I have had a 1968 Firebird Convertible for about 13 months now. I bought the car fully restored and don't have much history on the rebuild, especially the motor. I am very much a newbie mechanic and so I am asking you experts for advise on a performance question. The following are the specs on the car:
1968 with original 350ci (I assume not bored over, but an unsure) Originally a 2bbl carb car Currently a 4bbl Edelbrock 1406 carb Comp Cam P8 XE262H-10 2.56 gears, non-posi Turbo 350 trans Electric fan Vintage Air (never use it) Estimated by dealer at 300HP I only run 93 octane
This is the oldest car I have ever driven. So I don't really know what to expect on the performance side. She has highway gears and I get a nice 22MPG on road trips. About 3K RPM at 80MPH. It starts and runs well with no over heating issues (195 degrees max). My question is hole shot performance. I can't spin the tires no matter how hard I try. Not that I plan to do this every time I drive her. However, given the above specs, should I be able to roast them If I choose to? Or is this normal for a 2.56 gear, automatic, 350ci car? I have had her into a local performance shop for tuning.
Sounds pretty normal for a '68 350. I doubt I've ever had 22 MPG with any of mine, so you are doing great in that respect if your numbers are accurate.
Did you put the TH 350 in your's? That would not have been available from the factory.
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold
I have had a 1968 Firebird Convertible for about 13 months now. I bought the car fully restored and don't have much history on the rebuild, especially the motor. I am very much a newbie mechanic and so I am asking you experts for advise on a performance question. The following are the specs on the car:
1968 with original 350ci (I assume not bored over, but an unsure) Originally a 2bbl carb car Currently a 4bbl Edelbrock 1406 carb Comp Cam P8 XE262H-10 2.56 gears, non-posi Turbo 350 trans Electric fan Vintage Air (never use it) Estimated by dealer at 300HP I only run 93 octane
This is the oldest car I have ever driven. So I don't really know what to expect on the performance side. She has highway gears and I get a nice 22MPG on road trips. About 3K RPM at 80MPH. It starts and runs well with no over heating issues (195 degrees max). My question is hole shot performance. I can't spin the tires no matter how hard I try. Not that I plan to do this every time I drive her. However, given the above specs, should I be able to roast them If I choose to? Or is this normal for a 2.56 gear, automatic, 350ci car? I have had her into a local performance shop for tuning.
My coupe came with 350 2bbl and 2.73 gears. It would spin tires every time I was in gravel lol
I would change out your gears to sometime a bit better say 3.2+
I'll bet you have a 2sp powerglide as well. If stock get a TH400 or TH350 3sp automatics.
Nice wheels!
Good luck
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________
She originally came with a 2 speed. It was upgraded to a 3 speed Turbo 350 at the time of restoration. 4 bbl was also added at that time. I love her all the same. I just want to know if this is the performance I should expect or if there is an issue that needs to be fixed.
Doesn't sound like anything needs to be fixed. That rear gear is probably never going to put a big smile on your face when you leave a stop sign. Three ways to go: 1)keep it and enjoy cruising, 2) swap out gears and give up your 22 mpg, 3) buy another car to get your tire smoking fix in.
I had an almost identical original set-up (350 2bbl, 2 speed, 2:72), now a Qjet with 3:08 open rear end and I can spin the tire(s) all day. That rear end could be your issue, but with a 3 speed you should be able to get a little bit of tire spin. I'd have the engine tuning checked out and dialed in first.
I have bone stock 69' 350 with 2bbl and stock highway gears with non posi. Rebuilt but not overbore. I can do a decent 1 tire power brake. What a sad statement that is lol! Sometimes it will give a nice chirp off the line and maybe even a solid spin. And yes she love a little gravel.
However I would very much doubt you are making 300hp unless the heads have had some work. What heads are you running? The stock 68' 350 heads are #17 which is real good 350 head. But don't waste your money on the 93 gas. 89 or 91 will be fine. Hard to say if the 4bbl is even helping you? With that gas mileage it sounds like it is tuned well so maybe. It might actually bog a bit when you stomp it off the line until it builds enough RPM to use that extra gas and get those heads flowing.
As stated above you will need to change gears to get those tires going. A nice 3:08 set with a posi will do it and be fine on the highway and give you some nice get up.
sounds normal...the 68 350 I once had , I don't recall which automatic transmission I had, but it would slightly spin tires...but car was almost new at the time in 1969 .....my 69 I had ore recently , WAS a 350, but got replaced w a 400, and was much peppier.....
I have the same issue with mine. Mine is the stock original 400 (145k miles), with TH400, 3:08 gears. The car just feels lazy getting off the line. I never checked compression in mine, but I get steady idle, 16 inch of steady vacuum at 650 RPM, Timing is at 12 BTC, new plugs, plug wires and the original quadrajet seems fine (I put a new gasket kit in 2 years ago).Anything I'm missing?
I think, as stated by all others, is that you are enjoying a well running normal 350 with a basic gear and rear end set up. It looks nice! Sounds like your only "performance" mod it the 4bbl. Not sure about that cam. No mention of what heads you are running or if you have duel exhaust (stock log type manifolds?) etc. Making 300hp with a 350 isn't hard but just swapping a cam and adding a 4bbl isn't a guarantee and depending on how its set up you might even hurt things down low. And the AC is stealing a few horses even when off. I would bet you are not making 300hp. All that being said if you abuse it enough you'll figure out how to get that wheel to spin. If you don't care about gas mileage you can add of few of those other performance pieces and change the gears and you will really impress the teenage boys at the Dairy Queen when you leave a nice patch!! Even with your 350!!! My tired old stock 350 likes a little sand at the start. But then she really burns tire.
Smoking the tires is generally for people with something to prove or small penises.
it does nothing for performance, old drag racers did it as their power increased until one smart guy got better traction and blew them away then they all switched to doing a burn out to heat the tires first and traction and moving became more important
you don't have a performance firebird, you have a mid grade model that was designed to capture the family guy who wanted a car that his wife could drive but he could still could pretend he was cool, the 400's move but the ramair versions become funky depending on how built they are, a RAIV with 4.11 rear is really only for an experienced driver as many got wrapped around poles and trees, these cars are not full frame like GTO"s and when launched, banging a gear, or getting sudden severe traction coming out of burning rubber they can and will do unpredictable things, they bend, the front end twists, then you'll want frame connectors, still they twist
I have a 67 conv 400 built to RAI spec's with 3.42 gears, 4sp, she likes to lift the front end and not go straight, for whatever reason the comb of the HD conv springs and a 70 10 bolt rear give the car ungodly traction and I have to go full bore nutso to smoke the tires, she generally wants to grab and launch, one freaking screw up like when I was 17 and I will lose @ 50k
enjoy your cruiser, it's a nice car with good mpg and stuff won't break