Building up my 68 340

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txbullets

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Starting to buy parts for my 68' 340 to put into my 72 dart swinger and looking for guidance or suggestions.

Motor has x heads and not sure about the cam but the motor was built for stock class racing 10 years ago so guessing not much. (Ran very little and the guy put a 360 in. Been sitting indoors since) Standard 10.5/1 compression. I already acquired an Air Gapper intake.

Looking for suggestions on what to do with this thing. Cam, carb, headers, etc. I am not looking to go crazy here just good power for street with an occasional trip to the track.

Thanks in advance.
 
GEO said:
Use the search function ,there are plenty of builds on here
Click to expand...


What would you suggest I search to find other 340 builds? I am being serious with this question because when I search 340 build I get pages and pages of threads not pertaining to this.

For what it's worth I am considering the following:
Xe268 cam
750 carb (have not started researching this much so not sure here)
Doug's D453 headers (still considering TTI but leaning towards Doug's)
2" exhaust. I have the flow master exhaust that were on the car. Considering using those but the pipe is trash so gonna get new pipes. Thoughts?


Thoughts on how this would be? What would you change? Running 727 trans column shift. No tub so biggest tires I can fit on the 8.75 rear. I have the rear and 3rd member has drag gears in it so gonna change them out. Probably gonna go 3.73 gears.
 
What you listed sounds good , with 3.73 gears should be strong on the street . Biggest tires I could fit was 235 60 15 on 15 x 7 rallye wheel with 4.25 bs without trimming the quarter panels .
 
If it was built for NHRA/IHRA stock class racing, the cam definitely has to go. The above mentioned XE is a fine street cam, but if your engine has been "blueprinted" for maximum compression, I think you should get some measurements before you pick a cam if you want to run regulation pump gas?
 
I am pretty sure it was dirt track racing. Don't know if it was blueprinted or not. Unfortunately I don't remember what he said about the cam or what would be allowed in that class. I bought the motor 8 years ago with intention of building this dart. Life got in the way and now I am able to get on it. Don't remember many of the details but the guy had it built then decided to put a 360 in. I think he said he only ran it a couple of times.
 
Whatever cam that you use, consider using Rhoades lifters. They bleed down at idle and take about 15° and .025" of lift, and then pump up to full lift and duration of the cam by 3500 RPM. It's like having an adjustable cam.

I have used them on many engines for over 25 years and have put over 250,000 on a set with no problems or issues. they run great, increase vacuum at idle, smoother idle, more low end and mid range torque and power, and better fuel economy.


Read the second article on this page to get more info:

http://www.rhoadslifters.com/Pages/Articles.html


Here is where you can look up what part number that you need:

http://www.rhoadslifters.com/Pages/PartNumber.html


You can get them from Summit Racing.


Find an old dual plane Edelbrock LD340 intake manifold or try the Wiand Stealth dual pland with a power band of idle - 6800 RPM.

https://www.holley.com/8022.asp
 
I was gonna get the ld340 but then I read where the RPM Air Gap was just as good. Then I found out my dad had one on a 340 he has sitting. He will not be using it for a long time and said I can have it just got to replace it when he needs it. If I know him and his projects i have a long while.

If any of these are worth the added expense I will buy one. I will look into that and thank you for the info on the cam.
 
Stay with the air gap
Go to a 2-1/2 exhaust pipe. 2 inch is way to small
Skip the Rhodes lifters and ge a new cam that is a split duration.
Everything else is good.
 
thank you everyone for the input. I have done a lot of reading this past week and there is a lot more to continue to read.

One more question: the transmission I bought is suppose to have a "small" stall in it but I have no idea what small would be or if it really does. That said, should I readjust my thoughts on the cam and go with a larger duration or stick with the XE268
 
xe268 is a great cam, even for a small converter. Had one in my 360 with a 2200stall
 
Figure out the power you want and go from there.

If you want 330-350 then the XE368 or Lunati voodoo 268 are good choices. Both those cams require nothing special in the valve train to run and idle well on the street. It's all in the tune up.

LD340 or Air Gap, use whichever you have handy. Block the heat crossover on the LD.

Save money, run Dougs headers
 
crackedback said:
Figure out the power you want and go from there.

If you want 330-350 then the XE368 or Lunati voodoo 268 are good choices. Both those cams require nothing special in the valve train to run and idle well on the street. It's all in the tune up.

LD340 or Air Gap, use whichever you have handy. Block the heat crossover on the LD.

Save money, run Dougs headers
Click to expand...

X's2!
 
Thanks again guys. Power range I am going for is right there around the 330-350. Really just whatever it gets out of the combo listed. We are gonna inspect the motor this week. If it needs to go to the machine shop I might rethink the build and go for more power but for now it is just whatever added power I get out of the intake, cam, carb header combo.
 
Ok guys. Took the heads off and the cylinders had some lines on them. Nothing bad at all but I figured while I had it out take it to the shop and get a hone and new rings and bearings. The cam looks brand new and we are gonna see what is in it.

I have read the dyno derby article and it said 392hp. Pretty much identical to what I plan to do. Have others had similar experience? I have decided I would really like to be close to 400hp if it is easily achievable while we have the motor apart. How much difference would a bigger cam add?

Fwiw I have decided to go with my original 904 transmission and before I buy a converter I need to make this decision.
 
I run an xe 262 and have 440 tq 420 hp , you should make around that with your setup . You should be in the low 13 - mid 12 sec bracket depending on traction
 
txbullets said:
I have read the dyno derby article and it said 392hp. Pretty much identical to what I plan to do. Have others had similar experience? I have decided I would really like to be close to 400hp if it is easily achievable while we have the motor apart. How much difference would a bigger cam add?
Click to expand...

Don't believe everything you read about HP... Without porting the stock heads will get you in the 340-350 range. If you build that exact engine expecting it to push your car to a high 11- 12.00 second time slip like it should, you'll likely be disappointed.

That mag build will get you in the 105 range for 1/4 mile MPH
 
crackedback said:
Don't believe everything you read about HP... Without porting the stock heads will get you in the 340-350 range. If you build that exact engine expecting it to push your car to a high 11- 12.00 second time slip like it should, you'll likely be disappointed.

That mag build will get you in the 105 range for 1/4 mile MPH
Click to expand...

Pretty much what I thought. Sounded a bit optimistic.
 
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