Terry

I'm looking at picking up a '84 Z28 HO 5speed with a 305, 4bbl. I would like it to be a safe, get to school, car for my kids. It has some exhaust mods (not headers) and a cam and currently gets about 13 mpg.
My question is: Could I put a 2 barrel on it for a few years to get lower performance and better mpg while the kids use it? What carb? and what mpg could I expect? Later I would return it to stock condition.


Thanks, Terry

RB83L69

Best thing to do would be to remove the link between the primary and the secondary throttles, or bend it or something, so the secondaries never open. just make sure you do it in a way that's non-destructive; that carb is different from most others, and is rather hard to find.

Terry

So maybe this car is out of tune. Or maybe different rear end gears would make a difference. I think they're stock right now.

Anybody know how a HO engine varies from "standard" or do all Z28's have HO's?

Sorry for the ignorance, my background is more about 6 cyl. BMW's.

84305HO

The stock gears that came in that car are 3:73, so thats
not going to help the mileage.

99Hawk120

Try grabbing a set of DD rods and a T hangar for the carb. That's almost as good as disconnecting the secondaries completely

pimpinthaz28

Not all z28s are the H.O. engine. The H.O. is the l69 which has about 40 more hp than the lg4 or standard 305.

five7kid

iTrader: (14)

Let's get back to 1st principles:

You want a safe, reliable, reasonably economical school car. Right now, it has some modifications, exact nature unknown, but gets pretty bad gas mileage and has scary performance (to you, as Dad, at least). You didn't indicate any problems with how it runs, so we'll assume it is in a reasonable state of tune. If not, then you can handle that after you bring it home.

The cam is probably the key - it's too big. Put a nice, mild Comp or Crane cam in it with known properties, and right there gas mileage will probably jump back up to where it belongs (again assuming it's in a good state of tune).

The stock q-jet is absolutely the best carb to have on it, both from a "detuning" standpoint, and for economy. The computer controlled, feedback system can't be beat for economy. To "detune" it from a performance standpoint, just put so much tension on the secondary air valve spring that the secondaries will never open - same effect as RB's linkage removal, but a lot simplier to do and un-do.

A 2-bbl would be a terrible idea, both from a cost and economy point of view. You'd need carb, intake, and distributor; and 2-bbl economy was always factory cost, never owner operating cost. Keep the CC q-jet.

"HO", or L69 engines, had a better cam, better exhaust, and were tuned differently than the standard LG4. They also had the much-coveted dual-snorkel air cleaner (that'd be another way to de-tune it - put the dual-snorkel air cleaner in a box, and install a standard, single-snorkel LG4 air cleaner until the kids are out of high school).

Inwo

Here's a better idea... put the car in storage and let them drive a $400 escort to school. Then you can be certain your car won't be beat up like school kids tend to do to their first cars... I hate to see anyone young driving a camaro cause they tend to beat the snot out of them, ding them up, then smash them into a tree or something because they don't know how to handle a RWD car at high speeds. It's better to just get a crappy car and let the thirdgen be in storage til they can handle it

Terry

Thanks for the inputs guys. Those of you that have 305 HO's; what is your mileage with what gears in the rear end and tranny?
Thanks

Sitting Bull

Taking the cam out is a bit of job just to detune the engine. Try retarding the timing about 4 degrees from stock. That ought to make it a bit more of a pig off the line

The trouble is that kids are a lot smarter than we think they are. We don't tend to remember what we got up to in high school. There will always be a certain gaggle that is attracted to the 3rd gen Camaro and one of them will know how to tune it, or know someone who does. Then the cat is out of the bag

Damon

Get an MSD ignition box with rev limiter and put a 3500 RPM "pill" in it so they can't take it over that RPM level no matter what they do. Yeah, they'll figure out how to get around that pretty quick so you'll have to do some "spot checks" from time to time with harsh penalties if they've messed with it.

The MSD will also help the mileage some. Even stock, the L-69 HO should do better than 13 MPGs. I agree the cam is probably a bit too big and probably making the mileage worse. I'd make sure it's tuned as sharp as you can get it with no "check engine" codes before you put on the MSD box or do any other mods.

five7kid

iTrader: (14)

Locking hood pins. Dad keeps the key...

eightTfourTA

iTrader: (3)

Mine gets 13-15city, 23-25 highway depending on how I drive it and whether or not the a/c's on. Enginewise, it just has a 3" catback and Hedman hedders. 3.42 rear, 700R4 auto. Stock L69 'DR' rods with a 'B' hanger, base timing at 10*BTDC, and stock engine internals with over 110K miles on them.

Sitting Bull

Hah, hah!

I remember my dad's huffing and puffing tended to keep me in line

Of course, I only had a 64 Parisienne witha 283. But on rare days I'd get my aunt's 68 Parisienne and it had a 396 4 barrel

jocww

im 17 and my first car was and is a 65 elcamino with a 350 bumpin out 420hp with a wild cam and headers, hei distributor, heads, roller rockers gear driven. and i havent crashed it yet sure ive done 4o foot burn outs but i do that in my 84 z28 ho. so kids dont always crash their cars but some do. i get 12 -13 miles street and 15 on the highway cuz i speed a lot. did i also say im azn and that i hate fwd cars i respect the rwd imports tho.
P.S
let ur kids have fun and dont do anything to the car just say this if u crash ur car or if u get a ticket u lose ur license. dats wat my parents said and so im doin fine now.

fast86z28

yea im 17 also, and my dad helped me build the 350 thats in it, i learned alot from it and got a new engine...he uses the same analogy, get a ticket and its up for sale, so ive actually done good on the streets, its friday night when i go to the track and i get all of my speeding out of my system for the week...i say dont detune and take it away if they get in trouble, if you have a track semi close allow them to go to the track occasionaly so they can get any wild urges they may out of their system, legally.

David M

I'm getting 13-15mpg around town. No hwy mileage figures yet. I've got stock 3.73 gears and a 700R4 tranny.
The car has 121k mi. on it.

kev_n_ang_ta

put a LG4 in it and keep the HO and if they pop the LG4 put the HO back in it and dad has a nice car.