Building a 383 Stroker

[greg82255]

Re: Building a 383 Stroker

Can I get aluminum vortecs with some kind of corrosion inhibitor? I haven't before, but I may want to use the boat in salt water 3 or 4 times a year with this new motor. Do I even need a corrosion inhibitor if I don't leave the boat in salt, and flush it after each use?

 

[HT32BSX115]

Re: Building a 383 Stroker

Can I get aluminum vortecs with some kind of corrosion inhibitor? I haven't before, but I may want to use the boat in salt water 3 or 4 times a year with this new motor. Do I even need a corrosion inhibitor if I don't leave the boat in salt, and flush it after each use?

The best corrosion inhibitor is closed cooling.


If you're going to spend the roughly $1200-1500 for aluminum heads why not put closed cooling on it for an additional $800 or so?

 

[greg82255]

Re: Building a 383 Stroker

If you're going to spend the roughly $1200-1500 for aluminum heads why not put closed cooling on it for an additional $800 or so?

Didn't realize aluminum heads were that expensive. I can get a set of remanufactured 062 vortec heads for 520 shipped from Ebay... seems like a much better option.

 

[HT32BSX115]

Re: Building a 383 Stroker

Didn't realize aluminum heads were that expensive. I can get a set of remanufactured 062 vortec heads for 520 shipped from Ebay... seems like a much better option.

The price I indicated was from Jegs, and they're GM Performance heads... They're something like $585--659 + shipping (each) depending on how you want them set up.... includes valves and springs but doesn't include rockers.....

I sure you can buy cheap imports for less on ebay but you'll probably have to have a machine shop install valves, springs, guides, seats, and surface them. I would not trust imported heads unless a (local) machine shop set them up and then I would want them to get them for me. They're not gonna be all that willing to guarantee something they don't sell.....

 

[John_S]

Re: Building a 383 Stroker

FWIW: The Black Scorpion I mentioned, is running iron vortec heads. Not the stock assembled ones based on having a lift 0.510I/0.530E, though. The Merc 6.2L uses iron vortec at 9:1, and the HT383 also uses iron vortec9.1:1. Aluminum heads would allow for a higher compression ratio because of the ability to better pull heat from the combustion chamber.

 

[greg82255]

Re: Building a 383 Stroker

The price I indicated was from Jegs, and they're GM Performance heads... They're something like $585--659 + shipping (each) depending on how you want them set up.... includes valves and springs but doesn't include rockers.....

I sure you can buy cheap imports for less on ebay but you'll probably have to have a machine shop install valves, springs, guides, seats, and surface them. I would not trust imported heads unless a (local) machine shop set them up and then I would want them to get them for me. They're not gonna be all that willing to guarantee something they don't sell.....

I agree that I don't want any kind of imported aftermarket part. The link I put below claims to have a set of brand new 062 vortec heads made by GM and not by an aftermarket part. Would something like that work? or would I be better off getting a rebuildable core and having the machine shop recondition them?

http://cgi.ebay.com/ebaymotors/062-...r_Truck_Parts_Accessories&hash=item4cfaaf9246

 

[John_S]

Re: Building a 383 Stroker

Those look like genuine GM, but with shipping are they a big savings? I think you need to sellect your cam before you can say the most cost effective heads to go forward with. If you are keeping to the merc 350 cam or less, the fully assembled heads would make sense. Higher lift requires heavier springs and possible machine work, including screw in or pinned rocker studs, where new bare heads or good cores probably make more sense.

Another thing to consider, is the exhaust seat. http://www.gmpowertrain.com/Libraries/Marine_Engines/Vortec_5_7L_V-8_Marine.sflb.ashx The marine heads have it, but the fully assembled heads typically do not. You might get away without it. A good core might be better if you do though.

 

[Bondo]

Re: Building a 383 Stroker

Those look like genuine GM, but with shipping are they a big savings? I think you need to sellect your cam before you can say the most cost effective heads to go forward with. If you are keeping to the merc 350 cam or less, the fully assembled heads would make sense. Higher lift requires heavier springs and possible machine work, including screw in or pinned rocker studs, where new bare heads or good cores probably make more sense.

Another thing to consider, is the exhaust seat. http://www.gmpowertrain.com/Libraries/Marine_Engines/Vortec_5_7L_V-8_Marine.sflb.ashx The marine heads have it, but the fully assembled heads typically do not. You might get away without it. A good core might be better if you do though.

Ayuh,... From GM, the 906 castings have exhaust valve seat inserts...
The 062s Don't...

 

[John_S]

Re: Building a 383 Stroker

Ayuh,... From GM, the 906 castings have exhaust valve seat inserts...
The 062s Don't...

That is what allot of articles say, but info on Sallee Chevrolet seems to indicate differently. But there has been allot of conflicting info on the web, such as max lift. Early articles indicated a max lift of .420 - .430, and now it seems .475 is where most indicate. If sellecting a core, should be able to tell if there is a valve seat from a visual inspection???


http://www.sallee-chevrolet.com/Cylinder_Heads/Vortec.cfm


Please Note: The casting number myth debunked:
The myth is that there is a difference in the head performance produced by these two castings. This myth was started by some Magazines that didn't do their homework before publishing their articles. This is the truth the whole truth and nothing but the truth. So sayith the Grand Wizard GM and his Apprentice Wizard Chevrolet.
10239906 casting has one large single hump.
12558062 casting has 3 small humps.
If either of these two castings have not been altered by GM and the part number changed from 12558060 or altered by someone else (previous owner, etc.), the heads produced by either casting will be identical except for the external cosmetic difference. Both castings are used to make the 12558060 Vortec heads which are the true unaltered Vortec heads. Heads from both castings come out of their cast IDENTICAL except for the minor cosmetic external differences!!!!!!!!


They also inserted this info into an article from Chevy High Performance. From that link:
Inserted by Chevrolet
There is no difference between either of the Vortec head (P/N 12558060) castings except for a couple of minor external cosmetic details. The two casting numbers are 10239906 and 12558062. GM has and does take some of the P/N 12558060 heads made from either of these castings and makes alterations to them to better fit specific applications. When GM does this, they change the part number of the head. Buying Vortec heads used is risky unless you know what vehicle they came out of, what part number the head is, and what modifications where made to the head to make it that part number. You can not go by the casting number, as suggested by this article, you have to go by the part number of the head when buying used Vortec heads.

 

[greg82255]

Re: Building a 383 Stroker

So does this mean if I want to use a cam with lift over .475, I need to get some work done to whatever heads I buy?

I haven't looked into selecting a cam yet. That was going to be my next question on the thread, so I might as well ask it now... I don't know if my block is roller compatible or not, but if it is, I'd like to use one, and either way I'd like to use a cam thats more aggressive than the stock Mercruiser cam. The machine shop says they can tell as soon as they look at the block if it works with roller lifters. If I want to be between 350 and 375 hp @5000rpm, what kind of lift/duration #s should I looking for? I'll be pairing the cam with whatever heads are necessary to work with them. I've been looking at Comp Cams on CP Performance a lot, they appear to have a wide selection of all different specs.

http://www.cpperformance.com/c-362-comp-cams.aspx

 

[joewithaboat]

Re: Building a 383 Stroker

Ive been watching your post. Ive been thinking of building a hopped up small block fro my boat as well. There are two members here that have pretty nice stroker motors that i have seen threads on. I think they are a little more camed up than you might want but you might give it a look. One is member 45auto the other is wca_tim. If i recall 45auto has iron headed vortec 406. I think tims is 383 with big alum heads. They both give good info in their threads. There is a third guy but i cant think of his member name. If you search their threads you will find him as well.
Good luck, ill continue to follow.
PS
If the block you are reusing was yours and you can see that the main bearings were worn evenly, line honing is waste of money. I only metion it because you are tring to keep a tight budget. As to the roller cam you can use one regardless of weither it was a factory roller or not, the lifters are a little different is all. If you are buying new rods and pistons and 6 inch set up doesnt cost too much more it will only help power and most would say worth it.

 

[John_S]

Re: Building a 383 Stroker

All of those recommended I/O cams will require modification to stock assembled iron vortec heads, except for the smaller hyd. That cam is very close to stock lifts. Even the more agressive I/O ones will put you slightly below your 350hp (crank) goal. Most cams will also require heavier springs. Buying the assembled heads and throwing away components, may be more expensive that starting with the bare heads.

 

[John_S]

Re: Building a 383 Stroker

You might be thinking of Mntrat. He had a 383 build going. I am not aware of any "budget" stroker builds though.

 

[greg82255]

Re: Building a 383 Stroker

All of those recommended I/O cams will require modification to stock assembled iron vortec heads, except for the smaller hyd. That cam is very close to stock lifts. Even the more agressive I/O ones will put you slightly below your 350hp (crank) goal. Most cams will also require heavier springs. Buying the assembled heads and throwing away components, may be more expensive that starting with the bare heads.

Alright I'm new at this so please bare with me, but if a 383 with an aggressive cam and vortec heads won't bring me to 350+ hp, what else do I need to do to get there? And about how much $ are we talking about? I was planning on using a 750cfm Holley or Edelbrock carb, performer rpm intake and some kind of performance exhaust.

I was trying to keep a budget for the machine work so I could possibly spend some more on parts that will give me more power. I also think that most of my 350 parts are still good (pistons, crank, heads, intake, etc) so I might be able to sell those and get some more $ to play with.

 

[John_S]

Re: Building a 383 Stroker

While those cams say "aggressive" for an I/O, overall, they are not "that" aggressive as far as cams go. I believe you still plan to run an alpha drive, so you need a smooth idle at 600 rpms, so you don't slam the gears. While a performance exhaust will help, an "aggressive" cam with lift in the 0.500+ range will get you to the 350HP (crank) that you are looking for, with iron vortec heads. The heads will need springs and/or other work to run the cam.

This build, while a "performance car" build, outside of the headers and non-marine safe parts (carb, ignition), up through stage 4 has great torque and meets your HP requirement. http://www.hotrod.com/techarticles/engine/gm_ht383_crate_small_block_tune_up/viewall.html

 

[greg82255]

Re: Building a 383 Stroker

I assume a roller cam would help with keeping a smooth idle? Here's what I don't understand... I've seen 350's with iron vortec heads that put out 315-330 hp advertised online (Michigan Motorz, US Engines). If they can get 330 hp out of a 350, it shouldn't be that hard to get an extra 20 hp from the 33 extra cubic inches, right? Maybe even a few more hp.. US engines also advertises a 400 hp 383 long block for $3295... How do they do that so cheap?

I remember wca_tim posted on one of my other threads about a 383 he built. I'm going to see if I can find him and ask exactly what he did (his was 450hp if I remember correctly).

 

[joewithaboat]

Re: Building a 383 Stroker

If you want to use your old stuff (block and crank) You can get 350 hp from a 350ci but you will prob have to push the limit on comp/ratio. Your cheapest power will come from the vortec heads. Roller cam will prob help your idle and your alpha, also will make more usable power. Higher overall average. Flat tappet saves lots of $$$
I would look at the Performer RPM Air Gap, Holley marine 650 (new to eliminate problems)
You could look for a near stock 406. They are out there, I scooped one up on craigslist not too long ago. 350 hp easy with a flat tappet and vortecs.

 

[John_S]

Re: Building a 383 Stroker

Advertised, in many cases, is just that. Compare what they say to a known build that has been on a dyno. After reviewing that article, I do think you will be close to 350 at crank. Now, 350 at crank will be about 320 at your prop, which is what the Mercruiser 383 MPI is. But, you can get more hp from mpi than a carb or efi. Now, that Black Scorpion I mentioned is 350hp at crank, but is MPI and has 0.500+ lift cam.

 

[mhouse40]

Re: Building a 383 Stroker

http://www.gmpowertrain.com/Libraries/Marine_Engines/Vortec_5_7L_V-8_Marine.sflb.ashx

Kewl motor!

 

[mhouse40]

Re: Building a 383 Stroker

Now, that Black Scorpion I mentioned is 350hp at crank, but is MPI and has 0.500+ lift cam.[/QUOTE]

John, you wouldnt happen to have some sort of knowledge on the 400 horse scorpions cam would ya? Any body?
( I know probably a crazy question to ask but I have been wondering this for some time now,,,, Holy grail of cams?) Every supplier says " Special grind" (*&^~!!!!!


Greg.. I have been looking at aftermarket exhuast,,,,,, brand new a good set can run all the way up to 2 grand (ouch) This is for a good set. Not sure what one can find them for on ebay?