Identify Engine Help - SR84476

Casey Hill

Asked by Sep 14, 2016 at 11:03 PM about the Pontiac Firebird

Question type: Shopping & Pricing

I am trying to identify the engine Horsepower/Torque of my newly acquired
1968 Firebird. Here is the information I have so far. 1. Has 3 Freeze plugs 2.
Has 350 casting 3. Has Service Replacement stamp of SR84476 4. Has
Transfer Lug by Distributor.

I can't get access to any date code without pulling parts off the car, so I
wanted to see if anyone can help me identify more information on my Bird.


5 Answers


67-68 were transition years for GM V-8's. 326 to 350, 389 to 400. No other options unless you are running one of two in-line 6's. By your hood vent it is tagged as a 400 CID engine. However, previous owners could have changed the hood tag or the engine in the car is not the original. Sorry I could not assist anymore than this. Very nice 68 though!

Casey Hill

Thanks Taver91.... yes, that car has been badged incorrectly by either the seller or the owner prior to that. The engine is a Service Replacement (see stamped number) and it is a 350. BUT there is a huge difference between a 1976 350 and a 1968 350 by about 150 horsepower! This is why I am looking for information on SR engines. How can you figure out how much HP and Torque I have without getting an expensive dyno or trying to find a date code that may or may not be on the block.


If it SETS you Slam Stuck in your seat its an Older Mobetta Motor " and if yet just Spinnin 1 wheels yet F+#:#"d


With so many variants of the 350 block out there, it will be almost impossible to determine what someone dropped into your car at some point in its life. Getting that info from a previous owner would be one way but without that, the dyno will be the best way to see what power you are generating. There are data codes on the rear side of the block though and maybe someone who knows their exact location could get to the stamping without pulling the engine. Good luck.

Casey Hill

Taver91, I guess I am looking for someone who knows how to identify the casting numbers on a Service Replacement block though. Yes, there are multitudes of original Pontiac 350's but there are a limited number of SR engines, because they were just warranty replacements. That stamping should tell me something about the block, so are there any Pontiac experts on here that might know how to decode the SR numbers? Casey

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