1969 Dart 340 cam selection help !!!

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motobro

motobro

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My 440 big block dart project has now turned into a 340 small block project.
I found a date coded 69 340 block had it broken down ex rayed and magna fluxed.
I plan to use the bottom end minus the pistons as they were some 11.5 to 1 old school stuff. I will use a 9.5 to 1 piston.
I will also be going with the edelbrock rpm aluminum heads, edelbrock rpm air gap intake and some tti headers.
The car will have a 727 auto with 323 or 355 rear end gears. Tourque converter stall speed is undecided.
I want the car to be mostly a street driver, but I may take it to the dragstrip to see what it can do. But be able to get up and go !!! and sound mean!!!!
I am trying to pick a Comp cam out of their chart that will work well for my situation. Not sure wether to go flat tappet or roller.
Has anyone built something similar ?????
What cam did you use ?
Tourque converter stall speed ?
Thanks
 
I like rollers, they bring you into the power curve sooner and keep you there longer. Here is my cam specs
@ 50
231 in/239 ex
.535"in/.550"ex
110-106
2400-6200 rpm
Requires 2500 stall and 3.42 or better gears.
 
No such thing as a "9.5:1" piston for a 340. There's the early (10.2) late (8.5) and domed (12:1). To get something 9.5 you'll have to go custom or work with your heads and head gaskets.
 
Rob, there are some aftermarket OTC pistons from other makers that will yield approximately 9.5:1 with 68cc heads (naturally, dependent on deck clearance)...I wanna say DSS makes some, I bought their pistons for my 4.6 4V-real nice pistons.

Edit: http://www.dssracing.com/6300X_p/6300x.htm

There they are. Math says they'll come to .020" below nominal deck height. If you zeroed it and ran an .030"x4.1" gasket, it would yield 9.5:1 on the money with those pistons and a 68cc head...
 
txstang84 said:
Rob, there are some aftermarket OTC pistons from other makers that will yield approximately 9.5:1 with 68cc heads (naturally, dependent on deck clearance)...I wanna say DSS makes some, I bought their pistons for my 4.6 4V-real nice pistons.
Click to expand...

Correct,

Custom-made,

We got them any way we wanted from Arias Pistons.
 
Yes,

Arias will have their typical 'in stock' Warehouse Supply.

But, we have a connection in their shop that will make us anything.

Ford_302_flat_1_medium.jpg
 
69 Cuda 440 said:
Yes,

Arias will have their typical 'in stock' Warehouse Supply.

But, we have a connection in their shop that will make us anything.
Click to expand...

That's really cool-I don't have those kind of connections, but I do have friends who do.

...the point I was driving at is those pistons are not "custom"...

Edit: and I'm derailing the OP's thread...my apologies
 
Ok. Cool. Used to be all there was for a 340 was the stock stuff, 12:1 and custom.
 
OP: IF it were my ride, I'd probably lean to one of Lunati's Voodoo grinds...and likely a solid. Even their smallest solid Voodoo grind (264/272, 235/243 @050, .526/.546") is pretty sporty and should wake a 340 right up with the other parts you mentioned...it would probably run like a scalded dog with about 2800-3000 stall and those 3.55s.

That being said, if you like/prefer COMP, no worries, their XE274S would probably float your boat too.

I'm going to assume (I know, dangerous), you plan to use adjustable rockers, but if you want to run non, the XE274H or something similar.
 
pm 340 man he has a stroker he just built and needs to go bigger with his cam he will give you 1 hell of a deal I gotthe comp cams ca -20-227-4 nice can 3k stall I have 2 727s I neeed to get rid of now im going back to a built 904 pm me
 
The person that is doing the actual work on the engine has informed me that the rods need to be resized and it would be cheaper to get new ones.
So.....now I have a good 340 block and crank to start out with.
He is suggesting hydraulic roller cam, roller rockers and a .600 lift cam
along with the aluminum cylinder heads. What type of behavior does the .600 lift cam give the motor, does it rev higher ? I never really understood the cam grind numbers.
 
In looking at the comp cam chart, the .600 lift stuff is for drag racing.
I also looked at the lunati chart and saw the the 20200712 with a .530/.550 lift
 
Those heads are Brodix Track 1's for a Chevy. I would get the head flow@at what lift,to choose the right cam.
 
"Mostly a street driver" and .600 lift roller usually don't go together. If your shop charges more to install new rod bolts and resize rods than buying new ones, their prices are too high. The stock connecting rods are some of the strongest rods from any auto maker. Properly prepped, they will have no trouble seeing 7500 RPM on a regular basis. They are also probably made out of better metal than almost all but the most expensive aftermarket rods. Throwing lots of money at something is certainly your choice, but remember, money is no guaranty you will have a good product in the end.
 
Pick a power output level you want first. Otherwise you may waste a lot of time and money buying things 2-3X

It's not hard to get ~450hp out of a 9.5-10:1 340

Decent heads (RHS, ported ede), xs282s camshaft, 1.5 or better 1.6 rockers, air gap/victor, 750-950 carb, headers
 
You will need to have your machinist check the deck height because it might already be decked and if it's shorter than 9.600 you wil lwant to consider the piston choices carefully.
Operating under the assumption it's factory which is usually somewhere around 9.630:
Pistons - I'd use KB hypers - KB243s. They are cheap, light, & strong. You will want to deck the block down to 9.610-9.600. This will yeild a static compression around 10.3-10.5:1. You will also want him to gap the top ring per KB's specifications.
Rods - Eagle SIR rods are cheap and fine for your application - in addition to being very light. Have them cycled and the big ends checked afterwords to make sure they're good.
Cam - If he wants hydraulic roller - stay much smaller. I would be looking at the XR274HR-10. You will need to replace the valve springs that come on the RPM heads with the ones that Comp recommends - that's fairly normal. Also watch the lifetrs you run. There's a post about it and you might want to run Howards or Hughes lifters on it...
That would be my recipe following the direction you asked for. Personally - a hydraulic flat tappet would be just as good for less money and the same maintenance & I don't read this post as "I want to run low 12s" or "I need a 450hp 340".

Edit - assuming the RPM heads are the closed chamber LA versions and you're going to have them checked and the valve job fixed by a competant shop. If he says they're fine out of the box without having them apart on his bench - I'd go somewhere else.
 
He likely won't be able to run a 274R cam in California on our 91 pump swill at a true 10.3-10.5:1. I had an ede headed SB quench engine with 10.7 and 8-12* more cam timing and it pinged like a byatch on 91 pump gas. 50/50 mix cured it. It was a mess without the mix. Ended up putting in a cam with 10* more duration, fixed the issue.

I threw out that build because it ran on CA pump gas, sounds nasty while running very well.

Not enough from the OP to make any kind of suggestion on where to go IMO. Very vague. Pick a power output and build to it. Want it to sound nasty, get a cam cut on a 106 centerline. Pump gas is going to be an issue out here.
 
crackedback said:
He likely won't be able to run a 274R cam in California on our 91 pump swill at a true 10.3-10.5:1. I had an ede headed SB quench engine with 10.7 and 8-12* more cam timing and it pinged like a byatch on 91 pump gas. 50/50 mix cured it. It was a mess without the mix. Ended up putting in a cam with 10* more duration, fixed the issue.

I threw out that build because it ran on CA pump gas, sounds nasty while running very well.

Not enough from the OP to make any kind of suggestion on where to go IMO. Very vague. Pick a power output and build to it. Want it to sound nasty, get a cam cut on a 106 centerline. Pump gas is going to be an issue out here.
Click to expand...

Why do you insist on spreadin the BS? You know all that stuff is hogwash. Where's Gary Busey when we need him? lol
 
RustyRatRod said:
Why do you insist on spreadin the BS? You know all that stuff is hogwash. Where's Gary Busey when we need him? lol
Click to expand...

I saw Gary was on not long ago wanting to get his car on the street with registration... or at least that's what I got deciphering it with my capt'n crunch decoder ring.

:)
 
Ok so not a .600 lift cam.
He said he wants to make it so it could handle a .600 lift and maybe go with something that has only a max .550 lift.
I'm going to go talk to him on saturday and find out :
1)why we can't use the connecting rods
2) pick out some parts
3) give him some money

Someone else mentioned the lunati voodoo camshaft.
I took a look at their site and found the :
20200712 that is a hydraulic
Roller with @50 231/239
Lift .535/.550
Rpm 2200-6200
Requires 2800 stall speed ,9.5:1
Compression. Likes upgraded intake, carb and exhaust.
Has anyone used this model lunati ?
.
 
My builder wants to use a cam profile that he designed on some software that he has. Hydraulic roller
Adv. dur 292/300
@50 242/248
Gross valve lift 549/549
lSA- 112*
rpm 2800-6400
Edelbrock heads
Victor intake
carb?
roller rockers
355 gears
727 auto
What do you guys think ???
 
He wants to use a 9.5 -1 piston.
He claims by changing the lsa to 112 he can make the motor think it has higher compression by limiting the time that the intake and exhaust are open together.
 
Abodybomber is nail on the head, with cylinder head flow against cam selection with this kind of build.

That's still a lot of bump, from duration. LSA at 112 will help a bit increase in compression, if you need it. What is the centerline advance of the cam? That also changes compression. Bumping the LSA also helps with idle quality.

It's still gonna have a chunk of overlap at 300 degrees. That's a ton of duration.

Something you should also consider is that while your static compression ratio goal is 9.5:1, your dynamic changes with LSA and degrees of advance from centerline, closing the intake valve sooner, before the piston comes up from BDC.

You should plug those numbers into a good dynamic compression ratio with your altitude to come up with your dynamic ratio, which is actually what you will end up with.

Ask your machinist what his goal cylinder pressure is. That's all that matters in the end.
 
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