tc7761

iTrader: (1)

Looking for suggestions: I have a 91 RS vert with the original 305 TBI. It's in great shape, but I'll be 'tweaking' it a bit with headers, exhaust, roller cam, and chip if necessary. Not looking to break speed records, just a little more power and a mild idle. Also considering a 3.42 posi. I'm pretty good with the mechanics, but inexperienced with cam related technical specs. Any ideas from the experts out there? Thanks!

cardo0

For a mild roller cam upgrade try a "B" or "D" body LT1 cam from '94 to '96. 191/196 duration and 0.418/0.430 lift on 111 LSA. And 1.6 rockers on the intakes gets you 0.446" lift for more torque. Those early roller cams where most likely billet steel and still in good used condition. Camshaft #10243779 is no longer available as a new part from the GM vendors. But it reads like what you are looking for. What are your current cam specs? I'm guessing the B-body LT1 cam 10243779 will have more of everything.

Good luck.

Vanilla Ice

I don't understand why oem cams are perpetuated on here. It's as if the community enjoys the thirdgen being thought of as slow.
Sure it's cheap, but there's a reason why.
Not that it's bad on a 305 tbi but I wouldn't bother with a cam swap unless the cam was at least optimized. That time and money is much better invested on something else.

redneckjoe

i agree. ^^^^

Go for the headers and higher gear ratio posi.
For such a mild cam, may as well just toss some self-aligning 1.6 rockers on there. that will give you a little more lift and reduce friction.
maybe consider a performance pulley set?
That ought to give it some noticeable seat of the pants performance.

tc7761

iTrader: (1)

Thanks all for the input. Agree. the headers and posi are a good place to start. Your suggestions are helping me formulate a plan.

DynoDave43

iTrader: (11)

Well, I think for a MILD upgrade, the factory cam is a safe bet in any number of ways.

- It was designed to, and proven to provide, 100-200k mile dependability. Easy on the valvetrain, durable in material and design. Not a knock on the current aftermarket, but these cams are a proven commodity.

- With factory goals that included working with fairly low stall converters, smooth idle, and good vacuum to support accessories and computer sensors, you know you are not risking much of a mis-match with the LT1 cam. Someone over-buying on a cam in the aftermarket is a story as old as the cam business itself. While it's easy to get the cam choice right, with modest goals and other limiting factors (displacement, bore size, head design), more cam would not seem to be necessary.

- When looking for modest increases in efficiency, there is plenty of capacity in the LT1/factory cams. You are looking at a motor (L03) that makes 170 hp. These cams supported 275/300 horesepower. Now, the otherwise stock L03 will not MAKE 275 horse with this cam...there are other factors holding you back. But the cam won't be the limiting factor in an otherwise stock engine.

dmccain

iTrader: (2)

3.42-3.73 gears, posi rear ,headers +3in exhaust, Lt1 cam, S10 Torque Converter, Re-tuned chip... Will be a different car altogether. Just a 3.73 gear swap, S10 converter, shift kit, 3 in exhaust ,etc really woke mine up. I have an aftermarket chip and bumped up fuel pressure also but cant really say how much that helped. Gears will really give you that seat of the pants bump though for sure.

tc7761

iTrader: (1)

I've been thinking exactly along these lines. Found an LT1 Cam out of a 95 Buick Roadmaster. Have a new set of shorty headers ready to go. Hope to have a 3.42 Posi, exhaust, chip and torque converter by springtime. It's a convertible, so I might add a pair of sub-frame connectors just because. Thanks for all the help!!!!

Fast355

iTrader: (2)

I would not waste my time putting a B/D LT1 or Vortec truck cam into any engine I owned. I pulled them out of multiple Vortec engines including my heavy Express van. The F/Y car LT1 cam or 1996 LT4 cam run much better. I also run full roller 1.6s on everything.

The GM 395' Marine cam also runs very well and can be found for under $200.

cardo0

You have a beautiful Camaro there. That mild B-body cam will make it frisky instead of a headache to drive. I don't expect you will need to change the tune as is though tuning even a stock car can help performance. Please let us know how that cam performs.

Vanilla Ice

Most people take an ENTIRE weekend to do their first cam swap.
After all that headache, When you think you're impressed with the results imagine triple the gains with the same work done for marginal cost increase.

There's a reason the been there done that guys are telling you it's a waste.

cardo0

The B-BODY cam ain't that bad of a cam I have to say in it's defence. That tighter LSA makes like 50ft-lbs more torque in the mid-range and is very EFI friendly with smooth idle and high vacuum. That's why GM put it in big heavy cars even the small 4.3 liter L99. It makes great torque and uses weak stock valve springs to. What I'm saying it's a proven performer and you will know what to expect.

Choose a bigger cam and you have to evaluate valve springs for it and a ECM tune. You can do that whenever you're ready for it. Nothing wrong with taking small steps in performance.

Merry Xmas everyone.

Vanilla Ice

If you are doing a cam swap in a 25+ year old car and not doing springs, you've already started off making a mistake.
On top of that doing a cam swap and not tuning for it is just as foolish.

If you're unwilling to do it right, do something else.

cardo0

Quality cam = $300 min.
Valve springs chaep as possible at least $100 but can easily run $300 when done. Sorry to bust your bubble but there's no shelf life on valve springs. It's the use and abuse they've had that weaken them and from the picture of that Camaro I don't expect they were abused.
Tune can run $1000 easily or more so because he doesn't have a flash memory ECM and will have burn a cheap for each time attempt or purchase the Ostrich setup.

He already has the used cam now so it's down to the cost of gaskets. Well I'm trying to save him money and still improve performance - not get him to spend thousands more for a modest cam/gain. He is doing it right and will have more money for later changes when he is ready and knows what he wants.

Vanilla Ice

Have (or maybe half) it your way.

Fast355

iTrader: (2)

Hahahaha at he 50 ft/lbs of torque from that horrible cam. Compared to what other cam? The L03 makes 255 ft/lbs stock and a L30 with better heads, the cam, better exhaust system, and port fuel injection only makes 280 ft/lbs stock. The F/Y-car cam makes just as much torque in the midrange as the B-car.

cardo0

Well I had to drag up the L03 cam part # 10111773 specs = 207/207@ 0.050" with 0.413"/428" lift on a 114.5 LSA.
And the L99 cam specs = 191/196 @ 0.050" with 0.418"/0.430" lift on a 111 LSA.

So I think you are partly correct as I expect a smaller improvement in torque than 50ft-lbs. The difference in lift is to tiny to make a difference. So you are trading tighter LSA for 16 degrees duration on the intake. I still think the L99 cam will be more frisky as the added overlap with better exhaust blowdown also will help it breath and make more power in a little 305. Won't have as much top end/high RPM power though.

Myself I like my ramjet cam with 196/206@0.050" and 0.431"/4.51" lift on 109 LSA. That's kinda late now but I have to say this cam loves to burn rubber. Like $225 from Summit.

Fast355

iTrader: (2)

That would be the 395' Marine cam that came in marine engines long before it was used in the Ramjet/HT383.

The L03 cam is 179/194 @ 0.050, .350/.385" lift, 109° LSA and sits 3° advanced in a 106° ICL.

The cam you speced is the HO cam. It was 202/207 @ .050. The LB9 and L98 as well as 9C1 Caprice used a very similar roller cam on a 117° LSA.

I can tell you after driving thousands of miles with both the factory L31 cam and a 1996 LT4 cam, the LT4 cam performed better everywhere. Even down in the 1,500 rpm range it gave up nothing to the L31 factory cam and that was pulling around a 6,000 lbs Express van with 3.42 gears.

LT4 cam with 1.6 rockers was 203/210 @ .050, .476/.480 lift, 115° LSA and sat 1° retarded on a 116° ICL.

My brother had a 1999 Suburban that we put a LT1 F-car cam in. Also ran much better than the factory cam. It was 201/208 @ .050, .446/.459 on a 116° LSA straight up on a 116° ICL.

cardo0

Well from post #1 the OP has a 91 RS vert with the original 305 TBI. Everywhere I look that is cam part # 10111773 (specs = 207/207@ 0.050" with 0.413"/428" lift on a 114.5 LSA) - I'm assuming it's called a L03 but maybe not and I shouldn't call it that. I think you are looking at a different year 305.

Yes to bad the OEM LT4 cam is no longer available - it's what should have been in the LT1 cars. But IMHO that smaller 305 with smaller valves will benefit more from tighter LSA of the L99 cam. And if it was mine I would install it with 1.6 rockers on the intake valves only .

Fast355

iTrader: (2)

The 305 TBI engines all came with the GM 155' peanut roller cam. It is 179/194 without a doubt. I have had 10 of them apart. As for your tighter LSA vortec cam, they are garbage. My only use for them is a paper weight. Very little performance increase to be had with them. Even the Marine 395' cam is a noticeable improvement over the Vortec cam. I currently have a 395' cam in my Express van that I pull a 6,000# travel trailer behind. I have had 5 different cams in the Express and the factory cam was the least powerful of the bunch. I pulled the LT4 cam searching for more torque for a 206/210 comp on a 110°LSA until it flattened a lobe. I hated it because I gave up 1,000 rpm for a few ft/lbs down low. The next cam was a 215/220 @ .050 on a 114° LSA, it pulled hard until a lifter let go, the roller locked up and wiped a lobe. The latest cam is a 395' I payed $168 for from a GM dealer. I run it with 1.7:1 rockers and it ansolutely falls on its face at 5,200 rpm. I lose 20 rwhp from 5,100 to 5,300 rpm.

I have used numerous single pattern flat tappet 216/216 to 218/218 @ .050, .45x/.45x on 110° LSA cams in 305s with great results. My brothers 1999 Tahoe has one in a L30 Vortec and it runs great.

dmccain

iTrader: (2)

Look into Herbert Cams we have always ran them and had great luck. Roller and flat tappet alike. Had one on a Vortec headed 350 218- 218 465 lift, thing made great power and tremendous torque.

cardo0

I agree short cams don't make RPM. But in trade they close the intake valve sooner trapping more of the air fuel charge behaving like the motor has higher compression. And it's more than just a few ft-lbs of torque if you have ever seen a graphed comparison of different LSA's you would see the result is fairly large. Can't speak for your experience but again that is why GM used them in big heavy cars with only 265 c.i. (L99). Towing above 5000 rpm I don't know where you are coming from (or going to)??

My experience with my ramjet cam is I have feather the throttle or I get tire spin at any time. I never plan to race it to 6000 rpm or even want to. I have all the fun I want below 5500rpm and the motor will live forever to.. Take or leave it.!

tc7761

iTrader: (1)

Really appreciate all of the input. Lots to learn. Planning to clean up the engine compartment, convert the AC and do some upgrading in the spring, so I still have lots of time. I found that Roadmaster cam from a local guy for $30 but haven't committed to it since he is out of town for a few weeks.

When a friend of mine found this car a couple of years ago, the only good things on it were the drivetrain and NO rust. Otherwise it was a mess. He cleaned it up adding the wheels and got it street worthy. It had a 84 nose, bad MAACO paint job, and butchered wiring in it. The price was right and I needed a project. (have some photos on my page)

New Top, Interior, stripped it to bare metal, Repainted in original color, new door/window/top gaskets and seals, stereo, all new suspension and steering from the column down to the control arm bearings. Everything in it now works. Rides and looks like a new 91 RS which is both good and bad.

The car gets a lot of compliments and is fun to drive. Want to make a few more modifications to wake it up while trying to keep it true to its origins.

Thanks again!!!

cardo0

Wow, you have a whole lot of blood sweat and tears in that car. Glad to hear and see it turned out well. Congrats and best of luck with whatever you choose to do with the engine.

DynoDave43

iTrader: (11)

Let us know which way you go on the cam, and how it runs.

tc7761

iTrader: (1)

Update - After finding out that the 305 block in the vehicle was a pre-87 non roller, I decided to go another route. Purchased a crate l31R vortec from GM, Edelbrock intake, and a new chip from TBI Chips. Hooker headers and exhaust. Bored out the TBI to 46mm and installed 5.7 injectors with a spacer. Install went perfect but tranny went out after 20 miles. Got a B&M from summit and since I was all in, had a 3.42 posi dropped in the rear. Turned out to be exactly what I was looking for. Smooth cruiser with a little extra something under the pedal.

DynoDave43

iTrader: (11)

I'll bet. An 85hp jump and a gear change, should be quite lively.

dmccain

iTrader: (2)

Bet it moves pretty good huh? Did you bump up the fuel pressure also or go with a different fuel pump?

tc7761

iTrader: (1)

Went with an ACDelco EP381 fuel pump and 18 lb spring. Installed the adjustable bowl and a gauge on the TBI. Running at 18 lbs.

Mortorq

tc7761-
What did you think of the tune that TBI chips supplied you for the L31, 46mm & the rest of your combination?
Multiple attempts with data logging or anything?

tc7761

iTrader: (1)

It was a pretty straight forward swap. with the exception of the TBI and headers, the engine is a stock crate. Brian from TBI Chips nailed it first time. smooth idle, nice acceleration, no dead spots, no check engine lights. Honestly, I can't tell you if I'm leaving any horsepower on the table, but it's more than enough for what I was looking for and ended up putting 275 60 15 tires on the rear for traction.

Mortorq

tc7761,

From what I've read , that's pretty impressive for a 1st time out on a mail-order tune.
Sounds like fun. TBI Chips must have done a few of those L31's before!
Thanks.

tc7761

iTrader: (1)

I believe TBI Chips has done quite a few of these RS chip mods. It may have helped that I used an unmolested new crate engine from GM, so the characteristics were probably very predictable. I understand this process becomes a little trickier when using different heads, cams, etc. I took Brian's recommendations for fuel pressure and timing and I am very pleased with the results.

tc7761

iTrader: (1)

The speed shop I use is already telling me this is an addiction I'll be wanting to eventually upgrade the cam. And yes, found out we had to run the bypass hose from the water pump to the intake even though the block had the water port hole bored.

dmccain

iTrader: (2)

Good job! I'm thinking L31 with L98 cam and retaining my TBI