Identifying Engine

[slumbers]

Hi Gentlemen and greetings from the UK !

I have a 1968 Dodge Charger R/T that I am restoring and am just getting around to thinking about sorting the engine.

It has a 1968 RB block that i don't think was the original engine and despite the crud has at sometime not too long ago had a rebore and new pistons ..............

There is virtually no wear in the bores and the honing marks are still there.

However after trawling the Mopar forums for info I am uncertain if the engine has the right pistons and heads to make some suitable power ....

The pistons stop approx 5/32 from the block deck as shown and are .040 and I have measured the bores at 4.35"

The cylinder heads have the number 2406516-1 cast into them and the valves are approx 2" inlet and 1 3/4 " exhaust.

Bearing in mind that getting parts to the UK is'nt that cheap can I use what I have or do I have to change some major lumps ?

Also are these valve springs correct ?  I was going to replace them with a new set that comes with the Camshaft Kit.

I was going for a fast road type cam Edelbrock Performer and manifold from Summit Racing with a Holley 750 Carb and electronic distributor to keep it all fairly

basic but any info would be good !!  Thanks

 

[John_Kunkel]

The piston "down in the hole" dimension is typical of the '72-later low-compression pistons, the correct '68 pistons would be .050" down in the hole. The 516 heads are from the '64-'67 era with closed combustion chambers and, typically, 1.60" exhaust valves. That piston/head combo would yield a compression ratio of around 8.5-1. Installing the correct '68 906 heads would lower the CR to around 7.8-1. Can't tell the valve spring specs without actually removing them and testing their pressure. 

[Challenger340]

Those are unfortunately the notoriously low compression pistons, that have been the subject of numerous frustrations over the years, and absolute wonderment as to WHY they were even produced ? ... or used in any "performance" Engine rebuild effort ?
Here is just one thread for background, although in it the piston discussed is better than yous. (Yours is even worse than the one discussed)
http://www.dodgecharger.com/forum/index.php/topic,118292.0.html

IMO, if you are contemplating "any" kind of performance whatsoever in your build,
you would be well advised to change Pistons as a starting point.

[slumbers]

Thanks for the info so far    Can anyone tell me Which would be the correct pistons to go for .040 over ( Do they need to be flat top or have cut outs )  ? and is it worth sticking with these cylinder heads ? The exhaust valves are definitely 1.75 " not 1.6"  so maybe they have been opened up at some time to be the same as the 68 heads ?   

[John_Kunkel]

The SpeedPro L-2266F piston would yield a CR of around 9.5-1 with your heads and they are available in +.040".

http://www.summitracing.com/parts/slp-l2266f

[BSB67]

The SpeedPro L-2266F piston would yield a CR of around 9.5-1 with your heads and they are available in +.040".

http://www.summitracing.com/parts/slp-l2266f

There are several ways to increase the compression ratio to gain the additional power that comes with it, and what John recommends is probably the lowest cost solution to move the compression ratio in the right direction.  

There is an old saying, speed costs money, how fast do you want to go?

Budget, parts availability and goals are key in deciding the path to take.

[Challenger340]

If you are only going to change the Pistons, and then re-use your existing 2406516 Cast Iron Heads, then as John Kunkel says the L2266 Pistons are a good choice.

If you are unsure of Valve Springs ? may also wish to consider,

Option 2,
if the budget allows ? and you are contemplating both new Pistons and "aluminum" Heads as an upgrade to some REAL performance worthy of these old classics while you have it apart ?
would be to step up to the L2355 Piston in conjunction with the Aluminum Stealth Heads, which will net around 10 to 10.2:1 C.R., and will run absolutely fine on Pump Premium Gas of 91 Octane with a Camshaft in the 226* to 232* @ .050 Intake duration.
The Aluminum Heads can run higher Compression Ratio(10 to 10.2:1) than your stock cast iron Heads(max 9.5;1) without detonation due to the aluminum's greater combustion heat dissipation characteristics.
Not to mention the Stealth Heads Flow more air out of the box than your cast iron heads ever dreamed of(even with the 1.74" valve upgrade)

These option 2 combo's typically yield 500+ Ft/Lbs of Torque and 500 hp all in by low 5,000's rpm, have plenty of vacuum for power brakes, with a nice " musclecar" exhaust note like the street warriors of old.
L2355F Piston
http://www.summitracing.com/int/parts/slp-l2355f/overview/

"Stealth" head... which once painted looks exactly like the stock heads outwardly.
http://store.440source.com/Stealth-Aluminum-Cylinder-Head-COMPLETE-SINGLE-HEAD/productinfo/200-1055/
Good idea to upgrade to 10* Locks and retainers, buy their Head Bolts as well.

We did a bunch of testing with these very similar combo's, look through the "proven"  combo's section here:
http://www.dodgecharger.com/forum/index.php/topic,106687.0.html

[slumbers]

Gentlemen Thanks very much for some top advice . 

[redmist]

Also look at SRP's piston offerings, I went with the SRP Pistons because they were a whole bunch lighter than the other ones on the market.

[slumbers]

Great Thanks !
I think the stealth heads are the way forward , they are also considerably lighter....By the time I have paid to have the valve seats recut etc on the iron heads the ally ones start to look good value. I will put them on my Christmas list 

[slumbers]

Stealth Heads ordered and on Their way ! Pistons next ... Thanks for the Advice 

[Challenger340]

Stealth Heads ordered and on Their way ! Pistons next ... Thanks for the Advice 

We still do Stealth Head builds as a cost effective price point for the resto guys who want the stock appearance.
Sounds like the direction you are headed ? so I will direct you here for further ideas.
Long read, but might be some relevant stuff in there for you ?
http://www.dodgecharger.com/forum/index.php/topic,106687.0.html

[slumbers]

Thanks