Looking to Re-Build Gen IV 454

[Ramjetfish]

I have a 1990 Howard 21' River Cruiser that has the original motor in it, has not been re-built. Currently it is sitting at 632 hours. I'm debating having the motor re-built, although it runs great. I'm hoping I can keep the longevity of the engine as I plan on keeping this boat forever, it's a family heirloom. My question is about adding power on the Gen IV block. I have heard they can take it and have also heard they can't. Would it be better for me to look into a Gen V/VI block or keep the Gen IV block and use better internals. I'm not looking at making extreme power. Looking to make anywhere between 450-500HP. Want to keep the carbureted setup and use IMCO Thumper Power exhaust manifolds. There is a lot of knowledge in these groups and would like to learn as much as possible from all of you. Thanks for all of the input.

 

[Shlbyntro]

gen4s can definitely take the power, but before rebuilding it or adding power, Id have a leak down done on the engine before your rip apart something that has been dependable for you all these years

 

[Your ad here]

What 454 do you have? The 1990 21' Howard I had had the high horsepower 454 so it had 7/16 studs and some other things I guess that help with performance mods.

 

[Ramjetfish]

What 454 do you have? The 1990 21' Howard I had had the high horsepower 454 so it had 7/16 studs and some other things I guess that help with performance mods.

I don't know off the top of my head. Probably need to get the SN off of the engine and the drive to really tell.

 

[rivermobster]

Confucius say...

'If it ain't broke, don't fix it'

Really nice looking boat.

Maybe get another engine and start slowly building it up on your own? Then just swap em out when the time comes. This way you avoid any downtime. Things seem to take a LOT longer than they should these days.

 

[obnoxious001]

Maybe get another engine and start slowly building it up on your own? Then just swap em out when the time comes. This way you avoid any downtime. Things seem to take a LOT longer than they should these days.

Good advice, or do it over the winter. Still takes more time than usual to get machine work, pistons, balancing and camshafts. Most of the other stuff is not so bad anymore.

 

[Ramjetfish]

Good advice, or do it over the winter. Still takes more time than usual to get machine work, pistons, balancing and camshafts. Most of the other stuff is not so bad anymore.

Barry, I have read a lot about your builds and your quality and detail you put into your engines. Is this a build you would be interested in even though it isn't a high horsepower motor. I could get you a short block or just a block all together. Really looking for a mild 454 around 450HP-500HP. Would DM you but since I am new I don't have that luxury yet. Thanks.

 

[obnoxious001]

I have a 1990 Howard 21' River Cruiser that has the original motor in it, has not been re-built. Currently it is sitting at 632 hours. I'm debating having the motor re-built, although it runs great. I'm hoping I can keep the longevity of the engine as I plan on keeping this boat forever, it's a family heirloom. My question is about adding power on the Gen IV block. I have heard they can take it and have also heard they can't. Would it be better for me to look into a Gen V/VI block or keep the Gen IV block and use better internals. I'm not looking at making extreme power. Looking to make anywhere between 450-500HP. Want to keep the carbureted setup and use IMCO Thumper Power exhaust manifolds. There is a lot of knowledge in these groups and would like to learn as much as possible from all of you. Thanks for all of the input.

There are a lot of very good reasons to stick with a MK IV block. They've always been plenty strong enough for blown and turbo builds, and 500 hp is what I would consider pretty mild by today's standards. I am currently building a 489 cubic inch MK IV block for a jet boat with a reliable 700 horsepower in mind.

If you went to one of the newer Gen 5/6 blocks, you would need a different oil pan and timing cover. The greatest percentage of Gen 5/6 blocks have no provision for a mechanical fuel pump, so that would mean switching over to an electric pump, unless you already have one. There are a number of other variables.

Your intake and carburetor and exhaust will all work with any of the 454/502 based blocks, as they depend only on the cylinder heads, which can be interchanged providing that the correct head gaskets are used.

I am happy to answer and other questions you have about them, good chance I know the correct answer.

 

[obnoxious001]

Barry, I have read a lot about your builds and your quality and detail you put into your engines. Is this a build you would be interested in even though it isn't a high horsepower motor. I could get you a short block or just a block all together. Really looking for a mild 454 around 450HP-500HP. Would DM you but since I am new I don't have that luxury yet. Thanks.

Obviously to you, I sent you a DM and phone number so we could discuss, but for the others I did talk to Matt and told him I would put something together for him if he is interested.