496 Build Up Questions

Ok, I've decided to build my own marine engine. I've built my own race engines successfully, I'm going to tackle my boat engine. I've purchased a used 454 Gen V, same as my '93 7.4L/Bravo 1. I'm going to bore it .060" and buy an eagle or scat stroker kit. Here's my question, aside from clearancing issues which I will work out, is that I like to balance/or have my engines balanced. The 454 is an externally balanced engine with counterweights on the flywheel / harmonic balancer. Should I buy an already internally balanced kit and use a 427 flywheel/harmonic balancer or go ahead and just take the whole assembly, the crank, pistons, rods, flywheel and balancer to the machine shop and have them externally balanced? Any takers on this? I personally think internal balancing is better.

Re: 496 Build Up Questions

NautiNights said:

Ok, I've decided to build my own marine engine. I've built my own race engines successfully, I'm going to tackle my boat engine. I've purchased a used 454 Gen V, same as my '93 7.4L/Bravo 1. I'm going to bore it .060" and buy an eagle or scat stroker kit. Here's my question, aside from clearancing issues which I will work out, is that I like to balance/or have my engines balanced. The 454 is an externally balanced engine with counterweights on the flywheel / harmonic balancer. Should I buy an already internally balanced kit and use a 427 flywheel/harmonic balancer or go ahead and just take the whole assembly, the crank, pistons, rods, flywheel and balancer to the machine shop and have them externally balanced? Any takers on this? I personally think internal balancing is better.

Click to expand...

Ayuh,.... To what degree will each vendor balance to,..?? plus or minus how much,..??

Where's yer Trust,..?? With the local Machine Shop, or the mail order parts house,..??

Re: 496 Build Up Questions

Bond-o said:

Ayuh,.... To what degree will each vendor balance to,..?? plus or minus how much,..??

Where's yer Trust,..?? With the local Machine Shop, or the mail order parts house,..??

Click to expand...

Yeah. I would pretty much ALWAYS have a local machine shop balance the rotating "mess" (mass) internally by HAND.

Also, be vewy vewy careful with compression ratio and cam selection. get the compression ratios too high and you'll have a detonation event on your first full throttle run that turns that rotating mass into junk!

Re: 496 Build Up Questions

I tend to agree with both of you on the balancing. I suppose I'll just get the whole assembly balanced at the shop. As for compression ratios, no more than 8.6:1 and plan on using the comp. cams XM264M hydraulic. I do have both underwater exhaust and open above the water line but with that cam I don't expect any reversion issues. I'm only using 3cc domes with 119cc heads. It calculates to the 8.6:1. I'm just using the standard peanut port heads with new springs, valves and a good roller tip roller. You don't need rectangular port heads unless your exceeding 5500 RPM's which I won't be. I just want a good, strong engine with good torque. Or at least a little better than my current 7.4L which isn't bad.

Re: 496 Build Up Questions

I have a stock 454 and I'm using 3" riser extensions.

If in doubt, use as much extension as possible to help prevent either reversion or accidental "wash-back" etc...