Engine Boss Location on a 383

[Curiousyellow71]

No because there was no HP stamp in the bottom right corner of the block pad. It probably started out as a 2bbl standard with 290 horsepower with 9.2 compression but the crank is the same as the HP. Basically the only difference in a standard 383 block and an HP block is the HP block has the stamp, same block. You can add a windage tray, 10:1 pistons, hotter cam, 4 bbl intake, HP exhaust manifolds, dual exhaust and you have an HP motor.

I don't believe the 330hp had a hp stamp only the 335hp??? I have not heard of one anyway?? 330hp was smaller cam/ weenier valve springs and typically a ac car. 906s were used on all the big block engine in 68 even the 2 barrel.and the 440 magnum

 

[69 Sleeper Bee]

There has been a lot of debate on the horsepower numbers. I think I read somewhere that only the Road Runner came with the 335 horsepower and others got the 330 horsepower engines but I thought both were HP engines. I am not completely sure about this but I am sure we are about to find out.
Edit: looks like it was RR / Superbee got the 335 HP engines.

 

[69 Sleeper Bee]

I did find this from an old FBBO thread about 383HP. Looks like camshaft,springs and exhaust pipe diameter were different between the 330/335 hp motors
Edit: you need to look at this chart on something other than your phone

..........................1967 Engine Specs................. 1968 Engine Specs............. Road Runner/Super Bee

* Engine.................... 383/325 HP............................ 383/330 HP ..................... 383/335 HP

* Engine Dyno ............ 278 HP ................................. 288 HP ........................... 310 HP

* Compression............ 10.0 - 1 ................................ 10.0 - 1 .......................... 10.0 - 1
* Piston..................... Flat Top ................................ Flat Top ........................... Flat Top
* Piston Height.......... {-.014" } Below Deck ............. {+.021" } Above Deck ....... {+.021"} Above Deck

* Camshaft............... {Hydraulic} .......................... {Hydraulic} ....................... Hydraulic
* Lift........................ .425"/.437" .......................... .425"/.437" ...................... .450"/.458"
* Duration................. 256*/260* ........................... 256*/260* ....................... 268*/284*
* Overlap.................. 32* ..................................... 32* ................................. 46*

* Intake Manifold...... {#301 666 968} .................. {#2806301} ....................... {#2806301}
* Type..................... Cast Iron.............................. Cast Iron ............................ Cast Iron
* Style .................... Dual-Plane............................ Dual-Plane ......................... Dual-Plane
* Height................... Low-Rise.............................. Medium-Rise ...................... Medium-Rise

* Carburetor................{Carter AFB} ...................... {Carter AVS} .................... {Carter AVS}
* CFM Rating............... 575 .................................... 625 ................................. 625
* Throttle Sizes............ 1.437" x 1.563" ................... 1.437" x 1.688" ............... 1.437" x 1.688"
* Venturi Sizes............. 1.186" x 1.313" ................... 1.186" x AV ..................... 1.186" x AV

* Cylinder Head........... {#2506516} ....................... {#2843906} .................... {#2843906}
* Combustion Chamber. {Closed}............................. {Open} ........................... {Open}
* CC Level {Factory}......79.5 .................................. 88.0 ................................ 88.0
* CC Level {Minimum}... 73.5 .................................. 79.5 ............................... 79.5
* Intake Valve............... 2.08" ................................ 2.08"............................... 2.08"
* Exhaust Valve............. 1.60" ................................ 1.74" .............................. 1.74"
* Valve Springs............. Single-Coil.......................... Single-Coil ...................... Single-Coil w/Damper
* Load Rate.................. #134 lbs. {Valve-Closed}.... #134 lbs. {Valve-Closed} ... #134 lbs. {Valve-Closed}
* Load Rate.................. #208 lbs. {Valve-Open}...... #208 lbs. {Valve-Open} ..... #256 lbs. {Valve-Open}
* Gasket Thickness........ .021" ............................... .020" ................................ .020"

* Exhaust ................... {Dual} ............................. {Dual}............................. {Dual}
* Primary Pipe............... 2.25" ............................... 2.25" ............................... 2.50"
* Tail Pipe..................... 2.00" ............................... 2.00" ................................2.25"[/QUOTE]

 

[Bigtime]

No because there was no HP stamp in the bottom right corner of the block pad. It probably started out as a 2bbl standard with 290 horsepower with 9.2 compression but the crank is the same as the HP. Basically the only difference in a standard 383 block and an HP block is the HP block has the stamp, same block. You can add a windage tray, 10:1 pistons, hotter cam, 4 bbl intake, HP exhaust manifolds, dual exhaust and you have an HP motor.

I did not sand the paint off of the lower right corner.....Hmmm.....will have to go back and check that.

 

[Bigtime]

It should have 906 heads with flat top pistons and a forged crankshaft. All good things.

I will use my borescope to look at the top of one of the pistons. So, to be clear, if it has a dished piston it is a low compression [9.5:1] and if it has flattops it is higher compression? I know that I keep saying this, but I really DO appreciate your help and the help of all others involved with this.

 

[Bigtime]

It's a 68 (verified by the D on the pad) so there may be a VIN stamp don the back of the block near the oil sending unit. This is the best place to start to see if it is the original assembly.

I'll check it out. My guess is that the last person that owned the car added the Tarantula intake and the headers to dress up a low compression motor to LOOK like an HP motor [lipstick on a pig]. The confusing thing for me is that I can tell by the idle that it has a small, mild cam. Wonder why go to the trouble with a low compression motor? Two clues here......check the boss [lower right corner] to make sure that it is not stamped HP and also use my 'scope to see if it has dished pistons. Damn, am I learning a lot here, or what?

 

[69 Sleeper Bee]

I will use my borescope to look at the top of one of the pistons. So, to be clear, if it has a dished piston it is a low compression [9.5:1] and if it has flattops it is higher compression? I know that I keep saying this, but I really DO appreciate your help and the help of all others involved with this.

I am not clear on the dished pistons in the 9.2:1 but I do know the 4bbl & HP version used flat tops. An easy way to up the compression is to go with a steel shim head gasket instead of the composition head gasket as they are thinner.
https://www.manciniracing.com/mrstshhega.html
With today's pump gas lower compression is not a bad thing as far as detonation goes. The factory advertised 10:1 in the 4bbl / HP motors but in reality they were closer to 9.5-9.7:1 from what I have read. Remember these were the days of the horsepower wars so they tended to fudge things a bit.
Please load up some pictures of the engine.
Here is a 383HP motor I found in a garage of a house I was drawing remodel plans for.
Someone added a factory 2x4 intake on this one but I am going with a Mancini 6 pack because dual 4's are so much fun to tune.

 

[69Coronetrt]

There has been a lot of debate on the horsepower numbers. I think I read somewhere that only the Road Runner came with the 335 horsepower and others got the 330 horsepower engines but I thought both were HP engines. I am not completely sure about this but I am sure we are about to find out.
Edit: looks like it was RR / Superbee got the 335 HP engines.

Which model receives which assembly (330 or 335 horse) varies by year. The application also varies by transmission and whether the car had A/C or not.

The 1968 model year applications are different than 1969 and 1970 is different than 69. So, you have to be specific as to which year you are discussing when it comes to 330/335 horse installs.

 

[Bigtime]

I am not clear on the dished pistons in the 9.2:1 but I do know the 4bbl & HP version used flat tops. An easy way to up the compression is to go with a steel shim head gasket instead of the composition head gasket as they are thinner.
https://www.manciniracing.com/mrstshhega.html
With today's pump gas lower compression is not a bad thing as far as detonation goes. The factory advertised 10:1 in the 4bbl / HP motors but in reality they were closer to 9.5-9.7:1 from what I have read. Remember these were the days of the horsepower wars so they tended to fudge things a bit.
Please load up some pictures of the engine.
Here is a 383HP motor I found in a garage of a house I was drawing remodel plans for.
Someone added a factory 2x4 intake on this one but I am going with a Mancini 6 pack because dual 4's are so much fun to tune.
View attachment 1154963
View attachment 1154964

 

[Bigtime]

I'll know more after I "see" inside the cylinder with my 'scope which, BTW, just arrived today. I have a correct alternator bracket assembly coming to replace the "homegrown" assembly on it now [although it does work fine, I'm just ****], so when the bracket assembly arrives I will remove the alternator and completely sand down the pad. Also, I have a low deck dual-quad Offy intake and a pair of 500 CFM Edelbrocks. I found photos here on B Bodies of a really trick "tuner" that someone made from a carb hat & will perhaps give that whole thing a try later.....but...one project at a time.