The Dodge Challenger Message Board

hey every one!

I'm rebuilding my 360 right now, and found out the crank is total wasted...
so i'll have to raise my budget, and I was thinking of some "racing" crank with bearings, maybe also light weight connection rods and a nice set of pistons... any sugestions or price info?

I also heard that it's possible to make from X-heads from J-heads, the guy who told me said that is was simple and easy... but is it so? what do i have to chance? Is it worth doing it?

i also found these numbers on my engine block : 4w 360HP 35560 ; blok vin = 4B373198 ;
and on the heads : AAWJ 360 L ; 3303 ; 3671587-12.

i Read somewhere that an HP indication means its a high performance engine= is this so and what's the difference between a normal engine then?

is it always better for performance to bore your block a bit over?
the cilinders are a little bit oval so i was thinking to bore the block .30 and then installing new pistons... or would this be very expensive?

what do you think guys?

I am not an expert on small block engines so I will leave others to fill in the details. However I will tell you a few things if I may?

You cannot tell what heads you have by the J or X. This is a foundry reference and has no bearing on the head itself. Many 340/360/T/A engines have one of each on them! go by the casting numbers not the letter. (Thanks to Alex for teaching me that).

Also some 360 heads were identical to the 340 head. Casting number 3418915 for example has the big 2.02 intake valve I think?

I guess what your guy was saying is that it is easy to replace your 1.88 intake valve with the 2.02 because both versions of the 340/360 head had the same intake runners and ports so it is just a case of making the valve seat bigger.


The LA engine was cast with as little metal as possible to keep it light. That is what the 'L' in 'LA' stands for.
The thinner the cylinder wall the more power you will loose due to flex in the wall and poor piston ring seal. NEVER bore the cylinder oversize unless you have to and then only bore what you need. Most common aftermarket pistons are 30 thou oversize so normally you would fit those but if you can find 20thou use those instead.
To make the cylinders as good a fit as possible you should use a torque plate when the engine is being machined. This is a thick metal plate (like a one inch thick head gasket) that bolts on in place of the cylinder head. When the head bolts are tight the cylinder wall will warp slightly. So getting the cylinder machined with the plate in place will make it perfectly round when you bolt your heads on.

Not sure I was very clear there.

Also you buy the pistons first and then get the block machined to the correct bore for the pistons you have. This is because diffferent piston types require different amounts of clearence.

Have a look at http://www.hughesengines.com/ for prices on cranks and pistons. Also check out the complete long blocks and stroker kits.

here is an article i found it might help

MOTOR TRAXX MOPAR TECHLINE
by Bob Doty
Small Block Heads
The subject for today....deals with the small block head, and some confusion about the casting numbers. and the potential of each head. There are numerous all-out performance heads available on the market, but I prefer to deal with readily available, relatively inexpensive swap meet and junkyard material. The focus is on the restored or restified street driver and occasional performance Mopar.

Small Blocks

The introduction of the 273 in 1964 heralded the way for the thin wall casting 318, 340, and 360 engines. As most of you know, these small block engines were loaded with performance potential. With the new block design came a new wedge head. By 1968, performance had reached a new level: the legendary 340. The well-known X-Casting, with 2.02 intake and 1.60 exhaust valves proved to be the key. Gone were the poly heads and heavy blocks. Small block performance per cubic inch was on par with the big boys.

The 68'-71 X-head had large intake valves, 65cc closed chambers, and ample intake and exhaust runners (ports). They are considered the premier performance bolt on for the small block engine. The downside is that they command relatively high prices at swap meets. and are usually in need of work. The last X-head was produced almost 25 years ago.

Along comes the next generation of small block heads the common 340-360 head the " J ". (I have personally seen early J heads with 2.02 intake and 1.60 exhaust from the factory, although the books and expert say they were never made.) 99.9% of these heads were garden variety 1.88 intake and 1.60 exhaust. Chrysler was downplaying performance by 1972 and the 360 was about to take the place of the 340. (the last 340 was produced in 1973 and the first 360 in 1971 .... allowing for a three year overlap.)

This is not bad news. J castings are plentiful and inexpensive. The small intake valve is actually an advantage. Why? When you find a set of heads and take them to your favorite machine shop, have 8 new 2.02 intake valves in your hand. When you enlarge the seats for the oversize valves, it will be on fresh material, and will not sink the valve in the seat. As for the intake and exhaust ports or runners: every 340 and 360 head has identical port configuration. With a good 3-angle valve job, minor pocket porting and cleanup you will have a very good street-strip head. After 1973, most 360 heads had hardened exhaust seats installed for today's unleaded fuels. This is an added bonus for street performance and reliability. The 68cc head will be approximately @c after milling for straightness.

The T/A head

The T/A heads have identical porting and runners as any 340 or 360 head. In fact, the head carries the 360 J casting number. The intake rocker was offset and the pushrod hole was elongated (to provide provisions for porting). There is no performance advantage to these heads as cast. In addition, not one of these engines was every produced with 4-bolt main caps. They did have provisions to install 4-bolt main caps (a thicker main web and filled pan rail.) Do not spend big dollars on identical heads. Leave these for the people who need them for a restoration. Note: when I say not produced. I am referring to production line vehicles.

Remember:

all 340 and 360 heads have identical port size and configuration.
installing 2.02 intakes is simple and inexpensive (they all have 1.60 exhausts)
the heavy duty stamped steel rockers and shafts of the small block (hydraulic) are good and stable to 6000 rpm, and are maintenance-free.
the exhaust flow side of the small block head is the weak side. This is why the small block responds so well to headers or the early 340 exhaust manifold.
Bob Doty