Waffle99

I have a ported and polished TPI manifold I am putting on in about 2 weeks. I have decided to go down all the way to the head gasket to make it easier to replace my valve guide seals and valve springs. If I am going down that far, what all should I replace?

1985 L98 Motor.

I am going to order a gasket set (suggestions for stock heads)?
I am going to order valve guide seals (suggestions on seals/links to seals)?
I am going to replace the valve springs, which springs?
Roller rockers and cam possibly?
Any other suggestions such as going deeper or things to replace on this budget? The budget includes the new valve springs and seals and gaskets.

bassackwards

Removing the cam is a whole separate job that includes pulling the radiator and everything off the front of the engine.

383tpimachine

how strict is the budget? for a few hundred more you can get some new alum heads. China casting but still shave a bunch of weight and flow much better.

The newer heads will come with new seals and usually springs so all you would need are the headgaskets.

Waffle99

Link to head? I may be able to spare some here and there. Plus not having to spend that time and money on valve seals, springs, and with the new head comes new valves as well. Is there any machinist work required in getting a new head?

John A. Marker

Use Fel-Pro INTAKE seals on the intake and exhaust valves.

1.5 RR on the intake and 1.6 on the exhaust. You can buy split ratio. This combination works better that a straight 1.6 on all for the 85.

See this thread for valve adjustment.....
http://forums.corvetteforum.com/c4-t...ajustment.html

mtwoolford

You really do NOT need to pull the heads to change out springs and seals (and shame on anyone that implies that you do).

let's see you've got a thousand dollar budget and people want you to buy a new set of heads? And head gasket's aren't all that cheap either.

For your budget, spend the money on a cam, matching springs, seals, lifters and timing chain set. Dollar per dollar this is what will really wake up your engine.

And get a new, good quality water pump. Any money left over, do a complete ignition tune up, cap, rotor, wires and plugs. Sure this is labor intensive, but it's a whole lot easier AND a whole lot cheaper than a head swap.

with all that said, you can think about a head swap at some later date; personally, a cast iron head on a cast iron block is, from a durability standpoint, a very good combination, even if they do weigh more.

383vett

Interesting. I used to run 1.6 on the intake and 1.5 on the exhaust. My car ran quicker with this set up. My theory is that the intake needs more help sucking the charge into the cylinder than the exhaust needs to spit out exhaust gas under pressure. That is why split ratio cams favor the intake side and why intake valves are larger than exhaust. Increased filling of the cylinder with the intake charge is like increasing compression. I did quite a bit of track testing with my car and this is what worked for me.

DanielRicany

I would not waste your time with a cam with such a little modification. It was a ridiculous amount of time to install mine and that's with 2 people who have a lot of experience working on cars. You'll need to change your lifters too by the way. You're better off just getting 1.6 RR since you're getting new ones anyway. Too little cam is no good, and too much cam is no good. You should be okay with 1.6's and the P&P intake. And as others have said, if you're going to do the head gaskets you may as well get better heads. It seems like you are going more towards performance, and you're better off doing it all at one time.

I would also steer away from the TPI intake manifold, let's be realistic here, the only time you're ever in the torque range of the TPI in a race is in first gear, then you're all out of steam.

But I definitely would not do the head gasket unless it gave you a reason to. All the stuff you listed can be done above the head.

ghoastrider1

got headers? got dual exhaust?

mtwoolford

Well, since it's an 85 with close to a zillion miles (yes, it's only a guess) and probably has significant cam lobe, lifter and timing chain wear, and since the spec's when NEW were only a middl'in 202*/206* at 0.050 lift and 0.403"/0.415" lift, I'd speculate that there's lots of room for a more aggressive cam before having "too much cam". And replacing whats certainly a streched, sloppy timing belt with a new double roller timing chain will help maintain both valve timing AND ignition timing.

New rocker arms are definetely in order, but before blowing a third of that $1,000 budget on a set of roller rockers, I'd consider spending (last time I checked) $90.00 or so on a set of roller tipped rockers. Depending on the cam choosen, either 1.5 or 1.6 ratio rockers would be more appropriate.

Waffle99

A little more info. 85 with 126,000 miles. There has been some engine work done around 70k from my maintenance record but the paperwork is so old that is all I can really tell.

milsurpman

I ran this cam in a iron head 86 4+3 stock with just a cat back and It really woke the car up.

http://www.compcams.com/Company/CC/c...?csid=125&sb=2

There was a noticable change in drivability and performance in the positive. One of the better mods in my old car when it was running the stock long block and injection.

Waffle99

With something like the cam, all of those recommended parts should be bought with it as well to keep it as a set? A little new to the performance side of things. I have a catback exhaust in there and no cat.

mtwoolford

It sounds like you're on a tight budget, and all of us (most of us anyway) have been there.

Jegs or Summit sells Comp Cams Xtreme Fuel Injection cam in a kit #249-SK-12-364-4 which includes cam, lifters, and timing chain for $230 - $235, which IMHO is a heck of a deal; you really don't need to change out the springs, seals and rockers at this time, you can come back and deal with those later.

A complete kit, which includes all the above plus springs, seals (and retainers ?) $460, but thats half of your budget.

Never ran one of these myself, but if the claims are to be believed, this cam sounds like just the ticket.

milsurpman

Actually with the cam I ran back then. You will only need the cam and lifter set and a timing chain. The stock springs handled it well. Just make sure nowadays with the low zinc oil to use their camshaft breakin lube. This group is well worth the install on a pre 86 stocker as I noted before. Wish my roller equiped stock 89 had this profile cam. It really impressed me and others back in the day.

Waffle99

Budget just plummeted. I have to do some clutch work as it gave out today. I think I am going to just end up replacing the valve guide seals, springs, and put in roller rockers to stop the oil burn plus put on the intake manifold I already have from my friend (ported/polished TPI intake manifold). (only burns a bit on startup)