A friend of mine has a 68 and is trying to find out wether the 327 engine the car had from the factory is 300 or 350hp. The 68s didn't have the engine label on the console but isn't there a difference in redline on the tach? His tach has the redline at 5700. Any other telltale differences? Even though it is not numbers matching, he wants to put a correct block in there when he redoes the car. Thanks for the replies! :cheers:


[Modified by Marks69BB, 8:58 AM 3/12/2002]

 

Mark, I can't find what the tach redline should be for the base and/or L46,but if he's sure it was a small block, then the engine block casting number for both 300 and 350 horsepower 327 in 68 is the same, 3914678. There is also unverified reports of 3914660 in early cars. I would go with the first number; it'll make life easier for him.

If your friend is going so far as to try and get the correct casting number, he may as well raise the bar a little higher, and try to find a "correct" casting date that precedes the car build date by no less than three weeks to no more than six months. That would be even MORE correct.

He may want to find some "correct" heads as well, since there is quite a difference in compression ratio between the base (10:1) and the L46 (11:1) :D . For the 300hp engine, the head was casting number 3917291, and for the L46 (350hp) the head was casting number 3917292. The casting number and casting date are covered by the valve cover, however, and are not visible to the whole world without removing the cover. The heads will need to have the appropriate "casting marks" on the end of the head for the year and horsepower of the car.

Oh yeah, and don't forget the intake manifold. It is cast iron and the same casting number for both small blocks...casting number 3919803. Same comments on the date as above for the engine block, since both cast numbers are right on top of the manifold in plain view.


[Modified by Chuck Sangerhausen, 8:34 AM 3/12/2002]


[Modified by Chuck Sangerhausen, 8:36 AM 3/12/2002]

 

Thanks Chuck; as usual, great info! I'll pass this along to him. He's not trying to join the 'Proteam Cloneheads', he just wants to get the car as close to original as he can for a NOM car. Anyone else know about the tach redlines?

 

Check the redline again; 300 HP engines typically had a yellow zone from 5000 to 5300, with the red zone beginning at 5300.

350 HP engines typically have yellow zones from 5800 to 6000 with the red zone beginning at 6000.

Duke

 

The redline on my 68/L79/327/350hp starts at 6000. The tach also uses a screw in cable at both the distributor and tach housing. The 327/300hp redline should start at 5300 rpm. The 427/390hp at 5600. The 427/400hp at
5600.


[Modified by 68rdstr, 2:35 PM 3/12/2002]

 

Doesn't sound like his tach matches any of the engine options. The yellow zone on the L79 start at 5700 or 5800 (can't remember which), perhaps he's confusing the yellow/red lines? If he has an M21/3.70 rear or higher (trans would have the s/n derivative on the case) with a "B" (A=M20, B=M21) he would more than likely have had an original 350hp motor as the M21 was the more common trans. choice. If an automatic, definitely the 300hp motor as this was not available with the high horse small block.