Author Topic: engine primer (Read 6464 times)

lajos · « **on:** June 08, 2015, 10:29:01 AM »

Stripped the paint off my 550 crank case and was doing some research on primers, but I've found conflicting information.

I was going to get some self etching primer because I figured it will be tough to get into all the nooks and crannies to scuff up the surface. One of the primers I found recommended on forums was the VHT SP307 high performance self etching primer.

But then I called Duplicolor/VHT customer service and they told me that I can't use self etching primer because it won't hold up to the heat. They recommended using the VHT SP148 engine primer.

I'm also going to paint the cylinders/head when I get them back from the machine shop so it would be great to find a primer that will work on the whole engine.

Could you guys please give me some recommendation on primer? Any tricks on getting into the tight spaces for scuffing up the surface would also be welcome ;)

flybox1 · « **Reply #1 on:** June 08, 2015, 10:35:01 AM »

After stripping off the existing case coatings, i scrubbed and washed in acetone, several times.
I applied Duplicolor high heat engine enamel (no primer) directly to the metal.
It has held up well.

edit: I baked all parts 250F for 30 min after several coats

lajos · « **Reply #2 on:** June 08, 2015, 12:30:57 PM »

Thanks, I've ordered some red primer prep scotchbrite.

I've seen that not everyone uses a primer, but wouldn't a primer make the finish more resistant to chipping?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #3 on:** June 08, 2015, 12:35:07 PM »

Chipping, probably not. Peeling, probably. Prep work is imperative. Bake it on.

Davez134 · « **Reply #4 on:** June 08, 2015, 02:55:56 PM »

I used that VHT SP148 primer on mine, along with VHT engine enamel top coat. Have used it on 2 different engines with GREAT results. No chips or peeling. Of course, as everyone has stated, prep is key. When you think it is clean, scuff and clean it again, then do not touch with bare hands. Heat curing is essential! Bake before hand per instructions on cans. If not, heat cycling on a running engine will work, just be VERY careful no fuel or oil leaks on paint before startup.

As far as scuffing up tight spaces... I used a pair of medical clamps called hemostats, cut a square of scotchbrite, folded in half. Then I clamped into hemostats and scrubbed away in spaces I could not otherwise reach.

http://forums.sohc4.net/index.php/topic,139768.msg1637893.html#msg1637893

lajos · « **Reply #5 on:** June 08, 2015, 04:40:17 PM »

Your engine paint came out great! I also want to do the cylinders black, although I was thinking flat or satin black. But the crinkle black looks very nice!

Thanks for the tip on the forceps to hold small pieces of scotchbrite, will definitely use it.

flybox1 · « **Reply #6 on:** June 08, 2015, 04:55:53 PM »

Duplicolor low gloss black engine enamel...

lajos · « **Reply #7 on:** June 08, 2015, 05:21:52 PM »

Looks really nice! How did you get the highlights on the fins? Sanded off the paint after it was cured?

Maybe I should consider all black. It probably doesn't require as much cleaning as gray.

flybox1 · « **Reply #8 on:** June 08, 2015, 05:36:46 PM »

Yes. I block sanded the fins after paint.
If you don't prep the cases really well, I'd go with a textured paint, as cal suggests, to hide the surface imperfections.

przjohn · « **Reply #9 on:** June 08, 2015, 05:45:08 PM »

Bead blast then VHT Paint.

Davez134 · « **Reply #10 on:** June 08, 2015, 05:48:13 PM »

I think you should prep/clean the same no matter which color you choose. Do it once, do it right. I went with wrinkle because I just love the way it looks, especially out in the sun.

I guess it would obviously hide imperfections well.

Sent from my iPhone using Tapatalk

lajos · « **Reply #11 on:** June 08, 2015, 07:02:49 PM »

Yes, I don't want to take shortcuts on prep, the only reason I thought about self etching primer was to make sure it grabs onto spaces I might not get to. But according to VHT the etching primer can't stand the heat.

It looks like you painted the crank halves together. I was going to do them separate so I can lay them flat for easier access. You didn't have issues separating them/cleaning up where they join?

The inside of my crank cases still has the original paint on it. Is acetone safe for degrease considering it might seep in there?

Davez134 · « **Reply #12 on:** June 08, 2015, 07:24:11 PM »

Quote from: lajos on June 08, 2015, 07:02:49 PM

Yes, I don't want to take shortcuts on prep, the only reason I thought about self etching primer was to make sure it grabs onto spaces I might not get to. But according to VHT the etching primer can't stand the heat.

It looks like you painted the crank halves together. I was going to do them separate so I can lay them flat for easier access. You didn't have issues separating them/cleaning up where they join?

The inside of my crank cases still has the original paint on it. Is acetone safe for degrease considering it might seep in there?

As Cal stated, acetone is great choice for cleaning. Only reason I painted with cases assembled is I knew I was not going to be able to heat cure them, and I knew some hondabond (grey) would get on the incurred black paint upon reassembling the cases. I thought it through in my head a few times and that was just the way I chose to do it.

lajos · « **Reply #13 on:** June 08, 2015, 07:35:52 PM »

Thanks for all the help! I would be totally blind without everyone's knowledge here.

I have the primer prep scotchbrite on order from amazon along with the locking forceps. So for the next two days I'll clean the oil gallery, plastigage the cranks, work more on the carbs... the awesome thing is that there's so much to do that there's never any waiting around ;)

lrutt · « **Reply #14 on:** June 09, 2015, 01:18:32 PM »

Quote from: flybox1 on June 08, 2015, 10:35:01 AM

After stripping off the existing case coatings, i scrubbed and washed in acetone, several times.
I applied Duplicolor high heat engine enamel (no primer) directly to the metal.
It has held up well.

edit: I baked all parts 250F for 30 min after several coats

I've done this many times, without the bake as the engine will bake it on. Never a peeling problem. If possible, get the complete engine soda blasted, that will clean it up right nicely.

lajos · « **Reply #15 on:** June 09, 2015, 01:51:46 PM »

I'm not sure how long it will take to get the engine back into the frame, I only have time to work on it when my kids go to bed at night. So I'll probably bake it in the oven, that way it's done. Unless I can figure out how to start the motor on the bench ;)

I've considered soda blasting, but I've seen videos on youtube and it seems to make a lot of mess. I think my neighbors would kill me if I did that in the driveway.

The aircraft stripper work very well, the bits of leftovers are easily cleaned up with a small stainless steel brush tool in the dremel.

flybox1 · « **Reply #16 on:** June 09, 2015, 02:55:27 PM »

a 5" brass wire wheel in a power drill is lots faster

gets between the fins, too

tlbranth · « **Reply #17 on:** June 09, 2015, 08:20:46 PM »

That's a beautiful paint job flybox. How did you prep the chrome cover?
I've always wondered what they use on the new Triumphs. That is some nice looking paint.

lajos · « **Reply #18 on:** June 10, 2015, 05:35:41 PM »

Got the primer prep scotchbrite in the mail today, those pads are amazing. Scuff up the surface to a very nice satin finish pretty easily.

What gloves do you guys suggest for handling the parts to avoid finger prints and oils?

Ujeni · « **Reply #19 on:** June 10, 2015, 07:30:49 PM »

I've done this many times on my restorations. Here's what has worked well for me.

Clean the cases (I carefully bead blast them). Then clean with a paint prep (to remove wax and grease).

Then duplicator high heat engine primer. Then duplicator cast aluminum engine paint (1650)

Then bake at around 225F for 25 minutes.

Comes out looking like it did originally and the paint will resist heat, fuel and oil.

Good stuff!

lajos · « **Reply #20 on:** June 16, 2015, 01:50:55 PM »

Had a couple busy days with end of school year stuff for my kids (why do they always make the last couple weeks so busy?), but I'm back to paint prep.

Fixed some casting imperfections and deeper oxidation and ding spots and scuffed up half of the crankcase. Also got the primer in the mail (all my local car stores were out of VHT engine primer).

How long do I have between scuffing and priming? I assume at some point oxidation will start messing up the surface of the bare metal, if I scuff one day and paint the next day, will that work?

flybox1 · « **Reply #21 on:** June 16, 2015, 01:55:04 PM »

i skipped the scuffing.
degrease/brush scrub
acetone wash
OCD acetone wash
ADD OCD acetone wash
prime/paint.

lajos · « **Reply #22 on:** June 16, 2015, 05:56:57 PM »

Quote from: flybox1 on June 16, 2015, 01:55:04 PM

OCD acetone wash
ADD OCD acetone wash

The OCD is exactly how I feel with sanding/scuffing the case. Every time I think I'm done, I find a new spots of little buldges or a nook that looks it could be better. In fact I just took this photo and all I see is little buldges... I'll have to put a deadline on this or I'll never get past it.

lajos · « **Reply #23 on:** June 17, 2015, 11:34:08 AM »

Ok, so I did acetone wash and it pulled the masking tape right off. So I guess I'll have to put masking tape with gloves on after the last acetone wash?

flybox1 · « **Reply #24 on:** June 17, 2015, 11:56:58 AM »

wipe down the areas to be masked with acetone.
when it dries, mask it all. trim off excess.
grab a few clean shop rags, over your finger, dip in acetone, and wipe the remaining areas clean.
if the shop rag brings up dirt/grime, go over it again until it doesnt.
store the case in or under a black garbage bag to prevent dust settling on the case/before paint.

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Author Topic: engine primer (Read 6464 times)