340 Combo advice needed

[STXCuda]

My plan is to build a stout rowdy 340 for street and some track use. It will be backed by a 904 and rear gears are yet to be determined. The rotating assembly is balanced. Pistons are SRP 142068 flat tops with 2 valve reliefs. Comp ratio (70cc) 9.2, (60cc) 10.5.
Heads are freshened 340 X with mild port cleanup and upgraded springs and milled. My question is the following, should I switch to Magnum heads (benefits?) and of course what cam is recommended. with my current budget aluminum is out of the question. Thanks for any help!

 

[STXCuda]

I don't know 340 X heads CC. Waiting for cc kit to come in.

 

[moparleo]

Has the block been machined yet ?

 

[moparleo]

Magnum heads can be adapted but why not just build a 5.9 Magnum ? The 340 and 360 were both backed up with a Small bell housing patterned 727. Why a 904? With the 5.9 you start out with 20 more cubes and they are plentiful and reasonably priced. The magnum heads are better than old 340 heads and there are after market heads that are cheap and flow much better even without any port work.

 

[STXCuda]

I've already invested in the 340 block. Yes, block is fully machined and decked. I have the 904 from my 70 barracuda 318. I also know that the 904 has a lower 1st gear and less internal mass. But that's another thread. When you say aftermarket heads, are you referring to aftermarket replacement heads manufactured in China? I saw some and the price seemed good, I was wondering if anyone had used them in performance applications. Or did you mean aftermarket performance heads??

 

[moparleo]

Engine Quest cylinder heads. They have had write ups in several Mopar magazine with very positive ratings.

EngineQuest’s Mopar cylinder heads wake up small blocks | Search Autoparts

 

[STXCuda]

Yeah I saw those too. A very good deal on those specifically. Given that would put me to about 10.5 CR.,what cam would you suggest? I was considering the Purple 484 or the CC XE284

 

[Adam]

If you already have the fresh X heads you should use them. The EQ heads are great, but about $1100 a pair. Put the money to something else. Just my 2 cents.

 

[STXCuda]

Adam I think that's exactly what I'm gonna do.

 

[AUSTA]

My plan is to build a stout rowdy 340 for street and some track use. It will be backed by a 904 and rear gears are yet to be determined. The rotating assembly is balanced. Pistons are SRP 142068 flat tops with 2 valve reliefs. Comp ratio (70cc) 9.2, (60cc) 10.5.
Heads are freshened 340 X with mild port cleanup and upgraded springs and milled. My question is the following, should I switch to Magnum heads (benefits?) and of course what cam is recommended. with my current budget aluminum is out of the question. Thanks for any help!

If you use the E/Q heads on a 340 you may need to factor in the cost of pedestal rockers guides push rods roller lifters etc
also if using KB243 pistons you will need to mill the pistons or use a thicker gasket as the KB 243 pistons come up out of the bore by .018" leaving just .019" clearance at TDC using a .039"head gasket

 

[STXCuda]

After considering the additional expense and what's been invested. I figure it would be wise to use my
X heads. As far as pistons they are SRP 142068 flat top 2 valve relief. If I'm going to make the investment it will be down the road and go with aluminum heads. For now I just want to get this car driving again and have some fun with it.