1970 Dart 340/416 Stroker build help

[beck]

1970 340/416 stroker
Eagle 4.000 crank
Eagle I beam rods
Rebuilt x heads
Elgin rockers ( stock replacement)
Msd ready to run distributor
Edelbrock rpm intake
750 brawler manual secondary electric choke
Dougs headers
2.5 exhaust
New tank with 3/8 lines up
Carter 6270 mechanical fuel pump
Comp cam #20-212-2
4Spd, 8 3/4 323 sure grip
My question, Is the cam that the builder put in to small for this build. Comp cams describes it as a replacement for a stock 340.I am having problems with the carburetor holding an idle
Also Getting a vibration between 3000 and 4000 rpms, but I think it is the z bar
Also wanted to mention that the builder said it's making around 500 hp (LOL)After all, the reading and research, the best, I think this motor is putting out is around 375hp with this cam!

 

[beck]

Some more pics

 

[Murray]

Has the motor been dynoed? I don't see it. Red flags= stock heads, stock ignition, mild cam, no dyno. But nice car.

 

[remytherat]

Is the cam that the builder put in to small for this build.

What is your static compression?

Pretty small for those cubes but if it runs without detonation and you’re happy with the power it is just fine.

But not a very good choice, especially in the big 25 with all the cams to chose from.

 

[Professor Fate]

Sorry, but if the builder chose those heads (in reasonably stock form) and that cam to feed a 416 C.I. stroker, I'd be questioning the rest of his work too.
Did he balance the rotating assembly?
Not a fan of the MSD RTR distributors, either. But that's just me.

 

[beck]

Not dynoed,I wanted the x heads,had small valve j heads on it,he said compression is 10.5 :1used thicker head gaskets.

 

[a-bodyguy]

Iam running that cam in stock 68 340 stealth intake 650dp unilite thin head gasket 169 psi cranking comp manifolds 2 1/2 exhaust
good cam for 3.23s way small for a 416 thick head gasket lucky to be 9 to 1 if the heads are 70 to 72cc 360 hp sounds right
The builder is a blower would not trust anything he said

 

[B3422w5]

Cam is tiny, but sounds like all you have is X heads so you already have a stopper in the bottle.
I would have just had the J heads swapped to 2.02 valves , instead of buying another set of pretty much identical heads.
Cool looking car, it should run fine. I would guess 360-380 horse area.
It would take a whole bunch more to even approach 500.
You might also( because of the cam and tall gear) not notice much difference regards power even had you left the 1.88 valved J heads on it.
Probably take a bit of lift and rpm for the 2.02 valves to really pull away in any meaningful way.

 

[Ant]

Also wanted to mention that the builder said it's making around 500 hp (LOL)

Wow! big block cubes with stock X head small block flow? I'm not a professional engine builder, but I don't trust the entire build if that is the lies the builder gave. I think you may be close, possibly under 375HP.

 

[Bewy]

We all need to know what the builder is smokin'......so we can increase are HP #s...

What is the engine doing at idle? Do the idle mixture screws change the idle?

 

[beck]

No, they are set perfect.I tried new return springs and lubed throttle assembly, I set it at 750 and after driving around, it won't come down past 1200

 

[340sFastback]

We all need to know what the builder is smokin'.....

We need to know what builder smoking so we can get some for ourselves cause it must be some powerful stuff.....

 

[MOPAROFFICIAL]

1970 340/416 stroker
Eagle 4.000 crank
Eagle I beam rods
Rebuilt x heads
Elgin rockers ( stock replacement)
Msd ready to run distributor
Edelbrock rpm intake
750 brawler manual secondary electric choke
Dougs headers
2.5 exhaust
New tank with 3/8 lines up
Carter 6270 mechanical fuel pump
Comp cam #20-212-2
4Spd, 8 3/4 323 sure grip
My question, Is the cam that the builder put in to small for this build. Comp cams describes it as a replacement for a stock 340.I am having problems with the carburetor holding an idle
Also Getting a vibration between 3000 and 4000 rpms, but I think it is the z bar
Also wanted to mention that the builder said it's making around 500 hp (LOL)After all, the reading and research, the best, I think this motor is putting out is around 375hp with this cam!

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He built you a tractor motor.

Lose the manifolds for headers and 3" pipes. Cam needs to be 250@.050 w/at least 280 adv duration, preferably 288-294* for street friendliness and with a stick trans... 104-106 icl 108-109 lsa.
The heads are now the issue, port them or swap to speed masters,Trickflow, afr, shockers... your pick. Theyre all in the 250-290 cfm range heads
Rpm or single plane victor/xcellerator type manifold.

 

[340sFastback]

He built you a tractor motor.

Lose the manifolds for headers and 3" pipes. Cam needs to be 250@.050 w/at least 280 adv duration, preferably 288-294* for street friendliness and with a stick trans... 104-106 icl 108-109 lsa.

Rpm or single plane victor/xcellerator type manifold.

And do some porting on those heads too....

 

[NC Engine Builder]

Sounds like your "builder" wasn't very knowledgeable

 

[Ant]

No, they are set perfect.I tried new return springs and lubed throttle assembly, I set it at 750 and after driving around, it won't come down past 1200

How is the idle with the butterflies/throttle plates completely closed?
Are the secondaries closed at idle after driving around?

I suspect a carb issue or a vacuum leak.

Also, I bet your engine builder is the type of guy who sells 360' and 340's, and chevy 350's for 10K on marketplace with just a few bolt ons and claims the engines make 500HP.

 

[Cuda416]

OP, looks like you've been around here long enough to know that the people answering you know their collective **** so I hope you're not taking what they say personally. No one here knows who the mysterious builder is so we're all thinking this person is a bit of a clown. If it's someone you 'know' like a friend or relative etc, take all of this as constructive criticism and heed the advice you've been given, it's gold.

If you're not welded to your heads, pay attention to the black Friday sale for speedmaster heads. They will be much cheaper than normally priced and let that engine breath. Of course you're going to want a better cam as well, but it goes without saying, you're going to be way ahead of the game by letting that thing sing. Headers don't need to be crazy expensive to show an improvement either.

In a nutshell, you aren't that far from "fixing" this to a point where the stroker will actually run like a stroker and if you're frugal it won't cost an arm and a leg.

 

[NC Engine Builder]

As soon as he told you the compression was "10.5 to 1" he basically admitted he didn't have a clue, and probably doesn't even know how to measure and calculate it

 

[PRH]

If the heads are rebuilt using springs that are along the lines of “factory replacements”, then a change to a noticeably bigger cam might be more involved than a simple “cam swap”.

While it’s obvious to most that the described combo would be well short of 500hp, if the OP is satisfied with it, then there wouldn’t be any urgency to change anything.

 

[NC Engine Builder]

Looking up that piston part number in my Mahle catalog shows it to be a flat top, with 11.1 compression on a 70 cc head. 11.8 on a 65cc and 12.5 with a 60cc. Good luck ever getting that tuned to run on pump gas with your open chamber iron head, and 218 @ .050 cam

 

[Ant]

Looking up that piston part number in my Mahle catalog shows it to be a flat top, with 11.1 compression on a 70 cc head. 11.8 on a 65cc and 12.5 with a 60cc. Good luck ever getting that tuned to run on pump gas with your open chamber iron head, and 218 @ .050 cam

Yikes! Good catch!

 

[autoxcuda]

Looking up that piston part number in my Mahle catalog shows it to be a flat top, with 11.1 compression on a 70 cc head. 11.8 on a 65cc and 12.5 with a 60cc. Good luck ever getting that tuned to run on pump gas with your open chamber iron head, and 218 @ .050 cam

Ugg. To me that’s the biggest screw up! OP mentioned builder out on thicker head gaskets. I’m thinking he saw he tried to fix his screw up. And it will be a PITA. 9.5:1 compression for pump gas would have been appropriate.

Seems like the owners needs are: street car, limited tuning, calm idle, great vacuum, get in it and drive, low maintenance, 3.23 gears.

The before and after pictures have confused some. What I see it’s got:
Headers
RPM intake
750 double pump
stock X heads
stock stamped steel rockers
10.5:1 (11:1)compression
268H Comp 268, 218@050, .454”, 110 deg
3/8 fuel line

A simple Comp 268 XE would have been more fitting at least and would work with stamped rockers.

I bet it makes more power and torque than it did when it was a 340 with cast manifolds.

 

[Ironmike]

That is a VERY nice 350(maybe) horsepower car. A beauty. Yank that motor over the winter and make it what you want. All the info you'd ever need is right here.

 

[PRH]

Just an fyi to the op wrt idle settings…….
The idle speed and mixture screws should be set with the engine fully warmed up.

If the engine idle can’t be brought below 1200 by adjusting the carb, there’s an issue somewhere ……. It’s got to be getting air from somewhere(holes in the throttle blades?), and/or it has too much initial timing(for the combo).

 

[beck]

Thanks for everyone's input and l and not taking anything personally. 1st I want to make it clear that l asked the builder for a mild 416, around 400 to 450 hp ,and a cam with a nice lump, not to crazy. that is why I picked the x heads over aluminum. Hell I wanted to use the very nicely rebuilt carter (done by Woodruff)but told me that it was to small..2nd I did adjust the carb after full warm up and as of Monday, sometimes it would drop down to 750 and sometimes not.3rd as NC builder stated I did looked that up , but with out knowing the head cc and size gasket he used ??.Is there a way to figure it, compression test ,I do not know. Right now I am just going fix the zbar that rubbing against the header and put some miles on it before winter.