Mercury 410 Build

[Porkchop]

Hello,
I am starting the process of rerebuilding a Mercury 410 engine. I already built this engine but unfortunately it lasted <500 miles before developing a rod knock on #4 connecting rod.

I do not know 100% why this happened, but I would say it was a combination of too small of bearing clearances, cleanliness, and oiling issues. Rod bearings had 0.0015” clearance and mains had 0.002”, I understand now this is too tight. And I did not do the oiling modifications.

This time I’ll be taking the block, crank, rods, etc to a machine shop that knows FE’s.

Application: 69 F100 with 3 speed manual. This is a street truck, I will not be racing, but I will have fun with it.

Expectations: I would like 400-450 hp. No, I am not dead set on this. I know that is borderline for some parts I may want to use and so perhaps I would back off of that expectation.

Engine Details:
-Original Mercury 410 block, crank, rods 
-Block is bored 0.030” over
-Stock Deck Height (pistons 0.030” down)
-Crank main and rod journals are 0.010” under
-Howard’s Cam HRCCL250031-12
https://www.competitionproducts.com/Howards-Cams-Hydraulic-Flat-Tappet-Camshaft-Lifter-Set-Ford-FE-352-428-213_223-050-525_525-112-LS/productinfo/HRCCL250031-12/
-Stock Rocker assemblies
-Sealed Power 1139P 9.5cc cast pistons
-C6AE-R Heads with CJ valves. No porting. Measured 74CC chambers
-Stock 4 barrel manifold (will probably go to aluminum)
-Edelbrock 750CFM carb
-Stock truck exhaust manifolds with dual exhaust. Will probably go to headers eventually
-Compression ratio estimated at 9.6 static, 7.9 dynamic

I want to keep the same block and crank. Perhaps I need to change pistons and rods to achieve my expectations?

Regarding machine work, I want to make sure I give the shop direction or I walk out knowing exactly what will happen before hand (this didn't happen with first shop). I think the crank needs to be reground to achieve the advised 0.0025-0.003" clearances. I think I will want to have the block 0 decked to increase compression a bit. I think the bores will be fine with a hone. 

What are the thoughts/opinions on this?

Thanks for any advice!

[blykins]

Need a little bigger cam, but 400-425 hp would be no problem.

[Tommy-T]

Installing headers on these old trucks is a dramatic performance upgrade. The stock exhaust manifolds are awful.
Do it now while you've got it torn down.
You won't regret it.

[DuckRyder]

Agree with Tommy, do the headers and exhaust. IIRC stock truck logs have a 2" outlet so it's suboptimal....

Flowmaster makes an 2.5 exhaust, and hooker may still be able to make a 2.25 that matches the hooker comp headers... not sure. Mines pretty much rusted away no thanks to jet hot.

I think the issue with the Flowmaster is you'll have to make connector pipes.

[Porkchop]

Ok, I will probably try to get headers on when I install the engine.

So should I stick with the factory rods and cast pistons?

What cam would be recommended?

[DuckRyder]

If it was me i would talk to Brent on the cam.

Depending on what you find id closely compare the cost of the machine work to a new rotating assembly.

Keep us up to date on the build, sounds like fun.

[Kevin66]

Just some thoughts for you to consider. Are you absolutely certain that your crankshaft is an actual 3.98" stroke 410/428 one, and not a 3.78" 390/406/427LR one? The reason I ask is because I have seen issues where people have installed replacement 410 pistons (with a 1.66" compression height) into 390 engines (which want a 1.76" compression height). This results in the engine having the .025"-.035" deck height you describe, which substantially lowers the compression ratio, down into the 8.X:1 range. That has a LARGE detrimental effect on the engine's power output.

I believe your estimation of both your static and dynamic compression ratios is off considerably, and it needs to be brought up. To achieve that, I really don't think you want to be cutting .030"+ off the deck surfaces! Unless you can find some actual high compression 420 pistons in .030" O/S, you may need to look at custom ones.

I agree completely with Brent Lykins' comment about the camshaft, if you do want horsepower up in the 425-450 range. He knows a lot more about cams than I do, but I suspect would advise going up about 10° @ .050" on both intake and exhaust. What you have now is essentially just a 'very mild' improvement on the stock 428CJ cam. These motors made about 400 HP from the factory, and that's with the CJ heads, 10.6:1 c.r., a very good factory intake and 735cfm Holley carb. It also had much better exhaust manifolds than your truck came with. So as several others have suggested here, get some actual headers for your truck. In that regard, Jay Brown found in his testing for his 'Great FE Intake Comparo' book, that an engine in the power range you're talking about (425 HP 428CJ) would 'average' about 330-336 HP with several different headers, and the ancient 'log' style exhaust manifolds, as found on most factory FE's, would only muster 293-296 HP.

And definitely replace that 83 Lb. cast iron intake manifold! Almost any aftermarket aluminum 4-Bbl intake you can find will deliver more power (as much as 35 HP!), and will take 50 Lbs off the front of your truck!

[driveamerican]

Does that cam really have the HO small block firing order?

[DuckRyder]

Those are SilvOLite pistons right?

Howards webpage is messed up i cant get it to give me anything, unless i back door into it from google.

https://www.howardscams.com/hydraulic-flat-tappet-camshaft-1963-1977-ford-352-428-1400-5200-howards-cams-250031-12