I have about 1000 miles on my 383 now and I'm looking to do a nitrous setup in the future. My engine was built the old school way with stock internals and such. Being a relatively fresh engine could I buy a rotating assembly and just install it myself with some carefull part selections or is it absolutely a must to have a machine shop do the rebuild? I'm looking at AFR210s, forged bottomend and a bigger cam. I already have a Team-G intake and a 68 327 block bored .030 over and the block was 0 decked. The engine runs perfect now but I can't validate the so-called headwork or pistons to go with a bigger cam. The heads are the iron 461s with unknown valve size. I already have a 3k and a 3.5k stall converter to play with and a beefed up rear end with a dragvette 6-link. The rest of the specs are in my sig. I can do the assembling myself as long as it's just a bolt together job. I've done cam and head swaps before and even disassembled the entire L-48 just to see what condition the parts were in, so I can do most of the work in my garage. I can do the honing and ring gap myself but was worried about the crank fittment in the block. Even with all new crank bearings would I need a machinist do the install or is it a drop in procedure?
This will be a limited use vehicle seeing only about 1500 miles a year between the street and the strip as it's registered as a historic. As this thread goes along I'll probably have more questions but I just wanted to do some research before buying the parts. I know the budget is a big factor so I will say that around $1200 for the rotating assembly, $1200 for complete heads, $250 for a cam kit and then just odds and ends like gaskets. So whatcha think?

 

Why are you going back into the engine for such major changes when you just rebuilt it? How much nitrous are you going to run, and how often? You may not need a forged bottom end.

 

Well, I didn't do the rebuild, I bought it from a friend of a friends friend that went bigblock. He said it was a fresh rebuild but when I got it home I took the pan off and it was a GM 400 crank, used rods, and a used cam. Plus now that I have it tuned it ain't producing what the seller advertised. I can't even get the dang thing to make power above 5500 rpm. Don't get me wrong, it's running a strong mid 12 seconds but I removed alot of weight and got a good rearend setup with the 6-link so it hooks. It's good for what it is but I wanted to start out with a 150 shot which would be okay for now but you know how that goes.....200......250....etc.

I'm one of those guys who if he sees a way to make it better and if it's in his ability, will do so. I can't help it. I'm not married, no current girlfriend, don't own a house and drive a company vehicle most of the time, so most of my money goes to the cause. I also used to race pro motocross and still have a passion for riding too, hence I have 2 CR500s and a CRF450 in the stable as well. I always wanted a car that would rev and be able to shift at 7000 rpm, and that's what this guy said this engine would be able to do. At the time I didn't know that much about a true setup and with the specs he threw at me I was convinced. I mean in his driveway was a 66 BB chevelle and in the garage was another project car. The guy seemed on the level and came refered by a good friend that has cars that run in the 9s.

 

If you are looking at a 7000 rpm nitrious feed motor you had better have a forged bottom end in it. The block has been machined so no need to really go back to the machine shop if it was done correctly! New bearings on a new crank you just need to mic everything up and make sure all your clearances are perfect. You will need a solid flat tappet or solid roller cam to turn those rpms also. Your head $$$ are a little low if you want AFR 210 heads. Always figure more tah nwhat you expected as little things come up. When you start building HP the costs go up very quickly. Putting it all together is the easy part. Getting everything correct and measured correctly is the tough part. If you take your time and do it right you should have a very strong motor.

 

Yeah the heads are in the low $2k range as well as the rotating assembly. I guess the longer rod version is better right, 6.00in rod? Like every other semi-street machine it has to be pump gas friendly too, so maybe 11.8:1 max. That's about -5cc pistons with a 64cc head right? There's gonna be a decent size cam in it to bleed off some pressure too. I got some time before rebuilding so I'll have time to check out all the past threads on the subject and see what everybody went through and settle on something in between.

 

I am running a 5.7 rod with 7/16s rod bolts in mine and have no worries about running to 7000 rpm. You will never be able to feel or even measure any HP gains with a 6 inch rod. If you were going to run at 7000 all day long the 6 inch rods might be needed. If you get a deal on the 6 inchers go ahead. I got a deal on the 5.7 rods so tha tis why I am running them.
The 11.8 comp ratio is going to be on the edge if not over the edge as far as pump gas friendly. I am running at 10.8 the best I can figure with a large solid flat tappet cam 252/260 @ .050. If I do not run 93 or better octane I have run into some problems. On 93 gas it runs fine but Ithink if you add another point to the compression you would be really pushing it.

 

My 383 build is over $6000 now. AFR heads, good forged bottom end, roller cam and machine work. dont count exhaust, intake, disassembly, assembly and all the incidentals. No Dyno time either but it is next in line.

 

Thanks for that info Gordonm, I saw a few post here and there that mentioned the 5.7 rods are the cheap way to do it and haven't had any other info to convince me. It will def not be running all day in the upper revs like a track car but I'm looking to at least make the shift point somewhere close to that. I might be able to just use what I have in the block already then! Not forged, but I'll only want to hit it with a 150 shot so not to fry it. I still don't know what CR I'm at though. I think a cranking pressure is in order to give me an idea. So a head and cam swap are a must still. I do know that my iron heads have a 62cc chamber and that's probably why I seem to only be able to use 93 octane with 36 deg of timing. What do you think of the Brodix "Race Rite" heads with 200cc runners and a 67cc chamber?

 

Yeah I feel for ya there Mako, It's like a crack addiction.

 

I would not say the 5.7 rods are the cheap way to do it. My rods were in the 600 dollar range, definitly not cheap rods. The 6.0 rods just put a little less side load on the pistons than the 5.7 rods. You can go cheap on 5.7 or 6 inch rods or you can go expensive. I decided not to go cheap. I put in a forged crank rods and pistons, these all cost around 2 grand for just the parts. I saved a little on a solid flat tappet cam but my motor is right around the cost of 63mako motor. When you start turning rpm or feed it nitrous this is when it gets expensive. You can use your short block that you have but I would be very conservative on the nitrous and turning it over 6K rpm. I have seen stock L48s turn over 6K rpm but I have seen a lot blow apart also. I know exactly what is in my motor and have no problems with the rpms I turn it. I know of a drag car that shifts at 7800 rpm with the same components I am running for a short block.

 

Just kind of letting you know, the under $3000 figure in your OP, double it at least, just for the long block. Then, on top of that you have to upgrade every piece of the drivetrain from the clutch disk to the rear spindle to handle the HP you are talking. Also really need to fully weld the frame and add gussets and reenforcing in some critical spots. I am in the same boat, over 500 HP plus a 150 shot. Frame off is really the only way to do it right. Tom's Differential is in transit now, That is another $5141.06. Better increase your credit line on your cards, your going to need it.

 

I've been looking for a sugar daddy. How about it big boy!

 

Heck, just run it until it blows & then start from scratch. You could drop a kit in, but you loose the little things, like having the holes honed exactly for each piston. When you're spinning high & running a big shot, that's when all the details really matter.

 

Yeah, Toms diff will probably find it's way over here too, it's all a matter of time. I can do the frame work, and already upgraded the rear suspension to a 6-link for added symmetrical perfection. I have the original L-48 block w/ 50k original miles already dismantled that I can work with while the car can still be driven for fun. That way the car isn't sidelined for next year. That WILL require alot of outsourcing to a machinist though (more $). Like I said I have other hobbies I'm already committed to but will probably consolidate some of them to help with the funding. I'm not done squeezing more power out of what I have yet and after the winter will see what she can do. If I'm happy with it I might just go with a head and cam swap, not too big, but but I def want to shoot it with some spray. That will be the determining factor of what to do next, either keep spraying until she fries or build a stronger engine to handle it from the beginning. I'll be taking a chance with the bottom end I have now but it isn't pushing the kind of power that I thought to begin with. According to a couple 1/4 mile calcs, putting in my weight and using my G-meter I have an estimated 380-400hp right now. I don't think an additional 150 shot will kill it right away. That means about 450 to the wheels. I think I built the rear end of the car strong enough to handle that.
Soon I will be at a point where I won't be able to attend the strip without installing a proper cage and will have to rely on the G-meter for times. It was on the money the last time I compared it to the track times. For now any advise of some good parts to look for like heads, cams, or rotating assemblies would be great. I also have the Camquest software that I've been messing with but that doesn't have all the variables to enter in and still leaves alot of unknowns. For example the compression ratio and combustion size. Is that just the size of the head or both the head and the squish together. I have no way of changing the piston depth. It looks like they just want to know the basics of the engine you have and give out the cams that match. Is there any other software that you could enter in more variables and have it tell you if you are safe?

 

LOL Now that's what I wanted to hear It's what all of my friends are saying because I analyze everything too much. I know one thing, if I build it, it WILL be right. But for what I have right now, I didn't spend alot on it so I'm thinking what the heck, it should be ok for now. Still curious on what cam is in it though. I'm gonna play with it till spring and see what happens.

 

If you are looking for a high-revving motor, that still makes great torque, you may want to consider selling the motor you have and building a 377 (400 block, 4.155 bore, 3.48 stroke). Lots of circle track guys build them, and its going to rev up much faster than a 383 (I have had both). The 350 (3.48) stroke crank has a smaller main, but you can get special bearings or bearing spacers that make up the difference.

 

Find you another block and have it machined along with the balancing, etc. of the new parts. Make sure the shop checks all clearances and buy bearings, etc. from them. If you simply replace what's in there, you'll still need to have it honed to seat the new rings and you'll need it zero decked for best performance. Keep in mind that your used parts aren't going to be worth much - not nearly as much as a complete, running engine. Take care of it and sell it as a long block, the difference will more than offset the cost of a second block.

 

Sorry dude, im already taken.

 

I got the old L-48 block if I end up going that route. It only had 50k miles on it. I'm gonna start with heads and a new cam on the setup I have in the car first, then in the future if I decide to build something I already have the spare block to play scientist with.

 

Put in a cam that makes all its power under 6000 rpm and get a good set of heads and you will be fine. Later when you upgrade the short block you can put in a high winding cam.