I have some tuning issues with the ZZ9 cam in my 355 roller engine, the thing is/has been for years now running a MAP type 1227730 computer, and frankly recently, over say 4 years...I have been not happy with it's running....driveability is poor in various weather combinations.....

so as long as I have the engine out, and swapping trannies and heads and all sorts of crap around...I need some advice as to what to do about the cam, if anything,....

I am considering a 4-7 swap in firing order as the new LS engines have that....and it's common enough to be dooable from some grinder....

SO, what specific advantages to a 4-7 swap, as I beleive that ZZ cam is more a PIA than it's worth, and I"m NOT PAYING TPIS some 400 bux for a lousey chip....so what grinder is good at the 4-7 swap and making a cam that's fairly easy tuneable with a MAP system?? if not, I may in the radiator changes just include a over top air induction and change in rad angle to accomodate the hood clearance, and switch to a MAF type system to simplify tuning......

anyone with suggestions???

the entire engine is coming out along with tranny doing a swap to a 200 4r and ditching that damn 700r4, i'ts missed it's last shift for me....

about 200 lbs of car weight is coming off with these proposed swaps straight off....

 

Speed Density EFI systems require much more tuning (the chip) than do MAF systems, when using aggressive cams. I suggest you switch to MAF, it will run much better. The 4-7 cam swap will not do much for you except lighten your wallet.

 

I've heard lots of good things about the zz-9 cam. There are some good tuners in the c4 section, ask around. Good luck. Ron B.

 

I think that all you would need to do the swap, would be to swap the 4 and 7 injector and ignition wires.

SUPPOSEDLY

they smooth out the engine, make a bit more power.

 

NO WAY MAN...you would have the sparks firing when the overlap of the valves is both open....the cam has to be changed like what the LS series is....supposedly worth 5-10 hp?? dunno, but IF I decide to ditch the ZZ9 cam and get yet another, it's going to have the 4-7 swap, what the hell.....gonna buy the damn thing anyway....

but no way I 'm having that radical a lift anymore, ...but then again when I rip the engine out again...SOON, I am taking the rad support out, and changing the angle, further forward on bottom, further back on top, to allow room for an up and over airlcleaner assy....so that may include a MAF, and if so, well....maybe that will cure some problems and lemme keep the ZZ9 cam....at any rate as long as the engine is coming out, the tranny is in for yet another round of work, or the way I"M leaning is total replacement with 200 4r, and maybe better luck....

hopefully I can keep down time to less than 2 months....eh??

murphy and all that...

 

If your swapping your firing order, dont you think you ought to move your spark and fuel too?

I figured moving the spark and fuel around by physically moving the wires was more cost effective than reprogramming the thing.

Anyway the only change on a carbed motor is too swap the 4 and 7 spark plug. I expect with the fuel injection you need to move the fuel injection too so it fires at the right time.

 

Most PFI computers just batch-fire, anyway. Sequential is a lot more work to set up, and the performance and economy increase is negligable.

 

Guru, you are missing something here, the CAM has to change sequence so the intake and exhaust are firing opening in CORRECT sequence....as what you are saying, they would be 180* out of sequence, don't forget the cam rotates at 1/2 crank speed, so therefore with your conclusion there the valves would be timed in the exhaust stroke remember

intake, down stroke, intake valbe open....

compression....all valves closed, piston moving up....

power, all valves closed...firing power somewhere near top of stroke...

exhaust....ex valve open, intake closed, piston on way up to puch gas outta there, then the intake opens on some sort of overlap, whatever the cam design allows, and we back to sucking intake of fuel/air....

so it's 4 strokes/cycles for every ONE opening/closing of any valve....

so the piston does 4 trips for every valve opening/closing........

so if you don't change the cam profile, you firing the plug on top of the exhaust stroke.....ain't a gonna work so well....

try it on a carbd engine...see what happens.....

 

I considered the cam swap a given. Sorry for the confusion.