340 upgrade, $1000 budget

[Tonker1]

Next summer, for me in Australia, 12 months away I'd like to upgrade my '72 cast, '73 assembled 340. It is not the original engine to the car so any work won't be damaging a numbers matching powertrain!

I drive the Challenger daily and regularly go thrashing round corners and shifting up and down gears through the local mountain roads, the Hotchkiss sway bars and disc brakes do an awesome job of keeping it planted. The motor feels like it's a bit lacking at 3500rpm. I know for real pro touring the revs should be up higher, but I'd like some more low end when driving around town.

So the goal, I'd like to move the power band down or widen it to give more low end torque. I will have a $1000 budget, maybe a bit more depending on how the year goes to do some work.


Current configuration
- Holley 670 street avenger
- Edelbrock rpm airgap duel plane intake
- MSD blaster coil 2
- MSD 6Al ignition
- MSD pro billet distributor
- Engine temp can be adjusted from temp using the electronic fan controller
- Air fuel ratio gauge so I don't biff up the carb tuning!
- 4.10 diff gears
- 1st through fifth on the TKO 600.   2.87, 1.89, 1.28, 1.00, 0.64
- The head casting is 3671587, so the current valves are 1.88, 1.60.
- The headers are an unknown after market job that arrived on the car. Uncoated iron, 1 5/8" pipes to 3.00" collector and 2.5" mandrel bend dual exhausts with no H or X pipe. I prefer the choppier sound of separate pipes!

- By the time I start the engine work there will be cold air coming in from a t/a hood


The cam and valve train are stock, without lifting the cylinder heads I assume everything else is stock as well, so cast crank, pistons and 8.5:1 compression.

There isn't much I'm not willing to try and do I've spent the past 6 months reading all threads and books like Burt's 'how to rebuild the small block mopar.'

The three basic paths I can think of would be :
1.   New cam and lifters
2.   New cylinder heads
3.   New pistons

The cam and lifter swap is probably the only combination in my budget range, but I'm open to suggestions and ideas. What would people recommend?

[Chryco Psycho]

340s were never good for torque , they are a large bore short stroke engine good for RPM  , this is why the 360 was used to replace the 340 & also why a 340 was never used in trucks , a good modern cam will help math the cam to the rpm band where you want most of the power smaller RV cams will help build dynamic compression at least  , smaller chamber heads would help too but you ccould never get quench without swapping in high compression pistons.

[rUNCHARGER]

Jeez: I don't see gaining much torque from going with a different cam than the stock 340 one. Maybe it is worn out though. You could mill the heads to gain some compression  at the same time as a cam change I suppose.
If you were here where there's junkyards I would recommend swapping to a 360 Magnum longblock, but I don't think you could do that for $1k where you live.
I think your $1k budget won't fix it and might not set you up properly for future upgrades either. What you probably need is a stroker crank and that is $2k for parts. But the stroker would bring your power in earlier.
If it was my car I would probably mill the heads or maybe install light, high compression pistons, put in bigger valves, more cam and rev it higher. I love 340's and the way they rev. but they aren't a truck engine as was stated.

Sheldon

[cudabob496]

best bang for the bucks is a set of heads.

use cam to determine hp,torque, power curve.

you got headers? 2.5 inch X-pipe dual exhaust?

[CUDA JAS]

so the 4.10 gears are not in it now?

if not what gears are in it?

Jason

[RCCDrew]

I love the low buck theme. If it were me, I'd mill and mildly hand port the heads. Make sure you have the 2.02 intake valves. Back cut the valves or get some valves that don't inhibit flow. Port match the intake, and put in a modern, dual pattern cam. TA style iron adjustable rockers. If you use your own labor, that $1000 will go a lot farther. Sounds like you have a 4 speed car, so you have more cam choice.
Heads make the power. So make the most of the ones you have.

[Tonker1]

Cheers for all the responce, everyone's suggestions are addressed. Since the 340 is a rev monster as opposed built for low down grunt, I'll change my driving style for in the mountain turns. The big pleasure is in working the engine and transmission, I'll just push the rpms higher.

With stock cast iron: crank, pistons, conrods, what is the safe limit on the power band? 6300ish?

I also realise my $1000 budget may be a little too conservative, I do have a year to save and should be able to russell up some more.

To answer questions on current parts I'll update this information into the first post as well
- The 4.10 gears are installed currently!
- The head casting is 3671587, so the current valves are 1.88, 1.60.
- The headers are an unknown after market job that arrived on the car. Uncoated iron, 1 5/8" pipes to 3.00" collector and 2.5" mandrel bend dual exhausts with no H or X pipe. I prefer the choppier sound of separate pipes!


Options:

-Cam swap
As the engine has been a sealed time capsule for the past 40 odd years on a cam swap I would also replace the timing chain, lifters and so on. There is probably not much point in replacing the cam with a stock springs and rockers.

This cam has the wrong specs, I'm not going to buy it, but for sake of financial calculations;
-Complete cam & lifter kit: $1100 www.summitracing.com/int/parts/cca-k20-600-9/overview/make/dodge
-Hughes 1.6 Rocker kit: $550 www.hughesengines.com/Index/products.php?browse=category&level0=QS0gU21hbGwgQmxvY2sgIkxBIg==&level1=Um9ja2VyIEFybXMgJiBBY2Nlc3Nvcmllcw==&partid=26579
-Total: $1650

-Would new rockers make much of a difference?
-Instead of using the cam to bring down the power band, would I get a lot more for my money using the cam to improve the stock power band?
-In all honesty, is a cam swap on 8.5:1 compression engine a waste of time?
-If it's not a waste of time, what would the expected power gains be from the stock hp and tq rating, I know that is a hard question to answer. I just want to make sure I'm not wasting my time and money.


-Higher compression pistons
labour around me is not cheap (prices below are considered good, does not include take apart or assembly)
-Bore & hone $300
-Engine balance before Mallory $300
-Pistons: +$350
-In terms of bearings and other parts needed for a piston swap, what would normally be replaced? Very vaguely what would be the total cost?


-Cylinder heads, with stock rockers & cam
-Edelbrock rpm heads: $1780
-Deck block : $150
-Total: $1930


-Valve swap on current heads
I'll look into the costs of the valve swap on the stock heads option next week when machine shops  open up again.
Aside from the valves what other parts should be changed?

The last three options will require pulling the heads and intake, so I'd do a port match. Heck, I have an entire book by David Vizard on porting heads, I'll give it a read!

Cheers in advance!

[rUNCHARGER]

I would do a compression or leak down test before proceeding, just to make sure your ring and valve seal is good or not. I got thinking that seeing as this engine has not been opened up, your timing chain is likely stretched and that retards cam timing which would result in a gain in top end power and a drop in low end power. Which could be a part of your problem. I would guess the camshaft is worn to and replacing it is pretty much a given.
I would not spend the $$$$ on the rockers. That same money would be better spent milling the heads and touching up the valvejob. If you pull the heads you can do a bowl port, I would just use the stock, small valves if you want to keep lowend torque. The 2.02 valves aren't going to help much on this build.
If you think about putting in new pistons just go the extra mile and get a stroker kit.

Sheldon

[TelisSE440]

...If you think about putting in new pistons just go the extra mile and get a stroker kit.

Sheldon

That's the best solution for an engine rebuild. I wish I had done it sooner.

[Tonker1]

Just wanted to clarify, the cam kit listed above is probably the wrong specs for the engine, I'm not going to buy it, I just put the link there to list the price and what the kit includes.

I would do a compression or leak down test before proceeding, just to make sure your ring and valve seal is good or not. I got thinking that seeing as this engine has not been opened up, your timing chain is likely stretched and that retards cam timing which would result in a gain in top end power and a drop in low end power. Which could be a part of your problem. I would guess the camshaft is worn to and replacing it is pretty much a given.
I would not spend the $$$$ on the rockers. That same money would be better spent milling the heads and touching up the valvejob. If you pull the heads you can do a bowl port, I would just use the stock, small valves if you want to keep lowend torque. The 2.02 valves aren't going to help much on this build.
If you think about putting in new pistons just go the extra mile and get a stroker kit.

Sheldon

The compression on all the cylinders is even and the numbers are good, I last tested them about a year ago.

Not spending the extra money on the rockers would save $600! The porting should be good, half the fun of these cars is working on them!

I'll give a few cam companies a call and see what they recommend, voodoo, hughes, comp, crane all the big brands!

More suggestions and advice is still extremely welcome, I have a year to save money, plan and make a smart decision!

[HP_Cuda]

Sounds like you should hold off and then build a stroker 416!

Then you will have found your torque!   

[RCCDrew]

I got a set of the iron TA adjustable rockers for $100 on Craigslist. That's the way to go if you are squeezing your pennies.

[Tonker1]

Sorry it's been a while, had to go back to the homeland, elderly Grandparents in the UK.

Got back out on the bike today to clear some thoughts, back to car planning later this week!