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Engine Specific Tech
94-95 5.0 - Specific
Converting a small block 94/95 from MPFI to TBI - in case anyone else wants to go this route
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<blockquote data-quote="shovel" data-source="post: 1588399" data-attributes="member: 29855"><p><strong><em><span style="color: rgb(97, 189, 109)">Reminder that this is all what I chose to do, it is not a how-to guide, it's not the only way to do things. </span></em></strong></p><p></p><p>Throttle linkage, etc -</p><p></p><p>To maybe save some people some digging around I used a Ryanstar Throttle Cable Bracket RS-BT001 - there are a lot of different brackets on the market and brand probably doesn't matter but I specifically went with a billet aluminum one that has a slotted track for the cable adjuster because that allowed me to also use Allstar Performance #ALL54273 Ford throttle bracket, which has the correct size slot and set screw to hold the stock throttle cable for a ~83 Mustang GT (there are two lengths, I went with the 20" length) . Finally I ordered a cheap set of assorted throttle ball studs for the Ford cable to connect to. That all worked together - the bracket mounts to the TBI mount studs, the Allstar bracket adapter mounts to the throttle cable bracket, the OE style early 80s throttle cable mounts to that, the "carb" end mounts to the ball stud, the ball stud mounts to the Holley TBI, the cable mounts to the firewall and the other end of the cable mounts to the stock gas pedal. The only thing that needed any custom work was I had to enlarge the firewall mounting holes in the cable housing so it would screw into the stock holes in the SN95 firewall. This was painless. </p><p></p><p>Cruise control cable is a different story, I have not yet addressed that. I think I know how I will address it but that's going to wait for a future post because I want to get the car driving first (and I'll talk about why it's not driving yet, in another post below)</p><p></p><p>[ATTACH=full]50063[/ATTACH]</p><p></p><p>Other notes here:</p><p></p><p>Wiring is still messy, I want to get it all running first before finalizing the wire management.</p><p></p><p>Because the specific TBI system I decided to go with is the Holley Sniper 2, and I included the PDM (power delivery module) and the Hyperspark ignition module and the Hyperspark distributor - I mounted them like so.</p><p></p><p></p><p>[ATTACH=full]50069[/ATTACH]</p><p></p><p>The Holley TBI contains its ECU onboard, meaning there is not a separate ECU to mount somewhere else. The PDM is kind-of like their equivalent of our familiar CCRM, basically it's a wiring distribution panel with a few solid state relays in it. The Hyperspark ignition module is about the size of our CCRM so I literally just mounted it to the stock CCRM bracket. Can't really see it in this photo but it was super straightforward I just drilled new mounting holes and plopped it on there like it was made to be. </p><p></p><p>The ignition coil has a slightly different footprint than ours and it's not absolutely necessary to use Holley's, you could use your stock coil, but in my case since I opted to just go all in with their stuff I cut the little vertical tab off the top of the stock bracket to fit the coil on there, drilled and tapped new holes and plonked it on. I also deleted the power steering pump and a/c compressor but that's unrelated to this topic and not necessary for the coil perch modification on its own.</p><p></p><p>Notes about the PDM specifically.</p><p></p><p>First is that Holley's wiring schematic asks you to connect both the positive and negative leads of your fuel pump to the PDM. In our case the negative lead of our fuel pump goes to the inertia shut-off switch in the trunk and then grounds locally back there so wiring it like Holley says would be a pain in the butt and also bypass a safety feature. I just wired the positive side of it and it works fine, no apparent problems.</p><p></p><p>Second is that their fan controller is a single channel only and only supports 25A continuous, which means it will not run our stock fan in its high speed mode. It'll run for a brief while and then overheat the PDM. This is actually the third "Major Name Brand" solid state fan relay I've used that has lame, way too low current capacity for the actual fans actual people use in the real world. It's extremely disappointing that companies who are literally in the hot rod business don't seem to realize that people making big power are also making big heat and want to run big fans - in this case I'm not even running a "big fan" it's the stock one Ford specified for this car. So instead I'm running two 80A relays.</p><p></p><p>I wanted to have the fan turn on low speed when the A/C is turned on. I know that as of right now there is no A/C on this car - I'm putting an electric A/C system in there next but just like with the cruise control, I want to get it driving first and then put the amenities back in place. The Holley has an input GPI that can be used to tell it when the air is on so I've pre-wired that for later and it has a GPI output that provides "short to ground" in order to trigger a relay or the PDM for dedicated fan control. I have wired this to the trigger coil of one 80A mechanical relay and I've wired the high current normally open (N.O.) side of that relay to the low speed side of the engine cooling fan. That means the Holley can turn the fan on low speed either because its temperature has exceeded a threshold I set or because the air conditioner is on, or both. </p><p></p><p><em>I HAVE READ</em> that stock 2 speed engine cooling fan uses two different windings for low and high speed which means it's not good to supply power to both of them at the same time. This is different from some other fan systems that just use a 0.25 ohm 200W resistor to enable the low speed, in which case it completely doesn't matter if they're both powered at the same time. </p><p></p><p>Since a dual winding fan should not receive power to both windings at the same time I wired a second relay to the high speed input and wired its normally closed output to the high current input of the 2nd, low speed fan relay. In other words constant battery power is supplied to the high current input of the high speed relay and when the engine is cold that current passes through the NC output to the high current input of the 2nd relay, and then the Holley can turn the 2nd relay on and off whenever it wants to run the fan in low speed mode. But when the high speed relay is triggered it cuts off power to the 2nd relay and supplies power to the high speed winding of the fan. They can't both be powered at the same time. To trigger this first relay I got a 210F coolant temperature switch that I screwed into one of the bungs in the rear coolant passage of the Weiand intake manifold. That provides an analog "backstop" so if the Holley fails to power the fan on for any reason or the low speed fan isn't providing enough cooling a separate, independent analog thermal switch will kick in and run the fan in high speed mode. </p><p></p><p>That should make sense to you if you're qualified to do wiring, it's not complicated. I used a lot of words to make sure the information is complete. You don't have to do it this way. The most important part to remember is that the Holley PDM doesn't supply nearly enough power for the stock fan so you have to bypass it with a real relay rated for at least 60 amps. Do with that what you will.</p></blockquote><p></p>
[QUOTE="shovel, post: 1588399, member: 29855"] [B][I][COLOR=rgb(97, 189, 109)]Reminder that this is all what I chose to do, it is not a how-to guide, it's not the only way to do things. [/COLOR][/I][/B] Throttle linkage, etc - To maybe save some people some digging around I used a Ryanstar Throttle Cable Bracket RS-BT001 - there are a lot of different brackets on the market and brand probably doesn't matter but I specifically went with a billet aluminum one that has a slotted track for the cable adjuster because that allowed me to also use Allstar Performance #ALL54273 Ford throttle bracket, which has the correct size slot and set screw to hold the stock throttle cable for a ~83 Mustang GT (there are two lengths, I went with the 20" length) . Finally I ordered a cheap set of assorted throttle ball studs for the Ford cable to connect to. That all worked together - the bracket mounts to the TBI mount studs, the Allstar bracket adapter mounts to the throttle cable bracket, the OE style early 80s throttle cable mounts to that, the "carb" end mounts to the ball stud, the ball stud mounts to the Holley TBI, the cable mounts to the firewall and the other end of the cable mounts to the stock gas pedal. The only thing that needed any custom work was I had to enlarge the firewall mounting holes in the cable housing so it would screw into the stock holes in the SN95 firewall. This was painless. Cruise control cable is a different story, I have not yet addressed that. I think I know how I will address it but that's going to wait for a future post because I want to get the car driving first (and I'll talk about why it's not driving yet, in another post below) [ATTACH type="full" alt="1780947379544.png"]50063[/ATTACH] Other notes here: Wiring is still messy, I want to get it all running first before finalizing the wire management. Because the specific TBI system I decided to go with is the Holley Sniper 2, and I included the PDM (power delivery module) and the Hyperspark ignition module and the Hyperspark distributor - I mounted them like so. [ATTACH type="full"]50069[/ATTACH] The Holley TBI contains its ECU onboard, meaning there is not a separate ECU to mount somewhere else. The PDM is kind-of like their equivalent of our familiar CCRM, basically it's a wiring distribution panel with a few solid state relays in it. The Hyperspark ignition module is about the size of our CCRM so I literally just mounted it to the stock CCRM bracket. Can't really see it in this photo but it was super straightforward I just drilled new mounting holes and plopped it on there like it was made to be. The ignition coil has a slightly different footprint than ours and it's not absolutely necessary to use Holley's, you could use your stock coil, but in my case since I opted to just go all in with their stuff I cut the little vertical tab off the top of the stock bracket to fit the coil on there, drilled and tapped new holes and plonked it on. I also deleted the power steering pump and a/c compressor but that's unrelated to this topic and not necessary for the coil perch modification on its own. Notes about the PDM specifically. First is that Holley's wiring schematic asks you to connect both the positive and negative leads of your fuel pump to the PDM. In our case the negative lead of our fuel pump goes to the inertia shut-off switch in the trunk and then grounds locally back there so wiring it like Holley says would be a pain in the butt and also bypass a safety feature. I just wired the positive side of it and it works fine, no apparent problems. Second is that their fan controller is a single channel only and only supports 25A continuous, which means it will not run our stock fan in its high speed mode. It'll run for a brief while and then overheat the PDM. This is actually the third "Major Name Brand" solid state fan relay I've used that has lame, way too low current capacity for the actual fans actual people use in the real world. It's extremely disappointing that companies who are literally in the hot rod business don't seem to realize that people making big power are also making big heat and want to run big fans - in this case I'm not even running a "big fan" it's the stock one Ford specified for this car. So instead I'm running two 80A relays. I wanted to have the fan turn on low speed when the A/C is turned on. I know that as of right now there is no A/C on this car - I'm putting an electric A/C system in there next but just like with the cruise control, I want to get it driving first and then put the amenities back in place. The Holley has an input GPI that can be used to tell it when the air is on so I've pre-wired that for later and it has a GPI output that provides "short to ground" in order to trigger a relay or the PDM for dedicated fan control. I have wired this to the trigger coil of one 80A mechanical relay and I've wired the high current normally open (N.O.) side of that relay to the low speed side of the engine cooling fan. That means the Holley can turn the fan on low speed either because its temperature has exceeded a threshold I set or because the air conditioner is on, or both. [I]I HAVE READ[/I] that stock 2 speed engine cooling fan uses two different windings for low and high speed which means it's not good to supply power to both of them at the same time. This is different from some other fan systems that just use a 0.25 ohm 200W resistor to enable the low speed, in which case it completely doesn't matter if they're both powered at the same time. Since a dual winding fan should not receive power to both windings at the same time I wired a second relay to the high speed input and wired its normally closed output to the high current input of the 2nd, low speed fan relay. In other words constant battery power is supplied to the high current input of the high speed relay and when the engine is cold that current passes through the NC output to the high current input of the 2nd relay, and then the Holley can turn the 2nd relay on and off whenever it wants to run the fan in low speed mode. But when the high speed relay is triggered it cuts off power to the 2nd relay and supplies power to the high speed winding of the fan. They can't both be powered at the same time. To trigger this first relay I got a 210F coolant temperature switch that I screwed into one of the bungs in the rear coolant passage of the Weiand intake manifold. That provides an analog "backstop" so if the Holley fails to power the fan on for any reason or the low speed fan isn't providing enough cooling a separate, independent analog thermal switch will kick in and run the fan in high speed mode. That should make sense to you if you're qualified to do wiring, it's not complicated. I used a lot of words to make sure the information is complete. You don't have to do it this way. The most important part to remember is that the Holley PDM doesn't supply nearly enough power for the stock fan so you have to bypass it with a real relay rated for at least 60 amps. Do with that what you will. [/QUOTE]
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94-95 5.0 - Specific
Converting a small block 94/95 from MPFI to TBI - in case anyone else wants to go this route
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