Neil Settle

1986 Trans Am, VIN H, 305 V8 Q-Jet 4bbl. I'm finding conflicting info out in cyberworld. Reading that all VIN H F-bodies from 1982-87 are the anemic 165 HP LG4s. However, decals on both lower front fenders read "5.0 liter H.O.", which should be the 195 HP L69. Which motor do I have? I want to order a Hypertech power chip and want to be sure I order the right one. Thanks in advance for your wisdom!

1988 Iroc 5.7

iTrader: (3)

If you have an 'H' in the 8th digit of the VIN, you have an LG4. Sounds like the previous owner added some H.O. decals to make it faster!

Neil Settle

LOL! Thanks for such a prompt reply! Additional question: I notice that both engines supposedly have a 9.5:1 compression ration ratio. The owner's manual calls for regular, but, IMO, with such a high CR, I think premium is called for.

Drew

iTrader: (58)

LG4 and L69 use the same heads but different pistons. They are not the same CR.
Save your money, there isn't much a chip is going to do for an LG4. Fix the exhaust, fix the rear gears, fix the cam. Chip is really far down the list.

Fast355

iTrader: (2)

85+ LG4 had flat top pistons and the same compression ratio as a L69.

Disagree on the chip having read the timing advance values used on LG4s. Kinda hard to build power when the timing advance has a super limp wristed timing advance curve.

Drew

iTrader: (58)

Hmm, guess I should read up a bit on later LG4s. Or not, ya know, because 305.

How much better can an off the shelf Hypertech be? They're not exactly custom tuned, latest technology. I'd still put the money somewhere else...

Fast355

iTrader: (2)

Some of the Hypertech stuff works really well atleast for WOT. I have read a few of their chips that missed the mark but others do well.

I ran one of their programmers on my 2012 Titan when I had it. Dropped 7 tenths and picked up 4 mph in the 1/8 with no other changes.

Drew

iTrader: (58)

Weird. The chart in the old-school Chiltons shows 8.6:1 for the 86 LG4, 9.5 for the L69. I pulled the 87 Camaro GM/Helm manual and looked up the V8 engine specs, it shows 8.6 for the LG4. IDK...

Drew

iTrader: (58)

Great... The parts catalog shows the same pistons in the later LG4s and L69/LB9. BUT the Canadian export LG4 got the same 82-84 LG4 pistons, presumably the dished pistons allow the Canadian LG4 to run on high test maple syrup without pinging. Who knew?

I officially divest myself from the topic. Any SBC but the 350 is pure heresy.

Fast355

iTrader: (2)

I will take a 406 or 434 over a 350 any day of the week.

zed-028

Considering there is no lack of iron in that motor - im guessing you mean 'asthmatic' LG4

As was mentioned - exhaust, intake and cam

i wouldnt bother with a chip in an LG4 and believe me, as the owner of an LG4 i'm not bagging it, but you get better results elsewhere on this motor.

86LG4Bird

iTrader: (1)

Chiltons isn't very reliable for year-to-year engine data/changes.
86 LG4 in my sig had flattop pistons. Ran pretty well on 87 octane, even with base timing advanced. Pinged only when lugging up a hill on the hottest days with the TCC engaged in 4th gear.
Hypertech is not cost-effective for this engine. It wants more total timing anyway, especially if you're willing to run 89/91 octane fuel or better, so bumping the base timing up a few degrees helps all the way through the load/rpm curve.

Neil Settle

Main interest in chip is it claims it makes car run cooler. Any truth to that claim? I've installed a three row radiator and dual fans and this has helped.

What brand of exhaust, intake, cam, etc. should I buy?

Neil Settle

I've been told that doing away with the computer and putting a regular disrtibutor and carb on the car you could get a lot more power.

NoEmissions84TA

iTrader: (1)

If you have a 700R4 transmission, then I have a Jet Thermomaster chip. Stage 2. Stage 3 was offroad only. Check the code on your ECM and I will check mine. Maybe we can make a deal.
One of the best benefits of this chip is that it eliminated the torque converter lockup "hunting".
My TA is an 84 LG4.

NoEmissions84TA

iTrader: (1)

You could do that depending on emission regulations of the state you are in.

zed-028

i did this and have never looked back

few things to consider -
carb choice - i still stuck with an older quadrajet which i rebuilt
Distributor - basically anything for an sbc with vac advance will fit
tcc lockup - plenty of kits to solve this one

but most importantly - does you state allow it?

Neil Settle

Thanks for the input, as always. Since I have my car registered as an antique, my state (NJ) exempts it from inspection.

Neil Settle

Thanks! For some reason, I'm lucky not to have that issue of hunting. Had a big 'ol 84 Caprice wagon in the day that drove me nuts with that. It's in car heaven now.

MY87LT

iTrader: (2)

Don't forget, 1987 was the first year for the roller cam, center bolt valve covers, and this was the first year for 165 hp on the LG4 (170 for z28 and iroc by having larger exhaust). Also, from the records GM sent me years ago, the compression for the 8 cylinders in 1987 was 9.3:1

dmccain

iTrader: (2)

Ive went with non computer controlled carbs on these cars several times and never had trouble with my 700r4 being unplugged from torque converter lockup. Others say its not good for it. I had zero problems and put many miles on those cars.

five7kid

iTrader: (14)

The LG4 and L69 intake manifolds were exactly the same.

Except Canadian LG4's had a cast iron intake.

MY87LT

iTrader: (2)

Why were the Canadian's installed with iron instead of aluminum?

chazman

iTrader: (4)

Are we 100% sure that 5 hp difference if from the exhaust? My '87 is rated at 170 but appears to still have the puny 2.25" I-pipe.

MY87LT

iTrader: (2)

Every record I have seen from the factory has shown that the Sport Coupe and LT with the optional LG4 was only rated at 165. The Z28 and IROC always had the better exhaust since I don't own either a 1987 Z28 or IROC and I don't have my literature in front of me, I'm guessing their intermediate pipe was 2.5 for their LG4 base engine. I too had that 2.25 intermediate junk I got rid of finally a few months ago. Check out this link for now. http://www.nastyz28.com/camaro/camaro87.html

chazman

iTrader: (4)

Personally, I have no idea where that extra 5 hp comes from.

It's been suggested to me that those 5 extra horses come from the IROC-Z decals.

sonjaab

LG-4 VS L-69


Starting with a standard issue Chevy 305 small block, here are some interesting notes:

• both use aluminum intake
  • early LG4 models had a cast iron intake however
• both use the same heads
  • casting: 601
  • 58cc chambers (60cc ?), 178cc runners (158cc ?)
• valve size in L69 heads were larger
  • L69 : 1.84/1.50
  • LG4 : 1.76/1.46
• L69 has 9.5:1 CR (flat tops) [these numbers changed]
• LG4 has 8.6:1 CR (dished pistons) [these numbers changed]
• L69 has a special cam, from the L-81 Corvette (hydraulic)
  • This is NOT a roller cam
• L69 uses a performance calibrated PROM
• L69 takes advantage of special exhaust/catalytic converter
• L69 takes advantage of a higher stall torque converter
  • L69 : approximately 1900 RPM stall
  • LG4 : approximately 1200-1500 RPM stall
• L69 uses a better fuel pump (from the Z/28)
• (EARLY years L-69s had a fuel pump in-tank AND on block)
• the changes in the L69 setup yielded *roughly* 30 more horse power
• the same changes actually yielded slightly less peak torque for the L69, but had the advantage of a flatter torque curve overall

MY87LT

iTrader: (2)

Well you have to be banned now. You let out the IROC secret.


Good thing you didn't mention that when you ordered RPO DX3 decal and stripe delete, the car can go ludicrous speed.

MY87LT

iTrader: (2)

And almost all of the 1987 LG4's had both the in-tank pusher 3 psi electric pump along with the mechanical pump to prevent vapor lock.

zed-028

I can first handedly confirm the existance of that little bugger in the 87's tank

sonjaab

Did you miss the word "EARLY" ?


I should of added the early LG-4s did not have the pump
in the tank while the L-69s did.


Pasted post anyhoo................

84 Z-28 350

my first 84 Z-28 originally had an aluminum intake and my second 84 Z-28 originally had a cast iron one, there long gone now, but both were "H" engine cars, not quite sure what GM was thinking, I remember one of my first mods was taking the intake off my first one (my one and only car accident) and swapping it to the second Z-28, then my dad getting an old vacuum dizzy and a old mechanical choke quadrajet he had laying around and putting it all together...with the choke wired open....starting it in a NJ winter with no working choke sucked

MY87LT

iTrader: (2)

True and then there was the GM fix to the vapor lock too which some cars got as well. That one blower motor that would turn on and off and cool the carb. There's a picture of it here somewhere in the threads.

five7kid

iTrader: (14)

Not a very reliable list with regard to 3rd gens.

416 heads (more common than 601 in U.S.; at least my numbers-matching, never disassembled '82 and '86 LG4 both had 416 heads - oh, and aluminum intakes)
1.84"/1.50" valves (all 3rd gen 305s)
9.5:1 CR for LG4 in '85/'86, 9.3:1 for '87
Different q-jet calibration for L69 (along with PROM, cam, & exhaust)
Knock sensor for all L69s, and '85-'87 LG4s (with their higher compression)
Electric cooling fan for L69, electric for '86-'87 LG4

As is true with most any model of car, the year model equipment could be affected by when in the model year the car was made, availability of parts at the time of assembly, and post-sale modifications/repairs. In the early part of a model year, left over parts from the previous model year may be used; similarly, in the later part of a model year run, they may bring forward parts intended for the next model year if they have a shortage. Parts availability may also lead to a parts substitution from another model line. A cast iron intake manifold could have been used for any of these reasons (except it was never planned for any model year U.S.-delivered 3rd gen).

Warranty work makes anyone's personal experience suspect (unless you were the original owner of the vehicle, and you know everything that was ever done to it). I picked up a complete '87 LB9 that was supposedly pulled from a car that was all factory stock. Turns out it was .040" overbored with full dish pistons, had one TPI head and one TBI head (TBI wasn't even available in '87). Oh, and the block was cracked in the lifter valley (probably the reason it was worked on in the first place). So, take the "My car had..." claims with a grain of salt, especially considering how old these cars are getting to be.

84 Z-28 350

Ok...how did it work out that my second Z-28 had a cast iron intake...when I bought it I was the second owner, he had all the recipes from when the car was new (bought in NJ in Dec 83, 84 model year manufactued date of 8/83), everything under the hood looked stock and he told me that it never went in for major repairs...the VIN for the car was stamped on the front passenger side of the block, by the alternator (I think it was the vin...I know my dad mached the #''s there to somewhere on the body...it was 20 years ago lol) and I don't see anyone swapping a cast iron intake for an aluminum one

zed-028

Sounds like the previous owner cooked up a good story for you with one of those recipes

people lie, probably lie a little more when they're trying to sell stuff, probably even more when they're trying to sell off a used vehicle

84 Z-28 350

IDK, I don't think he had a reason to lie, it burned oil (the oil drilainback holes on the heads were clogged....shop vacs are awesome) it had a treelimb in the windshield and a scrape in the door, I bought it for $250 in 1998, and you could tell he was a drunk, he Def wasn't trying to talk it up, maybe sombody at gm had an off day back when it was built?.. hey the car has come along way since then

84 Z-28 350

Sorry for all the spelling errors...my Internet is out over here so I'm using my cell phone and I have fat fingers lol

MY87LT

iTrader: (2)

Just noticed it says you're deployed. Be safe.

chazman

iTrader: (4)

Agreed. Stay safe.


I'm thinking the 5 hp difference on the '87s is ECM programming?

MY87LT

iTrader: (2)

Well even though on paper it says 165 for Sport Coupe and LT and 170 for Z28 and IROC, I'm starting to believe that they just said that to make it seem a better engine for the higher end cars even though it's the same exact LG4.


Like I said before, my factory intermediate pipe was 2.25" and I never physically measured the Z28 or IROC's of 1987 specifically. Like the last years of the L98 on the Corvette like in 1991, it was stock 245 hp, but with the Z51 option it gained an extra 5 hp due to a less restrictive exhaust.

chazman

iTrader: (4)

Here is the stock exhaust from my '87 LG4, IROC-Z

The muffler/tailpipe assembly is the same 2.5" inlet used on all IROCs. As you can see, the 2.25" I-pipe is stepping up to meet the 2.5" inlet on the muffler. On the higher horsepower cars the 2.75" I-pipe steps down to join the 2.5" inlet.

What I'm saying is the 170 hp version and 165 hp version both have 2.25" I-pipes.

MY87LT

iTrader: (2)

You've got 4 IROC's?

chazman

iTrader: (4)

Yes.

MY87LT

iTrader: (2)

Bitchin'