1992 5.8 cylinder temp differences
03-17-2015, 10:59 PM
#11
Senior Member
Just don't go overboard on the timing. The initial number is not nearly as important as the total. Ten degrees will give a very good, clean idle. At the first hint of detonation, back it off about 2 deg.
03-18-2015, 01:34 PM
#12
I agree though, changing it back now would be rather useless unless he wants to do it just so it's correct for the engine.
Rob, in his original post he lists the cam as one of the mods.to the engine. I am assuming (yeah, I know what happens there) its an aftermarket cam. Since the 302 and 351W cams have the same physical dimensions (for a given grind) most manufacturers grind them to the older 15426378 pattern and advise the installer that the 351W will require re-ordering. Obviously if this was a distributorless/COP engine the cam would have to match the programming of the ECM. The part about having to rewire a 351W with an aftermarket cam is as old as the engine itself, literally.
FWIW, When the W motor was developed, the engineers decided it ran smoother with the revised order. All they did was took two groups of two cylinders (5-4 and 3-7) and moved them to opposite sides of the firing order. The crank is the same but intake strokes became power strokes and exhaust strokes became compression strokes. This also carried over to the 351M and 400. I think it was a change for the sake of appearances. You have to make it look like you're doing SOMETHING. The official answer was reduced torsional stress on the crank/improved harmonics. I think it was a solution in search of a problem.
As far as the injection system is concerned, I don't think it really matters does it? If my understanding is correct this is a non-sequential system so I don't think the revision would have any effect on mixture distribution quality. Oh well, maybe I'm way off base. I'll quit rambling.
FWIW, When the W motor was developed, the engineers decided it ran smoother with the revised order. All they did was took two groups of two cylinders (5-4 and 3-7) and moved them to opposite sides of the firing order. The crank is the same but intake strokes became power strokes and exhaust strokes became compression strokes. This also carried over to the 351M and 400. I think it was a change for the sake of appearances. You have to make it look like you're doing SOMETHING. The official answer was reduced torsional stress on the crank/improved harmonics. I think it was a solution in search of a problem.
As far as the injection system is concerned, I don't think it really matters does it? If my understanding is correct this is a non-sequential system so I don't think the revision would have any effect on mixture distribution quality. Oh well, maybe I'm way off base. I'll quit rambling.
The "incorrect" way does indeed work because it's all on the cam itself at that point. The crank matters, but we already know what that is and you're good to go. If you sense knock, you can drop it back a bit, or just go to a higher octane fuel and it will run better in general.
03-18-2015, 07:45 PM
#13
Senior Member
Most of my active engine building was done from the late 70's through the early 90's and back then it was the norm for aftermarket W cams to be 154. Crane and Isky both did it, can't remember if Comp Cams did or not. The last engine I built was a BBC for my old jet boat in 2003 so its been a while.
P.S. You ever play with the 231 Buick V-6? Popular Jeep swap. If you want your patience tested just wait until somebody sticks an odd fire distributor in an engine with an even fire crank (that you built for them) and then brings it back complaining that it misses and pops. Chitty bang-bang literally. Kinda funny in hindsight but not so much at the time. Customer had "a guy" who was going to do the ign. install and run-in/tuning. Of course when it didn't run right I became the first suspect.
P.S. You ever play with the 231 Buick V-6? Popular Jeep swap. If you want your patience tested just wait until somebody sticks an odd fire distributor in an engine with an even fire crank (that you built for them) and then brings it back complaining that it misses and pops. Chitty bang-bang literally. Kinda funny in hindsight but not so much at the time. Customer had "a guy" who was going to do the ign. install and run-in/tuning. Of course when it didn't run right I became the first suspect.
Last edited by PerryB; 03-18-2015 at 07:55 PM.
03-18-2015, 10:43 PM
#14
Most of my active engine building was done from the late 70's through the early 90's and back then it was the norm for aftermarket W cams to be 154. Crane and Isky both did it, can't remember if Comp Cams did or not. The last engine I built was a BBC for my old jet boat in 2003 so its been a while.
85-95 302 and 69-95 351W cams... over 80. All of them get the 1-3-7 FO
For the 260-302 and 351W, 1-5-4 FO cams all start w/ "31" and "35" is used for all 1-3-7 cams.
Isky doesn't spell it out as clearly, but does leave the note that w/ correct changes to wires, either can work, w/ exception of pre '85 302 not being able to use those hydraulic camps. They also leave messages that the 351W cams are 1-3-7, as are the 5L HO and they also don't just offer up a 1-5-4 grind.
Lunati does the same, but goes all the way back to listing the 1962 221 V8 and as new as '96 on the 302HO and 351W. Like the others, it says all 351W and 302HO cams are 1-3-7.
P.S. You ever play with the 231 Buick V-6? Popular Jeep swap. If you want your patience tested just wait until somebody sticks an odd fire distributor in an engine with an even fire crank (that you built for them) and then brings it back complaining that it misses and pops. Chitty bang-bang literally. Kinda funny in hindsight but not so much at the time. Customer had "a guy" who was going to do the ign. install and run-in/tuning. Of course when it didn't run right I became the first suspect.
A problem like that one is about as much a gremlin as any electronic problem can get and I'm glad it wasn't me.
03-18-2015, 11:10 PM
#15
Senior Member
I might have unwittingly said something confusing (go figure). By BBC I meant big block chevy.
03-18-2015, 11:56 PM
#16
Pay attention for a moment... I'm new here and trying to be nice. I do NOT want to argue w/ you, but your attitude's gotten beyond boorish.
Please- let this go.
03-19-2015, 11:45 PM
#17
Senior Member
I must've come across wrong on that one,Rob. I've never had any animosities whatsoever on this topic. I like tossing the technical football around. The only reason I threw out the boat motor thing was to illustrate the point that I've not had my hands inside an engine block for several years.
03-20-2015, 02:18 AM
#18
I must've come across wrong on that one,Rob. I've never had any animosities whatsoever on this topic. I like tossing the technical football around. The only reason I threw out the boat motor thing was to illustrate the point that I've not had my hands inside an engine block for several years.
Admittedly, I'd never even begin to want a 454 or any build from one, if for no other reason, their wretchedly poor rod ratio. Plus, honestly speaking, ya just seemed to wanna argue and I can do that any time. I prefer not to, of course. 
Not to be a smartass, I looked at COMP CAMS, Lunati and Isky... their 351W cams apparently all have the 1-3-7 FO as I thought. Sure, they'll tell us we can use the older FO if we have that grind by simply changing the wires, but they don't just make them w/ the old FO for the 351W in case someone wants one. I looked rather deeply through COMP and they seem to offer 40 cams for the (technically 221) 260-302 and over 80 cams for the 302HO and 351W.
I'm just glad he got the truck figured out! I'm just back from a very long day trip, so it's off to bed and tomorrow, it's ... well, I don't know yet, but I'll think of something!
