[chuck lombardi]

I have a 1966 Chevelle SS 396/375 Aztec Bronze, Aztec Bronze bench, which I race in the Pure Stock Muscle Car Drag Race (PSMCDR) and other stock tire/no mods muscle car races. I built another complete engine/trans combo within the rule limitations of the PSMCDR.The original engine/trans/posi/ring&pinion/driveshaft/distributor have been removed. The current engine is a early 1967 L78 block/heads built to rule limitations.The block/heads/intake are from a NHRA 1966 Chevelle stocker campaigned out of Long Island during the 1970'-90's. The car has a close ratio trans, and 4.56 rear.

My goal is to set the [FONT=Georgia, Times New Roman, Times, Serif]PSMCDR record for the 66/67 Chevelle with L78 engine. The car has the original idler pulley system and a two groove crank & water pump pulley.

Does anyone know what the correct L78 crank pulley diameter is?
Are than any larger diameter two groove pulleys?

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[yodersclassic]

Chuck the crank pulley is 6 and 11/16 in dia. outside to outside. What is the record?? I have a 67 L78 that ran at New England Dragway back in the day and was .0001 off the national record at that time. It was running in C and D class.

 

[jeffschevelle]

All 66 L78's came with 3-groove cast iron crank pulleys. The third (forward-most) groove was for the PS belt if the car had PS. But for whatever reason, even the non-PS cars got the 3-groove pulley, and the 3rd groove was unused on the non-PS cars.

I don't know the diameter off the top of my head, but it is the same as all other 65-67 Chevelle/Impala big block crank pullies, except for 67 TH400 cars. 67 TH400 cars received a larger diameter crank pulley for the fan belt and (if so equipped) AC belt. So you could use a crank pulley from a 67 396 with TH400 and air conditioning to get a larger diameter 2-groove pulley. However, that would not be a deep groove pulley, and would be much more prone to throw the belts off.

Also, don't you want a SMALLER crank pulley? If you are turning high-revs, a smaller crank pulley will turn the belts slower, and thereby slow down your water pump and alternator, and put a little less drag on the crankshaft. At least I think that's right, isn't it?

 

[chuck lombardi]

Thank you for the info. I was aware that all came with the three groove, but I did not want to take it off the original engine. I have a two groove on there now, but do not know the origin.
Yes, a smaller crank pulley will slow everything driven down. I am going to measure both of mine tomorrow night. My garage is about 20 miles from home/work. So I was trying to get as much info before tomorrow night.

I had the PSMCDR record for an A body L 78 at 12.33 @ 113, but we did not certify that engine. The cam would not pass tech. The new, rule abiding engine has run a best of 12.69 @109.8 with a 4.30 gear. It needs the 4.56....
That change is in the process now.
I will update with an progress or lack of.

See the action shot.

 

[yodersclassic]

Thanks for the information this car was running 11.84 in C stock.

 

[chuck lombardi]

Chuck the crank pulley is 6 and 11/16 in dia. outside to outside. What is the record?? I have a 67 L78 that ran at New England Dragway back in the day and was .0001 off the national record at that time. It was running in C and D class.

The current engine is a L78 block/heads built to rule limitations. It made 489 hp at 6200 rpm with stock exhaust manifolds and air cleaner. The rules allow up to 1.5 comp over stock, we are just under at 12.3 to 1, balance/blueprint, cam specs have to measure stock at .050 valve lift, no more than 130lbs of valve spring pressure, stock carb, intake, no ignition boxes (we use Pertronix), etc... The car has a close ratio trans, changing to 4.56 rear, Centerforce II clutch, Long shifter, one size up to a F70 tire is allowed, full 2.5 inch exhaust w/X pipe and non chambered style mufflers (no flowmasters or the like). The block/heads/intake are from a NHRA 1966 Chevelle stocker campaigned out of Long Island during the 1970'-90's owned by Tom Baird (not sure of the last name spelling). My father had the same car with bucket seat black interior bought new in 1966. He and I are having a great time. It is like a car show that goes.

 

[chuck lombardi]

That is a great photo. I will ask my father if he remembers seeing it run there or at Connecticut Dragway.