hey i have a 305 tbi and the engine had tons of wires that go into it as you know and im switching to a 72, 350 with a carb that has very few wires needed will i beable to pull out all the sensors from the trottle body engine and put in the 350 with a carb and it will run fine or will the car not start once all the comuter sensors are disconected
thanx in advance

 

If you sort through the harness,you should be able to just use what you need,starter,alt.,A/C,dist. power,etc.,and tie the rest back,and yes,it will run.

 

greg18269,

My son and I are just finishing up what you are apparently starting. Our Cross-Fire TBI 305's harness was trashed and none of the sensors or emissions wires were hookep up. The only major modifications the previous owner made were to install an Old-Style Vacuum Advance Distributor and Non-Computer Carb It ran with just the alternator and starter hooked up.

I don't think it will run with the dizzy from you '89 without the computer at least "Hooked up". It may run... like crud though....

We're using a Computer Carb and Computer Dizzy on our 1974 350 with the wiring harness out of an '86 Carbed Z-28.

Sincerely,
Kurt

 

I'm swapping to 350 carb as well. Just got my motor in my car this weekend, now hooking everything back up. A few things I came across this weekend - check BEFORE you drop the 350 in...

MOST IMPORTANT - don't cut ANYTHING - just tie back what is unused - this way you can make sure you keep what you need!

Starter: An older 350 block may well have a different flywheel and starter. My 1992 305 had a smaller flywheel, and my TBI starter wouldn't fit. So I had to get a new starter for the older motor with larger flywheel. Get starter shims at same time (in Help! section)- I guarantee you'll have to shim it!

OPSU: Oil Pressure Sending Unit - on the TBI motor, it connects dead center directly above the oil filter. An older motor may have a plug in this location. Make life easy - get that plug out BEFORE you drop the motor in. I didn't check mine, and now it's too late - so I have to relocate my OPSU. The OPSU is important - it not only feeds your dash guage, it controls fuel relay (shuts off relay in the event no oil pressure detected - a safety feature for a bad wreck I suppose - so fuel isn't pumping while you bleed your guts on the hiway).

Also, look at top of block, behind intake, beside dizzy. There is a small opening in the block there where the older style oil pressure guages connected (they ran a plastic tube to the guage inside, and the oil ran in the tube). Make sure to plug that hole IF you put your OPSU above the oil filter on the 350 - yor TBI motor should have a plug there you can swap.

After motor dropped in:

Dizzy: Unless using a computer carb, you'll have to get an older style vacuum advance one-wire dizzy. Get an HEI with coil on top, get the 50,000 volt coil, hardened gear, static capacitor, brass terminal.

When connecting the wires to older model starter, you'll see more connectors on older model starter - one marked S and one marked R - connect purple (smaller) wire to S and connect your larger wires to the larger connection (you may have to drill out the connector's hole to fit the older model starter - I had to).

Intake - many intakes have many different positions for water inlets/oulets, vacuum locatioons, etc. I found on mine that I'll have to put the coolant connector where my temp sensor was on the TBI, 'cause my new intake has an angled connector there which will keep the coolant hose from pinching. So I have to move my temp sensor to another location, which on my intake interferes with the water neck (thermo housing), so I have to get a different style water neck too. (Oh the joy of 85 trips a day to the parts store)!

Some other suggestions:

Tranny:

If auto tranny - It's just as easy to pull the motor/tranny together as a whole unit - this is a good time to install a shift kit, get a new tranny filter, and replace front and rear tranny seals.

To keep from spilling tranny fluid everywhere when pulling drive shaft, I got a Tylenol bottle and shoved in the tailhousing while someone else pulled drive shaft - the Tylenol bottle was just the right size to plug to seal.

Also a good time to get poly tranny mounts and poly torque arm mount.

Also if auto and deleting computer, you'll need a torque converter lock-up switch in the tranny, since the computer won't be there to lock the T/C. (Also a good time to get a better T/C - I opted for the cheap solution, a $140 S-10 converter)

If you have plans to swap rear gearing, you can install the new speedo gears while tranny is out as well.

I'm still working on mine - anyone feel free to PM me - I'm no expert like some here, but I'm doing mine in the driveway, I'm covered in grease from head to toe, and the mosquitos have bitten every chunk of meat al least once - and that's GOT to be worth something!

 

MOST IMPORTANT - don't cut ANYTHING - just tie back what is unused - this way you can make sure you keep what you need!

Starter: An older 350 block may well have a different flywheel and starter. My 1992 305 had a smaller flywheel, and my TBI starter wouldn't fit. So I had to get a new starter for the older motor with larger flywheel. Get starter shims at same time (in Help! section)- I guarantee you'll have to shim it!

OPSU: Oil Pressure Sending Unit - on the TBI motor, it connects dead center directly above the oil filter. An older motor may have a plug in this location. Make life easy - get that plug out BEFORE you drop the motor in. I didn't check mine, and now it's too late - so I have to relocate my OPSU. The OPSU is important - it not only feeds your dash guage, it controls fuel relay (shuts off relay in the event no oil pressure detected - a safety feature for a bad wreck I suppose - so fuel isn't pumping while you bleed your guts on the hiway).

Also, look at top of block, behind intake, beside dizzy. There is a small opening in the block there where the older style oil pressure guages connected (they ran a plastic tube to the guage inside, and the oil ran in the tube). Make sure to plug that hole IF you put your OPSU above the oil filter on the 350 - yor TBI motor should have a plug there you can swap.

After motor dropped in:

Dizzy: Unless using a computer carb, you'll have to get an older style vacuum advance one-wire dizzy. Get an HEI with coil on top, get the 50,000 volt coil, hardened gear, static capacitor, brass terminal.


Some other suggestions:

Tranny:

If auto tranny - It's just as easy to pull the motor/tranny together as a whole unit - this is a good time to install a shift kit, get a new tranny filter, and replace front and rear tranny seals.

To keep from spilling tranny fluid everywhere when pulling drive shaft, I got a Tylenol bottle and shoved in the tailhousing while someone else pulled drive shaft - the Tylenol bottle was just the right size to plug to seal.



I'm still working on mine - anyone feel free to PM me - I'm no expert like some here, but I'm doing mine in the driveway, I'm covered in grease from head to toe, and the mosquitos have bitten every chunk of meat al least once - and that's GOT to be worth something! [/B][/QUOTE]


Killer idea on the tylenal bottle,never thought of that one.I always just crammed a spare yoke in.

As for any of us being "experts",I think we're pretty much all like you,educated by experiance.The way your doing the swap,well,it's worth a lot.I'm sure every one of us has or will do a swap that way.Hopefully,I've done all I'll have to outside,but if it's ever a necessaty to build em' that way,that's what I'll do!

PS:A detached shop will improve property value by double what it costs to build.At least that's what I convinced my wife of!

 

168-tooth, 14", vs. 153-tooth, 12-3/4". The old block is likely the same as ours ('74) with a 168 tooth wheel. If the 305 is a two piece rear main seal you'd be better off ($$) using the flywheel (flexPlate) from the 305 with the 350 motor. If it's a newer 305 (two-piece) go the the J.Yard and get a 153 from an earlier motor probably cost all of $5 and that's much cheaper than a new starter.

It WILL have a plug in that location....
IMPO leave the plug in there and use the location next to the dizzy for the pressure sender. Why? One less thing to get burned by headers or Exhaust. I don't know about TPI but all the TBI's I've seen have the sensor in that location.

Any Vacuum Advance HEI from a J.Yard will get you running.... No more than $35 COMPLETE at J.Yards in our area.

We've done the same basic changeover except we're opting to keep a computer in the loop and keeping a CC Q-Jet and CC Dizzy. We purchased an original equipment '84 Z-28 Aluminum Intake Manifold (complete with water neck, a couple sensors, throttle bracket(s), and all the nuts & bolts involved) for $25 from the local Pull-A-Part J.Yard. It also cut almost 40 pounds off the engine.

You could do the same with a computer or non computer set-up...If you have an extra port plug it with pipe plugs from Lowe's or Home Depot. The biggest differences in the various manifolds is the heater (or lack thereof) for the choke..... Another possible problem for non-computer.... Not sure if that will still work without the computer?

IMPO (In My Personal Opinion) - You're better off keeping A computer than you are dealing with all the stuff that won't work or might not work. That's why we're sticking with it. By the time your done with the New Distributor, Tranny Lock-up, Choke.... Etc. you could have used a computer system and have something sort-of stock and likely MORE reliable and MORE fuel efficient and likely to PASS if you have emissions inspection to deal with either now or in the future............and saved $$$.

If you want more details about KEEPING a computer and what we did let us know. Attached is a photo of our Computer Compatible '74 350 4-Bolt to be installed July 4th weekend into my son's '82 Z-28.

Sincerely,
Kurt & Derek

P.S. The sensors in the Heads of your '72 are larger (5/8"??) than those in the heads of your 305 (1/2") don't toss any of those from the '72.

 

Well, I read on here that the smaller flywheel is NOT compatible with the older block - not sure why - but for $45 I got a starter and won't worry about it.

I agree with everything EXCEPT the computer. I have a 1990 TBI, and I did mods to the top end - ported/polished heads myself, larger intake valves, LT1 cam, AFPR, dual snorkel, headers, gutted cat. And now, after all my effort, and $300 in chip programming, it's driveable, but just barely - runs way too rich.

So many say "sure, we can do that" when you mention programming, until you give it to them to do, then it's months of waiting, and paying for more time, just to get it running. I won't spend another dime in chips. I figure for what I spent in chip programming trying to get yet another damned microchip controlling yet another portion of my life, I could have went carb there too, and thus REALIZED the potential my mods had, instead of WONDERING if I actually accomplished anything.

So on the 1992, thanks ECM, but no thanks - I'll pass. The only control I want is my foot, be it on a brake or accelerator. After Jan 06, no sniffer here anyway, but "suppose to retain all emissions controls" - Screw that!. If my inspector won't pass it, I'll register in another county - for what I pay in taxes in this state, I'll drive any damned thing I want!

 

You can use the smaller wheel you just have to have the right style. Your car is newer than '87 and therefore has the one piece rear seal that makes your 153 slightly different and incompatible with the old motor. A 153 from a slightly older motor pre-87 (?) would work fine. (pretty sure that '87 was the turning point not positive though)

That's where what we have done is probably better than some. The complete wiring harness & computer from a factory carbed 305 ('86) has been used and we've purchased a COMPUTER COMPATIBLE cam. We expect to do NO chip burning! Maybe have to replace the Knock Sensor if it screws up the timing.

Don't plan on THAT until it ACTUALLY happens..... We had something similar promised/proposed/planned in my home state only to find that the emissions & safety inspections got TOUGHER!

Good luck with the project... We have a couple old NON-CC Q-Jets on the shelf. One was damaged (base cracked) probably by the hoist chain and the other worked ok in our 305 but was probably in need of rebuild.... Let us know if you need 'em.

Sincerely,
Kurt

 

Thanks for the carb offer guys - but I have an Eldelbrock on standby. Now if it'll just stop raining so I can finish!