Alright you guys quick question..I got my 84z28 with a slow LG4 engine in it..and a T5 tranny...FYI Installnig New Ram Clutch and flywheel this upcoming week

Mods to it are.

Hooker 2055 Headers, 3" Straight Pipes, Flowmaster, New distributor, 8.5 MSD Wires, Edelbrock Performer Intake Manifold, Stewart Water Pump, K$N Open Air Element, Rebuilt OEM CC-QUADRAJET, KYB GR-2 All around, Eibach Sportlines All Around, 36mm Sway Bar (front), Wonder Bar, Founders Panhard Rod(Coming in this week)

I know my car has the "peanut" cam...but other than that What do you guys think....305 H.O?????????????w

 

L69s had flat-top pistons for 9.5:1 compression. They also came with more aggressive axle ratios. Mustn't get too serious with the cam while you're at 8.6:1. Nothing more than an XE256.

 

So ur telling that in a staright line a legit H.0 84 z28 stock will beat me?

 

No it is not.

Yes an actual L69 car, even if bone stock, will drill you so hard you won't know what happened.

 

hmmm....now u got me thinking about that...Now all i need is to find someone with a H.O 305 to really put my cat to the test....I still honestly think he wouldnt win...The advantage I have to is that mines a 5 speed, so...I really am curious...

 

Well I'll put it this way:

One of my little brothers bought a 84 LG4 car in about 86 or so. It was an auto, but it had 3.23 gears.

My 83 L69 could start out BEHIND his car at a traffic light, and before I was out of 2nd gear, I could pull out and go around him and get in front.

My car had around 60k on it at the time, and his about 35k if memory serves.

That's where you're starting out from.

 

aww man you guys just tore me awpart..=(.....O well....ill just have fun with this engine uintill it "blows" then drop a 350..=)....will installing some 3.42 gears on the rear make a big difference from my stock open differential? kus I really wanna get it done soon but just not sure if itll make a change?

 

swap your junk heads and you'll smash on any factory 5.0


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jaja i bet

 

The heads aren't the problem.

As already noted, it's the compression (due to dished pistons), and small cam.

 

But if he were to swaap to a set of 081 heads with 58cc chambers as opposed to 64cc his heads probably have and since they were off swap to a set of shim head gaskets would not that increase his compression ratio may not bring it up to factory h.o. specs but would help and if he swapped to a larger cam he could likely beat a ho 305

 

+1.

JamesC

 

LG4 and L69 used the exact same heads. Difference in compression is because the LG4 used dished pistons before 1985, where the L69 always used flattops. In 85 the LG4 got the same flattops (and, therefore, the same compression ratio as the L69) but still had the horrible peanut cam.

The exhaust on the LG4 was of the "strangulation" variety, all years (much smaller from the manifolds all the way back to the tailpipes).

 

Check out the difference in Y-pipe size, for example.

JamesC

 

Were the cats bigger also?

 

Oh, absolutely. The L69 HO used a 2-3/4" y-pipe, cat and cat-back. The LG4 used 2-1/4" all the way back.

 

Back in the day, I stuck in an after market catback on my LG4. At a later date, the swapped in a complete L69 system only to discover that the L69 intermediate pipe was larger the the LG4's after market piece, which was 2.5.

JamesC