ddahlgren

Will the hot cam springs and retainers work ok for a ZZ4 cam and what valve spring tension? Seat pressure and open pressure. The lift will be slightly less than a hot cam at 0.505/0.510 with 1.6/1.5 intake/exhaust rockers. Howards has steel ball long slot rockers for around 100 and for light springs would be just fine. Next question will the hot cam springs and retainers provide enough clearance for lift without machining the heads?

Kevova

should be ok on LT!/4
http://www.gmassie.net/13secss/lt4_hot_cam_specs.html

ddahlgren

Next question do the Hot cam parts all fit on a '91 L98 without machining and no binding or problems?

tequilaboy

I've used the LT4 springs/retainers and shims on my 1988 113 heads along with 1.5 rockers and a comp 503 cam (0.503/0.510 lift) and ran them for a few years before moving to an AFR head.

I don't think there is enough retainer to seal clearance to run positive seals on the exhaust valves, but intake side should be fine. The exhaust guides are taller than the intake guides. On the exhaust, I only used the old square ring valve seal and added some oil shields that would fit over the springs.

I still have the heads with this spring setup out in the garage if want me to pop a couple springs off and take some crude measurements. I may have some old pictures around somewhere. I will look for them and post them here if available.

ddahlgren

Any help you care to offer would be appreciated.

cardo0

Well the problem with the "Hot Cam/LT4 springs" is the LT4 had light weight valves and the spring rates for those springs aren't much more than other stock springs. LT4 valves are at least 20% lighter than LT1 valves using hollow stems and titanium. I've read that swapping LT1 springs to LT4 Hot Cam springs you with still have high RPM float and then I also read they will work well enough.

The trick spring swap these days is the LS6 beehive springs. But I found even though the LS6 springs are only 70 bucks the full hardware kit is $420. $220 just for the stupid passive locator cups. So the cheap LS6 spring swap needs to use hardened spring shims instead of locator cups, the stock valve locks and cheap aftermarket retainers (Comp Cams). Gets it done for closer to $100.

You can find the coil bind specs and springs rates on line but the safest way is to measure the distance from your retainer at the installed height to the top of the valve seal/guide boss.

Hope this helps more than it confuses.

ddahlgren

I just did not want to pull the heads to machine them if I go down this road as it only hs 70k on it and good compression.. Sort of a why fix it if not broken thing

tequilaboy

I dug up an old post of mine on this topic:

https://www.corvetteforum.com/forums...post1551701285

89onlyZ51

The zz4 head is the 113 casting l98 head with the same springs as the lt4. You'll have no problem dropping them on except maybe if you use 1.6 rockers on the exhaust with a zz4 cam. The springs are still stiffer than the stock l98/lt1 springs so I wouldn't worry about valve float at less than 6k rpm - far beyond tpi's limits.

ddahlgren

I was going to put 1.6 intake and 1.5 exhaust to give me 0.505 int 0.510 exh lift and the cam I believe to be 208/224. The springs retainers and spring cups should I need then are listed by GM to fit LT4 ZZ4 ZZ383. If I go this route it will be annoying enough to pull apart the front of the engine and still leave the heads on. Pulling the heads would be a deal breaker in that at 66 I am getting too old to do that in the chassis. With them off I know I will send them out for a valve job and do some pocket porting here. Then there will be new rocker studs guide plates etc. Everyone knows how these deals go. The while I am there thing sets in and a simple job turns into $$$$

89onlyZ51

You'll be good to go - all plug and play to .525" lift on intake & exhaust with the ZZ4 springs & matching retainers on an L98 head (which then makes it exactly what they install on the ZZ4 motor). At 70k miles, your valves/heads should still be in great shape. A ZZ4 cam should be a good mild upgrade (slightly hotter than stock LT4 cam) with TPI. If yours is a '90 with speed density, you'll probably still need a tune, though.

ddahlgren

What about the exhaust valve seals as mentioned having to remove them and just run the little o-ring type seal? Something I rather not do. I need to look into tuning tools and data logging tools that will accept a wide band input. Unless there is a spare in a 91 ECM

89onlyZ51

The ZZ4 head as configured uses the same (part #10212810) positive seal on intake and exhaust.

For tuning, I use an Innovate LC-1 w/b with their pc interace. I collect the car's data from the stock ECM with Tuner Pro and just marry them up by timestamp. It works well enough, and I just haven't taken the time to figure out how to feed the w/b data into the stock data stream though I know plenty of others on here have.

ddahlgren

That is part of the problem with scan and tune mixed in with tech. A lot of information while still there somewhere is about impossible to find.

Billygoatkid

Kevova

You will want to be sure there is no coil bind. It should be ok, but you won't know unless it checked.

Billygoatkid

cardo0

Problem with using LT4 springs is they were designed for the LT4 valves which are some 20% lighter than LT1 valves. But some reports they work well enough then some say they don't.

I don't know why you ask if the retainers fit when you can see that for yourself better than anyone over the internet. Just hold an LT4 spring over a retainer if installed to check. But to save money yes you want to use as much of your stock hardware as possible. Locks, and spring locators should work but those are fairly cheap as you can substitute spring shims for locators.

Billygoatkid