Need help with a 383 project - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-12-2004, 04:21 PM
Dieselfinder's Avatar
Registered User
 
Join Date: Jun 2004
Location: So Cal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Need help with a 383 project

I have a few questions i think you guys may be able to help me with. I am going to build a 383 to replace the 350 I currently have in my boat. I know "boat" yes boat that is my hobby. I restored a 24' 78 searay and now its time for the engine. The thing that concerns me is fuel. If any of you guy own boats you know the fuel can kill you. I run this in the ocean and I need to go approx. 100 miles out and 100 back. the boat currently gets about 1.6 mpg and i have 100 gallon capacity. So in sunny CA it cost me $250 to go 160 miles not very good.

Now if I build a 383 to get the tourqe will that help fuel economy. I, like most of you guys, am not looking for a lot of HPs the engine runs between idle and 4000 rpms. The block is currently 30 over. I would like to install vortec heads but compression is a concern 100 gallons at a time I need to stay with regular octane.

I know this goes against you building practices, but a freind of mine said you guys may be able to help.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-12-2004, 07:18 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,130
Wiki Edits: 0

Thanks: 25
Thanked 267 Times in 250 Posts
You won't need the Vortec heads in your application. Most big boats don't run over 4000 RPM. I would build a good solid short block, flat top hyper eutectic pistons, good roller chain setup and a mid range marine cam from one of the Cam marketers. Have the heads gone thru. A good three angle street type valve job done to them. Have them milled flat. I like to use a street type one piece stainless swirl polished valve and the Z/28 type valve springs. I also prefer the marine intake or a performer intake.I have built these before and had good luck with them. Your power/mileage and smiles will increase with that extra torque and the right cam!
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-12-2004, 07:27 PM
Member
 

Last journal entry: JB's 37 Pickup
Last photo:
Join Date: Oct 2002
Location: Smoky Mountains
Age: 76
Posts: 2,358
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
!00 gal tank, at 1.6 mpg and you go 100 out and 60 back. Guess you get towed the last 40 or so? Been there done that. Even with the mods Bob addressed you are still going to be a little short unless you put in a bigger tank. I would put an EFI on it and then you would be going past the 2mpg which means your knuckles will be white from the time you sight land and reach the dock..

Those old Sea Rays were a neat boat and in 78, they were not into the cutting back on the fiberglass so you have a real boat,

Trees
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-12-2004, 07:42 PM
killerformula's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Carburetor
Last journal entry: Clean up
Last photo:
Join Date: Oct 2003
Location: Northeast
Age: 34
Posts: 3,485
Wiki Edits: 3

Thanks: 13
Thanked 27 Times in 18 Posts
I don't know much about marine motors. I wonder, however, if doing things to help the efficiency of your motor such as roller cam, roller rockers, high swirl combustion chambers and EFI (for sure) would make the impact you're looking for? If I remember correctly, motors make their highest torque at their peak volumetric efficiency mark, and that's also the point where you're getting the most power per unit of fuel used, so I think its time well spent to research where you're going to spend most of your time (IE what RPM range) and pick your cam, intake and compression to suit. I really think you should talk to a cam expert about this, a cam can make all the difference. I also think a set of after market heads that are more efficient than the old school heads will put you ahead of the game. Cstraub on this board is a big-time cam man, he can point you in the right direction I believe.

Again, I'm not certain how much of this applies to a boat, but I figured I'd make some suggestions. Hope they help, sounds like a fun summer-

K
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-13-2004, 10:28 AM
Dieselfinder's Avatar
Registered User
 
Join Date: Jun 2004
Location: So Cal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I appreciate the help from you guys, If any one has those cam sugestions or can school me in that part of this It would help greatly.

As far as EFI what kind of difference am I looking at. One reason I like the carb it it is easy. never worked with EFI. Being a 78 there is no computer wiring and distributor has no vac advance. how hard would EFI be to install.

Another question, since I will not exceed 4000 rpm how important is the balance on a 383 kit. I have sunk a lot of money in this boat, i guess i should have started with the engine. I will reuse the 5.7 rods that are in my block now. also is internally balanced or external better.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-13-2004, 11:13 AM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 4,974
Wiki Edits: 0

Thanks: 2
Thanked 89 Times in 72 Posts
EFI on a boat? Forget it, marine engine run at constant throttle where FI does not help one bit, if the carb is properly tuned stick with it. The last thing you need on a boat is electronics on the motor.

I would build a real mild big cubic inch motor with as big a prop as you can run, keep the rpm below 3500 and tune it for bottom end torque.

Whats wrong with a diesel? Gas engines are hogs in a boat because they need rpm to generate power and must run smaller props as a result. For the money your going to spend a stock chevy V8 diesel engine might just swap in and give you the economy your looking for.

100 miles out? You picking up floating kilos out there?
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-13-2004, 11:31 AM
Dieselfinder's Avatar
Registered User
 
Join Date: Jun 2004
Location: So Cal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The funny thing is, I sell diesel trucks. I work at a Ford dealer and the price of a 7.3 diesel would be 5-7k plus then you have all the bolt on stuff I could only imagine. I will eventually go that direction but probably on the next boat. Not sure about chevy. Only looking at spending aroun 2k to upfit the one i have.

100 miles get you from newport CA harbor to the tuna (butterfly) If I were picking up kilos I more than likely would not care about fuel econ.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-13-2004, 12:06 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,130
Wiki Edits: 0

Thanks: 25
Thanked 267 Times in 250 Posts
To answer one of your questions: Yes, you would have to have an aftermkt 383 kit balanced UNLESS the kit states it is a balanced kit. Most aren't. They are just an assortment of parts to make a rotating assembly. With none of the manufacturers knowing what is going to be bolted on to their product.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-13-2004, 06:22 PM
Member
 

Last journal entry: JB's 37 Pickup
Last photo:
Join Date: Oct 2002
Location: Smoky Mountains
Age: 76
Posts: 2,358
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Chuck, I almost always agree with you, but the pleasure boating industry is going EFI all the way. The EFI outboard motors have really pumped the efficiency in both 2 and 4 stroke. I am not as familiar with the big marine inboards other than their computers are "ruggedized" for the severe corrosive enviroment and I'm sure the nominal wiring connectors are as well. The EFI, in theory is much more efficient over the carb in all ranges, particuarly at cruise (for a boat, that is about 2/3 throttle). Each cylinder is running at the same fuel/air ratio, and the spark timing is optimal for the conditions. Carb set up has 3 cylinders about right mixture, 3 cylinders too rich and 2 cylinders too lean and spark is a function of vacumn and mechanical advance curves that are more limited than with electronic curve. In an automobile, everthing I have read and discussed with the techies is an EFI is worth about 6 MPG over the same motor with a well tuned carb and there are not that many well tuned carbs.. Now we are talking about increasing efficiency in the 20% range. In the case of changing my 383 from carb to EFI, I added smaller chambered heads and better exhaust manifolds, gained at least 50 hp and raised my fuel milage from a little over 15 to borderline 22.

Having said all that, a friend of mine is a professional charter boat captain sponsered by Yamaha. He gets new motors every year and has been putting them on the same boat for the last 4. The first year was carbed 2 stroke Yamahas, the next two years were EFI (all were the same size motors), and this year is EFI 4 strokes that are rated 50 hp less) The EFI motors lower his fuel consumption by 25% and the 4 strokers another 25%. You are correct in that the biggest savings are near idle and he spends hours trolling in that range. But since he runs 50-75 miles out on plane, he realized great savings there too. The 4 strokes, although rated at less horsepower, tend to run at lower RPM at the same cruise speed. The cruise speed is more of a function of hull efficiency, but a good seaman will know how to balance the combination or he will not stay in business long!

Trees
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 06-14-2004, 03:23 PM
Dieselfinder's Avatar
Registered User
 
Join Date: Jun 2004
Location: So Cal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
OK, then how hard is it to convert from carb to efi
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 06-14-2004, 03:56 PM
Siggy_Freud's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Dec 2003
Location: Portland, Oregon
Age: 29
Posts: 2,371
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Its not super difficult. The main thing will be the wiring and computer (you can buy waterproofed computers). Depending on which EFI system you go with, you will have to make other modifications such as the fuel pump, a return line, etc. There are a few books out there on doing such a thing but all-in-all its not too difficult.
__________________
Bringing history and technology together.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 06-14-2004, 10:58 PM
killerformula's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Carburetor
Last journal entry: Clean up
Last photo:
Join Date: Oct 2003
Location: Northeast
Age: 34
Posts: 3,485
Wiki Edits: 3

Thanks: 13
Thanked 27 Times in 18 Posts
I would definately say it would be a pretty good challenge if you haven't done it before! I know I'd have trouble with it. But like anything, as long as you ask questions and take your time I'm sure you'll do fine. Read the directions!

K
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 06-15-2004, 07:11 AM
Member
 

Last journal entry: JB's 37 Pickup
Last photo:
Join Date: Oct 2002
Location: Smoky Mountains
Age: 76
Posts: 2,358
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Not difficult, just expensive initially. In your case you want to look at setups for marine use. This includes not only the "ruggedized" computer hardware, but the software optimized for the "push the throttle to the wide open position to get to cruise speed and set for cruise" type of operation. You have the ability to restore an old boat, which takes a high level of concentration and dedication. Use those skills to research the marine systems utilized in the newer power plants and go from there. If I ever get back into boating, rest assured my propulsion system will be EFI.

Trees
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 06-15-2004, 09:13 AM
Dieselfinder's Avatar
Registered User
 
Join Date: Jun 2004
Location: So Cal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
you guys have been very helpful, Thanks for the efi info. I'm going to build the 383 with carb for now then go to efi after intence research. Just to be ahead i need to get a new intake is there one that would be interchangable with the efi or are they diffent (looking toward the edelbrock pro flo (look easy) and what do you think of this efi system
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 06-18-2004, 03:31 PM
Dieselfinder's Avatar
Registered User
 
Join Date: Jun 2004
Location: So Cal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
One more question, in regards to fuel economy would the difference between running 5.7 a 6.0 rods influence fuel economy
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 02:31 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.