87_LG4

Seasons greetings!

So earlier this year I was driving home from a friend of mine. As I backed into my driveway I noticed a stream of oil on the ground coming from my car. Made a huge mess and I lost a lot of oil. Luckily there was no damage to the engine, but seen as how the engine was already coming apart I thought: why not do some upgrades while I have it out. So the engine has been stripped and cleaned, I've bought a new cam and springs, done some minor machining to the block to improve oil flow (see pictures below) and I'm about ready to start putting the thing back together. Now I need your help to figure out the last few parts and such.

As I've previously had some problems with my carb (traced it back to electrical malfunction), I decided to replace all the feelers, sensors, solenoids and whatnot, just to be on the safe side. As of now, my list has an O2-sensor and the cooling-fan temp sensor, but I know there are at least two other sensors (one on the the side of the head and another on the block). I have 14101081 heads and a 14093627 block.

I've also got a friend who has a friend (sounds sketchy right?) who works at a Rolls Royce machine shop. He has agreed to do some machining on my heads. Initially we're talking milling to increase CR, and some pocket porting. Hopefully I'll get some 1.94" valves as well. Now what I need to know is, how far can I mill down the heads before th valves start touching the pistions and whatnot? Easy put, how much should I mill down? I'll be running stock crank, rods and pistons and a Comp XE258 cam with 0.480 intake and 0.487 exhaust valve lift. Not sure about the gasket thickness, but I'll go out and measure when I get a chance.

Pictures will follow. Just gotta find them first.

Thank you for any answers, and if you have other parts, mods or performance suggestions, lay it on me

87_LG4

Lots of sludge and carbon buildup. Forgot to drain coolant before removing heads Rookie mistake.

87_LG4

Oil passage cleanups

87_LG4

Cleaning up some sharp edges and excess metal.




Also cleaned up the intake

Jeffs82TA

iTrader: (1)

Didn't "081" heads come on a 305 TPI motor? are you sure this is a LG-4?

87_LG4

It has the LG4 RPO, it has a carb, it is sluggish as hell. I'm pretty sure. But I will double check...

The heads are 081.


According to RB83L69 in this thread https://www.thirdgen.org/forums/tech...4101081-a.html they are:

"non-swirl-port 305 heads from 87 LG4, TPI 305 from 87 to 82, and the L69 and LG4 that was used in the Monte Carlos in 87 and 88."

87_LG4

I just now realized that my questions may have been poorly formulated. To simplify:

1: I have 1 out of 3 sensors (or solenoids ?) that I need on the block and heads. It's the cooling fan temp sensor from the one head. There is one on the other head and one on the block itself. Which or what are the two others?

2: How much can/should I mill from my heads before piston/valve-clearance becomes an issue, and how much CR will I then get?

Thanks again.

Damon

Hold on, my friend. You just opened a whole can of worms for me.....

Are you SURE that engine is original? LG4 carbureted motors should never have come with a roller cam (which you got, given the factory "dogbones" and roller lifters in the engine). I assume there was a lifter retaining "spider" that you already removed before taking the picture. Should be flat tappet stuff in there. So, that's odd from the get-go.

You've got flattop pistons in the motor which would be appropriate for an 85-up LG4 or a similar vintage TPI engine. So nothing too odd there.

-081 heads sounds right for an 87 LG4 (and ONLY an 87 LG4 in an F-body) since they went to centerbolt valvle covers and the unique 87-up intake bolt pattern in that final year of carbureted F-body engines.

Various sensors....

Sensor in the passenger side head would be to turn on the electric cooling fan at a certain temp...... which I also thought a carbureted engine wouldn't have. Thought carb engines in 87 still had old-style mechanical fans driven off the front of the water pump, but maybe I'm wrong about that.

Sensor in the driver's side head runs the temp gague in the dash.

Sensor in the block (down near the bottom of the block by the pan rail on the passenger side, right?) is your knock sensor. That is common to both LG4 carb motors from 85-up and later TBI/TPI engines.

At the very least you have to get straight on this roller/flat tappet cam issue. If you don't you might have bought the wrong style cam for it. Damn, it's odd to see a roller cam in a carbureted engine. Just shouldn't be there!

Then again, I had an 87 TBI engine in an F-body with a factory flat tappet cam in it, and nobody believed that, either!

87_LG4

I admit the 87 model was sort of a special one, but yes, it did have factory rollers (even the LG4), electric cooling fan and slight dish pistons (87 LG4 only?) (which you can't really see in the picture given my rookie mistake of not draining the coolant before removing the heads, thereby filling up the cylinders with lovely brownish water)

Thank you for the sensor info. Now I'm one step closer to completing my order at summit.

naf

iTrader: (7)

Yes, the '87 was the only year that came with the roller cam in the LG4.

Most of the sensors shouldn't need replacing. Failure of the temp senders and KS is pretty rare. The TPS in the carb is a commonly replaced item and you'll probably want to swap a new one in when you rebuild it (along with a new float). The VAC and BARO sensor are mounted on the firewall and failure for them is pretty rare too.

The 87 LG4 was pretty tight with the compression stock. Check with the cam manufacturer for their recommendations.

The cam you listed is a flat tappet? I wouldn't go backwards, especially when you would need to purchase new tappets and pushrods-you've already got the roller stuff.

87_LG4

My bad. Supposed to be XR258: http://www.compcams.com/Cam_Specs/Ca...?csid=185&sb=2

naf

iTrader: (7)

That's what I was thinking after I posted. Didn't remember a flat tappet at 258. I've used the 256 in LG4's before. You should be happy with the 258, should be friendly with your stock converter and gears. May not want too much extra compression though.

That cam and induction in a 350 though would be sweet on the street. IF that's an option?