Corvette Forum : Corvette Forums - Reply to Topic
Go Back   Corvette Forum : Corvette Forums > C3 Corvette Forums > C3 Corvette > Another LS3, T-56 swap into 1981 C3
Register Forums Garage Garage Mark Forums Read Auto EscrowInsurance Advertise


C3 Corvette
C3 Corvette General | Technical | Performance | Aftermarket | Discussions

Other sections:
Corvettes Classifieds
Corvette Detailing & Car Care
Corvette Audio/Video/Radar
General Automotive/Shop/Tools
Corvette Performance Driving/Racing

( Sponsored by: Zip Corvette Parts )

Custom Image Corvettes
A&A Corvette
Corvette tuner

Corvette aftermarket products


Parts & Products
Race Ramps
Melrose Motorsports
Parts Taxi
Pfadt Racing
Madvette Motorsports
Hi-tech Custom Concepts
Corvette Garage
Corvette Parts and Accessories
Corvette Car Care Products
Corvette HID

Bob Bondurant School of High Performance Driving
Corvette driving school

Cray Wheels

Thread: Another LS3, T-56 swap into 1981 C3 Reply to Thread
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the Corvette Forum : Corvette Forums forums, you must first register.
Please enter your desired user name (12 CHARACTERS MAXIMUM), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
City / State / Country?
Where you live
What kind of Corvette(s) do you own?
This field is not required.
Please select your insurance company (Optional)


Additional Options
Miscellaneous Options

Topic Review (Newest First)
07-24-2019 08:42 PM
Feather Fill Primer

Had a good day today. With the help of a couple of dedicated friends we got all the black epoxy primer prepped for the Feather Fill primer. Went so well I decided to spray all the parts except the main body. It's on schedule for tomorrow I believe.

The SPI Epoxy actually sands very well although it is not a high solids primer, hence the use of Feather Fill by Evercoat which is most definitely a high solids primer. I've never used it before but wanted a polyester based primer since it's going over SMC panels (thanks 7TRoadster!).

Feather Fill is essentially a very thin Bondo type stuff. It is activated with the clear (methyl ethyl ketone peroxide I believe) stuff from a plastic tube. Everything about it is just like polyester filler but much thinner.

Learned a couple of things:

1. You will need a big tip on the gun. The largest one I have is a 1.8, and I'd consider that a minimum. You will have a hard time getting anything out of a smaller tip. This might be a good job for one of those cheapo Harbor Freight guns, just be sure you can get a LARGE tip on it.

2. The instructions say to not leave any material in the gun for more than 45 minutes. In the mid 80's to low 90's temperature range, it's more like 20 minutes. This stuff is difficult to clean out of a spray gun. I use the DeVilbiss DeKups system, so cleanup is minimized, but just running gun cleaner or lacquer thinner through the gun WILL NOT remove all of the Feather Fill. The gun cleaner barely touched it so I broke out my stash of DuPont 3661 lacquer thinner which is some pretty hot stuff. It did better, but still wasn't totally effective in removing the stuff. So, if you spray this stuff, plan on getting it on the car and out of the gun quickly. I recommend removing the tip, needle, and anything else that was in contact with the Feather Fill. The primer was not completely set up, but has to be mechanically removed with gun brushes, compressed air, and solvent. Failure to thoroughly clean the gun will ruin it for sure.

BTW, the Dolphin Glaze and SPI epoxy seems to have completely cured the fisheye problem I had before on the hood. Only time will tell if everything stays in place. The odd color in the pic is because of lighting and sun shining in through some windows. It is actually light grey, just like the other things in the pic.
07-22-2019 08:38 PM
Refinishing Bumper Covers

Finally got the front and back bumper covers prepped for epoxy primer then base color/clear. I have to start another chemo session a week from today (29 July) so I have 6 days. Had a conversation with myself and I am going to get the C3 paint phase DONE! When I got home today I finished prepping the bumper covers and got them sprayed with epoxy primer following the recommendations from Southern Polyurethane.

The torn area on the front cover was a mess. It looked like someone had attempted a repair with super glue, spot putty and some rattlecan paint that didn't match very well. It would have far easier if the previous owner had not attempted the repair!

Here's a few pics...

07-18-2019 09:26 AM
Where to sell C3 original parts

Originally Posted by lsejlowe View Post
Classifieds is technically the right place for this. However, there's not much traffic through there, so I'd recommend a thread here in the C3 section to alert people to the fact that you posted a list. Not sure if that's technically "by the book" but it's the best way for a DC member to take advantage of quality used parts for sale!

Thanks, will do!
07-17-2019 09:40 PM
Originally Posted by zimmej51 View Post
Greetings to all! I have a pretty long list of original parts that I removed from my 81 C3. I'm thinking they might be of use to someone needing original parts for 80-82 C3. It's a pretty long list and none of it is junk.

Is the Corvette Classifieds the proper place to list the items? Or is there a better way? I would prefer to make them available to members of this forum. I will sell the stuff for a VERY reasonable price to anyone on this forum. I need to clear out some space in the shop. Again, no junk.

I'll be glad to compile a list of everything I have if someone is interested.

Classifieds is technically the right place for this. However, there's not much traffic through there, so I'd recommend a thread here in the C3 section to alert people to the fact that you posted a list. Not sure if that's technically "by the book" but it's the best way for a DC member to take advantage of quality used parts for sale!
07-16-2019 07:38 PM
Where to sell C3 original parts

Greetings to all! I have a pretty long list of original parts that I removed from my 81 C3. I'm thinking they might be of use to someone needing original parts for 80-82 C3. It's a pretty long list and none of it is junk.

Is the Corvette Classifieds the proper place to list the items? Or is there a better way? I would prefer to make them available to members of this forum. I will sell the stuff for a VERY reasonable price to anyone on this forum. I need to clear out some space in the shop. Again, no junk.

I'll be glad to compile a list of everything I have if someone is interested.

07-11-2019 08:12 PM
Tip for the day - Blind Rivets

Thought I'd share something with you today. You've probably noticed that the C3 has those large head aluminum blind rivets all over the place. These are the rivets that are commonly called "pop" rivets. Those that penetrate the cabin area are normally "closed" meaning the rivet end is sealed. Others are "open" and look like the blind rivets you have probably used at one time or another.

They are all aluminum, in several different lengths, and have a head much larger than common rivets. The head diameters are 3/8" and 5/8", the rivet itself is 3/16" in diameter, and the grip range varies depending on where the rivet is located on the car.

Here in the Heartland they are not commonly found in local supply houses. I don't think they are particularly rare, but I doubt you will find them at the local big box store. I finally located a source that stocks the rivets and they look to be virtually identical to the OEM rivets.

I don't know what the forum rules are regarding sharing information about parts sources, but if I get "gonged" then I guess I'll know not to do it again! However, sometimes the parts labels accidentally get into the pictures, and sometimes the labels show the source, description, and partnumber. And sometimes you love the price.

Since I completely disassembled the car, there really weren't any left to photograph. Then I remembered there were a couple of them on the rear bumper cover that appeared to not be fully seated. So I snapped a pic of a new rivet next to an original rivet to compare the appearance. They are very, very close to original. I doubt anyone other than a concourse judge would be able to tell the difference.

Couple of tips for use:

1. Clamp the pieces to be riveted together. Blind rivets are not designed to pull the pieces together. Sometimes you will get a gap (like the ones on my original bumper cover) or even worse, the mandrel can expand the rivet between the two pieces.

2. For C3 applications, be sure and use all aluminum rivets, including the stem that snaps off. In just about every case, the rivet(s) on a C3 have plastic of some sort on one or both sides. Steel rivets, or aluminum rivets with a steel stem will crush the plastic.

3. If you are drilling a new hole for the 3/16" rivet, use a #11 drill bit. The size of the hole is critical for the rivet to work properly. You did order that set of number and letter drills, right?

And here's another tidbit of information about blind rivets. The size is often expressed in what they call "Trade Size", consisting of two numbers side by side. The first number is the diameter of the rivet shank (NOT the head) in 1/32" increments while the second number is the maximum grip range expressed in 1/16" increments.

For example, if you see trade size 68 on a sack of blind rivets, the shank is 6/32, or 3/16". The maximum grip range is 8/16, or 1/2".

That's it for now, hope this information is useful for someone!

07-09-2019 09:57 PM
Pinholes in bare SMC hood

Follow up to post 125 about pinholes in the smc hood. The Dolphin Glaze appears to be working perfectly. As I mentioned, the stuff is kind of like real thin Bondo. You mix it up and squeegee it over the area(s) that have the pinholes, scraping the excess off. After it cures (only takes about 15-20 minutes cure time before sanding) gently block with about 150 grit. Keep going until the glaze becomes slightly transparent, then switch to 220 or so.

When you squeeze out the Dolphin Glaze I recommend squirting out a bead 2 to 3 inches long. Then add a bit of polyester activator and stir until the hardener is uniformly distributed in the glaze. This stuff sets up rapidly so work quickly and have a plan.

Remember to squeegee it out very thin. We aren't leveling here, we are filling pinholes. And just like ordinary body putty, once it starts to set up you need to STOP! Put your squeegee down and walk away until it's cured.

Couple of pics below. If you look closely you can see where the pinholes have been sealed. Based on my experience I'd say that I will get to repeat the process several times. A little tedious but the finished process is worth it. You can't get more out of something than you put into it!

07-09-2019 09:28 PM
Bumper Cover Repair (Continued)

Think I've got the urethane bumper repair (re post #121) done. The 3M 05887 bonding adhesive worked very well and has very good sanding characteristics. I used 3M 05907 adhesion promoter under all of the 05887.

Got a couple pics below but they make the surfaces look a lot rougher than they actually are. The repair passed the "wet test". For those that don't know, the wet test involves squirting some water from a hand held pump sprayer onto the area in question. The water will briefly coat the surface and looks like clear coat. By holding a light source just right you can see the reflection on the surface and easily spot high and low places. If the water tends to bead up try adding a very small amount of dishwashing soap to the water.

I think this repair will be a keeper, but you don't really know for sure until 2 or 3 years have passed.

07-09-2019 08:35 PM
lsejlowe enjoying following along, so thanks for posting! I don't think I have the skill or patience for bodywork, but seeing all this effort makes me appreciate it that much more!
07-08-2019 07:08 PM
A bit of humor

For those that might be interested, thought I'd post a picture of a bankruptcy starter kit....

Ok, that's it, back to work!!
07-08-2019 07:05 PM
Pinholes in bare SMC hood

Hood prep part deaux.... I got the entire car stripped to the bare SMC a while back and wanted to get the SMC sealed to preclude contamination since my schedule is a little unpredictable. Consulted several times with the folks at Southern Polyurethane (SPI) regarding their epoxy primer. They assured me the epoxy layer is a good thing to do and is 100% compatible with SMC on the bottom side and polyester products on the top side. So, this is my deviation from the excellent refinishing guide posted by 7TRoadster. I'll let you know how it goes, good or bad.

The rest of the car came out beautifully, but I expected to have a problem with the hood due to a proliferation of tiny "dimples" on the surface, similar to a golf ball but a lot smaller. And I wasn't wrong. Anyone who has sprayed at least 1 rattlecan of paint knows that a pinhole will cause a fisheye 99% of the time. I think it's due to the surface tension of the solvents in the paint - it tries to "walk" out of the pinhole creating the fisheye appearance. The consensus on this forum is that the dimples were likely caused by excessive mold release when the hood was made.

And, no surprise, looked like a school of minnows staring up at me. So, the second deviation from the paint sticky. I've dealt with this a LOT in one of my other hobbies, big RC airplanes. The fiberglass fuselages are notorious for pinholes. I've always used Dolphin Glaze with good success. It's a polyester based product, about like very thin polyester body putty. Sanded well into the epoxy primer and have spread the stuff very thinly over the surface. Then I'll repeat as necessary, block and hit it with another coat of epoxy. If you look closely at the pic you can see the pinholes. Since the pic I have applied the Dolphin Glaze. I'll keep you posted...

07-04-2019 06:55 PM
Southern Polyurethane Epoxy Primer

At least it's all one color again! Everything primed with epoxy primer. Uneventful, but took about twice as long as it should have, I still run out of gas pretty easily. A couple of my best friends showed up and took up the slack, not sure I could have gotten it all done today without their help!

All came out well except for the hood. I'm not happy with it yet. A couple pages back in my thread I posted some pics that showed the odd "texture" in the SMC that was revealed after stripping. The consensus was that it was most likely caused by excessive mold release when the hood was formed. It has zillions of tiny "craters" that triggered fisheyes. And I aggravated the problem by applying the primer a little too thick. Oh well, like a friend once told me, that's why they make sandpaper!

I'm also considering using Dolphin Glaze since it's a polyester based product. I've used it before, but never on SMC or fiberglass panels. Anyone here ever used it on SMC or fiberglass?

07-04-2019 06:38 PM
Originally Posted by 77blue View Post
Great to see you back at it Zimme - keep fighting the good fight !

Thank you, it's great to be back at it, I can tell you that for sure!!
07-04-2019 05:26 AM
77blue Great to see you back at it Zimme - keep fighting the good fight !
07-03-2019 09:43 PM
Bumper Cover Repair

Greetings to all! I have rejoined the world of the living, chemo keeps getting in the way of my hobbies. Thanks again to 7TRoadster for asking where I was!

Speaking of 7TRoadster, I have been following his excellent guide for refinishing with one exception which I shall explain. The car had original paint, and upon stripping I observed that first was the finish, then a light grey primer that was probably some kind of polyester based primer, then a hard, black primer that I believe was an epoxy based primer, and finally the bare SMC panels. The black primer was noticeably harder than the SMC.

So, the deviation is that I intend to spray the bare SMC with Southern Polyurethane black epoxy primer. I called the nice folks at SPI and they informed me that the epoxy primer was 100% compatible with SMC and it would make the perfect surface for the FeatherFill. In addition, they tell me that it also is an excellent choice for the urethane bumper covers and did not require any flex additive or adhesion promoter.

The main reason I'm doing this is that there is the possibility of unforseen interruptions due to health concerns. I want to get that naked SMC sealed up and durable in case I have another delay. Naked SMC will soak up just about anything that touches it, sometimes irreparably. So that's the deal.

Speaking of bumper covers, that brings me to the next topic in this build thread. The bumper covers are original. The rear is flawless but the front has an impact hole in the lower passenger side. The bumper covers are the yellow PUR stuff common to early 80's GM vehicles. Since there is no damage other than the hole/tear, I believe it's a good candidate for repair. I have refinished several bumper covers in my day, but this is my first foray into actual repair. I'll document it in real time as much as possible, so if I screw something up you'll get to see it first hand!

First, here's the products I'll be using. As always, READ AND HEED THE SAFETY WARNINGS AND PRECAUTIONS!

Here's some pics of the damage on the outside of the cover. To complicate the repair, at some point in the past someone had attempted an amateur repair using what I believe to be super glue, lacquer based spot putty, and rattle can paint. It was a mess. Anyway, in these pics I have prepped the crack lines, drilled relief holes, and smoothed out the crack surfaces so that there are no sharp edges anywhere.

Now for the inside repair on the cover. According to 3M, you want the inside to be absolutely clean and smooth. Any overspray should be removed so that the patch is applied only to clean, bare urethane. Again, no sharp edges.

To temporarily hold the cracked segments of the bumper cover in place I used foil tape on the outside of the cover. For this picture, I haven't applied the third piece of tape so that you can see the prepared cracks and relief holes.

Now we get to the part where I applied the 3M 05888 bumper patch kit. Using paper for a template, I cut out a patch that would cover the entire cracked area in one piece. That turned out to be a mistake. I'll tell you why in a minute. By the way, 3M says that if your repair area is bigger than the patch then you should probably consider replacement rather than repair.

Here's where I got into trouble. I was a little too confident that I could push the patch down into a confined area with several compound curves. My plan was to heat the patch with a heat gun to make it more flexible.

But here's the deal. The patch kit comes with a packet of adhesion promoter. It's a small sponge impregnated with the promoter. You wipe it on the bumper cover and wait 5 minutes. Then you peel the backing off of the patch material. I'm here to tell you this is the most aggressive adhesive I've ever seen. It's almost like a magnet pulling the patch toward the cover. When the patch touches the cover it instantly becomes one with the cover and the universe! You WILL NOT be able to reposition the patch AT ALL! So, I wound up missing one small area where a crack needed to be bonded. After consulting with 3M, they recommended cutting another small patch that would cover up the exposed crack. They also said the patch material can be stacked, sort of a patch on a patch. What you don't want is a crack that follows along the edge of the patch. In retrospect, careful placement of multiple patches would probably have been better, but as it is all the cracks are bonded under the patches so I think I'm good to go.

Finally, on the outside, I bonded the cracks with 3M 05887 flexible bumper repair adhesive. I used 3M 05907 adhesion promoter on the bare urethane anywhere the adhesive would go. The 05887 is a 2 part mix, and has a very fast cure time. Accordingly, I used one of the 3M mixing nozzles so that I wouldn't have to screw around mixing while the stuff cures. This is good for repair shops because it can be sanded after about 15 minutes. But the working time is only around 3 minutes, so have all your materials at hand and have a plan for what you are going to do, and don't go to sleep while working with it. Squirt enough out to thoroughly bond the cracks/damage with a little extra for smoothing with a squeegee, like Bondo. But it will not squeegee into a smooth feather edge like Bondo or Dolphin Skin. At least not for me. And when it starts to set up, STOP IMMEDIATELY! Don't try to force it around, it will only get worse. Just walk away for 20 min or so.

After it's cured, you will be surprised how it sands if you've never used it before. Even though the stuff is very flexible, and the sanding effort is almost identical to the urethane material, it will not clog your sandpaper at all. Even though I've always been a wet sanding fan, this stuff seems to work better dry. In the pics below you can see what it looks like cured but unsanded, then what it looks like with a quick few minutes from the sanding block. Still have a few low places that need more material but all in all I think it will be a success.

Next up: I plan to spray the black epoxy primer in the morning unless the humidity is wacko. I'll be using my newly built fresh, filtered air supply system that emulates a downdraft spray booth. I'm confident it's going to work quite well but if it doesn't, you will find out about it right here!!

And it's great to be back!!
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Powered by vBadvanced CMPS v3.2.2

All times are GMT -6. The time now is 11:18 AM.

Powered by vBulletin® Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
2003-2011, - All Rights Reserved