Buick Fuel Pump Modification
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This page is to house some pictures of the modification needed to a mechanical fuel pump on a Buick 455 to be able to run a double roller timing chain and not have interference problems. This information also applies to the 400 and 430 Buick engines. It may also apply to the 350 and other similar Buick engines.

The problem is that the fuel pump arm is reasonably close to the stock timing chain and the added width of a typical aftermarket double roller timing chain causes an interference problem - the chain and gear rub on the side of the fuel pump arm. Since the double roller timing chain is such a smart and common upgrade any time you have the front cover off the engine, this is something you'll want to pay attention to.

 

Solution #1 - Fuel Pump Arm Modification

The photos below show the original fuel pump that I re-installed onto my 1970 Buick 455 after replacing the timing chain. The section of the arm that needs modification is circled in each picture below - it's right where the arm bends towards the front of the block when the pump is installed. This area needs to be bent inward or ground down about 1/8" or so to provide the needed clearance. I just mounted the entire thing in a vice and gave it a few good whacks with a hammer and the appropriate punches to focus the force where I wanted the arm to bend. The overall effect was the make the "U" shaped arm bend together more on the bottom/open side. It's barely perceptible until you compare it to a non-modified pump up close, but I wasn't smart enough to take a picture of the new non-modified pump before I started hammering at it.

NOTE: If anyone has any better photos or descriptions of this mod - including before and after pics - I'd appreciate it if you could send them to me so I could post them here. I'll happily give full credit for the pics and details you provide.

Buick455FuelPumpArmMod1.jpg (141471 bytes) Buick455FuelPumpArmMod2.jpg (119093 bytes)

 

Solution #2 - Fuel Pump Mounting Modification

Another "courtesy of Jim Burek" idea. It was new to me, and it falls into the "well, duh - that's obvious and easy" category once you understand it. Thanks, Jim!

Basically, the fuel pump arm needs to move forward inside the front cover to clear the wider double roller timing chain set. You can grind and file at the pump arm, but Jim gave me a better idea - slot the mounting holes in the pump so you can slide it forward about 1/8" from where it normally sits. This will give the required clearance. To make the installation easier, Jim suggests drilling and tapping a small hole for a small set screw in the side of the mounting pad on the fuel pump. The set screw is used to ensure the bolt can only be in the newly elongated part of the mounting holes - you just tighten it down enough to allow the bolt to fit through in the proper plan when you have the pump off the engine, and you can't go wrong installing the bolt pump later on.


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Page last updated 01/02/2009 01:51:39 PM