Planning on building a 340

-
almostgone

almostgone

New Member
Joined
Apr 13, 2013
Messages
2
Reaction score
0
Location
Toledo, OH
I'm planning on buying a 340 bare block, 4 bolt main that has a 1969 casting date from a friend. This will be a project motor for my 73 swinger. It will be something to swap with the 318 in the rails now. I realize that being a mopar, it's not going to be cheap. I'd like to get as much hp out if it and still be streetable. Entertaining the thought of a stroker kit, and reading on another thread here, thinking aluminum heads. Not sure on how big a cam to go. I plan on running headers like what's on the car now. This will be my first build. It's probably going to take the better part of the year to finance it and build as well, so I'm really not in a hurry. Just would like to get some ideas for all the internals I know I'll need. Car has a 8.75 rear but I'm planning on changing the gears, its a jackrabbit off the line but no long legs. 70mph is about 2500 rpm on 15' rubber. Also realize the 904 trans won't handle the ponies I've envisioned so a 727 will be looked for. Any info on parts, size and from whom would be appreciated.
 
My 73 dart has a 360 in it, right now its out to getting some work. My old build was redone bottom end with stock stroke, eddy heads with about 10.5:1 compression, comp XE268 cam, headers, 904 and crappy highway gears that I am changing out now. Was a good combo besides the gears.

The cam was going flat so I took the motor out and am rebuilding it again. Will have the same bottom end and eddy heads, but I went with a fairly stout solid roller lunati cam, 904 trans with a shift kit with a better converter and 3.91 gears. Also if you go with eddy heads get them checked out...I learned that one the hard way..

Also I'd stay with the 904 trans. My engine before was making high 300s easy, and I wasn't easy on it, and the trans never skipped a beat. They are lighter and take less power to turn, just do a rebuild with some better parts and you wont have a problem with it.

Get the block magnifluxed as well to see if its even usable, then if it is get it bored the least amount possible, it will probably need the deck straightened up too, my 360 was pretty wonky that way.
 
First off...Welcome to FABO! :thumbrig:

I may have a few questions after I reread & digest what you've proposed?

But do let us know what type of power you want to make and how the car will be used on the street vs a little playing at the track? You may not need to stroke it?
 
Built a 408 a few years back,very responsive. You might use the "Search " function,in the small block tech forum. MRL & 0U812(handle here) IMM engines for information ,on 408/416 builds. Won't be cheap by a long shot,expect a 7,000-10,000 bill. Look for heads that offer mid range lift velocity, & a minimum of 250 cfm intake flow @ .500-.600 lift.
 
It doesn't necessarily need to cost a lot, parts are more expensive, but the basic 340 package doesn't need a lot help to make good power. Cam 270-285 , headers, 750 & airgap and maybe a little pocket porting should get ya in the 400hp range give or take. I wouldn't worry about stroking unless your looking to build 450 plus hp especially if you don't want to run a lot of stall and gear.
 
The block belonged to my friend's father who passed recently. He had the lower drilled for the extra bolts on the three center mains. I believe he was planning on building it for racing or something. I'm guessing that it may have been checked out while at the machine shop but I can always double check before getting too far into the project. As for power, I'd like to get somewhere between 400-500 hp. From what I've read, that shouldn't be a problem. As for the driving aspect, mostly cruising to car shows and cruise-ins. Probably every once and awhile on the track. My 318 in it now, has a mild cam, headers, straight duels and a 600 eddy carb on an eddy intake. It sounds good and doesn't do too bad but would like to have a bit more fun. I'm already thinking of upgrading the front suspension and going to disc from drums. Originally was thinking of rebuilding the 318 but when this 340 popped up, figured I'd build it the way I wanted and still able to drive while doing so.
 
4 bolt main is a chevy guy thing. No Mopar ever really needed them. The Hemi and I believe the Max Wedges had cross bolted mains. But everything else was 2 bolt. That's all that's really necessary. 4 bolt main just sounds cool when you're bench racin. When I hear people say it, that tells me who the fake car people are. It has zero bearing on power output or durability. It's been argued for decades that the extra holes in the block remove needed metal and actually make it weaker. In the end it makes not one crap load of difference.
 
RustyRatRod said:
4 bolt main is a chevy guy thing. No Mopar ever really needed them. The Hemi and I believe the Max Wedges had cross bolted mains. But everything else was 2 bolt. That's all that's really necessary. 4 bolt main just sounds cool when you're bench racin. When I hear people say it, that tells me who the fake car people are. It has zero bearing on power output or durability. It's been argued for decades that the extra holes in the block remove needed metal and actually make it weaker. In the end it makes not one crap load of difference.
Click to expand...

BAM! Someone, says it all.Make sure the machine work,is done correctly.And assembled correctly. Pay attention to fastener quality,& installation. It's; painstaking details, worth all you do.
 
You dont want a 727 for your build. Extra weight, friction and a bigger drum you dont need for a 475 hp SBC. 904 is just fine.
 
You must log in or register to reply here.
-

Back
Top