| [GMCnet] More on FiTech questions [message #301250] |
Sun, 29 May 2016 14:16  |
glwgmc
Messages: 1014
Registered: June 2004
Karma:
|
Senior Member |
|
|
Hi Gordon,
Letting the ECU control spark seems to be popular with people who are confident they have a reliable knock sensor installed in a location that can properly distinguish between pre detonation and other engine noises as it allows the system to dial in more advance under certain situations. To do so without a properly working knock sensor would be very risky to the health of the engine. By advancing more it appears to be possible to wring out one or perhaps even more mpg.
If you do not have such a knock sensor, then the electronic HEI distributor is a great choice if the mechanical advance mechanism is set to the needs of our 12000 pound motorhomes and if the vacuum advance also works properly. The HEI was used on millions of cars and trucks contemporary to our coaches with great success. Olds never did design and test a factory installed knock sensor on either the 455 pr the 403 that I am aware of. In fact a 403 was I believe the last GM carbureted engine to pass the ever more stringent emissions tests in all 50 states when finally phased out in the early 90s. It used an HEI distributor.
I use the HEI with the 600 hp (the only one available when I bought mine) FiTech EFI in my 1977 Clasco at the recommendation of the FiTech tech support people. It works well for our application. If the factory had ever designed a knock sensor for trucks using our gearing and our engines, I would probably use the ECU controlled spark that is standard with the FiTech 600 hp unit. The 400 hp unit does away with ECU spark control in order to sell at a $200 lower price point. Check with FiTech, but my understanding is their ECU spark control will NOT work with an HEI distributor, it requires a two wire distributor with the advance mechanism locked out.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
........
Message: 9
Date: Sat, 28 May 2016 13:04:24 -0600
From: Gordon Gibson
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] More on FiTech questions
Message-ID:
Content-Type: text/plain; charset="utf-8"
Jerry
I really appreciate your posts on installing a Fitech in one of your coaches - comments like this plus the fact that I was going to have to bear the
cost of buying a rebuilt Quadrajet to finish off my coach were what prompted me to go the Fitech route.
Full disclosure - although I have rebuilt old cars and motorcycles, my mechanical knowledge of anything more modern that the mid-60s is sorely
lacking. But rest assured - I am having the FI installed by a professional.
I specifically chose the 600 based on the understanding that the FI's computer module would control the spark advance of my "pointless" distributor.
Do I understand that according to Fitech, most of their customers stick with good old mechanical and vacuum spark control? And if this is the case,
any reason why? Is this what you did as well?
Thanks
Gordon
1976 23' Norris Upfit
Montreal West, Quebec, Canada
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Jerry & Sharon Work
78 Royale
Kerby, OR
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
