340 build help

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Chryslerkid

Chryslerkid

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Hey guys,

Back with yet another mission. I just got a really nice complete 340 out of a wrecked 70 Challenger with 65K original miles on it. It is complete from carburetor to oil pan and in running condition, but I want to go through it before I drop it in my dart. It has a mild cam, but I don't know the specs on it. From what I am told the engine is 95% stock original with exception to the cam and an 650 edelbrock carburetor. My current setup is a 318/727/8.75. I have a 1971 2-door dart swinger and my budget is a little over $3K. What can I do with this budget to make some power? Any suggestions are welcome. I have no idea what direction to go in yet. Thanks!
 
Chryslerkid said:
Hey guys,

Back with yet another mission. I just got a really nice complete 340 out of a wrecked 70 Challenger with 65K original miles on it. It is complete from carburetor to oil pan and in running condition, but I want to go through it before I drop it in my dart. It has a mild cam, but I don't know the specs on it. From what I am told the engine is 95% stock original with exception to the cam and an 650 edelbrock carburetor. My current setup is a 318/727/8.75. I have a 1971 2-door dart swinger and my budget is a little over $3K. What can I do with this budget to make some power? Any suggestions are welcome. I have no idea what direction to go in yet. Thanks!
Click to expand...

Nice find! This is a little bit of a wide open question though. If you want to pull it apart, you can look at the bearings and cylinder bores. If they look, measure ok, then a quick hone with new rings, bearings and maybe a fresh oil pump may be good enough for a driver/mild performance engine.
 
With a '70-340 engine, add headers, 2-1/2 exhaust, cam.
Your done.
To
Push it further, as in nicely stepping up the program, add gears, stall converter and a M1 single plane intake. (Or a RPM and a 750 carb.)
 
Some RHS heads ($1400), Comp 268H cam, lifters and timing set($250), Edelbrock air gap intake and 750 cfm 1407 carb ($600), rings, gaskets, bearings ($300), and headers ($300) puts you right about where you want to to be moneywise ($2850) with a couple of hundred to play with. Would put you in the 350-375 horse range. A nice running 340 that would be streetable and have plenty of power. That is of course assuming the block or crank are good don't need anything major done to them.
 
I have learned to never trust what someone else has done or says it has been rebuilt or only has XX miles on it. Usually has been BS from my dealings, so If it was ME, I would pull it apart and take it to my machine shop and let them inspect it, and the very least put cam bearings freeze plugs in it and give it a really good bath, hone cyl and polish crank. Go through heads and check guides, measure springs valve guides. For me that is cheap insurance knowing that the internals are good and will last a long time.
After the machine shop does its magic, A Voodoo cam kit, oil pump, Eddy RPM intake and a HOLLEY 750 and HEI conversion. You could also get a slight return if you put your unused parts on the NET to sell for a few hundred dollars or so.
Good luck!
 
I agree. Since we don't know what you intend to do with the car, we have to guess. But I'd do as advised above. If you could get a compression test before pulling it apart, that would help.

My machinist calls it a "farmer rebuild". New rings, bearings, gaskets and oil pump. Have them go through the heads and add hardened exhaust seats. A new cam with matching springs and a good timing set. Intake, carb and a decent set of headers. That should just about eat up your budget.
 
I know my initial posting was not clear in the specifications that I desire to get out of this engine build. I think it's because I don't know what my potential range is with the budget that I have. Therefore, I didn't want to get carried away and say something unrealistic. I would be more than happy with 300-400 hp/tq as long as I am not cutting corners to do so. I would rather have less horse power and more reliability and longevity.

On another note. I know and agree with the above statement about not trusting the word of another person that is trying to sell their old mopar engine, however, I saw the wrecked Mopar in this mans garage with the drivetrain in it. He started it up and ran the engine for me before he pulled it. Furthermore the odometer read the same mileage that he told me. Sounded like a very unfortunate man who lost his baby in a rainy day wreck. Again I know that he could have been bending the truth, but given the situation I think he was telling me the truth. That being said, I will definitely check the compression and pull the heads to look at the cylinders and valves. I will rebuild the bottom end if necessary and forget about making more horsepower if that's what it takes to get it in. Then maybe later I can ask you guys about more performance options... Thanks!
 
So the chally was too far gone to fix? I thought AMD could replace every bit of the body.

My 340 had what I think was a purple 508 and it ran pretty good with the (I think) stock heads. About 300 HP judging from the 8.40 1/8th that jumped to 7.20 with a 500 HP stroker and no other changes.
 
Yeah the guys e body was pretty far gone. Spun out into a ditch at about 45 mph and bent the whole frame. Not to mention the front end and passenger side were really banged up.

I think I'll bring the engine by my buddy's shop and do a compression test and put it on the engine stand to run it and do some tests. Once I have more information ill know whether I can go big or if I have to invest in a rebuild and machining.
 
Alright so here's the new info. The 340 I recently bought has good compression in all eight cylinders. Pulled the heads and intake and its very clean. Turns over easily. I stated before but ill say I again for info sake I saw the engine run in the previous car and it was really quiet with no unusual noises. Now... I don't think I'm doing a rebuilt so what can you guys recommend for easy bolt ons in order to bump up the horsepower and torque? Thanks guys!
 
Disassemble, check tolerances, if fine, hone the cylinders, polish the crank, add some new rod, main, cam bearings, and rings. (I would @ least check rod bearings for wear if nothing else) Have heads checked out. Chances are the exhaust valves are sunk into the head a little causing the exhaust tips to set higher than the intake valve tips (can check with straight edge with rockers off). If so a valve job and get the tips evened out. Cam her up (voodoo LUN-10200703LK 226/234 .494/513). Holley 750, good intake, some headers and rock and roll. I would recommend a higher capacity oil pan (i like my Kevko a lot) Don't run a high volume oil pump with a stock pan....
 
How much you looking to spend? A set of edelbrocks and an XE282S .520/.540 solid flat tappit cam will get you 400+ HP and TQ.
 
Great info thanks. I'm looking to spend about $3K. I have an aluminum edelbrock performer intake manifold and a 650 carter, I have TTI headers and my friend is helping me port match the heads and headers. Will the camshaft XE282S be too aggressive for street driving? Thanks!
 
If that intake is a regular performer, and not a performer rpm, it will be a DOWNGRADE from even a factory iron intake
 
With 65,000 miles on it, It is getting close to the end of it's life. 40 yr old rings and bearings, and you go and throw a bunch of go fast goodies on it, the engine will not last long. do yourself a favor and freshen it up now while it is out, for less money; wait a few thousand miles and pull it out to have double or triple the amount of money needed to have it completely machined and rebuilt.
As far as cam choices, a Comp 268 or the Voodoo equivelant. It is better to go on the smaller side of cam selections especially if it will mainly be street driven.
 
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