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FE Power Forums => FE Technical Forum => Topic started by: jholmes217 on September 09, 2017, 05:08:34 PM

Title: what needs done to 391 FT block to replace a 428 car block?
Post by: jholmes217 on September 09, 2017, 05:08:34 PM
Besides a bushing for the distributor, is there anything else that needs done to this block to run it in the place of an FE?  My 428 CJ in my 1969 Mach 1 was already bored .060 when I bought the car.  There is a 391 FT short block for sale close to me for $150.  I don't know if it has "428" in the water jackets or "C" scratch on the back.  I plan to just use the block, not the rest of the FT rotating assembly.
Title: Re: 391 FT block
Post by: thatdarncat on September 09, 2017, 05:42:03 PM
FT blocks usually have an oil return hole on the bottom side near the oil pan rail that was for the air compressor. It can just be plugged with a pipe plug.
Title: Re: 391 FT block
Post by: jholmes217 on September 09, 2017, 09:24:49 PM
FT blocks usually have an oil return hole on the bottom side near the oil pan rail that was for the air compressor. It can just be plugged with a pipe plug.

Thanks. 
Title: Re: what needs done to 391 FT block to replace a 428 car block?
Post by: Lowrider on September 11, 2017, 07:19:30 AM
Not a 428, but I used a FT block to repair a 406. I found the deck height with the FT left the pistons waaay more in the hole than I wanted. I think I had 0.015-0.020 taken off the deck and the pistons ended up where factory 406/427's in a FE block sat. Don't recall what the spec was.
Title: Re: what needs done to 391 FT block to replace a 428 car block?
Post by: BH107 on September 11, 2017, 09:07:01 AM
Not a 428, but I used a FT block to repair a 406. I found the deck height with the FT left the pistons waaay more in the hole than I wanted. I think I had 0.015-0.020 taken off the deck and the pistons ended up where factory 406/427's in a FE block sat. Don't recall what the spec was.

Not sure about your combo, but 406 pistons were way down in the hole from the factory. All FE/FT blocks have the same deck height.
Title: Re: what needs done to 391 FT block to replace a 428 car block?
Post by: BH107 on September 11, 2017, 09:07:45 AM
It's a gamble, and definitely have it sonic tested first. Not many will go to 4.13 bore without being thin.
Title: Re: what needs done to 391 FT block to replace a 428 car block?
Post by: Lowrider on September 12, 2017, 06:46:01 AM
Found the specs over on mercurystuff.com. 406 was .045-.065 IIRC that's what I measured before tear down. After taking .015/.020 off I got to the lower spec or just a few thousand more. This FT block must have had a hard life as it had a twist to it. End result is it runs fine, doesn't spark knock or overheat here in the Az. desert.