Suggestions on painting the block?

vettereddie · Posted: 8/15/08 11:21AM Post subject: Suggestions on painting the block?

Has anyone done this yet? I don't mean just the valve cover, I mean the entire long block (maybe minus the oil pan).

I am building a motor (new pistons, rods, bearings & headwork) so it seems like it would be an ideal time to do so. Would I just mask off any internal access parts (sensor ports, hose fittings, etc) and hit it with rattle can engine paint? I'm thinking black or gunmetal grey. The spare block I'm building is from a salvage yard and has that white powdery stuff all over it so it looks like poo. The valve cover and timing cover are easy, the head and short block, not so much. It will be in several pieces so should be easier to work with (head, short block, oil pan housing, valve cover, timing cover all seperate).

I do also have an HVLP spray gun if they make any two-part engine paint. My car is black and silver two-tone so I don't really have a ricey neon color to match it to. I could try and match the silver, it would at least clean it up a bit though wouldn't stand out much.

duck_dodgers_24_5 · Joined: 03 Jul 2004 Posts: 9392

yeah go with black

TerribleTed · Joined: 13 Nov 2006 Posts: 1106 Location: Atlanta, Georgia

I have painted a number of engines with regular automotive urethanes. The same paints that you would use for the exterior of the car but in a single stage urethane instead of base/clear coat urethane. I have also painted engines with base/clearcoat as well. Either base/clear or single stage work well. The single stage urethanes are a little easier to apply and a little more durable on engine blocks near high heat areas (exhaust manifolds etc...you can not paint the exhaust itself with these paints). I have found such applications to be very long lasting and you can choose any color you like:) It is essential that the surface be totally clean of oils and grease before application. The surfaces should be coated with an epoxy primer as an undercoat before color is applied (assuming bare metal). Any previously coated surfaces must be sanded. The products I used were PPG DP epoxys and either PPG DCC single stage urethanes or PPG DBU basecoat and PPG clear coats. The engines I have painted were various GM and Ford small block V8's as well as the sheet metal enclosures of numerous Chevy Corvair engines. If it works for these I see no reason why it would not work for yours.

vettereddie · Posted: 8/16/08 6:46AM Post subject:

Thanks, that's the kind of feedback I was looking for. Right now I have silver streak mica from Dupont Chromasystem. I also have two part urethane primer and clear. Think the urethane primer would hold up instead of an epoxy primer? Not trying to spend more than I have to on paint. I was also thinking about getting some black sand pearl.

TerribleTed · Joined: 13 Nov 2006 Posts: 1106 Location: Atlanta, Georgia

vettereddie wrote: Thanks, that's the kind of feedback I was looking for. Right now I have silver streak mica from Dupont Chromasystem. I also have two part urethane primer and clear. Think the urethane primer would hold up instead of an epoxy primer? Not trying to spend more than I have to on paint. I was also thinking about getting some black sand pearl.

The urethane primer may not truely be the best for adhesion to bare metal. Urethane primers are generally used for filling scratches and imperfections prior to final paint. On an engine block that without large amounts of surfacing is not going to br very smooth the build anf filling properties of the urethane are kinda useless. I would check with the Dupont rep/supplier (I assume that your primer is Dupont also...if it isn't it should be...mixing manufacturers in a coatings regimen is not the best idea) and ask whether what you have is the best material for adhesion to bare steel. The Dupont base and clears should be fine for this application as long as they are used over the best possible primer base.

vettereddie · Posted: 8/17/08 4:51AM Post subject:

Alright, thanks. Yeah, the primer is Dupont as well, but under the Nason brand / line. The only decent place for paint around here is Carquest, I'll check with them on getting something for bare aluminum. Any tips on prepping / cleaning the block beforehand? I do have a blast cabinet available and the block will be in pieces for a bit. Think walnut shell would do it if I was everything after? I'm not up for hand sanding.

TerribleTed · Joined: 13 Nov 2006 Posts: 1106 Location: Atlanta, Georgia

vettereddie wrote: Alright, thanks. Yeah, the primer is Dupont as well, but under the Nason brand / line. The only decent place for paint around here is Carquest, I'll check with them on getting something for bare aluminum. Any tips on prepping / cleaning the block beforehand? I do have a blast cabinet available and the block will be in pieces for a bit. Think walnut shell would do it if I was everything after? I'm not up for hand sanding.

Walnut shells is a good choice. Be sure to use a primer recommended for use under you base and clear and also recommended for use on bare aluminum. It pays to use the right products the first time:)