Thread:

BBC build..What works best?

Heres a question to anyone with some knowledge, I am trying to put a solid motor together, I have a gen 4 block with 781 heads with some porting and seat work, comp cams RR, the cam I have is 224in 230ex @050 .456 .461 on 114 lobe sep. not sure about the cam but machine shop said it works for my set up?? I am running log exhaust, 12jc "A" 19' boat. Where should I go from here for the best reliability, power, etc. I have not yet got an intake or carb, and I still have all the stock pistons, rods and cast crank but was thinking about going to all forged rotating assembly? Any info is appreciated! I had a falling out with the machine shop and I got all my stuff back in boxes!!

Nothing??

I am not an expert but a steel crank,forged pistons,and better rods,(Scat or Eagle)would be the way to go -that cast crank and your pistons is maybe a one season deal but thats just from my past experience and like I said I am not an expert.

Thats what I was thinking...build it solid the 1st time and no worries after that. I'm running logs so what should my max rpm be around? I was thinking 5000-5500 should a cast crank with forged rods and pistons work ok? Or just go all forged and never worry about it again? Forged is expensive...lol

Originally Posted by HawaiianPunch

Thats what I was thinking...build it solid the 1st time and no worries after that. I'm running logs so what should my max rpm be around? I was thinking 5000-5500 should a cast crank with forged rods and pistons work ok? Or just go all forged and never worry about it again? Forged is expensive...lol

You need to build an engine to suit your own set of parameters. You haven't stated what type of boat, or how you intend to use it.

Just remember that you run an engine in a boat much harder than an engine in a street vehicle. My pickup cruises at 80 mph on the freeway turning about 2500 RPM.

The logs don't necessarily limit your rpm,, it's more the setup of the boat and how you load the engine, I.E. prop or impeller size.

X2 on previous response. You really have to be sure what you want to do with your boat. Is it going to be used as a dependable cruiser? 2 bolt of 4 bolt main block? Do you have "Dot" rods with 3/8 or 7/16 inch bolts? The good news is if you keep the Rpm down the stock rotating assembly will live. I would use forged pistons and upgrade the rod bolts in any case. Pay a shop to do thorough inspection of the rods themselves. The bad news is sooner or later everyone wants to go just a few Mph faster. So you start upgrading the top end and forget you did not put a foundation in your engine to handle the new demands of the higher Hp. When things break on the bottom end, it gets very expensive. Intakes, can either be a dual plane or single plane. Righ now a dual plane will work better but again if you get the Hp disease, you will want a single plane later. So you may want to give up some of the lower Rpm response of the dual plane and just buy a single plane intake. Carbs are the same deal. A good 750 Cfm vacume secondary carb will work fine. Sooner or later you will hear all of the go fast guys are running 950Cfm and bigger with mechanical secondaries so you may just start with an 850 Cfm mechanical secondary carb up front. Will pay more for fuel but not have to buy another carb later. You can have a lot of fun with a stock boat, the faster you want to go, the more expensive it gets.

Suburban short block 454
Tunnel Ram
990 heads

Originally Posted by NORDIC454

Suburban short block 454
Tunnel Ram
990 heads

roflmao, perfect response. see ol' QJ is a learnen som of dem peeps out dar. You just keep pound'n that drum, it'll catch on.