PONTIAC FACT:
Untitled Document
National Parts Depot
428

 
Post new topic   Reply to topic    PontiacRegistry.com Forum Index -> Traditional Pontiac V8 Information
View previous topic :: View next topic  
Author Message
rchrdwjohnson



Joined: 27 Jan 2021
Posts: 2
Location:



PostPosted: Wed Jan 27, 2021 7:16 pm    Post subject: 428 Reply with quote

Hi. I'm Richard and I have a 1969 Pontiac Grand Prix SJ powered by a 428. I am getting ready to overhaul the engine and was wondering how to tell if it is a h/o or not. Any help available on this? I have the engine tore apart. Thank-you.
_________________
Back to top
View user's profile Send private message Send e-mail Visit poster's website AIM Address Yahoo Messenger MSN Messenger
Larry
Site Admin


Joined: 01 Jun 2006
Posts: 4768




PostPosted: Thu Jan 28, 2021 3:37 pm    Post subject: Engine ID Reply with quote

There is little info about the HO other than it was an option. Nothing I have goes into any detail of what the differences were. With only 20 HP gain, it couldn't have been much of any significant change. Perhaps just carburation, cam, and/or exhaust manifolds. That's about all you would need for just a 20 HP gain.

However, the blocks were stamped differently. Check this link for the 370 vs. 390 HP block codes: https://www.pontiacregistry.com/members/online_magazine.php?view=2&article=243&page=2

Also, in one of Pete McCarthy's books he does mention that the 370 HP had #16 heads and the 390 HP had #16 or #48. If yours are #48, that would help ID it.

We found this as part of a discussion at Pontiac Heaven: "The top 428 for 1969 was again the 390hp rated "HO" version with the low restriction manifolds and slightly larger '068/tripower' cam." You can read the entire thing at: https://www.facebook.com/PontiacHeaven/posts/the-428-was-pontiacs-top-engine-for-3-short-years-1967-9-the-bore-is-the-same-as/623219591159710/

Let us know if you find more information that we can pass on to others.

_________________
PontiacRegistry.com... building the single largest source of Pontiac information, services, and entertainment in the world!
Back to top
View user's profile Send private message Send e-mail AIM Address
rchrdwjohnson



Joined: 27 Jan 2021
Posts: 2
Location:



PostPosted: Sun Jan 31, 2021 1:25 am    Post subject: Reply with quote

Thanks. On front pass side I found 152410 above the letters XG. Does that make it a 390hp? Another question. When I pulled the engine I unbolted it from the transmission thinking that would be easier. I couldn't get it out. Eventually I tore the starter to pieces and got it out. What is the best way to put it back? Trans & engine bolted together with starter on? I don't think a starter can be changed without pulling the engine. Am I wrong?
_________________
Back to top
View user's profile Send private message Send e-mail Visit poster's website AIM Address Yahoo Messenger MSN Messenger
Larry
Site Admin


Joined: 01 Jun 2006
Posts: 4768




PostPosted: Sun Jan 31, 2021 4:55 pm    Post subject: 1969 GP Reply with quote

Looks like you got yourself a 390 HP 428! The only problem with those ID numbers is that they were used over again in various years. But the chance of a different engine, from a different year, with the same two ID letters is slim to none.

OOPS on the starter deal. I've changed many a starter even with headers and never had a problem. A pain, but doable.

The only thing to be careful of when putting the engine with flywheel and torque converter mounted on it is to make sure the transmission and torque converter engage properly. It can be tricky and you have to fool with it sometimes. If you can't get the engine to seat squarely against the flywheel, don't force it. That can ruin the oil pump.

_________________
PontiacRegistry.com... building the single largest source of Pontiac information, services, and entertainment in the world!
Back to top
View user's profile Send private message Send e-mail AIM Address
Display posts from previous:   
Post new topic   Reply to topic    PontiacRegistry.com Forum Index -> Traditional Pontiac V8 Information All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum
Untitled Document

PontiacRegistry.com, the ALL Pontiac Club for ALL Pontiac Lovers– dedicated to the preservation, restoration, and enjoyment of all years, models, and types of Pontiacs. Enjoy your Pontiac hobby at the only 24-7 Pontiac Club that brings you Pontiac News, Pontiac Information, and Pontiac Entertainment at the speed of light. Join today and help support and build the best of all Pontiac Clubs in the world. Clubs are for people too, not just cars. If you do not yet have a Pontiac, or just enjoy sharing information and learning about them....welcome!





 All Rights Reserved © 2012-2024 PontiacRegistry.com, LLC PRIVACY POLICY | TERMS & CONDITIONS | CONTACT US
Michael J. Gifford, Web Developer