Fat Elvis Z-28

does my stock 91 LB9 have a roller cam,and what is a peanut cam??

89ragtop

Yes, it would have a roller cam. SBC's 87 and after came with a roller cam
A peanut cam is the cam that came in L03's or LB9's with an automatic. It has a very economic profile, and isn't really aimed at performance.

Fat Elvis Z-28

So if I have a 91 Z-28/700R4 it has the small cam for sure, or is there a way to tell?

89ragtop

Yep.

Fat Elvis Z-28

Ya, 20 mpg around town sort of tells the story, still a hoot to drive!!

MrJ

It hasn't been established that Speed Density LB9 auto cars have the peanut cam. Have you run yours at the track before? The ET and trap speed say a lot, I ran 14.9@93.3 with wheelspin, with a catback and free mods. No small cam here.

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91 Trans Am WS6
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter

supposed 'peanut cammed' car (yeah, right)

MoreMoodThatMod

89ragtop

You may be right. Maybe I did read something about the S/D cars possibly having it, but as far as I know all the MAF 305's with an automatic had the smaller spec cam.

Fat Elvis Z-28

No I haven't been to the strip yet, I was hoping there was a way to check with a # code or vin or something.

Vader

FE,

Generally, most LB9 automatics had the "LA" (LameAss} cam, or "peanut" cam as some call it. All LB9s with automatics from '86 through '89 had the LA cam (P/N 10088155), and most '90-'92 305 equipped with automatic transmissions had the same cam. The design changed from a flat-tappet in '86 to a roller-type in '87, but the grind specifications were virtually identical (.350/.384 - 179/194 - 109.0). A few 305 automatics got an improved cam (.383/.404 - 191/202 - 112 ) , but most of those were B4C cars with LM1 engines, not LB9s. These were designed as SEO police vehicles, but some of those got out of that duty and into the general population.

'87-'92 LB(s with a 5-speed manual (T5) transmission got an impreoved cam grind (P/N 14093643, 10066049, or 10111773) which was even better than the B4C/LM1 cam grind. This same camshaft was stock in 350 automatics during those same years. These vehicles are easily identifyable by the tachometer red-line range. The red-line for a LA cam is 5,000 RPM, while the better cam offers 5,500 RPM.

The '88 and '89 305s and 350s had arguably the best factory can grind (.415/.430 - 207/213 - 117.0), with the highest lift, longest duration, and LSA of any of the breed until the LT1 was introduced. Speed-density schemes necessitated a reduction in lift and duration, and especially LSA (.413/.428 - 202/207 - 114.5), apparently to enable the ECM to tolerate the idle vacuum. MAF cars were a bit more immune to idle vacuum since the MAF could meter air accurately at any pressure differential.


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Fat Elvis Z-28

89 and up.... speed density ... right?

Vader

FE,

BTW - The results you get at the track vary due to a lot of factors. Instead of trying to measure your camshaft in such an arbitrary fashion, remove the four bolt on your rocker cover and stick an indicator in a magnetic base. A few slow revs by the crank bolt and you'll know EXACTLY what your lobe lift is - no more mystery or "guesstimating". My money's on the LA cam if you have an automatic.

If you don't want to go to that much trouble, the part number is engraved on the camshaft just behind the front journal. Just slide the cam out a few inches and you can see it clearly...


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Vader
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Vader

1989 was a year for MAF sensors. 1991-1992 used a MAP sensor only (speed-density theory). Your '91 should be SD unless someone went to a lot of trouble to change it.

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Vader
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[This message has been edited by Vader (edited September 11, 2000).]

MrJ

Hey Vader, how do you explain my car and it's performance? Factory freak? I know someone who also had a 91 LB9 auto T/A, and the performance was just like mine. It's a 14.6 second car with a decent launch. I don't see how the small cam could provide it with enough airflow to pull my trap speed almost bone stock. I had never heard of that cam grind you described, with .383/404 lift. Very interesting.

John Darragh

Vader, I purchased a used 88-89 cam off the boards a couple of months ago but haven't put it in yet. It is stamped .049 on the cam just behind the concentric lobe for a mechanical fuel pump (which of course is not used on a TPI). Does this verify the 10066049 part number? Also, can this cam be used without changing my e-prom chip? I am hoping that the change can be straight forward by just swapping the cams and putting in a new timing chain using the existing gears. This should net me about 25 horsepower-what do you think? Thanks.

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1989 IROC Convertible, 305 TPI/Auto, KB super subs, Koni reds, BMR strut tower brace, Accel air filters, MAF screens removed - just the beginning!

Pablo

iTrader: (1)

yes the cam is stamped with the last three digits of the part number

i found a 063 gm roller cam in a rebuilt motor i got im still trying to figure this one out its got more lift than a peanut thats for sure any one know wht its from?

Vader

Mr. J,

There are a lot more factors that affect ¼ mile times. Being closeer to the salt water can give you over a second difference compared to to someone drinking Coors straight out of the brewery.

Running in 60° air at 30% RH will provide a lot better fuel charge than 60° air at 85% RH.

More significantly, your rear gear ratio alone will make a major difference. I'd rather have the LA cam and a 3.45 axle than a "better" cam and a 2.77 (like my POS '86 TA). Your TC stall speed is also a significant variable. Most early ThirdGens had a factory K-factor of 100 (1,400 RPM stall), while later TH700R4s got a larger variety of TCs depending upon the application. You could have a 2,200 RPM stall converter from the factory (K-140) on a later automatic. That's almost as good as a higher gear ratio, on top of a possibly better ratio. Ever wonder why a stock 305 in a later IROC can outperform a 350 in an '86 'Vette? It's not all the camshaft...

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John D,

I'm not certain about the "049" stamped in the shaft, but it's a good guess. To avoid all the speculation, and since the cam is already out, why not just spend a couple of minutes with the caliper and measure the lobes? Once you find the lobe lift, the duration and LSA can be found easily if it's a factory cam. If you have some 'V' blocks, degree wheel, and a dial indicator, you can measure duration and LSA/overlap pretty easily.

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Vader
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MrJ

Vader,

It's a 2.73 geared car that had a 1654 RPM stall converter stock. Pulled the converter when the tranny died, and got the 4 digit code off of the sticker, it was a 1654 converter. Something is definately up here.

Vader

It's P/N 14093640, designed for the LM1 engine in the B4C police package cars. According to my data, it was only offered on that package in 1987.

The later cam is still better - we don't want to give the cops anything TOO good, since they're just going to wear then out in a couple of years anyway. Actually, the later B4C cars got the 350/AT with the better cam, like the other 350s. And none of the factory camshaft grinds are anything to get too excited about, just like the conservative valve sizes. There's just SO much room for improvement in the valve train, it's almost sickening. To me, any 350 2-bolt should be making 420 HP at the crank on a bad day. A 305 should do at least 275, even with the small chamber sizes and obvious valve restrictions. And that should be with a moderate camshaft grind. I guess I'm just old-fashioned...

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Vader
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Vader

So you got the K-115 converter and a 2.73 one-legger? What other mods have you performed?

Pull your rocker cover and throw a dial indicator on the short end of the rocker. If the lobe lift is more than 0.235" on the intake, you DON'T have a LA cam. If it IS at about 0.235", something is definitely up here...

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Vader
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[This message has been edited by Vader (edited September 11, 2000).]

MrJ

It's a 2.73 posi.

Mods:
160 degree Robertshaw thermostat, part number 330-180
Bypassed Throttle Body coolant lines
Removed air cleaner housing, filter clamped down by housing lid
Advanced timing (3 degrees, from 6 BTDC(stock) to 9 BTDC)
Shimmed Fuel Pressure Regulator (used a quarter, raised it by 5 PSI)
Ported & Exterior Polished Plenum (removed EGR walls behind plenum openings)
3” Flowmaster muffler, 2 chamber, 40 series, single in/out (PN 43443)
3” Mandrel Bent Intermediate Pipe (by Lou’s Custom Exhaust)
Catco 2.75” High Flow catalytic converter
Cold Air Induction
Trans Go shift kit
2000 RPM stall heavy duty torque converter

IROCracer

[/B][/QUOTE]
To me, any 350 2-bolt should be making 420 HP at the crank on a bad day. A 305 should do at least 275, even with the small chamber sizes and obvious valve restrictions. And that should be with a moderate camshaft grind. I guess I'm just old-fashioned...
[/B][/QUOTE]

I've never heard anything so perfectly stated in my life. Whatever happened to that mean *** 302 I had in my 69 RS Z-28?


Kelly

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If you've gotta fix it, fix it better than stock.