Tune up specs for a 454... - Chevelle Tech
Engine General Engine Discussion.

 3Likes
  • 1 Post By BillK
  • 1 Post By 1975TypeS-3
  • 1 Post By gnicholson
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 6 (permalink) Old Apr 18th, 19, 8:01 AM Thread Starter
Senior Tech Team
Jeff
 
Join Date: Jun 2009
Location: Pittsburgh, Pa.
Posts: 1,998
Tune up specs for a 454...

I want to tune my totally stock, low mileage 1978 454 in my 69 el Camino.. It has #336781 heads that have never been off. The engine has about 30,000 miles on it..

I use 87 octane, it has a Turbo 400 with a 2:87 rear end. It is 100% street driven...

It has a factory HEI distributor and I am using Atlas C36R4 plugs these cross with Autolite 25 plugs...

What would be good specs to tune it to?

It runs real nice now, doesn't ping at all and I want to keep it that way.. Thank you..
hydro462 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old Apr 18th, 19, 8:38 AM
Super Mod
Mr Bill
 
Join Date: Aug 1998
Location: Waldorf Md. USA
Posts: 11,815
Re: Tune up specs for a 454...

Quote:
Originally Posted by hydro462 View Post
What would be good specs to tune it to?

It runs real nice now, doesn't ping at all and I want to keep it that way.. Thank you..

If it is running fine now, why would you want to "tune" it ???? Whatever it is set to now you should leave it alone.


Only thing I would do different is use a set of AC Delco plugs, but that is my personal preference for GM engines.
lucifershammer likes this.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


1971 Heavy Chevy - original owner
1984 Buick Riviera - original owner (Wife's car)
Team Chevelle #100
BillK is offline  
post #3 of 6 (permalink) Old Apr 18th, 19, 4:48 PM
Lifetime Premium Member
Tom
 
Join Date: Oct 2017
Location: Traverse City, MI
Posts: 73
Re: Tune up specs for a 454...

Not that it would make a whole lot of difference, but what did the 1978 454 come out of? I mention this because the 3/4 ton trucks used a dish piston and the Suburban and 1/2 ton trucks used a flattop piston. The difference is the dish piston with 781 heads has a 7.3:1 compression and the flattop piston has 7.8:1. Either way you can easily run on 87 octane, but the dish piston engines can take a little more timing advance.
hydro462 likes this.
1975TypeS-3 is online now  
 
post #4 of 6 (permalink) Old Apr 19th, 19, 3:12 AM
Senior Tech Team
Gary
 
Join Date: Feb 2007
Location: Kansas City,Mo.
Posts: 4,342
Re: Tune up specs for a 454...

i would start with the advance curve try 36 degrees all in at 3400. make sure the mech advance isnt frozen up and the vac adv works. just bumping the timing up to 12 degrees initial will help
hydro462 likes this.
gnicholson is offline  
post #5 of 6 (permalink) Old Apr 19th, 19, 6:59 PM Thread Starter
Senior Tech Team
Jeff
 
Join Date: Jun 2009
Location: Pittsburgh, Pa.
Posts: 1,998
Re: Tune up specs for a 454...

Quote:
Originally Posted by 1975TypeS-3 View Post
Not that it would make a whole lot of difference, but what did the 1978 454 come out of? I mention this because the 3/4 ton trucks used a dish piston and the Suburban and 1/2 ton trucks used a flattop piston. The difference is the dish piston with 781 heads has a 7.3:1 compression and the flattop piston has 7.8:1. Either way you can easily run on 87 octane, but the dish piston engines can take a little more timing advance.
The engine came from a demolished Carnegie library Book-Mobile van.. They were these big trucks that carried books to different neighborhoods.. The truck had under 100 miles on it when it was in an bad accident..
My el Camino has a lot of balls, its hard to believe it only has 8:1 compression. I stayed neck and neck with a new Challenger one time. I don't race this one..
I enjoy tuning motors but like to have a base to start at.. In the past I have gotten additional power just from tweaking the mechanical timing..


Thanks for the input!
hydro462 is offline  
post #6 of 6 (permalink) Old Aug 20th, 19, 8:26 AM Thread Starter
Senior Tech Team
Jeff
 
Join Date: Jun 2009
Location: Pittsburgh, Pa.
Posts: 1,998
Re: Tune up specs for a 454...

This is with the stock 1978 HEI distributor. The engine has less then 15,000 miles..

I've disconnected the vacuum advance and rasied the initial from 12 to 22. It runs so much better!! It starts very easily when hot. But I still have all that mechanical advance, I think its around 20 fully advanced.. I didn't try full throttle but I'll bet it pings.

I'm thinking the mechanical in these HEIs put 20 in. So I'm going to have to limit the mechanical to 10-14ish..

It runs so much better mainly in the part throttle and just off idle..

What's the maximum advance without any vacuum advance you would run? This is a low compression 1978 454 factory stock. I switched the thermostat to 160 and have the under hood cleared pretty well. I removed that big HVAC box, compressor, etc. I am running a Champion 3 core rad with a 160 thermostat.

It runs pretty good but there always room for improvement.. It idles much better. Part throttle cruise without the vac advance is dead smooth with a nice mellow throaty tone. I no longer have to keep correcting the gas..
hydro462 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech 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. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Holley 800 Baseline Tune? bbc Gorrillasnot Performance 8 Mar 12th, 16 1:27 PM
Looking for local Knowledge to tune 454 6-71 Blower Referenced Carbs-2 brettallen59 Engine 0 Sep 14th, 15 8:38 PM
LS7 454 piston specs deadpool1988 Performance 3 May 25th, 14 5:27 PM
454 parts interchangable with other 454 regardles of year?? desert-rat Engine 1 Feb 8th, 13 9:34 PM
Ls5 engine specs stevenb8 1999 -- 2 Aug 23rd, 99 1:29 PM

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