bck

I need some advice on whether to rebuild or replace my engines. The old engines were running when removed so I don't anticipate any rebuild problems (hopefully). What I have is block# 10051107. From what I have found out this is a 454 MkIV Bowtie with 9.8 inch deck height and siamesed bores. Anyone have any different info? It seems to have a standard GM dual plane high rise intake #3933163. The carb is a 830cfm Holley double pumper w/ mech secondaries #9381. It has t-bolt distributer with Crane Hi-6m box. The rockers are gold colored Crane roller tip. It appears to have stock exhaust manifolds with stainless elbow/risers added. I would like to get as much reliable HP as possible. I would like to keep a budget of 5k per engine, maybe I'd go a little higher if it made a big difference. I'm hoping for 500hp minium. If I didn't rebuild these engines I would be considering crate engines from Runs New as they seem to be close to my budget and I haven't read of anyone having problems with them.

Reed Jensen

Some engine builders prefer "seasoned" blocks.... Where the molecules in the block have settled into place... then they blue-print the engine during the rebuild... I'd suggest that if the engines were running when removed... you just rebuild them and maybe do some simple upgrades like a different cam and exhaust.That is the least expensive thing you can do... I had crate engines arrive from Chevrolet and disassembled them and found some minor casting flaws.So going with new isn't always the best thing to do... if you have been running the engines in salt water... better look closely at the core areas to make sure they haven't gotten too thin.

bck

The engines haven't been in salt water and appear to have stock GM rectangle port heads. Most of the people I have talked to locally have said to rebuild these rather than go with lower priced crate motors.

Reed Jensen

Crate motors are lower priced?.... have you ever seen how some of these are assembled? I once got a crate motor that had the wrong size main bearings installed... I'd just have your existing engines rebuilt by a reputable engine builder... not just some assembly line rebuilder. Then you know exactly what parts went into it and there is a lot more attention to detail that way.

birdog

If you go the new engine route......I would be interested in your tired Bowties

bck

I meant lower priced crate motors as opposed to higher priced crate motors. I am probably going to rebuild mine, it's just hard to resist the low prices on some of the crate motors out there.

Infomaniac

I would keep the Bowtie stuff and make 496's out of them.

Zero deck the new pistons - good cam - good exhaust and be happy. Carb is OK.

More Money options:
Different manifold is a plus and new heads would really be a big help.

bck

What sort of reliable/worry free hp are these engines capable of. I believe that because they are bowtie blocks they should be able to tolerate a larger bore than a regular 454, correct?

cuda

The gold rockers make me think they may have been originally Merc 420's, which have a lot of good parts. They were the hot stock engine before the Hp500's.

bck

I've tried to put together the history on the engines and initially I thought they were the original Innovation Marine/Kaama engines that came with the boat. I think more likely all the reusable parts were put onto these blocks after a failure of the original motors.