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-   -   Bbc 454 gen 4 overhaul (https://www.offshoreonly.com/forums/do-yourself-boating-budget/368920-bbc-454-gen-4-overhaul.html)

Griff 10-14-2020 01:00 AM

The stock heads with some minor porting and milling them .020-.030 for a slight bump in CR will be fine to get you to 450+hp. The same heads are used on the HP500, 500efi and 525sc.

Baja 250es 10-23-2020 07:58 PM

Leak down specs
 
What is good and what is bad for my gen 4 454 for % results @ 90 psi of shop air on a cold engine engine is on stand and I am testing each cylinder i know it's supposed to be warm but its out of boat lol any hope

Smitty275 10-24-2020 11:47 AM


Originally Posted by Baja 250es (Post 4762949)
What is good and what is bad for my gen 4 454 for % results @ 90 psi of shop air on a cold engine engine is on stand and I am testing each cylinder i know it's supposed to be warm but its out of boat lol any hope

Your wasting your time doing it on a cold engine. Pistons are several thousandths smaller, ring gaps bigger, bore shape is slightly different. Just not a comparable situation.
I had a customer changing valve springs on a cold motor and was worried because so much was hissing by the piston and compressor runner Ng alot. When he was done we fired it and warmed to normal temp. No more hissing past the piston.

Baja 250es 10-24-2020 05:11 PM

Build
 
So since engine is out already if bores look good and engine wasn't using oil keep bottom end together v other than reseal everything and freshen up top end

Griff 10-25-2020 01:45 AM


Originally Posted by Baja 250es (Post 4763023)
So since engine is out already if bores look good and engine wasn't using oil keep bottom end together v other than reseal everything and freshen up top end

That is what I would do.

Baja 250es 10-25-2020 08:55 AM

Build
 
Ok Griff thank u ill get apart build top end and check bottom now ill throw a curve ball what if I decided to bolt on a complete weiand blower setup that's set at 5psi would u still install the cam that u recommended and or would u change up bottom end then

Griff 10-25-2020 12:27 PM

The same cam will work great with a 177. I upgraded to it on my 525SC which is a 454 with a 177 and 1050 carb.

Baja 250es 10-25-2020 01:25 PM

Build
 
That's awesome I guess I may go that route I found a deal on a a complete setup for my engine i really don't want to pass it up

ThisIsLivin 10-26-2020 10:53 AM

Biggest problem with adding a blower is will it fit under your hatch. I wanted to add one when I did my rebuild and there was no way I could get it under the hatch.

NC03GT 10-26-2020 11:30 AM

subbed! was looking for similar info when i go to pull my 454mag from my donzi! is your set up already carb or efi? my set up is a 2000 efi and still up in the air if i should drop the efi and go carb.


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