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V8-350 Swap 92 Astro

24794 Views 60 Replies 14 Participants Last post by  gwd
The old 4.3 in my 92 Astro made it to 282,000 original miles! A recent tick that developed into a knock turned out to be a broken piston skirt...not sure how it happened. Oil pressure still strong.

I'm swapping with a 350. I have no intention of using the computer. The 350 engine is carbureted, and is originally from a very low mileage 70 Caprice. (No emissions in Fla) The engine has a nice rumpity-rump high torque cam and intake installed, gets great mileage and runs AWESOME!

I have already purchased the custom swap V8 motor mounts, and Hedman shorty headers.

Here are my initial questions:

1) I assume the only issue with the 700R4 will be the lock-up converter (assuming I want to use it)? I've been told to either add a toggle-switch, or possibly a vacuum switch to operate it... assuming the converter is sufficient to use behind a V8? (I have a nice new TH350 with B&M 11" Holeshot converter, but I think I'd miss the overdrive).

2) The stock A/C system runs on a serpentine belt, the older engine is V-belt of course. I assume I will need to swap water pumps with a proper reverse pump that will work with serpentine system. What pump will I need? Will the V6 pump interchange? I'm assuming the powersteering and alternator will bolt up ok?

3) I also assume I will have to do something with the cooling system, fan, shroud, radiator, etc.

I will be pulling the motor from the front (working in my home garage)

The motor will be naturally aspirated (carbureted)... using HEI distributor. Fuel delivery will be stock system, with a regulator.

The other mods seem fairly obvious to me. I will have ALL the accy's available from the stock V6... if any are needed and can be used.

I have been waiting for many years for the V6 to finally die, the V8 has been patiently waiting! I just couldn't bring myself to pull a perfectly good running engine... but now the time has come.

I plan to run full dual exhaust as well.

I know there is a wealth of info here on this site... which I will be reading. I'm excited about my new advanture... as I have been a hot-rodder all my life! My last G-van had a supercharged 502. This current V8 was in my '69 Chevelle convertible.

Now it's the Astro's turn for an upgrade! It's a shorty with wide-tires and Centerline rims... and should be a perfect match!

Thanks for any advice and suggestions!
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According to rock auto that is a replacement for your stock fuel pump in the '92 astro, I chose that one as an example because it showed the most info on the pump ratings. Look up your the vehicle your engine came out of to find what you need. Look in the service manual from the donor vehicle to see what you will need as to return lines and evap systems.

edit- Your too fast for me Randy :lol:
One thing of particular interest to me are the engine mounts, If I understand correctly the mounts from the v8 are used on the motor and the bottom portion bolted to the frame are from the astro just swapped, drivers to passenger and mounted on a flat plate that moves them forward 3" or so. I'd make this plate myself if I could find the dimensions. If you use this method would you trace the plates on a sheet of paper and scan/ upload it to your photo gallery? ... 1423.l2661
Absolutely. Even without the V8 I found the elec fan to be a benefit in my '97. If for nothing else but the ease of repair to the front of the engine without that damn shroud,,,,,
Nice to hear. Funny though, when I did mine I put everything else on hold, even played hookey from work a time or two. If I still had a scoot in the dooryard I may have made an exception for a ride but only a short one.
Fandamntastic MM! Good to hear.
Little noisy w/ open headers, eh? lol
My landlord suggested I do the break-in on mine w/o the exhaust because he really hates the condo behind us. I was afraid the cops would show up half way through so I waited till I had the pipes done.
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