Is it worth it and can I put a TPI on the L69 or can I put my carb on it (it doesn't have a carb. It is a junk yard find and only $200 dollars. Let me know your opinions. Thanks.

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86 T/A 305 4BBL NO AC, HEAD LIGHTS WONT POP UP, HATCH WON'T LATCH, EVERYTHING STOCK

 

If it runs and is in generally good condition, it will be a slight step up. The L69 also had better exhaust, which you should try to get if you can for a more complete step up (if not, this is a good time for headers, high-flow cat & cat back). You'll also need to do the carb mods listed in the tech section.

Keep your LG4 knock sensor and the like. The '83 didn't have it, but it will swap over directly.

A TPI swap would be a big change, and probably wouldn't yield much performance increase. Certainly not considering bang-for-buck.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. 0.030 over 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlock header mufflers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, LT MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1/95.5 @ 5800' Bandimere.

 

rather than doing a whole motor swap, why not just do heads, headers, cam, and intake?

I know several people who have 14 second lg4 cars still running a q-jet on them, and they did it cheap, using either vortec heads, or ported tpi heads.

 

The '86 LG4 has higher compression (flat top pistons) than the earlier years, the same as L69's. There are no differences between LG4 and L69 heads, so if you are changing them, go to World 305's or shaved Vortecs (you'll have to plumb exhaust up to the EGR valve with Vortecs).

You didn't say why you were considering this swap, or if there is something wrong with your LG4, but the headers and cam are good advice. Don't stop at the headers, replace the complete exhaust. Tune the carb secondaries and improve the air cleaner flow as well. You'll have everything the L69 has to offer and more with those changes.

 

"86 had flat top pistons? I thought they were dished. The LG4 has 165,000 miles and leaks at all the gaskets and is burning some oil. I need to drive the car daily and this is about the only way I can do it without parking the car for a while. What cam would be good for this? I was thinking a COMP CAM but I'm not sure of the spec that would be right. Any help here?

 

My LG4 leaks at all the gaskets and is burning a little oil, so I probably need to rebuild it, but I need to drive it to work daily. Just thought it would be easier to build a new one and swap them when I'm done. I do need advice on a good cam. I was thinking a COMP CAM but I'm not sure of the specs that I need. I want a smooth idle and I only looking to make about 250-265 HP with this motor. Any suggestions?

 

86 L69 or HO 305 modles have flattop pistons with valve indentions. The compression difference is a whole point, example LG4 dished 8:?:? and an L69 would be 9:?:?.
As far as the cams concerned, what do you want out of the car? Tire shreading low end or passing power? A melling "MTC-1" Autozone/checker bla bla cam would probaby give you a bit of bolth.
SSC

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"I'm a steel tormentor and I speed around every turn"
Helloween..

 

Okay, check out https://www.thirdgen.org/newdesign/tech/techdb.shtml . You will notice that starting in 1985, even LG4's had 9.5:1 CR. '84-earlier, 8.6.

Your '86 has the higher compression. But, with the other problems it sounds like it has, go ahead and go for the L69. See the recommendations in my 1st response.

 

What carb do you recommend that will work with my stock computer and maybe a new chip? Or should I just keep the quadra jet and tune it??

 

The quadrajet is more than adequate for an L69, even a cammed L69.

 

If you are doing an engine swap, try and find a 350, and get one with at least 9.3:1 compression, then when you go to TPI you are already set. Going to an L69 will give you a little better performance, but you will be disapointed. Goint with a 350 will give you a bigger displacememnt and it is way cheeper to get parts for, even if you do pay more for the block.

As for Compression Hanes is wrong Wrong WRONG. The 87 GM Service Manual for the Firebird book sais it is 8.6:1 I trust it more than hanes). Compression for the LG4 was 8.6:1, even in 87 When I tore apart my 87 305 motor it had the dished pistons. I replaced them with 9.5:1 compression ( I had to get new pistons because I had to go .040 over. It was only about 4 or 5 dollars more for the set to go up to 9.5:1.

In my opinion, I screwed up when I rebuilt my 305, i got all new parts anyway, crank, cam lifters etc. The only thing I kept was the heads, Block, pushrods, and the rockers, I now know, Do it ONCE, do it RIGHT and be happy, I keep screwing with my car and have more than $15,000 invested into what I bought for $1,100. I just got done doing the TPI conversion and I don't think it is much faster than my 4bbl. and I put on SLP headers & 3" exhaust. I have considered my next step will be to either pull the TPI, and go with an LS1 or make my TPI a 383. (wouldn't mind a 420 sbc)

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87 Formula 5.1 converted to TPI Yellow/Black
SLP cam, headers, cat-back exhaust
Ported & polished TPI intake
Gil Younger (no yo-yo) Shift Kit
Aluminum Driveshaft
3.73 Posi gear
Baer 12" brakes 4 wheels
KYB AGX Adjustable Shocks & struts
Hotchkis strut tower brace
South side machine frame connecters
Custom reinforced control arms and pan hard bar.
Custom Leather interior
CUSTOM Yellow Gauge Faces

87 Formula TPI (5 Speed) Yellow/Gray STOCK

1967 Buick Riviera 430hp Turns high 14's (Not bad for 4300 lbs)

83 Camaro (Parts)
83 T/A (parts)

http://www.3rdgenformula.com

 

If your gonna go through the headache of swapping motors, put a 350 in it.Certainly wouldn't drop a 16 year old junk yard motor in it. If your gonna do it do it right.

As far as differences between years of motors. I know for a fact that if not all, a bunch of the lg4's in 86 had the higher compreesion. Both my 86 lg4's had the flattops with vavle reliefs(were both made on the same day as a matter of fact... wierd huh) and and my friend's lg4 we rebuilt for a project in college, had the flattops.
The stock carb will be fine as long as it's working properly, and in good shape, just gonna have to tune it.

as far as the burning oil and leaking, deal with it till you have a motor for it, My original lg4 lasted 200,000 miles of mild oil leaks, it would go through about a quart an oil change, but kept on keepin on.

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It's always SOMETHING

 

Thanks guys I see I really need to think about this a little more. It is just that 350's are so F@%&# hard to find on this little island (Hawaii). Well back to the drawing board.

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86 T/A 305 4BBL NO AC,'83 center console , '83 L69 being rebuilt now, and new beige interior going in soon