hey guys i want opinions on which cam i should chose. i have an 86 LB9, which is of course equipped with the famous peanut cam. anyhow i won't be able to afford to build a real motor for some time, so i want to at least get my 305 runnin good. i want the biggest power gain i can get, without burnin a chip. i have a tight 42,000 mile motor with headers and cat back exhaust, K&N filters, shift kit, and 3.23 gears. i just want a good stout cam to liven up my motor untill i can build a real one. i am fully capable of puttin it in myself, i just want opinions on which one to choose.

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

1MZ,

Since you have a MAF, life will be easy on you this time. You should be able to install a better cam with the stock heads and not have a worry about reprogramming to make the engine run well. Of course, PROM tuning can usually get a little more out of any setup, but the MAF cars are a lot more forgiving in that respect.

A key specification to watch is the overlap, and therefore the duration and lobe separation angle of the cam you select. There are several options for flat-tappet grinds that provide much better lift and maintain the LSA and minimal overlap of the stock profile. Comp Cams has a computer-friendly grind that works well with the TPI and MAF. Call them and ask about the 260AH-14 grind in your application. It specs at .444"/.444", 212°/218°, and 114° LSA. Since you have a 3.23 gear set, the slight loss of low-end torque will not be a problem, and the extra upper end should more than compensate in smile factor.

If you are a little concerned about the longer duration affecting the ECM, you can ask about the slightly milder 260AH-12. It specs at .444"/.444", 212°/212°, and 112° LSA.

The only difference between the two grinds is a bit longer duration of the exhaust lobe and necessary adjustment of the LSA on the first choice. With the smallish stock valves, the extra duration can be a plus.

With either choice, new springs are recommended, and new lifters and timing chain are a must. You can also change to 1.6:1 rockers on either cam to get even a bit more breathing and power without significantly affecting the low end torque and idle quality. Screwed rocker studs aren't a must, but are always suggested with new springs and a better cam. They are so easy to install yourself, it almost should be an automatic function.

Personally, I've considered the next step in grinds - a 268AH-14 for my '86 TPI as soon as I make 50,000 miles on it. I've put about 800 on it this summer and it looks like it may wait another year. With that cam, I'd have to use high-bleed lifters to keep the idle and low-end torque fairly stock, but throw a lot more fuel at the upper end to use the extra flow. You may not want to go that route, but it could be worth considering.

Whatever you do, don't take anyone's word for it unless they have solid proof of the outcome. You are the one doing the work and spending the money, so do some research first. It's free.

------------------
Later,
Vader
------------------
Justice and Freedom will Prevail

[This message has been edited by Vader (edited September 28, 2001).]

 

A 204/214 .423/.444 (Which is a fairly common grind) will work pretty good and wont require any reprogramming at all. I then tried the 212/212 cam listed above, it was not a whole lot different from the first one I tried, but it seemed to idle better. When I got that 212/212 cam, I was really thinking about the next one up which Vader listed, and I regret it to this day.

Thats my .02

 

Vader ive been cruising this board for the last 6 months and i just want to let you know that you are the MAN!!!!!

 

wow, thanks you guys. i really appreciate the help. you guys are really what these boards are all about. without you, we would just be a bunch of idiots talkin trash, kinda the blind leading the blind sort of thing.

to follow up on what Vader suggested, i'm not all that worried about idle quality. a little lump sounds cool. but i think what causes rough idle is overlap, which you said i should stay away from.

the 260AH-14 sounded cool to me. obvioulsly i'm gonna do more reading about it but this sounds like the direction i wanna go. however i still have some questions about the 268AH-14 you mentioned. i kinda like a mean idle, if i used regular stock type lifters would the idle be too rough for the ECM? or do i need lifters to bleed a bit and tame the cam down at idle? also you spoke of adding more fuel, i assume this would be done via an adjustable fuel pressure regulator?

one last thing, suppose i went with the 260 or 268. what kind of power increase would i be lookin at?

i have a set of 3.73 gears on the bench at home, if i do the cam this winter, i won't have the money to put gears in.(college stinks) however do you think i should put them in when i can afford to? would they compliment the cam? i guess it just depends on how far up the cam moves my powerband. thanks for the suggestions guys!

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

oh and one more thing. i was gonna use a dremel type tool grind the humps out of my plenum and do the best i could to clean up my base too. i'm not gonna get crazy, just clean up the really nasty stuff. i'm sure that will help too. any suggestions on that too?

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

As Jeff alluded to, tweaking the eprom will always get you the best results; even on a stock engine.

The biggest problem MAF cars have is with larger cams. The "reversion" through the intake when you have a large cam. This can cause havoc with the idle and one of the primary reasons of when a MAF must get a new eprom.

With the cams mentioned above, you won't "have to" burn a new eprom. But a good eprom will give better results. You can even get rid of that speed limiter if your eprom has one (which I believe yours does).

 

nope i don't have a speed limiter. but my tranny won't upshift to 4th at more than 2/3 thorttle which is normal. my buddies 86 is the same way

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

Check this file:

Plenum Porting.pdf

If you don't have Adobe Acrobat Reader, you'll need it to open the file.

------------------
Later,
Vader
------------------
Justice and Freedom will Prevail

 

sweet article Vader. that will be very helpful. i was probably gonna put in an adjustable fuel pressure regulator with my cam and porting mods. what kind of power increase might i expect on my low mileage motor?

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

ttt

 

would you suggest i install new valve springs too? thanks

[This message has been edited by 1MeanZ (edited October 01, 2001).]

 

Good question. It depends on the cam you choose, but I'll tell you right now that stock GM springs suck. It may not be a bad idea to replace those and the seals now, although you will need a few tools and its more work. As for HP, its hard to say. If I used my times as a guide, I picked up about 30hp but it could be more or less depending on the cam chosen and the car.