botieguy

I have a 86 model Lb9 I am going to use in a "low Buck" project I am working on. I wish it was a 350 but its not and I have it, so I am going to use it.Question is would I gain a small preformance increase from a cam swap without hurting my fuel economy? I have read other threads that suggest a LT1 or L98 but I would need a flat tappet cam.This is going to be a driver so mpg is important.I have heard alot talk about these "peanut" cams and none of it is favorable. I dont know how to identify one but I assume thats what I have. I would like to gain a little performance without killing my economy. This is a stock engine with the exception of headers and bigger exhaust.Anyone got any thoughts?

skirkland1980

iTrader: (2)

my best suggestion for choosing a cam is to download camquest software from comp. its free. you can play with different combinations and it even has a theoretical dyno sheet and gives possible hp and torque.

LAFireboyd

iTrader: (3)

If you want a better stock cam, the specs for the L98 cams were basically roller-version derivatives of the '85 LB9 cam, which was also the same cam used in the '83-'86 L69 engine(an engine also used in the Monte Carlo SS). So knowing all of those applications for that earlier cam might make it easier to find one. It was a very good "fit," so it might suit your wants and needs.

Otherwise, check with cam manufacturers. They'd all have something even more "fun" that you'd probably like.

botieguy

Thanks Skirkland I will check out the cam software.LAFireboyd so a 85 Lb9 tpi would have a L98 cam not the peanut cam? I didn't know that the L69 5.0 had a L89 cam either.And the Monte Carlo SS had the same cam as well. I owned a 85 ss back in the day and was pleased with the performance.When you said these other applications had the l98 cam do you mean the excact L98 cam or a very simular grind? This is good info to knowThanks

LAFireboyd

iTrader: (3)

The cams of those earlier engines were not roller, but, yes, they were the same basic grind specs as the later-known "L98 (roller) cam."

I said "basic specs" because the L98 grind was not 'exactly' the same as the earlier years, due to the different characteristics of the new roller cam, but they're almost exactly the same, so the intent was there.

The '85 LB9 was a strong performer, and you had an SS, so you know the L69 was also a strong performer(even stronger in a thirdgen). Then the smaller "peanut cam" came in 1986 to "de-tune" the LB9. But in 1987, the cam went back to the larger 1985 cam, but in a roller cam, and it became the "L98 cam."

I don't know if you can still get a new '85 LB9/L69 cam or not, but you could have one ground to those specs. It's GM part number 14088843, and at .050 it's 202*/206* duration, .403"/.415" lift, and 114.5* lobe separation. The 1987 roller cam was 202*/207*, .404"/.415", 114.5*. So you can see, for all intents and purposes, it's the same grind.

HOMEBREWED1986

iTrader: (1)

HI, i came accross this thread today and i have a question similar to the topic and i could really use some help. a have an 87 tuneport engine in my car now. i want to put another engine in that i have but it is a non roller block, i want to keep my tuneport setup though, what size flat tappet hydraulic cam should i run so the tuneport will work correctly ?
thanks

Atilla the Fun

For both of you, here's a link to a new, hyd non-roller cam of the correct L69 spec:
http://www.competitionproducts.com/E...ctinfo/E860SM/
I used one of these kits last summer. The lifters are American, despite the great price. Well, mine were.
Do the assembly with COMP lube, do the initial run-in with COMP oil, the lifters and lobes won't go flat. After 2 months of daily driving I pulled my valve covers just to check my lift, it was still within 0.001" of what it was when I measured during initial assembly, on all 16 valves.

HOMEBREWED1986

iTrader: (1)

ok thanks , another question, what is the biggest hydraulic flat tappet cam can i go with stock tpi ?

botieguy

Atilla the Fun What was the application you used it in ?Were you pleased with performance? What kind of fuel mileage?

Atilla the Fun

I didn't use this L69 spec, but I did use one of these elgin kits from Comp. Prod.
I had a legit L69 many years ago. I did put a new timing chain set on it, then installed it in a '71 Camaro RS with a TH350, 2.73:1 axle, 235/60R15 tires, stock '71 exhaust manifolds, Hooker Competition dual exhaust system, Thrush Calif. Boss turbo mufflers, and that's about it.
It made good power to 5500 rpm, probably woulda done 6000 with aftermarket intake manifold and headers. I have no recollection what the mPG was. Hardly matters, it was the wrong gearing for the engine.
An L69 really does want a 3.73:1 axle.
I do recall that at the end, I set out from Asheville NC to SLC, UT, and near St. Louis the TH350 failed. I found a used 700R-4, then found a shop to shorten my driveshaft. I didn't get the lockup working, but it would cruise at 1600 rpm, but would start surging at 1500. I didn't have any supplies on hand for adjusting my Q-Jet, but I'm sure the surge could be tuned away. After all, Asheville is what, 1000 feet elevation, and I was passing through Denver, which is over 5000. That'll affect the tune of any pre-computer car.
So, power from 1500-5500.

botieguy

I was putting the engine in about a 3800lb vehicle using a 700r4 3.42 gears and 29in tall tires.I am looking for the right combination to keep my cruising RPM low enough to get some good mpg buy not get below the torque range of the cam/engine with tpi.I would like to have the trans in 4th with converter locked at about 40-45 mph and not have rpms to low where engine is lugging or trans is shifting in and out during around town driving. With that said I also want to keep my interstate cruise rpms at 2000 to 2200 or so and not kill my high speed mpg.I don't want sacrifice all my performance.I wart to be fun to drive.LOL I guess I want the best of both worlds or as close as I can get.I am hoping the right cam choice will help me get there. I considering 3.73 gears but thought they would be to low for any economy even with the tall tires. Even though this is not a third gen project its not much different than what you guys have experience with.Is it doable/ What do you guys think?

Atilla the Fun

Oh get real. Even with 3.73:1s and 245/50R16s, you're still doing just 2200 rpm at 65 mph. So it costs you 1 mpg on the highway versus the 3.42s, but in town it's no loss, and if you don't have the torque of a TPI intake helping, well, I know how it seems, I was there once, and I do remember. But once you try the 3.73s, you'll never be okay with anything less.
The L69 cam is not something you choose if you have the option of something better. I've been speccing custom cams for years. PM me your info, I'll point you in the right direction.

botieguy

I think you didnt understand the cam choice I am making is for a tpi engine.So you think I am making to big a deal about the gear ratio? I will PM you my info thanks

LAFireboyd

iTrader: (3)

If you put an L69 cam into an '86 LB9, you'll be turning your '86 LB9 into an '85 LB9. And the '85 was offered with 3.23 gears, with 3.42 as the performance upgrade. The L69 was offered with 3.73 because it didn't make the torque the LB9 made, so it needed a little more "push" than an LB9.

So the economy and performance will be similar to, but probably a little less than, the '85 LB9, because of your slightly-heavier-weight-than-a-thirdgen vehicle, but probably not enough to disappoint you or hurt your wallet. 3.73 might help offset the "feel" of the weight for the "fun" category, but that's something you might end-up feeling in your wallet because of the heavier-weight. So the 3.42 gears will probably be right for giving you the best of both worlds, or at least, the better place to start. You could always go to the 3.73 later, if you feel it's necessary.

Atilla the Fun

The '85 LB9 came with 3.23:1, and 3.23s were optional for the LG4, but NO L69s were built with 3.23:1 gears. Yes, you can use 3.42s with an L69. torque isn't the only reason for 3.73s with the L69, it's also the extra 1000 useable rpm.

Atilla the Fun

With an LB9, 1900 rpm at 65 mph is great, but I'd still use a better cam. With 26" tires, this is a 3.23:1- 3.27:1 gear.
I wouldn't gear it for 2200 at 65 with TPI.

305sbc

iTrader: (3)

The stock 1988 & up L98 roller camshaft would be good for mileage and low RPM cruising. You can run it with retro-fit hydraulic rollers, a cam button, shorter pushrods, and a different distributor gear.

Atilla the Fun

It's not that great at low rpm, what with that late intake closing.

LAFireboyd

iTrader: (3)

Here, I'll recap this for you, from the beginning...

He's not building an L69. He's got an '86 LB9, and this topic is about replacing its cam with something better, for which I suggested an L69 cam, which is what the '85 LB9 had, thus essentially turning his '86 into an '85. So comparisons made have been between the '86 LB9 and the '85 LB9. "NO" body said anything about an '85 L69, nor has anyone said anything about any L69 having 3.23 or even 3.42 gears. The 3.42 gear reference was also about the '85 LB9, which was its optional gear, therefore making that a good gear choice if he goes with the L69 cam in his '86 LB9.

botieguy

LA sounds like you agree with my thinking for the most part so maybe im on the right track.I also share your thoughts about the exrea weight being a factor .No doubt the 3.73 gears would be more fun to drive but Im concerned it might be hard on the wallet to do much interstate speed cruising in even with the tall tires.I am hoping the lowend torque from the tuneport will help offset the higher gear choice.I am an auto tech by trade but not an engine builder.I have little experience with tpi and am trying to do my homework so I will be happy with the end result. Your input is appericated.I attend several events each year and plan on putting several miles on this setup. I have a 7 year old daughter who wants to go "CRUISIN" with daddy. LA do you agree that a newer version simular to the l69 is where I need to be?

LAFireboyd

iTrader: (3)

Well, for performance and economy, the L69 cam/LB9 engine combo works and has a documented history, having been an actual production combo in 1985, so it's a safe choice that produced known results. And the price for that kit that Atilla posted is pretty hard to beat... and a nice advantage over the price of roller cams, which would cost 3-5 times that for a retrofit/upgrade.

You could go with a little larger cam for even better performance, and as long as it's still fairly mild and computer-friendly, it would probably still be somewhat economical. But because "economy" means something different to different people, and that's an important factor here, I wouldn't want to suggest something that might not end-up being as economical as you'd want, so that's why I brought-up the L69 cam. It was the flat tappet version of the later L98 roller cam, and they were the best of all stock thirdgen cams. So again... a safe choice.

Regarding a 3.73 gear, it's still a fairly street-friendly gear, so it would probably be ok. Afterall, we're not talking about making radical power here anyway. No thirdgen stock engine did. So the torque and the gear will be important for making it feel like it's making more power(hey, it worked in the '80s), and that's where a 3.73 would make more of a difference than a 3.42. So while it wouldn't be as economical as using a 3.42, it probably wouldn't make a huge difference on your wallet, and the trade-off might be worth it.

Ultimately, the decision is yours, and it sounds like you've done your homework on this, so whatever your decision is, I suspect it will be a good one.

Lucid

iTrader: (4)

I actually have an 86 LB9 car that came with the peanut cam and the 2.73 gears.

When we rebuilt the engine we swapped the cam with the 85 LB9/L69 camshaft for more performance. The engine definitely ran better with the 85 cam. The peanut cam is actually a LG4 camshaft from the low performance base engine that GM decided to stick in the LB9 in 86.

I swapped the 2.73 open rear end with a 3.27 borg warner posi and there is a definitely an improvement in acceleration there. I think I paid $50 for the stock L69 camshaft from a local performance shop.

If nothing else, get the L69 camshaft because that LG4 camshaft is terrible.

botieguy

Lucid thanks for the info.Sounds like a cam swap served you well in your car.What did the cam swap and gear change do to your fuel economy.Do you have any numbers?

Lucid

iTrader: (4)

I used to average around 13-16 mpg with just the camshaft, 3 inch exhaust and a 160 t-stat and dual fans running constantly. This is spirited driving highway and city combined. We are talking about a fully optioned Z28 with a/c, power everything, even the rear wiper and 16" IROC wheels and crappy Bosch platinum spark plugs.

I am thinking running a 180 t-stat and tweaking the fan settings would get better gas mileage.

The power band runs out at 4500 rpm on this camshaft but it has really good torque.

83 Crossfire TA

iTrader: (2)

Too much is being made of "this is this and this is like this but not roller and..." Maybe the published numbers for the cams are that similar, but an '87 LB9 roller motor runs nothing like an earlier L69 cammed 305 (well, OK, it's obvious that when comparing the two you're comparing 2 stock engines...)

If you're going to spend the time/$ to do a cam swap I wouldn't go one stock cam for another unless you have it sitting around already (and even then I wouldn't).

OK, heavier vehicle is going to want a tighter LSA to move it around with the same authority on the street, same thing with worse aero and a number of other things, but what I would end up with would really depend on what the vehicle actually is, gearing, transmission, tires, intended use and how important MPG is vs performance. Why don't you give us exact details so people can throw out what they'd actually pick for it if it was theirs. Oh, and while you're at it, are you willing to swap valve springs (having to keep under the limitations of stock heads/springs dramatically limits what you can put in the engine)

Atilla the Fun

The '86 LB9 used the LG4 cam, NOT the L69 cam, so it's no surprise they run differently.
And is it anyone's place to say that "too much is being made of it"? Noone can doubt that aftermarket cams are always improvements over stock cams, if only because the aftermarket offers us more lift for the same duration, thus offering more power without hurting driveability.
But cams are confusing, even to those who think they're starting to have a good grasp, so staying stock is staying safe. Plus NO reprogramming is very appealing.

83 Crossfire TA

iTrader: (2)

My '87 LB9 is a 5 speed, so it shouldn't have a peanut cam, it should be the same as the cam in my '87 L98 formula.

botieguy

I have been away from the forum for several days.Thanks for the replys everyone. 83 crossfuire I you will find the specifics of the project in the my 5-10 post. I realize that fuel economy and performance don't usually go together, and everyones idea of performance is different. Thats why I asked my questions here to get some feedback. The mpg are going to be pretty important since I plan to drive this thing alot. I just got back from doing the Hot Rod Power Tour and was running with a friend with a 68 camaro with an LT1 that got 25-26 mpg every fillup and the car runs pretty strong. Another guy had a 55 chevy carburated 350 that got 20 mpg.We logged over 2600 miles on the trip. The 25 mpg might be out of reach but I hope to get 20 on the hwy. Anyone else got any thoughts or questions? If you guys have never done the Power Tour you need to its a blast.

Chevy86 IROC-Z

iTrader: (17)

The best one to get is a 1994 Z-28 Cam. It is called the LT1 cam. It has a bigger lift than the L98 engine which is in the 87 and up IROC-Z's. They are around $50 but you have to hunt it down on the net. I actually got lucky with mine from a fellow member and friend. I believe the intake lift was .451 (somewhere in the area). Now if you get a CompCam which is computer controlled, you'll be looking at around $250. But get this, It is almost identicle to the LT1 cam. Difference is age/usage and cost.

83 Crossfire TA

iTrader: (2)

Heh... my '83 crossfire car ran 13's at over 100mph, was setup for roadracing/autox, and got 35-37mpg regularly on the highway and was my daily driver seeing most of the east coast from Jacksonville Fl to Boston... I think I get the basic idea...


post 5-10? this thread started on the 11th...

botieguy

Crossfire thanks for the words of wisdom.The forum is lucky to have "inspiring members " like you.

83 Crossfire TA

iTrader: (2)

I don't know if you're serious or being sarcastic, but it doesn't matter either...

The thing is that you're worried too much if that's your goal... my brother's "race car" (a big 4 door ford) gets 23-24mpg highway with a supercharged 302 with an old school (meaning longer than typical advertized duration for a modern cam) 218/226(at .050")/112 with 3.73's and 275/40-17 tires.

With modern lobes like the XFI or Voodoo lobes and higher compression (in other words, something like the stock 9.3:1, my brother's car is running significantly less than that to work with the blower) you should be able to keep the 305 over 20mpg with something even bigger, maybe as big as 224/230 with a 110-114 lsa (that is not to suggest that's what I would necessary recommend for your car, I don't think that we really have the details here to give a good cam recommendation)

botieguy

Crossfire thanks for the input.So you don't think 20+mpg is unrealistic? What additional info would you need for a recommendation?

83 Crossfire TA

iTrader: (2)

Basically the same list that you'd get asked when requesting a cam recommendation from a cam grinder (look at some of their websites, most have forms to fill out). Some goals what is really the most important for you out of the car would also be nice ("better performance with good MPG is a relative thing, someone used to a 9 second street strip car would have a very different opinion of what that means than someone driving a Smart, concrete numbers both ways and what's more important to you like would you rather run mid 13's and get 25-30mpg on the highway or mid 12's and get 20-25), your ability to tune (or willingness to pay someone to do it right)...

Other mods done and what you're willing to do is also helpful, like if it's not done, a good exhaust (1-5/8" headers, the longer tubes the better, IE: long tubes>3/4 length>sortie, with a good exhaust behind it) really makes a difference on these cars (the stock manifolds and y pipe suck for both HP and mpg), good intake and free mods...

FWIW, lately I've been very impressed with Comp Cams "cam help" software (free download from their site). It's responses are only as good as your inputs (so if you're even a little bit off or unsure you could get totally the wrong thing), but it does impressively well at narrowing things down quickly and getting you in the right range.

Nelz

Sigh. Another Cam Question.... ok, I'm going to refer to the expert. David Vizard.

http://www.popularhotrodding.com/tec...ics/index.html




Select cam in this order:

1. Intended use-how much overlap required?

Based on engine size of 305 cu. inch.
Gas Mileage/Towing = 10 deg overlap
True Street = 35 deg. overlap
Street Performance = 50 deg. overlap

For you it seems like a true street motor.

2. What is required LCA?

LCA = 109 (305/8/1.94"valves = 19.65)

Determines Duration required.

3. What is max lift given constraints of overlap, LCA and duration based off overlap and LCA?

Go for max lift so install 1.6 comp magnum roller tip rockers. (1.6 lowers LCA by 1 so a 1.5 rocker on 110 = 110. 1.6 = 109.)

4. Look for a single pattern cam because extending the exhaust timing to get more power above the 4,000 rpm markcost mileage. A single cam is better here. pg. 104 (From his How to make max power small block chevy book published 2009). A duel pattern really starts to pay off when dealing with engines with higher compressions (TPI is not really), higher RPM capabilities (stock TPI and even mildly modified is definitely not going to spin past 5500 on a 305), or power adder. pg. 93

So...where does that leave you?

1. Just buy the comp magnum roller tipped rockers and install onto your current motor and leave the stock cam (increase lift). Because of the accuracy of these rockers and the stiffness, you should see about 5-10 hp increase with no real change in gas mileage.
2. Buy a cam with 110 LCA and use 1.6 rockers to get optimum 109 LCA (bonus = increased lift)
3. Buy a cam with 109 LCA and use your stock stamp steel rollers.
4. Buy something close.


Some people worry about vacuum with tight LCA. But it's overlap that determines vacuum.

I ran an Isky flat tappet 256 super cam (pn 201258) in my 88 Iroc (yes I know it's backwards, the guy I bought this car from installed this cam and I only found out on tear down last year. I was wondering where the heck that roller cam, lifter and spider went) with the following specs: Valve lift w/ 1.5 rockers (my car had the stock rockers on gasket matched heads, intake and runners) 4.25 in/ex and 202 @ .50 in/ex on 108 LCA. That cam works out to 40 degrees (http://www.empirenet.com/pkelley2/Overlap.html). So it was in between the true street and street performance.

I HAD power brakes, it idles very smoothly with lots of vacuum-no lumpy cam sound whatsoever. I wish I took that to the track before I spun a bearing. I'm guessing it would have run 14.4's. (Anyone with a cam/engine simulation program-desktop dyno?) Stock TPI system, stock motor w/ 180 degree thermostat. Just gasket matched intake system and MAF screens removed and lightened everything from the trunk. AC delete, power everything. Car weighed under 3380 lbs with driver in it.

As for mileage. If I didn't stomp on the car and lugged that thing (I have a T5 WC) down to under 1300-1400 rpm driving around town, I would get about 250 miles per tank. If I was really hyper-millling, I'd get closer to 280 miles per tank. So that's anywhere between 14.8mpg-16.5 mpg combined driving mostly city. (The EPA revised fuel mileage ratings indicated that an 88 Iroc got 15mpg city and 23 mpg highway.) It was really hard for me not to stomp on that thing. It had so much torque on tap off idle and when you did stomp on it, you'd heard that awesome whine of the motor screaming up the revs to 5300. I was running stock replacement ignition parts with that motor (NAPA) and maybe if I had an MSD or Accel module and coil with Autolite plugs I would have gotten better mileage. In fact, I'm sure if my ignition was stronger I would have had better mileage.

I would just worry about not having ZDDP with a hydraulic flat tappet cam. It was an ingredient with all oils that prevented premature wear on the cam before it was removed in 2006. Now you gotta run Amsoil, Redline, Royal Purple, Quantum Blue or Torco or some sorta ZDDP additive.

But anyways, think about the above. I know David Vizard released his own line of cams that are ground by Lunati and as he wrote it-will deliver optimal cam spec for a given intake timing 98/100 within 2%.

Otherwise, look around for a single pattern cam with the above mentioned characteristics. (I've only tried that Isky cam and I only found about it after tearing down the motor.)

Atilla the Fun

Vizard is not the last word in cams. He's not even all that good.

Nelz

That's your opinion and you are entitled to it! I'm not going to get sucked into the guru bashing. If I can learn something that worked well from someone (I don't care if it's Joe Sherman, Grumpy Jenkins, the late great John Lingenfelter-GOD rest his soul, Smokey Yunik, Kent at Scat Cranks, Dyno Don, Vader, Kevin, Mad Max or Vizard) that has been there before me, done it well, and can break it down to me why it worked-I've added a little bit more to my understanding of the topic matter. After all, isn't that why we are all here on this forum? To learn from each other? To figure out what works and what doesn't especially after the manufacturer of the part you just bought stops supporting their product because they already have your money?

83 Crossfire TA

iTrader: (2)

Vizard's biggest shortcomming is that most of his published stuff is either dumbed down for the masses or doctored for the advertisers (often not even with his work, like I've noticed articles that were reprints of stuff he published in other places with graphs and pictures added that have little to do with the text but support the advertising on the next page...

In the case of the quoted article, the biggest issue with it is that he made an attempt to make some easy to follow rules that will get most people 95% of the way there, and to be honest, 99% of cars have more to be gained in tuning and proper setup than they do in finding that final 5% better matched cam.

There are better "cam guys" out there, but most of them are strictly cam guys and don't take into account the rest of the combination (especially the vehicle...), which Vizard does well, especially for a more street oriented application.

I'm with Nelz, show me some interesting discussion that I can learn from and I'll listen, OTOH, I can name a few big a names in the industry (one particular) that are too full of themselves and amount to not much more than self important blowhards, and I'm surprised that they haven't destroyed their own business with things that they have posted online and with their attitudes.

botieguy

Neiz I can't agree with you more about learning from someone who knows more about it and has done it before.If I can gain a better understanding of why something worked(or didn't work)thats what I am after.Thats whats great about this forum and others. There are alot of people with alot of knowledge and some of them don't mind helping you get where your trying to go. I also agree with Crossfire about the big name companys that are so full of themself and much too important to deal with "joe customer". Everybodys stuff is the greatest when they are selling it to you.Like most everyone I have been disapointed in the past with products that were not what they were cracked up be. I always feel better about dealing with a vendor if you can talk to someone who's gotten the results your after with there product.

Chevy86 IROC-Z

iTrader: (17)

Your right on the money. Most customer service reps learn from specs and the books to where as us members learn from actuall experiences. I bought a roller cam from Summit and I was happy as ..... well I was extremely happy. I got my engine in tip top shape and she turned on after the 4 month rebuild. I immediately ran into problems so I called Summits customer service. They immediately gave me a number for the tech department. The catch was that the number wasnt a toll free number. Man I was furious. So I called the tech dept and they asked me general questions. He then asked something like this, "Wait a minute, is your Camaro computer controlled." I said yes. So he then told me to remove the camshaft even though it already had wear and tear, and send it back for a full refund. Once they got the cam back, they told me I couldnt get my refund and then persuaded me to buy a Comp Cams computer controlled cam for an additional $100. I said them heck no. Where was customer satisfaction? To make a long story short, I contacted the BBB and within the month, I had a refund of $150 bucks. The cam was for a 350 SB non computer controlled. My point is that even the reps at the big vendor companies can really flip your world upside down.

Chevy86 IROC-Z

iTrader: (17)

If you ask me which cam is good for a 305 or even a 350 which our ECM will support, I would recommend you a 4th gen Z-28 LT1 cam. There are differences though, so be aware when a seller tells you the they have a long or short dowel pin. If you find a cam with the long dowel pin, you can easily grind it down.