Engine Code Question

68 RT · Dec 27, 2017

I have a 68 Charger RT with a 70 440 engine. The fender tag decodes as a 440 HP engine. The stamp on the 70 engine is an L code or what I believe to be low compression code. There are many more markings and dates on the stamp pad, possibly by the engine rebuilder. my question is, would a comparable engine in 1970 be stamped HP and not L?

4mayhemi · Dec 28, 2017

Speaking stock setup, absolutely HP (not getting into rods/crank difference etc 68 vs 70). Loaded question though as to what's been done to your current setup and how important to you a NOM should meet what it was born with.

68 RT · Dec 28, 2017

From the odd stamping, I believe it may have been an RV or truck engine. it was rebuilt at one time, has a big cam and original 4 barrel intake. The only way to know if they built it to HP specs is to get it dyno'd. That's for another day though.

69Bee · Dec 28, 2017

Without going to my book, L should be for "Low Compression". As far as HP goes, unless the car is a collectible numbers matching vehicle, it is basically an ego trip wanting to have the HP stamp. All it meant anyway was a hotter cam/valve spring/ex. manifold setup, and possibly different carb and distributor. There is NO physical difference between a HP and a non-HP block.

4mayhemi · Dec 28, 2017

69Bee said:
All it meant anyway was a hotter cam/valve spring/ex. manifold setup, and possibly different carb and distributor.

1970 440 block castings = no difference.
HP vs. "non-HP" engine = big difference in how it ticks and breathes.

I would think if they did a cam swap they would have wanted it to breathe better also. At least your NOM is in the same color range as original.

PurpleBeeper · Dec 28, 2017

4mayhemi mentioned this... As far as I know, these are the differences between a 68 "HP" motor & a 70 "HP" motor + a little side info.

1. In general, "HP" motors got a slightly larger cam, better flowing exhaust manifolds (& maybe a different carb?). You already have a larger cam.
2. 70-73 "HP" motors will have "six pack" connecting rods (even 4 bbl. versions) and will be EXTERNALLY balanced. If you look at your harmonic balancer, externally balanced ("six pack" rod) motors will have a little "horseshoe" weight on them. They are the same thickness as a "small rod" motor (cast crank harmonic balancers are about twice as thick as the other harmonic balancers + all 70 motors should NOT have a cast crank from the factory). Non-HP 70 motors will have completely symmetrical harmonic balancers (& so will 68 "HP" OR 68 "non-HP").
3. In 68, they hadn't developed the "six pack" rods yet..... I also don't believe the 69 440 six pack motors had the bigger "six pack" rods either, fyi.

The bottom line is:
a. If your 70 motor is "HP" you can just look at the harmonic balancer
b. A non-HP 70 motor would more closely match a 68 "HP" motor (both would have forged cranks, but the smaller, non-"six pack" rods)
c. You've already changed the cam & if you've added headers too, that's 2 out of 3 "better than HP" items. Add a 750 vacuum secondary carb & you'd have "3 out of 3" better than HP.
d. The heads, block, crank, intake (all the important stuff) are identical

68 RT · Jan 10, 2018

PurpleBeeper said:
4mayhemi mentioned this... As far as I know, these are the differences between a 68 "HP" motor & a 70 "HP" motor + a little side info.

1. In general, "HP" motors got a slightly larger cam, better flowing exhaust manifolds (& maybe a different carb?). You already have a larger cam.
2. 70-73 "HP" motors will have "six pack" connecting rods (even 4 bbl. versions) and will be EXTERNALLY balanced. If you look at your harmonic balancer, externally balanced ("six pack" rod) motors will have a little "horseshoe" weight on them. They are the same thickness as a "small rod" motor (cast crank harmonic balancers are about twice as thick as the other harmonic balancers + all 70 motors should NOT have a cast crank from the factory). Non-HP 70 motors will have completely symmetrical harmonic balancers (& so will 68 "HP" OR 68 "non-HP").
3. In 68, they hadn't developed the "six pack" rods yet..... I also don't believe the 69 440 six pack motors had the bigger "six pack" rods either, fyi.

The bottom line is:
a. If your 70 motor is "HP" you can just look at the harmonic balancer
b. A non-HP 70 motor would more closely match a 68 "HP" motor (both would have forged cranks, but the smaller, non-"six pack" rods)
c. You've already changed the cam & if you've added headers too, that's 2 out of 3 "better than HP" items. Add a 750 vacuum secondary carb & you'd have "3 out of 3" better than HP.
d. The heads, block, crank, intake (all the important stuff) are identical

Thank you, great info here! I'll eventually get it dyno'd to dial it in anyway. It's a bit of a dog off the line

mopar 3 B · Jan 11, 2018

What you guys paying for duno time that makes it such a great option?

Engine Code Question

68 RT

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4mayhemi

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68 RT

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69Bee

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4mayhemi

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PurpleBeeper

Well-Known Member

68 RT

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mopar 3 B

Well-Known Member

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