I bought a 91 roller cam 5.0 out of a Mustang to go into my 1971 Grabber. it cam with the stock TFI distributor and I was wondering if anybody knows the easy way to make it work as a stand alone ignition in my car. What do I need to make it work? I want to use it to avoid cam gear issues and to save some money for the heads. I think the stock ignition in the 91 would be fine to the 6000 RPM redline I intend to use, (with a set of AFR 165cc heads and the stock roller cam to start with). CarCraft got 400 HP @ 6100 out of this combo with a freshened stock shortblock and a carburetor (if I remember right!).
Well, you have to understand some fundimentals between a carbed and a Fuel Injection engine, ignition control. 1. Your carbed engine uses centrifigal ignition advance springs and weights for basic timing control with either points or a pulse pickup to trigger either a coil directly or a controller to fire the coil. 2. In electronic control, there is no timing advance hardware to act directly for that purpose. The FI unit has a profile pickup sensor whose only purpose is to signal the computer what the rpm of the engine is and estabilish where #1 cylinder is for reference. This reference is done by the stator that has one space that is different than all the rest, in width. The computer uses this signal along with about 6 other sensors' inputs to "calculate" the timing signal sending it back to the TFI where more processing goes on, then back to the coil to fire it at the correct advanced timing point for each cylinder in turn. This is so fast and good that each cylinder can fire at a different amounts of advance based on changeing rpm, throttle position and the feedback from the oxygen sensors. ................... You should be able to see from this that the FI unit cannot be used because it has no mechinical timing ability, only supplies signals that are processed by the computer for final timing aplication as opposed to the dist that has the mechanical advance hardware acting on the rotor and breaker/pulse pickup plate position directly, allowing the ignition timing to change with rpm and when the coil will fire. Another difference between the FI and the mechinical design is that in the FI unit, the rotor never moves in relation to the spark plug cap post but has a very wide rotor tip so 'electrical' alignment will alway be there with respect to when the spark is fired by the electronics. The Ford FI ignition is very good as a factory design right up to and beyond the rev limiter built into the computer at 6250 rpm. As a side note to the ability of the Ford FI ignition to support operation of the engine, I run a Kenne Bell blower at nearly 8 lbs boost on the stock Ford ignition and the full factory spec .055 plug gap right into the 5500 rpm range without missing. Of course this must be supported by perfect plug wires, cap and rotor as well as good spark plugs. I took the time to explain this so others who have an interest in knowing have a chance to learn the great differences between the two systems.
Thanks Bluegrass, I thought maybe it could function with an aftermarket stand-alone box or the stock computor being fed minimal information like RPM and absolute pressure from a MAP sensor only. Anybody try the new Crane Cams distributor yet? I see it advertised, and it has a built in MAP sensor inside for electronically executed vacuum referenced advance. It also has multiple adavnce programs that are switchable exterally.
Hey Bluegrass, Can you buy a the Holley EFI kit & put it on top of the 302 block for an EFI engine. Or is it more to it than what they say at Holley.
Holley system should be much easier to install on a non efi engine but the cost, in my opinion is to high and the results are not quite as good as the factory dry manifold system. The system has a controller mainly for fuel control and has little to do with ignition. It does have oxygen sensor feed back to control injection and an adjustable controller for idle, mid range and WOT. If you couple that with one of the newer MSD ignition controllers then you have complete ajustability for ignition timing also in the same three areas. The cost for both systems would be well over $1000. You could convert to factory FI for much less if you have the ability to work eveything out with factory wiring, installing the two pipe fuel system and high presure fuel pump. It is better to use a 351 fire order cam installed in a 302 to start because there are issues with fuel injector order as well as fire order involving the computer that is setup to run the 351 fire order (5L HO.). One area that presents a problem of drivability with 302 fire order is the Ox sensors donot relate to some of the cylinders. What that means is the ox sensor normally looks at the results of combustion for cylinders in there own bank and apply correction to the next cylinder to fire, in that bank. The computer is that fast. If a cylinder fires in the oppisite bank and is not paired with that bank's operation, there is an incorrect correlation The two sensors only feed back for there respective banks so they cannot change all injection at the same time. I bring these things up so that one can see the involved relationships that exist in these various systems when planning a conversion because there is more to it than meets the eye.
Thanks Bluegrass, I think I better stay with a carb on top. It might do better for me. When I think about it, Comp Cams said that I colud use a 351 cam & change the fireing order. I'm going to stay with the 302 cam. Do you think I need to pull the 302 out & build it back up new with crank, rod, & pistons or can I just change the camshaft, timeing chain, intake, & a 650 carb on top with a set of headers. I will be getting new heads later.
Cams are interchangable between 5L (302) and 5.7L (351w) engines both flat tappet and roller in there respective blocks. The term HO is applied to differenciate between engine options over the years and not always applied to a cam other that to often say that a 302 HO fire order is the same as a 351. The cam depends on what performance you are after and if the profile is available in either fire order. That way you have a choice. The difference between the two is in the loading of one main bearing web in the block due to two cylinders fireing so close togather at the front main area, so they switched to the (351 order) rear main where the block is a more solid mass. For street use it makes little difference.
