I have a zz4 [603 crate] I race in the scca, I am upgrading the valve train, I have comp cams push rods, Lunati 1.6 aluminum roller rockers and am putting on LS6 beehive valve springs with comp cams retainers, the springs are good to .580 lift. With the 1.6 rockers I will have .506 intake and .544 exhaust lift. I know I am ok on the intake side but someone told me I might have a problem with the exhaust valve retainer hitting the valve seal. I cant seem to get a answer anywhere, can anybody tell me for sure?

 

I would check with a reputable machine shop, but if memory serves me right you start tapping the guides around .550".

 

Even with the LS6 springs amd Com Cams retainers?

 

With something as critical as that, I measure.

What do you think will happen if you go with what someone tells you and it turns out he's wrong?

Jake

 

Ok, well this being my first Chevy engine I thought with all you Chevy experts one of you would know, also with as many of these ZZ4 engines out there. I sure knew what the clearances were on my 550hp 351C and my 429CJ. Acording to my book that came with the ZZ4, stock zz4 spring installed height is 1.78 and acording to classof87z the retainers will hit at .550 of lift, that means they will hit at 1.23 open, the book says coil bind is 1.21, that means they will hit before coil bind?
Can anybody confirm that?

 

Once you swap to beehives don't assume that the installed height is going to be the same as with the standard retainers. Ditto the retainer-to-seal clearance. When you're on the ragged edge you have to measure everything for yourself if you want to be sure.

Yes, it seems believable with stock gear that the retainer would hit the seal before the spring binds.

 

Ok everybody, I went out and measured everything, this is what I came up with. Installed height on the springs is 1.74 not 1.78 as my book states. Height when the retainer hits the seal is 1.175, that gives 0.565 clearance. The book states coil bind is 1.21. Now if I was going to run the LT4 hot cam I would run 1.6 rockers and lift would be 0.525 intake and exhaust. If my math is correct that would mean I would have 0.005 clearance before coil bind. GM sells a kit that would do this??? Wow.

Anybody want to buy a almost new ZZ4? Im going back to Ford, goodbye Obama motors.

 

Ok, with much studying I have found a cam I am going to put in.
Stock ZZ4 cam is 208-221 @.050 duration, ,474-510 lift with 1.5 rockers

Am putting in Comp Cams 08-414-8, 230-234 @.050 duration, .474-.474 lift with 1.5 rockers.

I am putting in Lunati 1.6 full roller rockers, that will put me at .506-.506 lift.
Also Comp Cams beehive springs, retainers, locks, seats, and Comp Cams push rods.

Will see how it works on the race track and let you ZZ4 experts know, lol

 

when you say that the book claims that spring bind will occur at 1.21, what springs are you talking about?

 

Stock ZZ4 springs will coil bind at 1.21 acording to my ZZ4 book.
thats why I am changing to comp cams 26915-16 beehive springs.
with those springs you can use 1.6 rockers

 

this is what confuses me. Was you actually thinking about putting a cam in while using the stock springs? When I dropped the LT4 hotcam in, I swapped springs. You have to. Like you said, coil bind for stock is 1.21. Like you said, .565 clearance. So what are you so worried about?

Then you go on to say 0.005 clearance before coil bind, then you ask why GM would do that. They didnt. GM doesnt make a kit for the ZZ4. They make a kit for the LT1.

Maybe Im reading something wrong. It looks like at first you was running the LS6 springs, then you started talking about the stock ZZ4 springs. Im lost

 

Ok, read carefully, I had a stock ZZ4 that I wanted to upgrade. If you want to put the LT4 hot cam in you dont need to change the springs acording to GM. You do in a LT motor. All I had to do was change rockers and the cam acording to GM. The book says 1.78 instal height on the springs and 1.21 coil bind. Lift with the hot cam is .525 on both sides, subtract 1.78 with 1.21 and you have .570, thats fine cause that leaves you .045 to coil bind. My engines valves are 1.74, subtract everything and you get .005. understand? This is the way my engine came from GM, thats why you never believe the book and measure for yourself. .005 is way to close and engine builders recomend .060 minimum clearance for spring coils.

 

Based on your numbers, you'd have .005" clearance before the retainer contacts the seal, not coil bind. Re-check your math.

Jake

 

Yeah I did read carefully. You also said that you were swapping to the LS6 springs. Did you check the installed height with them? What was that value?

You go from saying that you are swapping the springs out, then you start worrying about the stock springs.

 

No, go back and look again at what he is saying.

1.74-1.21= .530 with .525 lift .530-.525 = 0.005 until coil bind

Im just trying to figure out why he talks about swapping to the ls6 springs, then does all the figuring with the stock zz4 springs

 

Ok, I am just trying to let everybody know that you should check your own engine before you go putting things in it, don't believe what a book says, I am glad I checked or I would have probably lost a engine. My engine is in a Busch road race car I race in the SCCA, it will be turning 5 to 6,000 constantly. I decided to change everything to get a good running engine and have plenty of clearance on everything.

This is what I am putting in the engine this weekend
Comp Cams camshaft 08-414-8 230-234 @.050, .506-.506 lift with Lunati aluminum full roller rockers, comp cams beehive springs 26915 and comp cams pro magnum push rods.

This was put together for me by a 40 year engine builder,
Acording to him it should produce 430hp and be very reliable, could even be a good street engine for reliability.

 

OK, I see it now. Thanks.

Jake

 

so what made you decide against the LS6 springs?

 

Just a higher quality spring, I was told by a engine builder they are lighter and for every gram of weight saved on the valve side of the rocker equals 40 rpms. For street use the LS6 springs are fine, they cost about $65 compared to $170 for the comp cams. The size and spring rate are almost exactly the same.

LS6 springs part #12499224
Comp Cams springs #26915-16

 

I gotcha now. Do you happen to have the coil bind figures on the LS6 springs?

 

LS6 12499224 coil bind is 1.085

 

I have the results, I have in my ZZ4,

Comp cams push rods 7608-16
Comp cams bee hive springs 26915-16
Comp cams retainers 787-16
Comp cams locks 648-16
Comp cams valve seats 4705-16
Lunati voodoo aluminum roller rockers 1,6 ratio

Installed height is 1.735, height to retainer valve seal contact is 1.08, that leaves .655, stock ZZ4 clearance is .565, thats a difference of .09.
This means you can run 1.6 rockers with the stock ZZ4 cam, you can run this set up and put a better cam in later and not have to change anything bu the cam. I am very pleased to finally find all this out. Feel free to ask any questions.