i bought an 88 Sport Coupe, that origonally had a v6 in it, it had a 305 dropped in it a while ago, how can i tell if its a HO, its got a roch 4bbl, headers, Mild cam (apparently so im told, but i dont believe it), is there any way of telling if it is or not?

 

The L69 305 HO, IIRC, was only available through 86. Check the vin number for a G (the common LG4 305 is H).

JamesC

 

Pistons.

The HO's had flat-tops to bump compression and the rest had valve reliefs/dishes. Only way to know for sure unless you have the vin from the original car.

I guess you could pull the camshaft out and measure it, because it could tell you as well. Unless it's suspect to be non-stock.

 

the thing is i dont have any idea where that engine came from, or what its out of origonally. All i know is that its a GM 5.0L (i sais it at the back of the block beside the distibutor), and the mechanic told me that there was a spot for an EGR valve so its probably from a late 70`s to mid 80`s GM

 

Oops, my bad. I thought you were discussing the car itself, not simply the engine. There's a thread in the FAQ section that discusses the HO. You might take a peek there.

JamesC

 

If you can pull a plug and find a way to look at the piston, you could tell if it's dished or flat top. Teeny camera? Good flashlight and mirror and SHARP eyes?

A dial indicator on the rocker arm could tell you lift of the cam. That'll ballpark it for you at least.

Might as well just assume it's a 145HP 1982 305 LG4 and go from there as far as mods go.

Computer controlled quadrajet on it or non?

 

Not good enough, guys. Lo-po LG4's got flat top pistons in '85 & '86.

Basically, assume it's not an HO. '83-'85 were the main years for the HO, the chance of it being an L69 is pretty much slim, and moot. If the cam has been changed and headers added, that's 95% of the difference between a lo-po and HO.

The FAQ thread tells all about "fixing" your 305, HO or no. Air cleaner is about the only thing left (I'll bet it has an open element air cleaner on it now, right?). Don't even start talking about putting flat top pistons in it - it doesn't make that much difference, and if you're going that far, it's time to find a 350 shortblock.

 

Plus, I didn't know about the LG4's getting flat-tops.

 

A smarter way to go about this, would be to figure out what you would do differently, depending on what motor it is.

Given that the biggest differences between the LG4 and the L69 were the cam (which has now been changed), the exhaust (which probably isn't either one, but rather is something completely else), the gears (which you don't have), the electric fan vs the clutch fan (which you're probably using whatever came in the car), and the dual-snorkel air cleaner if it came in a Camaro (which I'm assuming you don't have), then whether your motor was born as whichever one is probably not relevant now.

And if it makes no difference, then it doesn't matter, and is a waste of time and bandwidth trying to figure out.

 

there is no computer in the car, its all mechanical, the comp was removed and the engine was dropped in it

 

And ..... ?

 

i need to get the castin numbers on it so i can find out

 

Why does it matter if some marketing drone behind a desk attached a meaningless "H.O." designation to the engine in its previous application?

 

This is the stock 305 shortblock in my 1983 G20 van at about 240K miles with the heads pulled off. Yes it was converted to TBI and hence the wiring mess. The pistons are obviously flat-top, so before it is shouted out that only the L69s had the Flat-top pistons, think again. The cam was also a "929" from a 350, not the tiny LG4 POS. You can easily see why the heads are off in the first picture, the steel shim head gaskets litterally rusted away around the water passages. New head gaskets, ported the heads, changed the springs, and off it went.

 

The "castin numbers" are the same for the LG4 and the L69. Won't tell you anything.

You're not listening... at the point your motor is at, THERE IS NO DIFFERENCE between the LG4 and the L69, except in case it's an early LG4, in which case it's got low compression. Everything else that would make it one or the other, IS GONE. So, not only would it be a totally useless bit of meaningless worthless trivia even if it still applied; now, it's to the point that it makes no difference whatsoever, because any difference that there would have been, has been erased. All you have left are the parts (the castings) that the 2 motors had in common.

And of course, sounds like you've got a computer-controlled carb with no computer, which is guaranteed to run poor; and maybe a computer-controlled distributor as well, which is even worse for how it runs. You've got no "centrifugal" or "vacuum" advance, if it's the stock dist, because those functions used to be supplied by the computer but are now missing.