zz motor upgrades?

[Bygblok]

Picked up a first gen zz motor this past weekend. Wanting to maybe do the lt4 cam swap but also debating on using one set of heads or the other. The stock aluminums are L98 heads and not known to breathe well but have a 58cc chamber for a compression ratio up around 10:1. I have a set of 200cc/64cc dart iron eagles that would breathe waaaay better and also a set of WP Sportsman heads that cc the same as the darts but have had some major massaging done on the exhaust side and are intake port matched to a felpro gasket. I know I'll drop compression down to 9.1 with the larger chambers but if I use the thin .015 head gasket I might break even and an iron head will be more forgiving of the thin gasket as well. Any thoughts?

[Ron Sutton]

I'd take the flow advantage of 200cc Darts vs 160cc GM heads over a 1 point compression difference ... any day ... but I think you can get both, by milling on the 64cc head somewhat & getting the compression up. (be nice if you could get to 9.6-10.0)

I'd stay away from the .015 head gasket. It's a band-aid & I've seen too many problems.

Have you flowed the Dart 200cc heads against the WP heads? WP's Ported or not, I suspect the Darts may flow better.

[Bygblok]

I hadn't thought about the cc difference between head gaskets but another suggestion made to me was to use the .028 gmpp head gasket. Compression ratio would be within .05 of the same. That gasket should be happy as long as my block and head surfaces are straight. The Dart heads with an LT4 hot cam would be interesting.

[rchaskin]

Fast burn heads.....
I cannot get over how they run.
I have the 604 crate and it pulls like crazy....

[Bygblok]

Fast burn heads.....
I cannot get over how they run.
I have the 604 crate and it pulls like crazy....

Probably going to use my Dart 200cc heads. Going to toss a cc305 cam in it with full roller rockers also. Might make 350 or so. Good enough for a sleeper camaro!

[Ron Sutton]

What do you have for intake? ... carb? ... ignition ? ... Headers ?

[Bygblok]

Have a choice of intakes on the floor, performer rpm, victor jr are the two I'll think about. Leaning to the performer rpm because it's a tall dual plane. Using my 650dp holley on it until I get my tank to do the ez efi system and an msd hei is my fire. Works great on the sbc in it now. Motor is hurt though and its a metter of time before it hangs a rod out of it or kills the crank. The Darts are being used on the current motor and sure work well. Headers are 1 5/8 hookers. Need new headers anyway because these aren't set up for my angle plug heads. Been "modified" a bit......

[Ron Sutton]

The cam you're talking about makes me go .... Hmmm. I'm not sure I'm on the same page, so I have questions.

I'm sure you hear people often say the "combination" needs to work together. Let's talk about what your end goal is for the engine.

How are you going to use the car/engine?
What do you have for trans? ... rear end gear ratio ?
If auto ... what converter?
What kind of power are you shooting for?
What rpm range do you want the engine to really perform in?


With this info, I can suggest a combination that will work well together.

[Bygblok]

It's a street cruiser...the one in my avatar. Mostly driving in town, rod runs, cruise nights etc. with the occasional full throttle blast to hurt the tires, make noise and relive youth. Trans is a 700r4, gear is conservative at 3.31. Car has been on power tour(was going this year till the motor started trying to beat the bearings out of it) and is driven VERY often. Only doing a 2400-2800 converter and it also has ac to keep it nice for my wife on the really hot days/nights here on the gulf coast. Thats the biggest reason for the small cam but I want to maximize what cam I get without getting out of hand. Current cam in the car is a comp 272 magnum flat tappet hydraulic. Looking for about the same idle quality in a hydraulic roller without killing my budget. I figure I have the dart heads now, why not use them over the l98's even though the l98's would probably not give me any problems for what I do with the car. Thanks for all your time.

[Ron Sutton]

That helps. When you mentioned using Comp Cams 305 Magnum cam, that threw me off, because it is an upper RPM cam, low vacuum, weak throttle response, requiring a lot of gear. I think the 305 cam is too big for your application & the only thing you will like is how it sounds and how it runs above 4000rpm. Frankly, the whole Magnum family is an old design technology with the same lobes on exhaust & intake. I would suggest a more modern design with a dual pattern, tailored to the intakes & exhausts specific needs.

Working with the parameters ... your car weighs around 3700#, 3.36 gears, 700r4 trans, 2400-2800 converter, the 3.48" stroke of the 350 engine ... with the goal of a being street cruiser, mostly driving in town, rod runs, cruise nights etc. with the occasional full throttle blast to hurt the tires & make noise.

I have 3 cam suggestions, based on running specific lifters.

#1
Comp Cams Extreme Energy Hydraulic XE274H with regular hydraulic lifters
For specs, Click Here.

#2
Comp Cams Extreme Energy Hydraulic XE284H, but use Rhoades* hydraulic lifters.
For specs, Click Here.

#3
Comp Cams Extreme Energy Hydraulic XR282HR with hydraulic ROLLER lifters
for specs, Click Here.

All 3 cams will be drivable, build good power & fit well within your use & rpm range. Option 3 will build the most power & cost the most. Option 1 will build the least power & cost the least (of the 3). Option 2 is in-between. We're taking 7-8hp difference, so let your budget guide you.

*Note ... Rhoades lifters use a patented design to "bleed off" duration at lower rpms. As the rpms rev up above idle, the lifters bleed off less & less, until around 3500 rpm, they don't bleed off any ... acting like a normal high quality, hydraulic lifter. These lifters lets you run a bigger cam, to have more midrange & top end power, while still retaining low rpm throttle response, torque & better vacuum. They are a great street lifter, making any cam act "dual purpose." They DO TICK like a solid lifter. If you don't like that sound, don't use Rhoades lifters.

With each of these cams, I would install them slightly advanced ... around 4 degrees ... as long as there is plenty of valve to piston clearance. CHECK THIS.

Don't order pushrods until the engine is all together & you can measure what you need. Often with milled heads, thinner gaskets, different parts, etc, different pushrod lengths are needed. Comp cams offers a quality, affordable pushrods, in lengths every .050".


With any of these 3 cams, here is the rest of the package ...

Dart 200cc heads. Work with your machine shop to mill the heads enough to achieve 9.6-9.8 compression. (Don't do this until you checked the block, as it may need to decked).

Critical: Freshen the heads with a multi-angle valve job, TLC the guides to achieve correct valve guide clearance & install new quality seals ... plus NEW quality valve springs (specifically for the chosen cam), retainers & locks.

Stick with a quality head gasket & stay away from super thin gaskets for your street engine. I'd suggest the FelPro 1043 (.039" but only 8.2cc because it's bore opening is 4.080"). If you need a thinner head gasket, step up the quality of a MLS (multi-layer-steel) Cometic C5877-030 (.030" thick & also 4.080").

Intake: Use the Edelbrock performer rpm intake manifold you already have. Without enlarging the port runners ... match the intake manifold ports & cylinder head ports to the Fel-Pro# 1205 intake gasket.

Carb: Use the 650dp Holley you already have, but install a full rebuild kit with power valve, needle & seats, etc. ... not just gaskets. Spend some time on the carb, ensuring every orifice is clean, throttle blades are smooth, throttle blade gaps are set & the same in all 4 holes. Make sure the accelerator pump arm is adjusted correct & that the needle under the shooter moves super free.

*Note: It needs a 750cfm carb to be optimum, but the only power loss is above 4000 rpm, and it is small, so the 650 will be fine. You said you were going to EFI down the road, so enjoy it with the 650 until you invest in the EFI.

Distributor: Use the MSD HEI style you have. As a baseline, set up the timing advance curve like this: 18 degrees of advance at idle (with no vacuum), advancing to 36 degrees of total timing, all in by 3000 rpm. Once you're driving it, I'd suggest fine tuning this curve to optimize the torque curve. Test running more initial timing & also test bringing the total timing of 36 degrees in earlier in the rpm range until you experience small amounts of detonation, then back it up until you have a safe zone. This is going to vary with the quality of gasoline, so I suggest you buy consistent quality fuel as much as possible.

I can't stress the importance of working with a good machine shop/engine builder that cares about the details & not just running "volume" out the door. At a minimum, pay to have the block & heads surface checked ... and milled slightly if needed. Check crank bore alignment too. Don't cut corners here, these are important. Rebuild your rods & use NEW ARP bolts (around $72).

Have your engine builder take apart the pump & inspect it. If it looks good, have him deburr it & carry on. if it shows wear, buy a quality Melling high volume pump. High pressure is not necessary. Volume is. While it's out, weld the pick up tube to the pump with a 1/2" weld.

I would also suggest you do NOT re-use the stock head & main cap bolts that came out of the engine. Again, go with ARP bolts or studs. ($82 & $40)

Avoid moly rings or "low tension" oil rings for your street engine. Go with chrome rings & regular tension oil rings. It will take longer to "break-in" but the engine will last longer. Use quality parts, bearing & rings so your baby lasts. I recommend Clevite bearings & Cloyes true roller timing chain set. All just a little more $ than the cheap stuff, but long term insurance your engine performs & lasts.

Headers: Go away from the 1 5/8 headers. It is too restricting for this combination.
Either run headers with ...
Standard 1-3/4" diameter primaries 30-32" long, into a 3" collector, with a 2-1/2" exhaust system
-or-
Step headers, that start at 1-5/8" & step up to 1-3/4" diameter primaries 30-32" long, into a 3" collector, with a 2-1/2" exhaust system

I prefer Dynatech for optimum power & quality. Coated #740-19210 (around $650) & painted #740-39210 (around $325)

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This engine should dyno at 385hp (+/-5hp) with the XR282HR cam ... and 7-8 hp less with XE274H cam. Either combo should run great & meet your needs quite well.


I may have forgot something, if so, don't be afraid to ask.

Best wishes.

Ron Sutton

[Bygblok]

The motor is a roller cammed zzz type(early zz3) and it's so new that I won't be touching the bottom end at all. The only reason I had considered the cc305 is because a buddy of mine had it in his LT4 but it was procharged and that cam works really good on a boosted motor. My dart's only have 12-15k miles of easy street driving on them at this point so I may just clean them up and be done. The carb will be gone quick also in favor of my new in the nox FAST EZ EFI setup I hope to plumb and run very soon. Lots of big changes to make it even better to drive. Will be going with my serpentine belt drive and quicker steering box from a later fbody car. Hadn't planned all this until the current motor started to pound itself apart. Bummer for me because it runs so damned good!

[Bygblok]

got a pretty good deal on a near new set of Dart Pro1 200cc/64cc heads. Going to toss those on the ZZ motor using the factory cam(.480/234 I think it is) and use a new set of 1.6 rollers rocker to get the lift up to .512 or so. An .028 head gasket will keep my compression around 9.8 to 1 so it should live fine like that. Going to run the performer rpm with the FAST system so I hope the fuel economy will be a little better too. Won't be a stump puller but it should be fun to drive and have a nice little bump to it. CHanging the converter in my 700r4 to a 25-2700 stall with the lockup too. Still going to miss the SM Nats though now...dammit