87_LG4

Hi everyone.

I'm currently disassembling my painfully stock 87 LG4 to get to a head gasket leak. Whilst going at it, I came across some wires that weren't plugged in to anything, and also a radiator hose that had been cut and sealed shut. Can any of you help me identify this:



As you can see, someone has also been messing with the wiring for the headlights.

Also, since my engine is already being torn down, I was thinking about adding some power upgrades to it, whilst keeping it street legal (as it is my daily driver). So what would you suggest to get some more low/mid-ranged torque and a few extra hps? Perhaps a new cam or doing some grinding on my heads? I also read somewhere that I could swap a few parts to make my lg4 q-jet into an l69. Do you know where I could get these parts? I would be very grateful for definite answers, instead of general suggestions like I see in a lot of threads. Just ask if you need more info on my car or my drivinghabits.

Thanks

85Iroc-Z

iTrader: (4)

The hose in picture one is one of your heater hoses. https://www.thirdgen.org/forums/tpi/...e-diagram.html
And the electrical connections in picture two I believe are for the emission valve on the passenger side of the engine. I don't see the valve im talking about in your picture so I'm guessing that someone removed it, along with some of your other emission components. I am not sure on the one in picture three. For a performance boost, I would add a full exhaust from the headers back (headers, high flow cat, 3 inch cat back). If you wanted to add a new cam and heads, that would definetly give you a power boost.

87_LG4

So my radiator is from a TPI car? Thank you. I wonder what other changes the previous owner(s) might have done to my car.

And I will be getting new exhaust in the near future. I was thinking about doing a 3" true dual with an x- or h-pipe, and hooker competition headers. Or might that be a bit overkill?

But like I said, I'll be focusing on what I can do specifically to my engine now that it's in pieces. And this is where I need specific advice, since I don't have half a clue on what to look for when buying a cam, or if I need to upgrade my rockers, rollers, lifters and what have you at the same time.

87_LG4

So I went out to check if there were any missing hoses going to or fro my heater core. This is what i found:



It appears that the shortest hose has been cut, spliced (I'm guessing that GM didn't factory splice theirs) and re-routed.
Does anyone know how an '87 carb'd 305 with air con looks like stock? Hose-wise that is. Pictures?

85Iroc-Z

iTrader: (4)

That doesn't mean that you have a tpi radiator. I just sent that picture assuming you had a tpi to show you how it should go. I believe all the radiators are the same for third gen camaros though.

87_LG4

I remembered the previous owner saying something about the engine overheating when idling for a while without airflow over the radiator. Could this be the reason. I figure the mod has been made to get hot water flowing through the heater straight from the engine block, instead of waiting for the radiator to start circulating. Would this be a reasonable assumption?

Also, it appears I may need to replace the distributor, but I'm not sure what kind of system the car is currently running. Mechanical, vacuum advance, centrifugal advance, ECM controlled or what. Can anyone help me identify which kind of distributor I need to buy?



Thanks

five7kid

iTrader: (14)

Replacement radiators often would have the later style heater return, even if your particular car didn't use it. The heater supply is the one off of the intake manifold, which is before the thermostat. The return is like the old style, but it appears yours originally had the shut-off valve that closed off the heater core flow when in max AC mode. The earlier LG4 cars didn't have that valve.

It appears you have the correct type of distributor for an '87 computer controlled carb LG4. The advance is controlled by the computer, so there is no vacuum or mechanical (same thing as centrifugal) advance on the distributor.

The '87 A.I.R. diverter valve (which appears to have been removed from your car) was different than the '86-earlier of which I am more familiar, but I'd guess the green and white connectors on the passenger side went to that valve. I don't recognize the one you're holding in your hand, I'll have to go out and look to see if my car has something similar.

naf

iTrader: (7)

#1 Concur.
#2 AIR electrical pigtails
#3 Power steering pump pressure switch. There are two pigtails here for '87 LG4s with AC. The standard pigtail (looks like the one you're showing but I'd have to check) would engage the throttle bump solenoid when the pressure was low. When A/C was installed an alternate pigtail and switch would be used to cut out the AC compressor with a drop in steering pump pressure. When the AC setup was used the standard pigtail would be left hanging there, unconnected. I haven't seen these pressure switches on pre-87s but they are on TBIs.
#4 Someone has removed the vacuum operated heater diverter valve (it was probably leaking). When the control head switch is in the 'cold' position the AC head would provide vacuum to this valve. There should be a small, hard plastic vacuum line that would connect to this valve located above the pass side valve cover. Looks like it may still be under there? You may want to chase it down and verify that it has been plugged.
#5 Looks good. You may want to chase down the vacuum lines that run to the EFE valve that is located at the connection between the pass side exhaust manifold and the y-pipe. There should be a rubber connector between the metal vacuum line (that runs down from the cylinder head) and the EFE valve that doesn't live very long in that environment. The EFE closes when the engine is cold to force exhaust gas through intake manifold passages to the other head. Speed cold warm up.

That red positive lead running across from your alternator disturbs me.

87_LG4

Thank you all for your help in figuring out these unconnected bits. It's been frustrating not knowing, you know?

About the red wire from my alt, it's a part of the aforementioned DIY headlight wiring upgrade one of the previous owners must have put in. Rest assured thou, I'll make my own the same style as the one in the tech article as soon as I get a chance.

Now that we've sorted out the assorted unplugged wired and hoses, I'd like to ask you for some performance advice. I thought that since my engine was already being taken apart to fix the leaky gasket I'd put in some new performance parts. I was thinking of porting my heads (DIY or professionally, depending on my skill and their cost), installing a new cam and upgrading the exhaust. Here's the thing: I don't know enough about cams to select an upgrade candidate of my own. I do however know where I want my power. Since it's my daily driver I don't really need high rpm hp and torque, but a nice boost to the low and mid range is what I'm looking for. Of course, it would be nice to be able to give it wot and gravel all the pretentious Japanese tuner imports driving around However, if I can't have both then low-/mid end torque will do. If you could point me in the direction of a cam for my engine then that would be great.

Also, when I do get my heads ported, should I get larger intake/exhaust valves at the same time? I've read that 1.94" intake and 1.6" exhaust valves is a good combo. What do you think? And do I need to get new valve springs?

My plan is to eventually get new exhaust as well. I think I'll go with the Hooker 2055 headers, 3" mandrell bent tubing all the way and something like a magnaflow cat back. I'll do my research there before I make up my mind.

Any advice on the whole performance issue is gladly appreciated, but like I've said throughout the thread, advice on specific parts is really what I need.

Thanks

naf

iTrader: (7)

https://www.thirdgen.org/forums/carb...tions-lg4.html

I've had personal experience with the XE 256 from comp in an LG4 and it worked well with the stock converter/gears. You've got a roller motor though and I wouldn't down grade to a flat tappet. Maybe something close in a roller.

Comp Cams website has a downloadable program that will help you compare their models and match them with your motor. Kind of cool.

87_LG4

Oh man, that comp program was awesome. Someone really ought to do a public service announcement about it, or at least a sticky.

So what I've manage to find is the XR270HR. It looks to be about right, don't you think? That plus new valve springs from summit comes to $348.45. It requires machining on cylinder heads thou. What sort of machining would that be?

naf

iTrader: (7)

May be a little radical with stock gears and torque converter. That cam's going to want some higher gears and a looser stall.

87_LG4

Ok, so that's a bit radical. Well, how about an XR258HR? According to CamQuest 6 it gives strong torque, good mileage, fits stock to mildly modified combinations. Another possibility would be the 260HR. But if I'm to believe camquest it gives smooth idle, which I don't desire. I like choppy idling.
So the XR258R seems to be the best logical choice (according to camquest) Any takers? Yes? No? Maybe?

Thanks

naf

iTrader: (7)

I like the 258, but that's only one guy's opinion.

A more aggressive cam is going to move the power band higher in the RPM range, which means less power down low. Your car's stock gears AND the torque converter are optimized for low rpm torque. If you want to stick with the stock parts, get reasonable mileage and better around town driveability, you'll be happier with the smaller cam. If you're willing to change some stuff out and compromise on driveability you can go as radical as you want.

There's also a tech article here written by Sonix that has some good info on cams.

87_LG4

Ok, so +1 on the 258. I'm pretty sure I'll be going for that one (unless anyone else has anything to add). As soon as I get the money for it (might not be the most expensive part, but I make less than a grand a month (ca $500 after the bills are paid) and trans-atlantic shipping is a mother) I'll order a cam, exhaust and some misc for my car. Look for a my-car-build-thread about it, with pictures and progress updates. Hopefully I'll get a chance to dyno-test the car after I'm done as well.