Hey guys I have looked all over the forum and could not find a straight answer.

I am building a 86 vette L98 to replace my 3.1 in my 90 firebird. I plan on doing an edlebrock intake and runners ported, sending out the vette aluminum heads out soon to be rebuild and ported with Roller rockers, dyno don headers and cat delete but before that the only other thing i want to do is a MILD cam and new springs and everything it needs.. the car is gonna be a daily for the most part and would like good fuel economy when i want it so i don't want no thumper cam.

I have been seeing COMP cam kits around that include push rods, lifters not that i need new ones, valve springs and the timing chain. Does anybody know of a kit that has a mild cam for a daily.

I dont know much about cams and the lift duration or anything or what they mean or whats mild or not so anything that so any advice you could give would help. Trying to get 300-350 horses out of this engine.


I looked at this and researched the cam, it seems to be just a mild street cam and says it will fit the 86 vette tpi which is what i got my engine out of but says it wont fit the 90 firebird?

this is what my 86 vette tpi has for the cam specs I found
1985-1986:
Duration @ 0.050 202/206
Lift with 1.5 R 403/415
Lobe Seperation 114.5

 

Educate yourself, so you can determine if/when someone is feeding you BS.

First, find out what you have, so you can determine where you want to go. Stock L98 cams varied over the years, and this is a typical example for the 87 model year:

• Duration @0.050" 202/207
  • the first number is for the intake valve, and the second for the exhaust
  • measuring at the standard 0.050" lift is good for comparing "apples to apples"
• Duration advertised: 297/297 ... at 0.000"-0.006" lift. I only found this one place, so it may not be valid. It seems awfully big for a stock cam.
• Lift with 1.5 rockers: .404/.415
• Lift with 1.6 rockers: .431/.443
• LSA 114.5*

Lift is how FAR the valves open. More lift lets in more air (up to a point), but needs springs that can handle the distance, and the higher velocity required to lift the valves farther. Stock is in the low .4xx", streetable upgrade in the .50x" range, and racing into the .550" or larger range.

Duration is how LONG the valves are open. Longer duration let air flow into the cylinder for a longer time... more air = more power. BUT, too much and you are incompatible with the long TPI runners, incompatible with smooth stable idle, emissions, vacuum for brakes, etc. Longer duration also needs stiffer springs because the valves are being opened faster to get to maximum lift for longer. For a 350ci, stock is in the 20x* range, mild 21x*, solid performance, 22x*, and 23x* and larger is less streetable and more race.

Lets look at some popular upgrade cams are their specs:
ZZ4 - 208/221 @.050" .474/.510 w/1.5

ZZ9 - 212/226 @.050" .483/.520, 112 LSA Designed for use with Modified TPI, or a basic Miniram cam.

ZZ-409 - 226/226 @.050" .520/.520, 112 LSA Best with Miniram

LT4 Hotcam - 219/228 @.050", .492/.492 w/ 1.5 or .525/.525 w/1.6, 112 LSA

Other stock profiles, just for reference:
L31 - 191/196 .414/.428 - notice this is less duration than the L98. Because the Vortec heads are better (flow and chamber), they can get away with smaller/milder cam and still produce reasonable power.

ETA: for springs, go with what the cam manufacturer recommends.

 

Are you going to use a MAF setup or stick with SD?

I just put a hotcam in my 89 formula 350 with ported 86 vet heads. it runs just fine, nice and mild for a DD.
You will want to tweak the tune if you use the SD computer.

 

If you do add 1.6 rockers definitely update the springs due to the limited stock lift.

 

Thank you so much for all the information it will really help me make an informed decision thanks so much it really helped !

 

Yes I am going to switch the engine from MAF to SD I have the harness just need the new lower intake

 

I definitely want to do roller rockers and hopefully I can fine a whole kit that includes the new spring

 

I'm running 1.7's with stock springs on an L98

 

I researched this cam and seems to be a mild street cam. any thoughts?

 

230/244* duration at 0.050" and 290/307* advertised (seat-to-seat) is pretty hefty. The 112* separation is probably the only mild thing about it.

It looks like you are using a long tube runner intake (stock TPI style), which even with aftermarket parts, will likely choke off a substantial amount of the top end. For "mild" and LTR, I would think 225* @ 0.050" is milder timing, yet a bit more than factory.

That kit is a "stock roller lifter" type cam kit, and requires a roller cam ready block, which I don't think was available until the 87 model year.

Is your 86 L98 roller equipped? If you take the intake off, does it look like this? (Thanks to HotRod for the image)

 

Yep seems it is roller equiped but if you say this cam is too heafty for what i want then ill keep looking. I just would like to find a kit that has everything i need and i dont want to kill my mpg either when i put this engine in i want to so better than the V6

 

Comp cam 08-501-8 I have used on a lot on MAF cars with stock proms and it ran excellent. Also have used the TPIS super profile cam which barely lopes with 1.6 rockers and stock proms. If using a Comp cam make sure you use motor oil high in zinc once its broken in.

 

That looks good I found a kit here http://www.compperformancegroupstore...Code=K08-501-8

I am switching the engine to SD and gonna get an Edlebrock lower intake and runners and have them ported will that cam work well it seems less mild than this Lt4 cam kit?

http://www.summitracing.com/parts/na...gyQhoCJl7w_wcB

The Lt4 cam comes with the roller rockers but no timing chain but i have seen comp cam roller rockers eveywhere

 

I never really liked the LT4 cam esp with a long runner intake set up

 

Put 1.6 rockers on a stock L98 cam and you pretty much have a LT1-LT4 cam.
Not really enough of a difference to make a difference...

 

I have run both the production and hotcam in a TPI with LTR and they make a ton of grunt and pull past 6,000 rpm despite peaking around 5,200 rpm.

 

So that comp cam setup would be a better choice? It is less mild than the lt4 cam and I really want mild

 

You could run the GM Marine/Ramjet/HT383 cam. Its nice and mild and makes 350 HP when used with 1.6:1 roller rockers on Vortecs heads and the Ramjet 350 intake. With a 1.6:1 rocker in an otherwise stock aluminum head L98 I think it would make about 315-325 HP and a boat load of torque.

http://www.summitracing.com/parts/NAL-14097395

It specs 196/206 @ .050, .431/.451" lift, 109* LSA, 106* ICL.

That being said I would probably go a little more aggressive if it were me.

 

that one seems perfect for my application. I would just need to find everything else like the springs and such. Would somebody be able to get those parts for me if i send the heads out to be rebuild and i just get the camshaft? and what does it mean by Distributor with melonized steel gear required??

 

The melonized gear is hardened so it wont self destruct when run on a steel camshaft.
GM 10456413 ~$35 on amazon

 

Who makes 1.7 self aligning roller rockers for a sbc? I can't find them listed anyplace. I would assume springs need to be updated too.
stock push rods too?

 

What about the ZZ9 cam (0.483''/0.520'' with 112 degree LSA) from TPIS?

The specs are close to the ZZ4 cam (0.474''/0.510'' with 112 degree LSA) that GM has been using for years.

 

They are Ching Chang full roller non self aligning rockers. The iron L98 heads on my car have push rod slots so I didn't need SA rockers.

I'm running stock springs. They're good for up to .480 lift and the 1.7 rockers give me around .476 lift with the stock cam.

Stock lift is around .420 with 1.5 rockers. To do the conversion you take .420 % 1.5 (stock rocker) X your new ratio(in my case 1.7) which gives you .476 lift

 

Tyler you are bananas running stock springs!!

 

Geez you're everywhere mike!

 

I was thinking about doing the same thing but going to replace my springs. I could only find Ford rockers in 1.7 or BBC in 1.7. Both self aligning. Can you point me in the direction of these rockers. I'd rather spend the $on rockers rather than $200+ fir a roller cam.

 

I found them on eBay about a year ago. I'll look

 

http://m.summitracing.com/parts/scc-scp1025bl