drdrdaddeo

Just picked up a beautiful blue 1985 Base Firebird, 305 ECM/4bll carb.....completely factory, no rust, one owner....$400. Car had been garaged for last 5 years but was still running beautifully with completely original engine and 700R4 tranny despite 289,000 miles, California emissions, three inches of engine compartment sludge from leaking gaskets and mains, leaking T-tops/windshield, and wasted headliner/upolstery. I once owned a 68 Camaro 327 R/S with powerglide (I personally hand-rebuilt both its engine and transmission), and it was the best car I ever owned. With a young family of four at that time, I regretfully had to sell it 25 years ago. So I've long wanted another small block chevy pony car with no bullcrap ECM/emissions chokehold over it. My restoration/racing buddies tell me the '85 bird could be the winner. I don't ever plan on racing this car, and the factory 305 already has plenty enough zip and torque for my aggressive style of driving. Rather I just want to personally resurrect it into a strong, reliable, beautiful new/old classic using my own hands and ears again at age 64.
I have already stripped the car down to nearly bare bones (see attached picture) and have already fixed the leaking t-tops. Have completely removed the fully functional ECM, all its harnesses, all its sensors, and all its emissions devices (what a great feeling!). Have also pulled the engine and transmission (see attached picture) and sent the 700R4 for a complete rebuild including a pure hydraulic torque converter lockup system and corvette shift kit. Now working on completely dissassembling the 305 in preparation for its complete rebuild (I know..I know....you'll say trash it and get a 350!). Well, 289,000 miles on a stock 305/700R4 beats any engine tranny combination I've ever known, and I'm putting my faith and money into revitalizing that combination for another 25 years of fun, hopefully bringing them both up to the pure mechanical specks of the 60's/70's. Herein lies this thread: 1. What is the best mild cam for rebuilding a 305 and what would be the best piston, insert, and lifter kit that will still maintain factory compression. I really want a nice audible, smooth and throaty sound with good power/gas mileage at low/moderate RPMs. I hate lope, vibration, and/or excessively loud or inaudible exhaust noises. 2. What is the best manifold/carburator combination (currently considering the Edelbrock Performer and 1706 carb). Importantly, I am not afraid of any carburator, having rebuilt many over the years. 3. What is the best mechanical fuel pump and why? 4. What would be the best HEI mechanical distributer, wire and spark plug combination to use? 5. What would be the best Hedder, Cat (if necessary, as no emission checks occur where I live), and dual exhaust system. 6. What high quality Stereo/CD system (without external power supply) would fit into the factory double wide Stereo/Cassette player slot?
I'm no millionaire, but I'm willing to drop some serious coin into this last restoration project of my life. Thus, I would welcome any feedback from you young guns out there who've got more experience with these magnificent third gen firebirds (esp. 305's) than I do.

Thanks from drdrdaddeo!

jchaussee

First have fun. Second the stereo opening if not different then a 85 camaro is din and a half size. I have a pioneer. Several years old. Sounds good. As far as carb, you no a lot more then me but I was told to just rebuild my qjet vs buying an edelbrock. Header , I believe hooker 2055s bolt up nicely. Duel exhause, from what I read it is not easy nor cheap. Not a lot of room to work with.

bradley23150

iTrader: (10)

To answer number four, considering this isn't a high-horsepower build, I would go with an MSD streetfire distributor and wires, and ACDelco plugs, as these are what I have had the most luck with. I have also had good luck with Edelbrock brand shorty headers and y-pipe, which will work fine for a 305.

naf

iTrader: (7)

Your 85 LG4 came with fairly high compression for it's time and the associated KS and electronic spark control to retard the timing when knock was detected. I've found the EGR to be beneficial too for controlling ping at slow cruise + light throttle.

Anyway if you've already made your mind up:

A spreadbore carb would allow you to keep the factory aluminum manifold, which really isn't a major restriction on a mild 305 build. The Performer is certainly no step up from the stock manifold.

I'd choose a mechanical qjet any day over an Edelbrock. I like them better AND it seems that nearly EVERY carbed car at our local cruise-ins has a cheap Edelbrock on it.

A nice cam for the LG4 with stock converter and rear end is the XE256.

The AC Delco HEI will perform flawlessly for a motor that's going to live in the range of a stock converter.

Dual exhaust is difficult due to clearances under the car. You can do a search for some options and examples. A shorty system with 3" y-pipe and I-pipe would work perfectly well for your motor. Many swear by Hooker. I've used Hedman but had a Y fabricated.

You can peruse this:

https://www.thirdgen.org/forums/carb...tions-lg4.html

My 85 TA, original 305 replaced by 350, AIR system removed (the piping began to rust out) and converted to electrical fan. Still computer controlled. I've apparently started my compressor replacement in this pic as the coolant hoses are disconnected...

five7kid

iTrader: (14)

Even if you've made up your mind, I'll try to change it.

Keep the computer carb system. If you don't, you'll not only spend money on parts that are no better, and arguably worse, than the computer system, you'll also have to spend even more to make the non-computer stuff compatible with the TH700.

There is no reason to fear the computer carb.

Dual exhaust is nearly impossible on these cars and still maintain decent ground clearance. For a mild 305, you don't need dual, anyway. Get exhaust, including the headers (shorties with y-pipe made for the headers), for the '86-'90 TPI single cat application, and you'll be fine.

drdrdaddeo

Appreciate all the good advice thus far....and well taken. Fully agree that pure dual exhaust system would be near impossible, and will be happy to settle for a nice sounding single cat/muffler system with dual output pipes. Only reason for wanting to go with the mechanical carb/HEI is so that I can again tune purely by ear/strobe/vacuum the way I did in the 60's and 70's, without the need for engine lights, emissions chokes, and computer/sensors doing all the thinking for me. I do, however, fully realize that the newer ECM systems are lots smarter than I am, and will do a much better job at maximizing power and gas mileage than me. I just really like to be able to see/reach my engines, keep them shiney and tune them by hand, ear, and instinct. I can't go back to my old GM Quadrajet because is is ECM controlled and I'd have to reinstall all the emissions stuff (ugggghhhh!). But I really like the idea of rebuilding an older mechanical GM quadrajet instead of an Edelbrock....and that may be a smart option. The quads were reputably the best carbs made for years, and mine certainly held up well for 25 years. Also the XE256 cam and Delco HEI suggestions are much appreciated, as well as the Hooker 2055's. Will look seriously into all of these. Thanks again. This really is a labor of love.

Camaro305SB

Well said. Too add to it I can't see why someone would hack up a factory stock no-rust third gen. Plus, minus the factory crap catalytic converters, emissions components are practically non restrictive.

naf

iTrader: (7)

If you haven't already figured it out, you can pull the ECM harness out through the fenderwell complete without hacking anything. The only connection you should need to replace is the converter lockup going into the tranny-and there's a sticky on top of the carb forum for alternate methods of converter lockup.

Using the mech q-jet also allows you to re-use your existing throttle bracket, and more importantly, the TV cable and TV bracket. The TV geometry is pretty precise and a special bracket would have to be bought for any aftermarket carb...AND the stock fuel line from pump to carb can be re-used.

Resist any possible temptation to do away with the return style fuel system and use a stock style return pump. These vehicles were prone to vapor lock and the return is vital.

If you get going and find a need for EGR later on, the export models included non-computer controlled systems.

As an add, the ECM controlled system can still function fine with all of the emissions removed. My 87 no longer has EGR or AIR. I've never had an EGR related driveability issue with it, but it has much better heads on it than the TBI swirlports on my 85.

drdrdaddeo

Again, thanks for all the useful and knowledgeable comments. To NAF and Camero305SB, I agree with you both. I'm no hacker, so I "lovingly" removed all the emissions devices and the ECM with the intact harnesses (per NAF-through the firewall) and stored them all carefully in a big box before I removed the engine/tranny (just in case I ever have to restore to factory emissions specs again). I even saved the factory headers complete with their emissions pipes.

Of interest, I just got a call from my transmission pro friends who've already done a complete bench rebuild on my 700R4 including installation of a hydraulic torque converter lockup (no more need for electricals or an ECM) and a Corvette shift kit....total cost $700 (lock-up speed 50 mph). I want my FB's body/suspension to be completely factory in every way, but I really want to see a bright red chevy engine with ceramic headers and chrome valve covers/air filter every time I raise the hood. And I want to hear it talk back to me (rather than its computer) when I fire it up.

The GM stock return style fuel pump was in great shape so I'll just reuse it after I rebuild the 305. I did remove/store the fuel cannister and capped off its vapor return line. I plan to use a vented fuel tank cap to pervent fuel tank over-pressure/vacuum. Please correct me if I'm wrong, but I can't imagine a need for a EGR other than to pass an emission's test (which in my state currently requires nothing more than a driver's license, proof of insurance, a pen, and a $5 bill). Nice to know, though, that a non-computer controlled EGR system is available. While the engine is out, I'll also replace the A/C evaporator, vaporizing nozzle, compressor and freon lines to make sure I'll eventually have a fully functioning A/C unit (reviving the long dead A/C system), and then pressure wash/paint the engine compartment before dropping the engine/tranny back in and starting final body work/painting/decaling. I'm guessing two-three more months of work.

Next venue is total grime cleanup and teardown of my 305 with blueprinting to see how much cylinder bore and crank turning will be needed. Plan for a simple head/valve job with valve, posts, rocker arm, pushrod, and/or lifter replacements as necessary (.....any better suggestions?), and of course new bearings, inserts, seals, etc. to match. Then the real fun begins, final rebuilding and upgrading. May take some photo's and post as progress is made.

P.S. I don't fear the computer carb, in fact I enormously respect it. I just resent its total authority over my engine ("I fight authority....authority always wins"). It will sleep comfortably in a box with its ECM buddy beside it until I have died of old age.....and my '85 bird has passed on to some other lucky dude.

naf

iTrader: (7)

Before going too far with your 305 consider the swap to a 350 now. A rebuildable core can be had for under $200 and if you check prices you'll find the pistons and gaskets may save part of that. Your 305 heads would be an economical option to most 'truck' heads you'd find on a 350. You'd also have the option of going to a later, roller block and associated roller cam, albeit at more expense for the cam (new anyway). Used roller lifters and cam can be re-used and there's a lot of good options out there.

I'd hate for you to go to all this effort then down the road wish you'd spent the ~$200 more for a 350...

If you're not already aware, most auto parts chains will have a loan a tool program for all those specialty tools you'll wind up needing. My local Autozone is less than two miles down the road; pullers, tie rod removers, ball joint press they've even got a vacuum pump for the AC.

If there's a pull a part anywhere near you, make a trip. I stuff my bag with extra fasteners every time I venture out and have scored some sweet stuff. Just recently got a leather steering wheel and MINT grid tail lights for my TA (at least they're mint now after the 3M polishing).

Post your progress.

drdrdaddeo

Been to a local pull-apart and scored a couple of windshield washer plastic squirters (easily broken and hard to fine) off an old 82 FB ($1.62). Also score a primo right front fender blinker light assembly ($5.00). Not too many 3rd gen FB's and Cameros left in boneyards anymore....most already crushed and recycled for metal.

I already own one 350 ( in a '99 Tahoe) which I just love, and did think about going with another in my '85 FB. But I've just completely finished disassembling my 305 (which had 289,000 miles on it) and I could literally find no metal wear on this engine whatsoever (of course all the gaskets and seals were shot and leaking, the cam-timing sprocket had a small crack developing, and the timing chain was pretty slack). However, the mains bearings, rod inserts, rocker arms, push rods, pistons, oil pump and camshaft looked like new. There was absolutely no visible or palpable ridge noted in any of the cylinders, nor were there any cylinder wall scratches, flattened or leaking valve guides, or slack/play anywhere. This is my third small block chevy rebuild (including two '68 327's) and those latter engines had tons of visible wear with less than 120,000 miles on them. I just can't believe how strong/preserved this 305 is. Unless the machinist talks me out of it, I'm not going bore it or grind the crank all, but rather just polish the crank, and replace the rings and mains/inserts with standards. I'll do a minor valve job on the heads mostly just to tune up the valve guides, even though the heads and valves look like new. I am completely blown away by this engine and can't wait to rebuild it. I've decided to go with the MSD HEI distributer, the edelbrock performer manifold and 1406 edelbrock carb (pro-remanufactured Quad Jets seem overpriced and Holleys seem to be getting a bad online rap). She won't be a screamer, but should be beautiful and run reliably for a long time. Will post some more pictures soon.

drdrdaddeo

KC85firebird

sounds awsome, i bought a 85 from a guy he said it was a 350 with roller rockers, turns out it is a 283 from the mid sixties, no roller rockers. going to drop a 350 in it, at least it had edelbrock carb and intake on it with shorty headers and duel exhaust ran.

RocketyMan

I agree with five7. I rebuilt the computer controlled carb on my '84 and it was a sinch just as with any other qjet I've done.

If you plan on going with the qjet route, I can help you out with any Q&A. But yeah.. $500 for a remand holley qjet is COMPLETELY ridiculous!


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