I am collecting parts for the 350 buildup. It is going to be a zz4 clone. I was thinking about using 1.5's on the intake and 1.6's on the exhaust side. Is anyone running this, opinions, suggestions? Should I run the 1.6's on the far exhaust ports(1,2,7,8)or all? This is on a TPI motor with a ported plenum and Accel intake, stock runners for now, $$ for slp runners later.

Thanks
Jeremy

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WE WILL MISS YOU #3
92 Z conv
5-spd B&M shifter
home-made ram air, air foil, headers, no cat, TB bypass, kevlar pads, slotted rotors, BMR panhard, alston SFC, 3.42's, Edelbrock STB, 350 in the works

 

There is no benefit that I know of to downgrading any of the rockers in that application. IMHO you should run the 1.6s on all of them. OF course, if it's really a ZZ4 clone, you'll need some different valve sprimgs, of a larger diameter specifically, to accomodate the lift; so the heads will require some work if they're regular stock aluminum L98 heads.

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"So many Mustangs, so little time..."
ICON Motorsports

 

the springs are good to 525 lift and are new. The stock rockers off the 305 TPI are 1.5's correct? That is what I was going to reuse if I didn't buy a set of rollers. the heads have the work done already as well as some breathing help. If I go to 1.6 all around, the lift will be to high on the intake side. So wil I be better off geting new springs and the 1.6 or going 1.5 all around in this situation.

Jeremy

 

It's not just springs that you'll need for extra lift. Make sure the valve stem has been modified to take the extra lift also. If it hasn't the the spring retainer will hit the top of the valve stem. You'll also need to do a mockup assembly to check how much valve to piston clearance you have. The 1.6 rockers could give too much lift for the pistons. You need a minimum of .100" between the pistons and the valves when open. If the block isn't decked then there's usually not a problem but you need to check all the measurements anyway.

My big block just came back from the machine shop last week. .091" clearance on the intake and .139" on the exhaust. I could go with more lift on the exhaust but absolutly no more on the intake. Actually I could go from the 1.7 rockers on the exhaust to a 1.8 rocker and be right on the money for clearance but I'm not buying another set of rockers just to use 1/2 of them.

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So for a daily driver should I just not worry about it and stick with the 1.5's?

Jeremy

 

What heads? Are they really going to be the ZZ4 (L98) heads? If so, it's probably worthwhile to step up to the 1.6s... the 1.6s and 1.5s are the same price after all.... If you're going to run the actual ZZ4 cam too, that means that even with 1.5s you'll need to get the spring pockets cut, so again, there's no penalty, cost or otherwise, to using the higher lift.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I have alum. heads off a vette and I will be running the real zz4 cam. This is truly going to be a learning experience.

Jeremy

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WE WILL MISS YOU #3
92 Z conv
5-spd B&M shifter
home-made ram air, air foil, headers, no cat, TB bypass, kevlar pads, slotted rotors, BMR panhard, alston SFC, 3.42's, Edelbrock STB, 350 in the works