The wife wants to replace the stock intake with a Performer on our LG4. Right now the threads on the stock intake for the thermo housing are stripped (leaks a lot). Since I ordered a new carb, I was thinking about changing the intake as well. Will I get any gains? Anything special I should know before I do it? Thanks everyone Z28Bama

Nothing special about a performer, its a STOCK replacement and thats what it is a (stock replacement). Get the best intake useable for your application bigger is betterm a stealth would be choice but since you probably will go with a Qjet a spreadbore RPM would be better suited. Since you have the intake off and all the fluids drained you might consider upgrading cams since its only a couple hours more to do so.

Well on a LG4 that already had headers, the Performer dynoed 19 hp/23 ft-lbs more than the stock intake during a Car Craft test buildup on a LG4. Don't know how much of an impact having the headers on the car had on that, at least a little as with a better exhaust obviously the car would like more intake... The stock intake would have been a choke point with the headers, but it stands to reason you'll get a decent increase anyway. BTW, the Performer RPM then made like another 15 hp on top of what the regular Performer made, same torque basically.

Here's the article if you wish to read it: www.inter-scape.com/ray/305buildup.htm

I put the Edelbrock 1406 Carb and 7101 Performer RPM intake on my LG4. I got a huge increase in power, approx 50hp.
I was able to run a 14.94 @ 91.67mph.
What does a stock 86 LG4 run in the 1/4?

Stock replacement lol.
I should have saved the money and used an Lg4 manifold on my 383 then.

Get it. It will be a nice improvement over stock.

What about the stealth? Is it any better than the performer intake?

Also, are there any advantages in having the stock alluminum intake rather than the iron?

The performer is a decent intake, however with the lg4 the largest *single* power gain I think would come from a decent set of headers. If all the smog equipment is still there, go with a set that has the A.I.R lines and a y pipe, like the Hooker 2055s....

Intake is all well and good, and a better intake will improve power and economy, but the exhaust gases still need somewhere to go or else they block the fresh air/fuel from getting into the cylinders. It's all about balance and matching parts.

Since it's got a leak, replace the intake along with the carb. Then start looking at exhaust

Once you do that, you'll need new tires, though

As far as teh Stealth, you'd have to be alot more specific.... that's a whole product line, not a specific model.

The Performer is better than most stock intakes, it's roughly a duplicate of the old Z28 aluminum intake, with modern bolt holes and stuff. Not a massive upgrade, but usually a little improvement.

Most of the bottlenecks in teh LG4 are elsewhere. Until you fix the exhaust, all the way from the heads to the street, by replacing it with something NOT FOR LG4; and put a cam that has actual lobes on it in there; and port the heads, no intake is going to make very much difference. It's not the restriction in your induction system, so the flow through the engine isn't going to increase much no mater what you put there.

It's not a bad choice for the situation you describe, namely, fix the leak without regard to max HP. It's cheap, legal, and about as close to a straight bolt-in as you're going to find. The Holley/Weiand product is similar in that regard. Something like a Performer RPM is not.

Heheh.....forgot about the cam.....though I'm not really edumacated when it comes to cams in the first place. about all I really know is the theory behind how they work and what they do.....when it comes to designs, lift, duration, and even types I'm 100% ignorant

Ive seen that before, my money is on the headders being the reason for the improved performance. Ive used the standard SBC performer and can say its not worth the money since you can get a better intake for a few bucks more theres no reason to skimp here. If you notice all the manifold write ups they always change more then just the intake manifold durring the swap, they always add headders or a larger carb durring the swap.

THey didn't swap more than just the intake, it's just the engine already had headers for the baseline, so it wasn't a bone stock setup. With headers and the stock intake the LG4 made 197 hp, it made like 216 I believe it was then when they swapped on the Performer. 230hp with the Performer RPM, still with the stock peanut cam and stock heads.

If you're going to get a new one make sure you get one that works with your '87+ heads (#3706). It's more expensive than one made for earlier heads, but otherwise you would have to drill out the center intake bolt holes to make it fit.

I dunno about anyone else's set-up but on mine the performer made my car 0.8 seconds faster than the stock one did.

So if I get a performer RPM, will it all bolt right up or do I have to modify it? Thanks

Z28Bama

Let's go back to the beginning - what "new carb" did you order? Another CC q-jet? If not, you'll need a new distributor as well (vacuum/mechanical advance).

Assuming everything was in proper working order before (except for the coolant leak, of course), the performance gain will be right in the range of ----- zero. As has been stated before, the restrictions/limitation of the LG4 are not primarily in the intake manifold. Unless/until you do something about the other issues (exhaust, cam, air cleaner), the intake isn't going to make that much difference. If you're looking for an upgrade while fixing your coolant leak, you'll be disappointed. If you want to fix the coolant leak, get some Permatex Form-A-Thread. If you want to see a performance improvement, wait until you do the cam swap before you do the intake swap and save yourself a set of gaskets.

When my LG4 was stock, I had a 2-3/4" stock TPI take-off cat back, open element air cleaner, chip, Accel coil, rods/hanger, advanced timing. It ran a best of 16.85 @ 80 mph here (high altitude, remember - converts to 15.5 at sea level). I pulled the intake because I had a coolant leak at the front head passage (degraded gasket). While I had the intake off, I looked at the GMPP intake I already had sitting there, decided to put it back on instead. Back to the track, it ran a best of 16.80 @ 80 mph. That's not much of an improvement. The best part of the switch was that the stock manifold EGR passages were plugged, and the pinging problem I had previously had with the advanced timing went away.

If your q-jet is basically functional, you'd be better off keeping it and maxing out its performance potential than you would by putting on an aftermarket carb like Performer or Holley. It has plenty of capacity to flow what the engine can demand, will adjust itself to that demand, and will get better gas mileage than any non-CC aftermarket carb.

Aftermarket carb for the sake of performance improvement over a q-jet is a waste of money that would be better spent on cam, exhaust, air cleaner, and head work.

The "new carb" is actually a stock CC-Jet with approx 5,000 miles on it. The one I have was just rebuilt but the butterfly's are worn down so much you can get it to idle right, also it is just a crappy carb, (188K miles). I got the other carb for $50, so why not. I have no muffler right now, if that counts for exhaust

I am stuck on what to do now............

J/C What cam would be good to go with some headers. And some heads or head work?

Are you modding this car in the future? If so....get the intake now. As stated before, you may not see any difference in the swap but you won't have to buy everything at once either. My .02

Brandon

BTW...always do what the wife wants or you'll pay for it later .

I don't believe they make a Performer RPM that bolts right onto '87+ heads, so you would have to modify it. Also the Performer RPMs don't have EGR provisions.

five7kid

when i rebuilt z28bama's carb, the throttle plates are completely worn out, that is why i only did minimal work to the carb, who ever rebuilt it befor did not set the float correct, and also the secondary venture were stuck in the closed position, when i put the carb back on i adv him it would probably be a good idea to get a replacement carb. Also on the coolent leak, i tried to rethread the hole and did not hold, and tried a heli-coil and the aluminum would still not hold not hold but on the same note I did not think of the Permatex Form-A-Thread. The previous owner may have tried to do a few repairs of (his or her own) and crossedthreaded the hole and tried to install a bigger blot in its place. And also z28bama: what about your oil pressure, is it still on the low side?

yeah it is a little on the low side,

it is leaking a little oil down the valve guides, (only burns on startup). I just wanna get another carb/intake until I can get some aluminum L98 heads from my brother. I think I got one, with 6months from a rebuild. for $65 or so, thanks

Z28Bama