# 325 Hp with tri power on top



## Mr.409 (Apr 22, 2017)

Hi Friends
today i do check my engine code, the code is YX 4 this means a 1967 400 Ci 325 HP engine in my 66 GTO

The GTO has a Tri Power carburetor on the Engine, and how much can I count on the 325 HP with the tri power on top
Roundabout 348 HP, is this right?

How much Gas takes takes the 400 Ci with a Tri Power, according to my calculations 9 mpg, is this to much, or what do you think

Thanks for input
Carsten


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## PontiacJim (Dec 29, 2012)

I found block code YX as a 1966 - 389 325HP engine used in the full size cars and the 1967 400 325HP in full size cars. Further ID can be found by using casting numbers by the distributor hole, the head casting numbers, 2 freeze plugs on the side of the block verses 3 freeze plugs for 1967 and later. Pontiac Engine Codes

Either 325HP engine shows using the "066" cam, Intake Duration 273 Exhaust Duration 282 with 55 degrees overlap. The 3 x 2 engine used the "068" cam, Intake Duration 288 Exhaust Duration 302 with 63 degrees of overlap. Both cams have a .406" lift.

My opinion is that you might add another 15-20HP with the 3 x 2 IF the engine is using the "066" cam and it has not already been changed to a better/bigger cam.

My opinion is that you should get 16 MPG or slightly better on the highway at steady speeds on just the center carb and IF you have the "066" cam, highway gearing, and the engine is in good tune. Less MPG driving around town in stop/go conditions and less when you open up the 3 x 2. If you have a bigger cam, then gas mileage will indeed drop way down.


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## Mr.409 (Apr 22, 2017)

thats the casting number i have found, is this engine manufactured in 1966, right, there is only the 6 under the casting number


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## Mr.409 (Apr 22, 2017)

What does this number mean i have found under the passenger side valve cover


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## PontiacJim (Dec 29, 2012)

Hard to tell. On the head, that casting date E=May, 22nd, and 6? = 1966. The head part number, not the date, will be found cast under the valve cover and as I recall is cast on the upper left.

The block is not quite as clear, but I do believe the "6" is for 1966. The K=November, 03=third day. November would most likely be too late for a '66 engine and typically after August puts the engine into the next year model, or 1967 and that would make it a 400CI. So is could be November 1965 when the block was cast in order for it to be a 1966 engine. Again, 2 freeze plugs on the side of the block will confirm 1966 engine. That last number could be a "7" that is badly cast and it could be a November engine used in the 1967 body.

So still have not nailed it down yet. Head part number will clearly ID the head. Freeze plugs will ID the block better. You could have a mix of heads/engine block or a late 1965 cast block used for the 1966 production run in the full size car line. So more info needed.


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