toolsinbox

I am planning to build a bbc roller. I have never built a roller engine and never built a bb either. Lots of small blocks tho. I want a reliable good idler, with as much hp as can be achieved without sucking in water and I want to keep it reliable. Maybe even mpi. Where I am confused is with the various block generation type. I have great access to truck 454s but they are all flat tappet. Do I need a spicific block type to achieve my goals ? Is there a thread that speaks to cam, rod length, push rod length, and the likes ? Another question I have is how I know if a crank is internally balanced ? And if it is which balancer do I use ? Is internally balanced better ?
I guess I am after a parts list using forged stuff, and would like to get aluminium heads fully set up for my needs. What I don't want is to get a block all machined up and find out it's not suited .

I appreciate the help.

Vinny P

There will be many views and opinions on this one. Here are some of mine. First off, there is alot to talk about on this subject and my typing skills are terrible. I will try to bring out a few brief points here. The difference between Mark IV and Gen V or Gen VI are extreme. Most parts from Mark IV wont work with Gen V or VI. What I think you need to do is set a horsepower goal before trying to build anything. What year or Gen are those 454 truck blocks you have access to? Depending on your h.p. goals, they may be a good starting point. Once you have that in mind, I would suggest a good place to get a cam, lifter, spring recommendation would be Bob Madera ( RM Builder ) right here on OSO. He can set you up correctly.
Your rod length will depend mainly on stroke and deck height. If your planning on using a stock GM 454 truck block, to the best of my knowledge, they are all 9.8" deck height. I beileve they all had 6.135" rods. Push rods lengths can only be determined after the heads and block are fully assembled. Dont just order a set of standard big block push rods. They may fit, but its just not worth the risk. You have to check for fit on your particular application.

tx911

Definately need more info on the blocks you have available. You can build a roller motor out of any generation big block, but the generation of the block will dictate how you get there. If they are 454 blocks and you have to buy cranks, rods, and pistons anyway then you mine as well stroke them to 496's, this is where your rod length will come into play. If you already have factory GM cranks they will likely be externally balanced, if you go aftermarket you can internally balance, but that will be something you need to discuss with your machinist. If you give more info on the blocks you have, like casting numbers or year truck they came out of, and your HP goals and budget you will get a lot of sound advice from poeple that do this for a living just because they like to help out.

1BIGJIM

iTrader: (1)

Most likely Mark IV engines.

toolsinbox

My hp goals are 400 to 450. I will get casting numbers and post them. I think fuel injection is somthing I would also like to try. Is there a block prefrence for that?
These blocks are complete except intakes so the cams and cranks are there. Are stock cranks good to that hp?
So Let me see if I can take a stab at the order of things.
1 Block and type
2 Cam, crank
3 Rod, pistons, rings
4 heads ( complete)
5 push rods, lifters
6 intake

Rookie

iTrader: (4)

If your goal is only 400-450 I would just build a flat tappet Merc 420 clone. Maybe cheaper to find a used 420 and refresh.

If you were looking for more power 500HP then do the roller.

toolsinbox

thanks guys this is very helpfull to me to get a plan together.

They are all mark 4 except one is a gen 5 complete with injection. They all have less than 200,000 miles with the gen 5 having 70,000 miles.

What is a merc 420 ? What makes up a 420 ? What colour are the blocks ? How would I recognize one ?

With all things being the same will a roller last longer than a tappet ? How much hp gain from roller ?

I was under the impression that keeping it under 500 hp let me use any block. I am 99 % sure that the blocks I can get are all 2 bolt main caps.

The more hourse power the better I just don't want to step into a blower and /or super pricey internals. I have a fresh 454 in my boat right now with zero hours on it and I had it built. I expect it to push about 350 hp. I might get 65 mph out of that if I am lucky so I want somthing stronger in a 21 ft scarab.

I like the idea of freshening up an engine but my thinking is to lighten things up with alloy heads and once I do that I am most likely changing internals anyway. May as well go for all the hp I can. as far as a budget I really don't have one. The mark 4 blocks I can get are free and the 5 is 1200 and its running. Thinking about 2500 for internals and what ever the heads cost. I was quoted about 2 k for those.

getrdunn

iTrader: (7)

just a thought however if you stay with the mark 4 and cast heads it will be pretty easy to achieve your goal. years ago I started out with 454/330 with all cast internals and 3/8 rods- ARP rod bolts. the only thing i did was used a set of slightly ported dart oval ports (cast), bumped the comression to 9.5 to 1, edelbrock performer dual plane intake and holley 800 cfm. i do recall changing the pistons out to forged also. That was mostly to get the comp where i wanted to end up with, without decking the heads to much to achieve desired comp. ratio. i also used stock ignition. this was a very reliable package and made 485 hp. this was also with a hyd. flat tappet cam 502/465 hp cam. if i were to do the same type of build again i would consider going roller with something similar to the crane 731 cam - 139011. If I had to guess I would say you would probably gain another 20 to 25 hp going roller. i ran this set up extrememly hard yet sensably and never had any issues. optimum clearances and balancing to the key to survival.

The 420 Hps will be black in color and to my knowledge have the black finned valve covers as well. The will have all forged internals as well along with 4 bolt mains. In my opinion keeping your engine under or around the 500 hp mark you'll be fine with a cast crank and 3/8 rods if that's the way it works out for you. I've done it several times and no issues. I can't stress enough a good balance job regardless of what you do.

Hope this was of some help.

tx911

If your goal is 450hp you can do it easily and relatively cheap especially if you can get a free complete engine to start with. You can build a 2 bolt main, cast internal motor with 450hp and get it to live, especially at the rpms boats run, just stud the mains and build it right. Find some heads off craigslist or the swap shop here and use a roller valve train, and some good hypereutectic pistons and done. I think that is a realistic goal.

toolsinbox

This is just great. Thank so much. ok I have a brock duel plane intake currently on the rebuilt 454 with a 750 holley clone that has been shaved and tuned. ( not by me) I have and a marine msd ignition setup so I can swap thoes on the new project. Ok I am getting the feel for the parts I need. A few other questions.
I get the roller camshaft from edelbrock, as suggested, A roller valve train setup on heads, with forged pistons, and then take memeasurements for pushrods ? Is this correct?
What type of lifters are recomended ?
I know how to ballance the wieght for the con rods but I have no idea how to ballance a crank. Is this somthing the machine shop has to do?
How do you go about assesing what the future compression will be ? Can I give measurements and the like here in a thread and get feed back? That kind of stuff starts to get beyond me.