340 build

[Tonefiend]

I started collecting parts for my 340 build.  What I have is a '69 340 block 2780930-340-7  A forged crank 2532457  and forged full floating rods 3148645

This will be a slow build as I gather parts and money.   Once I have the heads I will have a machinist machine the block and have the heads done. 

For heads I am looking for a pair of 308 castings.  I also have a line on some X and J heads that need rebuilding. 

The block is stock bore. It looks like it might need only a hone, but I will leave that to the machinist.  The crank needs turning.  There is not much wear, but it's a bit rusty.

I am open to comments and suggestions.   

[Aussie Challenger]

If it is a '69 block it will need boring especially if rust is present. As you want to do this right plan on a re-bore, it might only need .020" or .030" but then you will know that it is good.   
I would go with the 308 heads.   

[Tonefiend]

Thanks Dave.   I plan on doing it right. Having the motor bored and honed, then balanced. 

I plan on using 308 heads. 

I am wondering if the local junkyard might have those? That might be a goodplace to score a set.  Anyone know how the casting number or what they are caller or came off?

[Aussie Challenger]

I believe that truck 360's 1989 - 92 pre magnum EFI.

[Chryco Psycho]

87-92 pre-magnum 5.9/360 engines will have the 308 heads

[Glennster]

I've got some J heads that are ready to go, I'd like to sell them.
I also have a 340 to 416 stroker crank that would come with 273 rods. The crank and rods are from my burned up 340/416, so they need to be turned/reconditioned........
 If you're interested, I'd try to get you a very fair price.......Anybody out there know what a fair price would be?

[Tonefiend]

Hmm I might be into the J heads. 

Anyone have any input oin the new RHS Indy LA-x heads?  http://www.moparmusclemagazine.com/techarticles/engine/mopp_1003_360_x_cylinder_head/index.html

[Glennster]

 The guy that's doing my rebuild likes Edelbrock over Indy for aluminum heads (that's what I'm going to). He says the Indy stuff is not not always good quality, I've also heard that they suck if there's a problem with their product. They walk away when there's a problem......

[dodge freak 2]

Well Edelbrock isn't like perfect either. I hear of valve giulds being too tight that when the motor is hot a valve sticks open and the piston hits and bends it..

I would have an Edelbrock head disassemble and inspected by a good machinist before using. Bet you he find one or more problems with each head.

Some places like Hughes  suggest that you consider adding our "Prep" work to the heads to insure a good valve to seat seal and correct any "AS CAST" flaws.

http://www.hughesengines.com/Index/products.php?browse=category&level0=U21hbGwgQmxvY2snTEEnIDI3MywzMTgsMzQwIGFuZCAzNjAgZW5naW5lcw==&level1=Q3lsaW5kZXIgSGVhZHM=&partid=10968

[72bluNblu]

Nothing is perfect! The valve guide thing is pretty common with the Eddy's. I've also heard of a few oil ports that were not drilled completely through on the Edelbrock's, not a good deal if you don't find it.

I've heard a lot of good things about the RHS X heads, their flow numbers are pretty impressive even without any work. But I haven't seen a set yet so I can't really say anything about the quality. There's a few threads with flow numbers and dyno results over on FABO.

[Tonefiend]

I am hoping to find some parts at spring fling.

Question,  Suppose I find a set of uncracked 308 heads.  I get them rebuilt, maybe even ported. Then I put them on a stout 340 thats putting out about 400-425 horses.  Doing burnouts and acting like a maniac...  Whats to prevent ME from cracking them?   I really want to build an engine thats bullet proof and totally reliable.

I am also looking at the new RHS Indy LA-X heads.  They look pretty decent.  http://www.hughesengines.com/TechArticles/311laxandmaxironsmallblockheads.php

[Chryco Psycho]

In my experience if tehy are going to crack they already will have , the EFI engines run leaner & hotter & even with crack seem to run well unless the crack is severe,
 with a carb it should run cooler unless you have it far too lean & should be ok

[72bluNblu]

I am also looking at the new RHS Indy LA-X heads.  They look pretty decent.  http://www.hughesengines.com/TechArticles/311laxandmaxironsmallblockheads.php

The RHS LA-X heads are fairly impressive heads. These are flow numbers for a set of RHS's with 2.02/1.60 valves from over on FABO

Lift          Intake(cfm)   Exhaust (cfm)
.100"         69                 58
.200"         141              119
.300"         197              161
.400"         241              184
.500"         267              193
.550"         271              195

The only problem I see with them is this- most of the piston choices for the 340's involve the pistons being around .018" over the deck. The RHS LA-X heads are closed chamber heads, so your piston-to-head and piston-to-valve clearances might be a problem. I don't know if they'll hit or not, but I would certainly ask a lot of questions before I bought a pair. Edelbrock heads are also closed chamber, but they make a special open chambered version for the 340's. I wouldn't think they'd do that unless there was a clearance problem, at least for their head at any rate.

[Chryco Psycho]

Worst case Cometic makes a thicker head gasket to get the minimum clearance

[Tonefiend]

Thanks!  Good to know about the piston clearance.  I think I will stick to the 308s if I can find a set.