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I've been having a ton of fun with my 81 since I towed it home back in Feb. I try to document as much a possible in THIS THREAD but for the next big step I think it makes sense to start a new thread over here in the Performance / Tech section.
The stock motor only has about 75K but it has a noise in the bottom end that has me a little concerned and it's not going away. I'm still driving the car today but the plan from day one was always an engine upgrade (apologies to the purists... I'm keeping the original drivetrain) and the overdrive trans will be a nice addition.
I'll get more into the details as the project unfolds but it will be a engine replacement and install of a nicely built 700R4. I'm going to do an elec fan and a few other things along that way.
I've learned a TON on this site already and will undoubtedly need some help as I go but I figured I'd share the project so other can enjoy.
The valve cover are cool, Looks like you have vortec style heads with classic style ´finned aluminum valve covers... Havent seen that before. Are they custom made?
The engine isn't anything crazy. Just about 10:1 with flat top pistons and some headwork done. I'm going to swap to a nice duel plane intake from the old Holley single plane.
I'm excited about the 700R4 which has the Trans Go kit and a 2600 stall.
The valve covers are the standard centerbolt style that were painted.
I've always been a chevy guy but never a big fan of the orange block on newer cars. The block on my 81 is black so this is going to get a spray before it goes in.
I've seen a ton of threads on the RPM Air Gap intake for C3 and people who have made it work and other who haven't. I'm going for it and will plan to use a drop base air cleaner and hope for the best.
Question regarding the install. I've pulled a few engines before but not on a C3. I'm going with the Flowtech headers. Has anyone put them on the engine and dropped it in or do they need to be installed AFTER the engine is in place?
I would never consider dropping in an engine with the headers installed. I would drop the headers into place and let them rest on the floor, drop in the engine, then lift the headers up into place and install them.
Headers going on after...too tight to try to squeeze it in with the headers attached, especially if dropping the motor and trans together...
I also had the core support out of the car--I cannot imagine the two pieces going in together with the core support in place...I could be wrong, but I just don't see how it would have worked out well!
A quick update... I got back to spinning wrenches last week and did the biggest part of the swap. Out with the old 350/TH350 and in with the new one and 700R4. All went pretty smoothly and I can't believe it but the RPM Air Gap fits with the 1.5" drop base AC I have on it.
Pay no attention to that Ford Racing fender cover..... left over from my one trip to the "dark side" with a sweet little fox body mustang.
Wow... it's been a while since the engine and trans swap was done but I'm happy to report all is well and I absolutely LOVE driving this car! The more miles I put on my C3, the more I enjoy everything about it.
Going from the stock 190hp to about 360hp was a big change but I have to say the 700R4 was the best part. The shift kit and 2600 stall combined with the OD makes the car so much more fun to drive. I put a ton of miles on last Summer and into the Fall and that's when I started to notice the rpm I was driving at on side roads and around town. With the 700R4 I was sitting around 1000rpm (or less) when I was just cruising. The highway was great but I still didn't need to be at 1900rpm when I was close to 80mph. All this got me thinking it's time for some gears.
A little reading and some help from the good Corvette guys on the forum and I was off to make it happen.
The hardest part of the entire job was getting the frozen strut rods out of the trailing arms. Penetrating oil, heat, you name it and they weren't coming out. I also didn't want to hammer too much on them. I ended up cutting off the rest of the rod, shock post for clearance of my angle grinder to start. I then made two cuts (180 degrees apart) on the end so I could open it up and pull it off. FINALLY, I was left if with the bolt (and frozen sleeve) and I had to make a cut on either side all the way through. It was a process but they're off and I've got some new adjustable rods coming.
The rear end is all cleaned up and off to get freshened up and a set of 3.54 gears. More pics and updates to come.
Electric fans. Have you purchased them yet? The setup I like is a used set from a C5. shroud is the same size as our radiator. And they are OEM fans designed to last. eBay around 100 bucks.
Last edited by derekderek; 01-18-2019 at 12:00 PM.
derek - Yes, I did the fan install and it performed well all Summer in 90 degrees with traffic. I used a Ford Taurus 2 speed fan with a DC Controls controller. I've used this setup on other vehicles and it works great and there were no fitment issues with the C3. You have the ability to wire it into your A/C controls as well so I can turn it on manually if needed.
I realize this post is a few years old,but checking to see where you got your gears from,and any issues with them,as far as noise,or grinding.as I am going through the same thing with my 81.
10-05-2017, 12:17 PM
Fall Project - 350 / 700R4 Swap
