I have a 73 Dart Sport 340, auto, 3:55 gear. Car has 41k miles all stock and mostly original. I have some noise, worst when cold and have figured it is the cam and lifters causing it. When I first put the car on the road cylinder 1 compression was 125 and the rest were 145. My plan is to do a leak down test and see what the problem is. I suspect its is due to a worn cam. If the bottom end is good and passes the leak down my plan is to get the Mopar performance Aluminum heads p5153849 a new cam, roller rockers, and Peformer rpm intake. I don't want to change the converter and this is a street car only. Will these heads work well with the stock pistons? Is a roller cam worth the money. Has anybody used the performer rpm cam?
Budget 340 Upgrades
- Thread starter Tech857
- Start date
-
Is the 340 the engine the car came with? The reason I ask is because the earlier 340's have a piston that pops up above the engines deck which would require clearance in the head. Closed chambered heads will not work.
The MoPar heads you list (part number wise I don't know what they are, I'll have to lookater myself as to the exact head it is.) can be Edelbrock heads. For the most part, you can do better than a MoPar head, for a street vehicle. Race wise, there hard to beat.
IMO, contact MRL here on the board and speak to him about you head and cam combo personnaly. Mike is a pro engine builders. He can set you up with a set of heads all ready done and ready to bolt on combined with a cam that fits into your perameters.
A new cam, roller rockers & intake are great and easy upgrades.
Considering that you do not want to change the torque converter, your limited to cam size. The stock cam is a decent size cam. The RPM cam is OK. But it's duration would require a converter change.
The problem with a roller cam is the expense vs. power return on low powered vehicles. Yes! You'll make more power everywhere! But the cost is expensive.
leak down test will not tell you anything about the condition of the camshaft...it only tells you how the engine is sealed....leaking either from the rings or valves....
take the valve covers off...and slowly turn the engine over...watch the action of the valves....or turn engine over 90 degree at a time on the crankshaft according to the firing order...then check the rocker to valve relationship ..look for excessive clearance between the rocker and tip of valve.....
take the valve covers off...and slowly turn the engine over...watch the action of the valves....or turn engine over 90 degree at a time on the crankshaft according to the firing order...then check the rocker to valve relationship ..look for excessive clearance between the rocker and tip of valve.....
close chamber heads will work...just adjust the thickness of the head gasket to ensure you have clearance...been there...done it several times..
72 and later 340s are low compression...the piston is a half mile down in the bore...
get the heads from edelbrock they are less expensive then the same head from mopar
72 and later 340s are low compression...the piston is a half mile down in the bore...
get the heads from edelbrock they are less expensive then the same head from mopar
Right on if the engine is sealed then the problem must be the cam. If there's excessive leak down past the rings then I'll pull the motor and do the whole thing. If I need too do the top and bottom it will take longer to get the money to do it all. I'm pretty sure it needs a cam due to the noise.
EL5DEMON340
Well-Known Member
Gezz 73 dart sport with 41k! I think I would have the stock heads gone over pop some 2.02 valves in it with a good 4 angle vj bowl blend it, the intake is a very good flowing intake, and the thermoquad when dialed correctly is just as good as any aftermarket. I would replace the cam with something in the 475 lift range and no more than 220 to 224 @ .050 range
EL5DEMON340
Well-Known Member
Now if your hell bent on new aluminum heads and a aluminum intake , carb roller cam or a big cam. You might as well redo the bottom end and get rid of the heavy cast pistons and get some nice flat tops with some real compression while the engine is out I would get a 3k stall also.
Can you beat Ede's for 668+ tax on the heads?
There are much better cams available than the Performer RPM camshaft.
There are much better cams available than the Performer RPM camshaft.
Why ruin a fairly rare numbers matching car? Build a 360 instead.
I would be careful doing this on a hydraulic cam engine. You could be fooled by a lifter bleeding down when you turn the engine over slowly and give you a false impression.
If I were to try this, I would crank the engine over with the starter and watch how much movement is in the valves, but the lifters may bleed down a little also.
The most accurate way to check your cam lobes is to put on a set of v-blocks and use a dial indicator.
I can get them for less than that but I can not resell them.
I don't think it will be ruined at all the stock heads are good and will stay with the car. I eventually will put a stroker kit into the #s matching motor. The whole motor will be painted factory blue after assembly and will look stock. I may stick with the OE manifold.
Ok.
As said...build a 408 based 360...paint it the right color.....99.99999999% of people will not be able to tell the difference just looking at them...
my 73 340 Duster has been running a 360 for 10 yrs....but the air cleaner says 340....stickers on fenders say 340... 73 340 has externally balanced crank just like 360...unless you climb under car to look at casting number...they don’t know...beside the car is faster with 360...
original engine and trans sitting in shed...
my 73 340 Duster has been running a 360 for 10 yrs....but the air cleaner says 340....stickers on fenders say 340... 73 340 has externally balanced crank just like 360...unless you climb under car to look at casting number...they don’t know...beside the car is faster with 360...
original engine and trans sitting in shed...
Will building a stroker out of the original block hurt the value? It could always be put back to stock if you wanted to. The car is very cool all original, sunroof convertriple, hood scoop, stripes. It sat outside under a cover and needs paint bumpers rechromed and stuff is a little oxidized. Its a driver I want a car that I can use with out freaking out about it. I'd like to be at about 400hp.
You can exceed that 400HP number substantially by building a 360/408 stroker, depending on how much you want to spend.
I suspect the engine needs to be bored anyway. The car sat outside for 30 something years before I got a hold of it. The engine did not turn at first and I carefully freed it up with mystery oil. It does not smoke or use oil but when I did head gaskets it had a coating of leaded fuel and dirt baked on to the pistons and combustion chambers. The leak down test will be the deciding factor as to how far I will go with it.
It probably does, but like Rob said and I agree, tuck that original 340 numbers matching engine away, and bore the heck out of a 360 and have at it.
Ultimately it's yours to do what you wish, but if the car is in really good shape, a convertriple etc, that #'s matching 340 is an important piece of the puzzle.
400HP is easy with a 340 , mine is basically stock , holley street avenger , Air gap , mahle 10.5 forged pistons light porting of stock heads making 398 hp 413 tq and a comp cam . Now going with Edelbrock Alu heads and crane 1.6 rockers . It's a spare 340 , the original is sitting in my garage .
With a stroker 360 or 340 400++ hp is easy . I would not stroke the numbers matching 340 , put it aside and build another 340 , or the cheaper route a 360 .
I agree with these fellas. The car is worth more on a clue tots level with the stock engine intacted.
Our old club had a PR guy get a deal from the local Dodge dealership. Fly thee banner at meets, gatherings and races and they have us 10% over cost on everything except clothing, belt buckles, mugs, etc....
Those were the days!
A 400 hp 340 is easy except the torque converter wod need a change out to have it operate properly. Otherwise, it'll be slow out of the hole. Real slow.
Our old club had a PR guy get a deal from the local Dodge dealership. Fly thee banner at meets, gatherings and races and they have us 10% over cost on everything except clothing, belt buckles, mugs, etc....
Those were the days!
A 400 hp 340 is easy except the torque converter wod need a change out to have it operate properly. Otherwise, it'll be slow out of the hole. Real slow.
-
