There have been a number of body off threads lately that have inspired me to do an engine build thread. This particular build has been in the works for at least 3 years. During that time i switched jobs, moved accross country and got two new antibiotics approved. Neadless to say, I haven't spent much time on it. I did move the machined block accross country and damned if I'm doing that again so the tiime has come to get this done and get it in the car!

Let's start with a little background. Around 4 years ago, I put the best small block that I've every driven in my 73. It was a stroker with a solid roller lifter custom cam. Never had it dynoed but it lit up the tires on my TH400 at will and sounded awsome with the stock sidepipes. That motor kind of blew up. We will not speak of that again

Whle the block and exploded pistons from that build were junked, the rods, crank and heads were all cleaned up and tested and were good to go. I got a good deal on an O-ringed Motown block that needed a bore. As such, it had to be substantially decked to remove the o-ring grooves. A lot of this build will make more sense with this in mind. My theory was to build this on the cheap but given the machining already done and add the retrofit hydraulic roller lifters going in, I've probably lost that theme a long time ago.

First, a few general motor specs:

Bore: 4.185 inches
Stroke: 3.75 inches
CID: 412 (closer to 413, but that's unlucky)
Deck height: 0.010 inches (approx) TBD on final assembly
Piston relief: 4.8cc
Head combustion chamber: 72cc
Heads are Dart Iron Eagle Platinums
Target SCR: 9.8 to 9.9:1 (with 0.072 inch head gaskets)

 

A couple of weeks back, while it was still too cold to take the block outside for washing, I started on the heads. They have been in my garage for a couple of years and were showing surface rust (and spider webs. Sad). Another member,Mooser , suggested using fine Scotchbrite pads lubed with WD40 to clean it up. Worked very well!

Heads before cleaning:



Heads after cleaning:



Just hosing them down with brake cleaner and then WD40 made most of the surface rust go away but I did spend an hour or so with the pads cleaning up the mating surfaces. One area that I did avoid was the valve sealing surfaces:



These two are about the most pitted. I was thinking of getting fine grade valve lapping compound and those rubber tipped sticks that no one ever uses and see if they'll clean up adequately. Any other thoughts?

 

I didn't.. & I called mine a 413".
Anyhow, I'm cruising junkyards today looking for donor parts.

https://www.corvetteforum.com/forums...400-ci-14.html

 

Dang! Guess I know what I'm going to be reading the rest of today instead of working

 

The chambers are more detonation prone with a rough surface like that - best to polish it out. Myself i would polish each chamber to match the volume in every other chamber as the same volume. U will need to install the vlvs each time u measure the vol.

Sorry but i dont think lapping will clean up the seats. U can try lapping. But u may still need a new vlv grind. Or worse u may need new vlv seat inserts.

Sorry for the bad news but thats my 2 cents from the pix.

 

Brush some dye kem on the seat then do a quick lap....that will tell you lots. Bet they are Ok though; unless youre real good with a grinder leave the rest as is and run em.

 

Thanks for your opinion. I'm not sure lapping will do it either. If it needs to be re ground, then so be it.

Funny that you mentioned this. When I was cleaning them up, I was quite surprised how tough they were. This is how they were new.

I'm thinking about polishing them some. Getting the CR down a point or two would do no harm at all in any case so very little to lose.

 

It has been a couple of weeks since my last update but I've been getting some parts and doing some work too.

First off, I receive the valve lapping compound a few days ago. i went with a fairly fine, 1000 grit from Clover. The abrasive is Silicone carbide in a grease paste. I went with a manual "toilet plunger" type lapping tool rather than the egg beater type as I really didn't know how much or little effort it would take and I didn’t want to damage the seat or valve sealing face. The results are a little hard to capture in a cell phone pic, but suffice it to say they are better than I'd hoped. Have a look at the intake seat sealing ring after about 2 minutes of spinning:

 

The real test is once u install the vlvs w/springs u can put gas or oil or whatever in the chamber and look for leaks. Or u can put the liquid in the runners and look for leaks into the chamber.

 

Not a bad idea. I might use a little ATF in each chamber to see if any pink shows up in the ports.

 

For this build, I decided to go with a retrofit hydraulic roller. Doesn't exactly fit my goal of building on the cheap, but it should maximize what I get out of the motor without losing too much in the way of street manners.

I called up our friends at Comp Cams and spent about 90 minutes on line with Adam. What I was looking for was good vacuum, decent idle and mostly low end power. I figured that the stock style side pipes would be so restrictive that it'll choke long before hitting 6500RPM.

This is what we came up with:

Valve lift intake: 0574
Valve lift exhaust: 0.556
Duration at .050 Intake: 225
Duration at .050 Exhaust: 231
LSA: 110
Advance: 4
Small Base circle
Melonized timing gear

It's essentially a 268 cam with more lift.

The cam and the rest of the valvetrain, including the beehive springs, is already in my shop and ready to assemble.

 

For checking sealing of installed valves, the private aircraft service industry used to use kerosene poured into the ports and let them sit overnight. The thought being the low surface tension of kerosene would be the best to reveal leakage.

On another note, de-burr the edges of the cast chamber edges for detonation prevention. Also do a thorough cc-ing of all the combustion chambers.

 

Need to get the dangged thing off my workbench. I was doing a final cleaning on the head and finishing lapping but really didn't like the soot that had accumulated on the valves. I tried using my new found favourite cleaner, Brakleen full strength (banned in CA), but it just made the soot dull. I tried ATF but it didn't make any difference. What should I do, use something else or just assemble as is and let the motor burn it off?

I know that I could remove it mechanically by putting it in the drill press and using a ScotchBrite pad, but I'm a little reluctant to do this on valves.

 

Why? you're not going to hurt them.

A wire wheel on a bench grinder works well too.

 

I agree:
"A wire wheel on a bench grinder works well too."
Since you are taking your time to do it right, polish those beautiful chambers and then cc them.

 

I don't think they'll clean up that way either. Don't be afraid to use the wire wheel on the bench grinder.

Keep us posted.
Steve

 

While you are at it, make sure the valves are not shrouded.

 

So what are the new antibiotics??