340 Build Advice

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Alexhetti

Alexhetti

Well-Known Member
Joined
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Location
North Carolina
Hello all, I’m seeking advice on a 340 build. I have no experience building engines need some guidance on matching parts and what all will be required for the build. Im going to try and locate an experienced builder to put it together but figured it would be nice to know what I should gather before that time comes. I’ve located 2 340 blocks, one a 73 and one a 69. Both have been machined .030 over. The car it’s going in will be used mostly for street driving and some auto cross and would like it to produce around 400-500 hp. Additional, it’ll most likely be using an efi system. If you’re knowledgable in this area let me know.
 
Here’s a few questions to ask yourself. What’s your budget? Heads and parts. Headers? What transmission, rear end and gearing, tire size, car weight.

400 HP out of a 340 is easy, 500 is a little bit harder.

I’m at 400 right now in my 340 duster. It is .30 over, 2.02 J heads cleaned up, not ported with comp magnum roller rockers, 10.2/1 with a comp XE285HL which is a hydro 241/247 on 110. MSD and a 750 double pumper. This a solid build for an Auto, but with a 4 speed sucks until your up on the cam. Ask me how I know.

be prepared to spend a bunch of money if you just have a block as parts add up really fast.

A lot of members here have the 408 from Blue Print. You can’t beat the price unless you know people to get “jobber” pricing on parts and know a machine shop that hood and cheap.
 
Your goals are easily achieved, and it looks like your in NC? if so, and your interested, send me a PM, I am a engine builder, and I especially like helping out another mopar guy!
 
Scody21 said:
Here’s a few questions to ask yourself. What’s your budget? Heads and parts. Headers? What transmission, rear end and gearing, tire size, car weight.

400 HP out of a 340 is easy, 500 is a little bit harder.

I’m at 400 right now in my 340 duster. It is .30 over, 2.02 J heads cleaned up, not ported with comp magnum roller rockers, 10.2/1 with a comp XE285HL which is a hydro 241/247 on 110. MSD and a 750 double pumper. This a solid build for an Auto, but with a 4 speed sucks until your up on the cam. Ask me how I know.

be prepared to spend a bunch of money if you just have a block as parts add up really fast.

A lot of members here have the 408 from Blue Print. You can’t beat the price unless you know people to get “jobber” pricing on parts and know a machine shop that hood and cheap.
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Imo you need gears.Only good with auto and 3200+ stall is more like it.
 
Go to Replicaracer43 and make full use of an experienced engine builder. There’s so much to take in consideration that separates a so-so engine (or a time bomb!) and one that runs as good as you like and meets your target goals. I’m all on board with the stroker crank for 500hp and auto crossing.
 
Use the 69 crank and rods in the 73 block.

Promax or trick flow for a good ootb head
A solid cam in the realm of..250'[email protected] dur .560 or so lift 108lsa intake 286 or so dur.

Or solid roller.
 
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As mentioned a 400 horsepower 340 is fairly easy but 500 the price goes up quite a bit along with the RPM range and the street ability heads the other direction. a little more manageable with a four-speed. A 500 horsepower 340 is awesome but it ain't cheap.
 
Alexhetti said:
Hello all, I’m seeking advice on a 340 build. I have no experience building engines need some guidance on matching parts and what all will be required for the build. Im going to try and locate an experienced builder to put it together but figured it would be nice to know what I should gather before that time comes. I’ve located 2 340 blocks, one a 73 and one a 69. Both have been machined .030 over. The car it’s going in will be used mostly for street driving and some auto cross and would like it to produce around 400-500 hp. Additional, it’ll most likely be using an efi system. If you’re knowledgable in this area let me know.
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I think I would go 4.00” stroke crank and flat top pistons with tight quench.
K.O. SWINGER said:
As mentioned a 400 horsepower 340 is fairly easy but 500 the price goes up quite a bit along with the RPM range and the street ability heads the other direction. a little more manageable with a four-speed. A 500 horsepower 340 is awesome but it ain't cheap.
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Okay I dig the stroker crankshaft suggestions but then it's not really a 340 it's a 416 or whatever, if that's what the OP Wants then that's cool but I thought he was talking about a 340ish =stock stroke cubic inch motor.
 
Alexhetti said:
Hello all, I’m seeking advice on a 340 build. I have no experience building engines need some guidance on matching parts and what all will be required for the build. Im going to try and locate an experienced builder to put it together but figured it would be nice to know what I should gather before that time comes. I’ve located 2 340 blocks, one a 73 and one a 69. Both have been machined .030 over. The car it’s going in will be used mostly for street driving and some auto cross and would like it to produce around 400-500 hp. Additional, it’ll most likely be using an efi system. If you’re knowledgable in this area let me know.
Click to expand...
Find your builder first...the ask HIM what he would like for parts...not the other way around.
 
Scody21 said:
Here’s a few questions to ask yourself. What’s your budget? Heads and parts. Headers? What transmission, rear end and gearing, tire size, car weight.

400 HP out of a 340 is easy, 500 is a little bit harder.

I’m at 400 right now in my 340 duster. It is .30 over, 2.02 J heads cleaned up, not ported with comp magnum roller rockers, 10.2/1 with a comp XE285HL which is a hydro 241/247 on 110. MSD and a 750 double pumper. This a solid build for an Auto, but with a 4 speed sucks until your up on the cam. Ask me how I know.

be prepared to spend a bunch of money if you just have a block as parts add up really fast.

A lot of members here have the 408 from Blue Print. You can’t beat the price unless you know people to get “jobber” pricing on parts and know a machine shop that hood and cheap.
Click to expand...
As far as budget, I'm not entirely sure because I really don't know an average for a build. I know I've seen people saying they've spent anywhere from 5k to 20k on an engine build. I have funds available for the process, however. Currently, I have a 904 trans that I'm considering switching to a 4-speed or 727 (haven't decided), 1 5/8 TTI headers, 8 3/4 rear with 3.55 gears, 27" tires 15x8 in the back and 15x6 front, also considering moving to 18's.

My main thing is I don't have the knowledge to match parts to what I would like an engine to achieve. Like I said, mainly a strong runner driver with occasional autocrossing.
 
K.O. SWINGER said:
Okay I dig the stroker crankshaft suggestions but then it's not really a 340 it's a 416 or whatever, if that's what the OP Wants then that's cool but I thought he was talking about a 340ish =stock stroke cubic inch motor.
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I'm definitely not against a stoker. My car is not stock in any way so I don't really care about correctness. I'd just like a fast, fun, and dependable engine. Currently, my car has a tired '78 360 in it with a mild cam in it. It kinda seems to have just been thrown together by someone who didn't know what they were doing (among other things in the car). I have no previous history of its build or what all was done to it and I'd prefer to have an engine built so that I know exactly what's been done and it works for my setup.
 
Garrett Ellison said:
Go to Replicaracer43 and make full use of an experienced engine builder. There’s so much to take in consideration that separates a so-so engine (or a time bomb!) and one that runs as good as you like and meets your target goals. I’m all on board with the stroker crank for 500hp and auto crossing.
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Agreed, I just sent him a pm
 
For street and autocross with the 3.55's, i'd look for torque in the 3500/4000 rpm range. How much & how you get there depends on engine size and budget. I personally would prefer the 4spd for what you want to do.
 
Alexhetti said:
As far as budget, I'm not entirely sure because I really don't know an average for a build. I know I've seen people saying they've spent anywhere from 5k to 20k on an engine build. I have funds available for the process, however. Currently, I have a 904 trans that I'm considering switching to a 4-speed or 727 (haven't decided), 1 5/8 TTI headers, 8 3/4 rear with 3.55 gears, 27" tires 15x8 in the back and 15x6 front, also considering moving to 18's.

My main thing is I don't have the knowledge to match parts to what I would like an engine to achieve. Like I said, mainly a strong runner driver with occasional autocrossing.
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the 904 is plenty strong for 5-600 I'd run it before buying a 727. But a 4 speed is king. The gearing, tire setup you have is good. Would not mess with it.

as for budget, you can figure 10 grand is a solid number as the cost of things just keeps rising. A stroker crank set up is around 2 grand. Machining about 2K, 2K in labor, there’s 6. Add 2K for heads, 1000 for rockers, lifters, push rods, 500 for a carb, 500 for MSD, 500 for water pump, alt, starter, **** adds up quick….. did not even get to the 4 speed swap yet…
 
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Scody21 said:
the 904 is plenty strong for 5-600 I'd run it before buying a 727. But a 4 speed is king. The gearing, tire setup you have is good. Would not mess with it.

as for budget, you can figure 10 is a solid number as the code of things just keeps rising. A stroker crank set up is around 2 grand. Machining about 2K, 2K in labor, there’s 6. Add 2K for heads, 1000 for rockers, lifters, push rods, 500 for a carb, 500 for MSD, 500 for water pump, alt, starter, **** adds up quick….. did not even get to the 4 speed swap yet…
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One of the main reasons I'm thinking about changing trans is because the 904 appears to be original to the car and definitely needs a rebuild. Also the converter definitely isn't sized correctly for the current engine so I'll need to be buying one anyways. I'd prefer to have a 4 speed just for the experience if anything.

With the budget, I figured I'd be looking at around 1ok for a build, which I'm okay with. The car needs a new engine one way or another and I prefer to put the money into building something good rather than just a rebuild of the 360. Thank you for the info.
 
Alexhetti said:
One of the main reasons I'm thinking about changing trans is because the 904 appears to be original to the car and definitely needs a rebuild. Also the converter definitely isn't sized correctly for the current engine so I'll need to be buying one anyways. I'd prefer to have a 4 speed just for the experience if anything.

With the budget, I figured I'd be looking at around 1ok for a build, which I'm okay with. The car needs a new engine one way or another and I prefer to put the money into building something good rather than just a rebuild of the 360. Thank you for the info.
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10k engine?
Wheres the other 5 grand going once the motor is done?

Lol
 
Upgrading the 904 to a 998 or an 999 (2.47 1st and 1.55 second) with six thin clutches in place of 5 with a custom converter and a Trans-Go TF3 manual valve body kit would make it perform like you want. It's the route I would take if I kept it at a stock stroke. 3.58 inch stroke is also a good option for 367-379 inch combination. I do like a four speed for auto cross though.
 
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