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Engine ID help.

53street

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I inherited a 53 f100 with a pontiac engine. It was claimed to be a 400 out of a trans am. The code on the front shows YN and has 595396 stamped above it. It looks like the YN is associated with the 326s I can’t find any other markings on the block. Help please!
 

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melsg5

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The C116 is March 11 1966 it's a 326
9778840 casting number, last year 66.
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53street

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Thanks! I’m thinking a summit 2800 cam, 4 barrel carb and headers. Any opinions?
 

92 Sunbird LE

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1965 - 1967 326 CID with 2 Barrel Carb Engine Code - WP,ZN(1965) - WP,WX,YN,XF(1966) - WP,WX,WC,WH,YO,YN,XF,YJ,XI (1967)
Max Brake Horsepower: 250 @ 4600 rpm
Max Torque: 333 @ 2800 rpm
Stroke: 3.750
Bore: 3.71875
Compression: 9.2
Firing Order: 18436572

4 bbl 326 had 285 HP 10.2 compression..

Doug in P.R.😎
 

92 Sunbird LE

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Butler Performance recommends only the 389 cam below:

Melling SPC-5 ( RockAuto , AutoZone, etc)
Description: OE stock replacement grind

Intake duration: 272°
Exhaust duration: 280°
Intake lift: .407
Exhaust lift: .411
LSA: 112
Overlap: I believe would be 52°

This being due to the pressed in rocker studs, anything bigger would require pinned or screwed in studs with springs . It's a 389 cid cam, both 2 and 4 bbl 326 engines used the same cam which is smaller than the 389 cam.

They also recommend a 500 CFM 4 bbl carb.

Doug in P.R.😎
 

cammerjeff

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I agree with Doug and Butler performance. Anything larger and you will be pulling the rocker studs out of the heads. Plus those heads use pretty small (for Pontiac) 1.88/1.60 valves so they will restrict a larger cam anyway. But it is a 65 or later engine so the good news is most aftermarket Pontiac engine parts will bolt on.
A cam and 4bbl intake and carb will help. I would skip the headers for now, but run a good exhaust system. The small HP gain on a street car with headers to me is not worth the hassle of installation, assuming you can find a set off off the shelf headers that fit your chassis? Not a common swap.

Post some pictures when you get a chance. I am interested in how the engine fits in there!
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53street

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I agree with Doug and Butler performance. Anything larger and you will be pulling the rocker studs out of the heads. Plus those heads use pretty small (for Pontiac) 1.88/1.60 valves so they will restrict a larger cam anyway. But it is a 65 or later engine so the good news is most aftermarket Pontiac engine parts will bolt on.
A cam and 4bbl intake and carb will help. I would skip the headers for now, but run a good exhaust system. The small HP gain on a street car with headers to me is not worth the hassle of installation, assuming you can find a set off off the shelf headers that fit your chassis? Not a common swap.

Post some pictures when you get a chance. I am interested in how the engine fits in there!
Thanks for the help guys! Here’s it currently sitting in there with the clutch fan pulled off. This trucks been in the shed since 94.
 

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melsg5

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You mean the water pump has been removed
 

92 Sunbird LE

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Check out that wiring on the firewall........🙄 I would change the distributor to 1974 + factory HEI for ease of maintenance.....

Doug in P.R.😎
 

53street

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92 Sunbird LE

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Factory HEI for parts availability, aftermarket not so much if you need to replace something, Factory HEI with a Accel brass terminal cap and rotor , Accel coil, Accel module and advance curve kit, pretty much bulletproof to any rpm.

Used Distributor: GM stamped module is the best, auto parts store over the counter modules don't last that long.

Doug in P.R.😎
 
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