.com/stroker-kits/mopar/sb-chrysler-cast/chrysler-small-block-9000-cast-crank-340-main-372ci-416ci-street-strip.html

Add in a Lunati Voodoo like a 10200701 or 702, and you will have a pretty nice street machine, with a nice little 'rumble'...
 :2cents:
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #4 on: October 02, 2017 - 06:51:02 pm »
also, if you are running vacuum advance, ditch it by disconnecting it and just run mechanical... you'll need 15 to 20 initial timing, so will probably have to limit the mechanical advance, too...

I ran into problems on my 340 with higher idle needed for cam was racing with the start of the mechanical advance (initial timing bouncing around 5 degrees at 900 idle), so I added a plate with 1/8 in. shorter slots to the inside on top of dizzy mech. advance unit, so springs were a bit tighter, and it raised the 'start' of mechanical advance from 1000 to 1500 RPM, with all in at 36 degrees advance at 3000...
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline mcemond

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Re: 340 recommendations?
« Reply #5 on: October 03, 2017 - 08:46:38 am »
Thanks 73. Now we are getting into an area that scares me because of how little I know about how one component change has a chain reaction. I like to follow a manual when doing repairs and not have too many variables to contend with. Originally I thought stroking would be a self contained upgrade. I am beginning to see mission creep. I think you guys have helped me make my decision to keep the stock CI. Will I run into chain reactions by using a timing gear and that rocker set up? If you could upgrade the internals for better wear/ longevity without affecting other aspect of the motor what would they be?
Thanks!
Mike


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Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #6 on: October 03, 2017 - 12:17:58 pm »
So are you tearing the engine down before deciding what to do?

Only reason I ask is if you know if it's been bored before (no longer at 4.040" bore...), or if crank/rod journals have been ground... may make it all a moot point!

I wouldn't think timing gear drive or 1.5 ratio replacement rockers would mess up anything, unless the pushrods aren't right length for lifters/cam/rocker setup.

What does your machine shop have for a plan on the rebuild? What is your budget?
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline mcemond

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Re: 340 recommendations?
« Reply #7 on: October 03, 2017 - 02:34:26 pm »
More stuff I had no idea about. This is good though, I'm learning a lot.

So, I have two blocks that were already torn down and 030 bore. However, I'm trading one block with a friend for one he has mixed in with a bunch of other blocks that more closely aligns with my build date (I know, who cares if its not matching, but I kind of like the search). We haven't dug it out yet and he didn't have any info on if its standard bore/ journal.

So basically by your comment I'm gathering that if its been machined already, it shouldn't be stroked?  I tried to read up on this a bit this morning and couldn't find anything really definitive.

That's good to know about the gear and rockers as they came out of one of the 340's and when told how much they were originally I about choked. I think the cam they went with is pretty aggressive and I know the valve springs were extremely stiff so I wasn't going to use that stuff but I'll ask and make sure the rods are appropriate length.

As for plan:
I've been on the wait list for about 7 months now to have my shop completely rebuild one of the 340's to stock specs. We discussed maybe one step up on the cam (before I knew that a cam influenced horsepower) and hardening the seats for unleaded.

Since then, I've been talking with my friend that is going to let me swap blocks with him and he has trying to educate me a bit on stroking which he is a fan of. He also has offered to help me blueprint and build the engine to save some $$. He also said for the amount I'd be driving the car I shouldn't do the hardened seats and save some more $$. I think he's right on that as I put 500 or so miles a year on my 71 scout with no valve issues so far.

The car will be used for fun not racing. Ice cream with the kids, car shows, highway to work on nice days... Something that pops a little off the line and cruises well at 65/70. The budget is around 5k for complete rebuilt motor but if I can get by with 3k even better. I'll spend money on quality components that last if there's a real benefit.

Thanks
Mike

Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #8 on: October 03, 2017 - 05:18:18 pm »
Sounds like you have a few choices...

The reason I inquired on machining was that if it's already bored oversize by .030, there should be new pistons that were put in for that size bore, so you might be ahead of the game already... you might get by with honing and re-ringing, and new bearings all around (mains, rods, and camshaft bearings).

One other concern was if crank was ground previously, and journals are questionable, you 'might' not be able to grind again. The most you could take mains down is about .050, rod journals about .030), then you should get new crank. If that is the case, a stroker kit would be optimal - you're already .030 over on the bore, and need crank, so then I'd probably go with stroker kit. (Both of my 340 engines have stock bore, so I was lucky to just have hone, re-ring, crank grind, and re-assemble).

One thing to consider - how much is shop charging for the head work? It may be cheaper to buy new fully assembled ones... all threads will be good, valves, guides, and seats good, too... if you go aluminum, you shave a TON of weight!
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #9 on: October 03, 2017 - 06:22:30 pm »
 :2cents:

A good machine shop would/should be able to work with you and make suggestions/options/packages that get you where you want to go, and still be withing budget... with the lead time you have been waiting on 'the list', did you get an estimate of turnaround time to get it back...?

Just as an example, the first thing I did was get my block disassembled myself, took it to my shop and had it cleaned and checked, new welch plugs installed and decks trued, and then J heads reworked - new welch plugs, heli-coils, valve guides, valves, springs, keepers, and new hardened seats pressed in for the bigger valves I put in... It cost me 1,400 in 2004 for that... added another 250 for crank grind and new bearings... I did all the assembly...
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #10 on: October 03, 2017 - 07:00:08 pm »
...and that is just me - worked on engines and cars since I was 14, was welder, machinist, electronic technician, and test/development engineer... so I have all the needed tools and gauges... and just enough lack of brains and common sense to attempt to do most of it all myself... LMAO!!!

But wouldn't change how I've done a thing... several times on some of them... HeeHeeHee...
 :cheers:

And... any advice from members here on this site (Like Chryco or 1 Wild or Alan G.) is some of the best advice you'll ever get...!!!
« Last Edit: October 03, 2017 - 07:02:18 pm by 73_Cuda_4_Me »
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #11 on: October 03, 2017 - 07:29:33 pm »
I'll take that back.. FIRST THING I did was buy Factory Service Manual and Factory Chassis Manual... Read, Read, Read, and still Reading...

I had this to work with:

70 340 spare, 3 burned exhaust valve seats/valves, bent pushrods, and rocker shafts installed upside down at some point in time (wear on shaft should only be on lubricating hole side, not the top! It must have puked a LOT of oil out of the oiler holes when running!). Also had oil pump block mounting surface with a hammer ding in side that prevented oil pump from seating tight to block, previous owner said it always had low oil pressure... I found it when I was re-assembling/test fitting things... file and whetstone cleaned it up.

Here are a couple of pics of some of the major stuff I ran into...
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline mcemond

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Re: 340 recommendations?
« Reply #12 on: October 03, 2017 - 07:45:56 pm »
Yikes. Well, Im all ears when it comes to suggestions on how to achieve goals. I just feel like I blew off the whole semester perfecting stuff with no deadline and now Im rushing to study for finals! Im cramming now though :) thanks guys for all the help. Keep it coming!


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Offline 73_Cuda_4_Me

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Re: 340 recommendations?
« Reply #13 on: October 03, 2017 - 10:38:44 pm »
 :2thumbs:

You will be burning the midnight oil a lot... but passing the exam when that engine fires up afterwards is what makes life worth it...

Your best - errr - 2nd best after your spouse - should be your shop manager... talk it all over with him, and he should be able to explain and provide choices that will get you the fun and reliability you are looking for... and still not break your bank...

And always feel free to ask questions here... I've had so many wonderful members lend sound advice and help on every part of my journey so far....

They have earned these many times over.... -   :angelwings:
1973 Plymouth Cuda BS23H3B567783

R11 V6X EN2
M21 M25 M31 M88 N41 N42
V1X U B41 C56 G37 J54
JY9 A6X9 0 703 501616
E55 D34 BS23 H3B 567783

Offline Chryco Psycho

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Re: 340 recommendations?
« Reply #14 on: October 17, 2017 - 12:48:58 am »
JMHO but... If you are building a car that needs a 340 you should build a 340.... If you want a stroker small block why spend the $$$ for a 340 block?  build a 360... And if your gonna build a 360 I'd get a 88-92 360 roller block..... That way you run a roller cam & lifters with minimal expense...

Add a Scat   48035bi stroker kit  & your off to a great start...  Forged 4" stroke crank, depending on head choice around 10-1 C/R  If you want 12-1 order kit 48033bi

best deal I've found is through Clegg    http://www.cleggengine.com/chrysler-small-block-4340-forged-crank-360-main-365ci-408ci-competition.html


 Yup use a 87-92 La roller 360 block

Challenger - You`ll wish You Hadn`t