Crankshaft question - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 08-07-2019, 06:06 PM Thread Starter
 
Ohio66GTO's Avatar
 
Join Date: May 2014
Posts: 39
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Crankshaft question

I’m looking to start the engine rebuild on my 65 block I picked up. The engine was seized from sitting when I got it and I was finally able to break it loose and disassemble it. My question is weather I should just have a regrind and polish of the original crank or spend the money and get the forged crank? I’m not going to be racing the car so just wondering what everyone thinks about using the original one. New one is in the $600.00-$700.00 range and the regrind and polish is about $180.00.
Ohio66GTO is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 08-07-2019, 06:37 PM
 
Join Date: Jul 2016
Location: North Louisiana
Posts: 535
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
I'd go with a forged stroker assembly, & 6X heads. Easy 400hp/500 torque, on pump gas, with a 4.25 stroke assembly.

https://butlerperformance.com/i-2459...tegory:1234862

But, if you really don't want that much power, don't wanna spend that much, AND your crank can be used that cheap, then there's pretty much only one choice. No problem makin 300hp+, with a pump gas stock stroke engine. The factory 4-barrel GTO 389 was factory rated at 335hp. NHRA factors it at 300hp.

EngineSpecs

There are obviously lots of things to consider, like which heads, how much compression, cam, intake, carb, etc.

Also depends on how original you want the engine compartment to look.

Last edited by bigD; 08-07-2019 at 06:51 PM.
bigD is online now  
post #3 of 6 (permalink) Old 08-07-2019, 07:52 PM Thread Starter
 
Ohio66GTO's Avatar
 
Join Date: May 2014
Posts: 39
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Yeah, I’m going for the more stock/original look. Have a period correct block and heads. I have the original numbers matching tri-power setup. I am just seeing what people think about using a crank that is 54 years old. I don’t think I need a forged crank but I like the piece of mind having it. I see Kauffman has a stock steel crank made by Ohio for $325. I’d be happy using the original but just wondering if it will be a weak point in the assembly being so old or will it be just as good as the new Ohio one once I get the regrind and polish done? First time building an engine so maybe I’m overthinking it.
Ohio66GTO is offline  
 
post #4 of 6 (permalink) Old 08-07-2019, 08:29 PM
 
PontiacJim's Avatar
 
Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Posts: 3,473
Mentioned: 0 Post(s)
Tagged: 1 Thread(s)
Quoted: 350 Post(s)
Garage
Quote:
Originally Posted by Ohio66GTO View Post
Yeah, Iím going for the more stock/original look. Have a period correct block and heads. I have the original numbers matching tri-power setup. I am just seeing what people think about using a crank that is 54 years old. I donít think I need a forged crank but I like the piece of mind having it. I see Kauffman has a stock steel crank made by Ohio for $325. Iíd be happy using the original but just wondering if it will be a weak point in the assembly being so old or will it be just as good as the new Ohio one once I get the regrind and polish done? First time building an engine so maybe Iím overthinking it.

Should not be a problem, especially with a stock application. Using a stock crank will ensure it is correct from the get-go. Pontiac cranks are pretty stout. Your machine shop should first vat (clean) the crank, then magnaflux it for any cracks, and check for straightness. If all passes, then they will mic the journals and let you know how much the crank needs turning.

I would not purchase a new crank unless the factory crank proved to be bad. You will not need forged even if you do buy a "new" crank unless you plan on severe use or going big stroker.

What I do recommend replacing is the factory cast connecting rods. They too are failry rugged, but they are cast and you don't know how hard they have been run up. Even if you rebuild them and had the upgraded ARP bolts installed, you still could have a rod go bad. For the price of a new set of forged I-beam connecting rods, you get the stronger forgings & better rod bolts. You do not need the H-beams. The I-beams are like factory and will hold up just fine for your application. https://butlerperformance.com/i-3164...tegory:1234812 Jegs also has them and may offer free shipping. Summit for some reason does not offer them, but am sure if you email, they will get them. They offer free shipping over $100.
PontiacJim is offline  
post #5 of 6 (permalink) Old 08-08-2019, 01:55 PM Thread Starter
 
Ohio66GTO's Avatar
 
Join Date: May 2014
Posts: 39
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Thanks for the info guys. I’m going to use the original one. I just wanted to get some experienced opinions before putting the money into it and having problems later.
Ohio66GTO is offline  
post #6 of 6 (permalink) Old 08-09-2019, 05:26 PM
 
Join Date: Jun 2019
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Good information and advice. I'm about to start down the same road with my 65 389.
It has been run hard - new rods are something to think about.
DustyOldGTO is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
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:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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

 
For the best viewing experience please update your browser to Google Chrome