jorlebar

My car is a 1993 Z28 M6 with about 80,000 miles. Car still runs strong but I have a hunch it could use some freshening up - especially the valve springs.

Here is what I am thinking about doing:
New 1.6 Roller Rockers
New Valve Springs
New Valve Seals
(I do not intend to touch the cam at this point)

My questions are:
1. Are the 1.6 ratio rockers worth the expense? What (if any) gains can be expected? Which manufacturer makes the best value product in terms of performance/quality/price?

2. What valve springs should I use? GM or aftermarket?

3. Are the valve seals something I should be considering under the category of preventative maintenance? Or, should I adhere to the theory of "if it ain't broke don't fix it".

4. Lastly, are there any aspects of this projet that I need to be forewarned about? I understand it is a time consuming process - but, technically not that tough for a capable hobbyist.

Informed opinions only please. Thanks a bunch for your help everyone!

Jason

jonaddis84

The rockers will give you a substantial gain, worth the money in my opinion, you could see around 20hp possibly, depending on other mods, number would increase as mods increase. CompCams ProMagnum rockers are the choice of most, highest quality at a reasonable price ($250ish).

Valvesprings, you might as well go aftermarket, it would be smart with the rockers anyway. The two "best",IMO, springs that will fit on an unmachined LT1 head are:

Comp cams 986-16
Crane Cams 99893

For either spring you choose, you will want the below CompCams hardware (yes, even for the crane springs):

740-16 retainers
4770-16 seats/locators
611-16 locks

I would say on the seals, go ahead and do it, I would assume they would be quite difficult to change with the valves still in the heads, but possible, I would just go GM on those though.

Things to look out for...quite difficult to get springs on and off while heads are in car, find the best spring compressor that is short enough to fit. You will need an air compressor and a fitting that is the same size/thread as the sparkplugs so you can keep the valves up. Thats about all..oh, be very careful taking the locks off, and putting new ones on, that you dont drop them down into the lifter valley, dont wanna have to take the intake off if you dont want to.

Which brings me to another thing, new pushrods wouldnt hurt, hardened one piece ones.

truedualws6

I suggest you do a search for info on this topic. There
is a lot out there just waiting to be read.

shoebox

1. Comp Cams Pro Magnums

2. Besides the advice already given, Combination Motorsports has some springs that don't require machinining of the head.

3. Any time you have the springs off, replace the seals, IMO. They are easy to do.

4. Guide

96capricemgr

Combination Motorsports usually has a deal going on the Comp ProMagnum rockers and thier springs which are good as well. Valve seals are easy to change once the spring is off, if you order the other parts from CM just get the seals from them as well otherwise then get some ones for GM. No need for compressed air to hold the valves up, if you bring the piston to TDC the valve can only fall a short distance.

Really if you plan to stay with the stock cam you could even consider the HOT cam kits springs those would do the job just fine with a stock cam.

OldSStroker

With 80k on it, you probably should do a valve job, and not just change valvetrain parts. How about doing a leakdown check to see if valves and rings are still sealing?

IMO, the 1.6s aren't going to do much good by themselves. If you plan to change the cam later, put compatible parts on then rather than have to change again.

My $.02

rskrause

I am not sure you will find this exercise worthwhile. You will gain a few hp, but it's a lot of work and cost for a few hp. How is your car running now? Do you have trap speeds or dyno numbers that suggest a loss in hp? I agree that your springs are probalby "tired", but the stock cam is not too tough on springs.

I'd say that if you want to do this it's easier with the heads off, and then you can also do a vailve job, as Bret suggest. You will see more hp from a good valve job than from the rockers/springs!

Rich Krause

96capricemgr

I hope I do not offend anyone with this but, are the aluminum heads that weak that at 80k he might need a valvejob? I am not saying you are wrong I am just asking.

On the Impala boards we have guys reporting 200psi compression in former cop cars with well over 100K, and just imagine the idle time on those things besides the miles.

OldSStroker

Good point.

It probably isn't the head material it's the seat and valve wear that causes the valves to leak. Do the leakdown check.

My Imp has 92K on it and still runs strong, but I think I'd do a valve job before I changed parts. IMO, idle time at the Krispy Kreme isn't as hard on the valve seats as all my 5800 rpm WOT shifts. Those 5.0 Mustangs still like to "60 punch" it.

Fastbird93

Here's a thought. Why not grab some LT4 valvesprings and associated hardware or the like, some LT1 guideplates, and give the Scorpion 1.7 rockers a shot??? Since you already have hardened pushrods, you could do this for approximately the same cost, maybe a minimal amount more than the 1.6 rocker setup, with the only added cost being the guideplates (Thunder racing sells them for about $20 a set).

jorlebar

Car still runs strong Runs 14.0 s in the quarter at 103/104 mph. Not bad considering street tires and very poor 2.5 sec 60' time.

Just get the feeling (and maybe its just because I have had the car so long) that I it is loosing a bit... especially in the higher end of the rpm range.

In terms of valve seals.... I get a weeee bit (only lasts for a second)of dark smoke at start up after car has sat a long time (week). Very normal considering millage.

It sounds like I would not realize an appreciable HP gain with the 1.6 roller rockers. Does every body agree with the post that suggested this?

I included my sig. this time so that you know what else is done to the car.

Thanks again for everyones quality input.
Jason

joeSS97

I would say it is worth it.

MauriSSio

i would say the 1.6's are worth about 15hp you can probly do it on srock valvesprings but from what i hear,the stock springs will be close to coil bind,though some peopl DO run them.

MauriSSio

also my friend has Proform 1.6 Roller Rockers (they look like the Crane Gold Race but Blue) they work great and only cost about $180. Also from what i hear,the Crane Gold Race rockers are the best rockers,so everybody has there own opinion on whats best.