Can anyone tell me ( FOR SURE ) which one of these Intake Manifold styles was FACTORY install on thier all original 83-86 L69 "HO" motor ??

These are all 82-86 Aluminum intakes with the same part number. The intake with raised "ribs' on ports 2-3-5-8 is about 1 pound heavier than the other 2. ( I removed ALL the fittings before wieghig each. ) The second style has a "checkboard" stamped into the front and back and the third design is plain.








Thanx in advance !

 

Well, from what I'm seeing...all three have the same cast number, so if one is an L69 manifold (which I doubt the intake is different between it and a standard 305) all three are.

Doing some google searches on the casting number, looks like that intake was used on alot of 305 and 350 engines all the way up to '86 so I again doubt they used a different intake. Mostly I believe the L69 had different heads, and cam.

 

LG4 and L69 used the same intake. I think the different styles is more down to production date. My 8/84 built '84 Trans Am has the checkerboard intake.

 

The cam is different, the heads are the same.

 

Ahh ok, I thought I remembered reading somewhere that the heads on the L69 was the same as on the LU5 crossfire engine and the LG4 heads were different.

 

'82-86 LG4, LU5, and L69 all use the same "416" heads. The reason for different compression ratios is that '82-84 LG4s used dished pistons to yield 8.6:1 compression ratio instead of 9.5:1 with the flat tops the LU5, L69, and later LG4s had.

 

Source: http://www.goingfaster.com/spo/praisetbi.html

 

The 1984 L69 engines received bigger valves in the common iron heads, the cam from the 1982 Cross Fire 350 Corvette, flat top pistons, larger H.O. exhaust manifold castings, and the larger exhaust system all the way back. That was what accounted for the 30 HP increase over the regular 305.

The intakes on the L69 was just the same as the ones used on ALL 305 engines. I would say that your intakes were cast during different runs or years, which would account for the difference in appearance. As far as performance goes, the Stock aluminum intake on those cars wasn't too bad and it actually flowed as well or better than some of the lower end 'performance' replacement intakes.

My 1984 15th anniversary T/As have the intake that looks like the lower one in the last picture, from what I remember. I know they don't have all those ribs on there. I will have to go see if they have those 'checkerboards' near the rear.

 

I can pull the intake from my 85' L69 out of storage and get a pic if your still wanting to know

 

My 85 has the 2nd style- production 12/84.

 

My car has the second intake manifold (checkerboard pattern). It was built in mid-'84 (July, I think).

 

None of the above
This is off my 85' L69 Iroc

 

Interesting ! The same casting number ( again) yet a combination of the "checkerboard" and the ""ribbed" styles !

Thanx for the pic !

 

It would be intresting to find out how many other variations their are.
I wonder if the numbers cast below the "GM CFM" (15, 19, 38, and 45) mean anything?

 

I've had 2 '84 l69 cars and both had the middle checkerboard style intake. My current '83 LG4 also has that same intake.