280Zrewind

I was wondering about the ACDelco solution, but didn’t know if friction modified meant more or less friction. Less didn’t seem like a good idea. Bottom line, if it works, it works. Maybe I’ll use the fill of Redline to ‘wash away all the remnants of my sin’ of using GL5 and then give ACDelco a try. Still, I would be interested to know if anyone had tried the stronger spread spring solution asked about in the original question. It was billed back in that old original post as maintaining good shift performance when the transmission was exposed to a life of ‘spirited’ shifting. Dennis

I hope that’s it. I had a fill of GL5 80-90 for about a month and only a few miles, figured out that was a bad thing and drained it out. I have Redline MT 90 on order and will give it a try soon. This question was just about getting a step ahead should further action be needed.

I have an FS5W71B of unknown history that goes into second and third just fine except for a frequent grind. I understand it’s a fairly common problem and I’m pretty certain it not a clutch release issue because I don’t have a problem getting it into reverse. May need new synchros, but I read in a really old post on another forum that putting stronger spread springs behind the shifting inserts helped avoid that problem. The idea was that it pushed the synchros into the cones with more force. Any experience with that? Dennis

Sorry I don’t recall a reference. I read this more than two decades ago when I was trying to figure out if my 95 Ford engine needed the injector cleaning that my Z got. The 95 went well over a 100,000 miles and never needed the injectors cleaned. The 76 Z couldn’t pass our Phoenix, AZ area emissions test if the injectors weren’t cleaned more frequently. It would run too rich. Nothing that was noticeable in performance, just failed emissions on high HC. Sometimes as an old guy you wonder why you remember certain things with great clarity and are vague recalling things of far more importance!

Very interesting ignition discussion! I have some info on fuel injectors that I read many years ago. The injectors in our Z’s need cleaning more often then those a generation late. The vintage of injectors in our Z’s we’re tested by running a test engine for many hours continuously and there were no issues with gumming up. What they missed was that an engine doesn’t run continuously during its life. When the inservice engine was shut off a bit of fuel would remain in the injector, evaporator and leave behind varnish. That would make the injector slow to close after the electric signal was cut off and would lead to a fuel mixture that was too rich. Later generations solved this problem though I don’t remember how. The most effective way to clean was a cleaning kit that consisted of a pressurized can of concentrate cleaner that could also serve as engine fuel and the associated plumbing to connect this to the fuel rail, control the pressure and a pinch clamp to block off the gasoline return line. (I think you blocked the supply by pulling the fuel pump fuse, but I don’t remember for certain.) When I owned my 76 (bought it new), I owned one of these kits and it worked very well.

Here’s what seems strange to me - three in a row that are showing the symptom. Could be random chance, but how likely. So looking at my rust bucket donor car it appears that the fuel rail is a little lower in the back than in the front. Is it possible some contamination made its way into the back three injectors? Pretty far out, but I can’t think of anything else that matches the three and three plug situation I like the suggestion of pulling the cold start valve and checking operation. I think it’s more likely a continuous dribble than a faulty signal. Not sure how that would match the three and three situation though.

Thank you! I do wonder though why maintaining vacuum with injection is more critical than carbs. Maybe the difference is with injection the intake manifold is pretty much wide open except for the throttle plate and carburetors have venturi and such that provide a little restriction and help maintain vacuum?

Got some camshaft info that may be of interest. Canceled my order w Motorsport and went straight to Schneider cams for a regrind of the stock cam to their equivalent of Motorsport Stage 3 for fuel injected and rocker arm reconditioning. According to Schneider: - The stock cam is made of better steel then any cam blank you can get in the US - You should check for cracks in the area of the dowel pin. This can be caused by not pulling the cam gear off straight - The stock rocker arms have a wear surface against the cam that is better then most - Keeping the valves properly adjusted is important because excess clearance can cause the arm to wobble and increase wear. The springs on the pivot end are not very effective at preventing this. - Stage 3 is the hottest they recommended for a car that will have AC w a manual transmission. It requires an upgraded fuel injection system (which I’m planning). From another source I was told the difference between an injected and a carburetor cam grind is the need to maintain adequate vacuum w injected. Not sure why this is so. They both restrict air w throttle plates. Maybe somebody has a better explanation. I really appreciate suppliers that are willing to share knowledge.

Thank you for the replies! This could be very useful to me going forward.

Just for my info - I saw in previous posts that the ZX ignition was an improvement over the Z. What did they do to upgrade? I may be interested in the upgrade for my project down the road.

Just saw in a previous post that you removed the ballast resistor.

I looked up coil resistance for GM HEI on line and found the range should be .6 to 1.5 and you probably know this, but according to this post, you shouldn’t use a ballast resistor (or equivalent wire is more common now). The wiring diagram for the 78 doesn’t show one, so unless someone’s done something funky in the past, you won’t have one. I don’t know what output circuit the HEI uses, but I could be current controlled so any coil impedance in the range doesn’t make a difference.

Thanks! I’ve seen some of them. Let’s hope this choice of system doesn’t make me guilty of excess cleverness. 😁

I may be sorry later, but for fuel I bought the Fast fuel injection control system designed for the Z and aftermarket injectors. That system has oxygen sensor feedback in the exhaust and can handle a variety of setups. It does away with the cold start valve and a number of other devices that were part of the OE fuel injection system. I don’t know if anybody else is having this problem, but my camshaft kit bought through Motorsport Auto (a Schneider cam) is being held up because Schneider’s magic formula that goes in the break in oil is on back order. I promised I wouldn’t start the engine w/o the formula if Motorsport would send me the cam kit so I could get the head to the machine shop. They won’t budge.

My project combining one complete rust bucket with one no rust, but missing stuff 78 Z isn’t running yet, but in both the OE electronic ignition were making a strong spark. Tested it by powering up the system and spinning the distributor. Their idea of putting the control box in the cabin make have been a good one. For now I’m going w the OE and time will tell if I made a good choice. I grew up with 60’s vehicles when break point ignitions and carburetors were the standard and both are not without their problems. It almost seemed like a miracle to me when I bought my new 76 Z with it’s ‘advanced’ systems.