TBI computer controled distributor on 4.2L? - Pirate4x4.Com : 4x4 and Off-Road Forum

YJ4LIFE · 07-19-2012, 09:14 PM

Is there a way to get the TBI computer to control the timing on a 4.2L? Do you just need a GM distributor? Why wouldn't the howell kit include something like that?

CSP · 07-20-2012, 11:54 AM

The stock distributor can be modified to do this. The mechanical advance springs need to be welded to prevent mechanical advance and the vacuum advance can just be disconnected from the vacuum line. At that point the purple and orange wires on the stock distributor are connected to the correct terminals on the GM 7-pin or 8-pin ignition module.

Your TBI system must first have this capability. Howell, for whatever reason, has just made the choice NOT to allow for computer controlled spark. You'd have to ask them why.

Affordable Fuel Injection's kits do control spark timing.

the freeak · 08-02-2012, 08:44 AM

Can the Howell system be retrofit to the OEM style where timing is controlled, or is the wiring/ ECM an issue?

CSP · 08-06-2012, 02:43 PM

You would have to add wiring to the Howell harness and reprogram the ECM to incorporate spark timing. I did it to the Howell kit in my CJ.

07-19-2012, 09:14 PM	#1 (permalink)
YJ4LIFE Registered User Join Date: Dec 2001 Member # 8867 Location: Los Angeles CA Posts: 537	TBI computer controlled distributor on 4.2L? Is there a way to get the TBI computer to control the timing on a 4.2L? Do you just need a GM distributor? Why wouldn't the howell kit include something like that? __________________ -Taz, '89 YJ Last edited by YJ4LIFE; 07-19-2012 at 09:17 PM. Reason: typo

07-20-2012, 11:54 AM	#2 (permalink)
CSP Registered User Join Date: Aug 2000 Member # 1533 Location: Parker, CO Posts: 2,779	The stock distributor can be modified to do this. The mechanical advance springs need to be welded to prevent mechanical advance and the vacuum advance can just be disconnected from the vacuum line. At that point the purple and orange wires on the stock distributor are connected to the correct terminals on the GM 7-pin or 8-pin ignition module. Your TBI system must first have this capability. Howell, for whatever reason, has just made the choice NOT to allow for computer controlled spark. You'd have to ask them why. Affordable Fuel Injection's kits do control spark timing. Last edited by CSP; 07-20-2012 at 11:56 AM.

08-02-2012, 08:44 AM	#3 (permalink)
the freeak Zeus of the Sluice Join Date: Jan 2005 Member # 41185 Location: In the garage Posts: 2,877	Can the Howell system be retrofit to the OEM style where timing is controlled, or is the wiring/ ECM an issue? __________________ WARNING TO ALL WELDERS!! NP205 for sale

08-06-2012, 02:43 PM	#4 (permalink)
CSP Registered User Join Date: Aug 2000 Member # 1533 Location: Parker, CO Posts: 2,779	You would have to add wiring to the Howell harness and reprogram the ECM to incorporate spark timing. I did it to the Howell kit in my CJ. __________________ 75 CJ5, 258, T18a, 4.27's, Warn 8274, Howell EFI

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