406 - first kick
So, having not touched an since high school, and now retired from the Navy, I decided to start 'tinkering' to see what I could remember. I decided to try find an old 350 to play with over the winter, so what actually happened was I picked up someone else's project engine:
Freshly bored 406, polished crank, new pistons, rings, cam, oil pump, flex plate, balancer and a few other odds and ends - most of the rotating assembly..
What I still need are
intake (likely some sort of FI)
Somewhere I have a note with recommended head numbers, but the part I *do* remember is that the PO recommended 76 mm combustion chamber for a lower compression ratio. And to get the heads drilled for steam holes.
Some way of figuring out what will work well with the current parts. :confused: Any pointers towards what I should be looking at for the top bits would be most appreciated. I'm way out of practice and don't really know what to be looking for when it comes to the options available these days.
The engine will likely be going into a 68 C10, or possibly a farm find 48 dodge, complete with farmyard bullet holes - if I can convince the 80 year old owner that he's likely not going to be doing anything with it...
If you have them unassembled, give all the info you have on the parts. Piston diameter, piston compression height, part number if you have it, rod material, rod length, etc. There are lots of smart guys on this board who can help you assemble a motor that will do what you want it to, but we must know every little detail of what you have now in order to help you. Do you have the EXACT diameter of the bore?
You may want to use heads with a larger combustion chamber volume or you may want to use a more conventional head with a dished piston rather than what you have. You will want to engineer the build at somewhere around 9.0:1-9.5:1 static compression ratio with iron heads and no more than about 10.0:1 with aluminum heads if you plan to run the motor on pump gas. The more static compression ratio you run, the more cam you have to run to prevent excessive cylinder pressures that will detonate on pump gas. It's all a balancing act, involving all parts that must work in symphony with each other toward a final goal. It's what's referred to as a COMBINATION.
This afternoon, I DynoSimmed a combination for one of the other members of this board that used ProFiler heads. These are excellent aluminum heads that come in 64, 70 and 72 cc configurations and could be matched with the proper piston crown configuration to make the best static compression ratio to meet the needs of your build.
See the Sim here on post 18....
You want to first establish what you want this engine to do (performance level-purpose-operating parameters)
and what you will be feeding it (fuel octane) A engine that operates on 87 octane regular gas is different than
a engine designed to run on 92 octane premium.
You need to make these decisions and clear distinctions now before you start buying stuff.
Thanks for the pointers! Just back from a quick parts muster in the garage, and here is what I have:
- Block - tag says .030. I also discovered, when unwrapping it, that one bolt hole was chipped. An easy fix according to the welding instructor across the street. It's been bored, requires a bath to remove the protective coating, and a hone.
- Sealed Power rings E243K
- Melling M55 oil pump
- Crane Blazer 284-2H cam
Deg duration @ .050 - 224 234
deg adv dur 284 295
deg lobe separation - 114
open/close .050 cam lift - 3 56, 41 (2)
gross lift .465 .488
valve springs 2620
push rods 1000
timing chain and gear assy 3405
- Pistons Speedpro H615CP. Hypereutectic Chevy 400 .030 dish pistons with relief valves. Found this link: 400 CHEVY Speed Pro Dish Pistons H615CP 5.7 Rod +30 - KMJ Performance
Misc - rods (not enough)
Clevite 77 bearings
flex plate for 350 (and apparently 700R4
Everything is completely unassembled. Mostly new in box, except connecting rods and pushrods, which will be new by build time.
Is this enough? I can post pix if that helps.
F-bird - Thanks for the questions and pointers. This is a purely street engine, with the truck, a chopped 68 C10, currently getting a C notch and air suspension added to the rear.
I run premium in everything (lawnmowers and ATV included) and this will be the same. Our premium is 92, with one vendor selling 93 (methanol blend).
I was originally planning on picking up a thrashed 350 simply to try a rebuild to see if I remember anything from the 70s, and wound up with a 406 block and some parts, but no heads or intake. A decent street build is the target.
Crane Cam Blazer 284-2H (.465"/.488" 284/294 duration, 224/234 @.050" tappet lift) (2200-5700 RPM range) 112 degree lobe separation angle, 9.5 to 10.75:1 static compression ratio advised.
springs 99848-16 e,f
or springs 96802-16 j
retainers 99915-16 f
or valve spring and retainer kit 11308-1 e,f
valve stem locks 99097-1 m
e standard diameter valve springs, no machining required.
f for 1967 to 1987 with 1.700" installed height.
j standard diameter chrome silicon valve springs for 1.750" installed height.
m machined steel, heat treated.
With the piston crown dish you have, here are the approximate SCR's you would end up with using different chamber volumes....
64 cc 10.8:1
68 cc 10.4:1
70 cc 10.2:1
76 cc 9.6:1
Your "stack" of parts will measure 9.0". Crank stroke radius 1.875", rod length 5.700", piston compression height 1.425" add up to 9.0".
Stock SBC block deck height is ~9.025". On a 350 block, you can play with the piston deck height (distance from the crown of the piston to the flat part of the block deck where the heads bolt on) a little because there are some thinner composition gaskets available such as 0.026" and 0.028", but there is nothing like that for a 400 block, so you have little choice (If you're going to run a tight squish) but to cut the block decks to zero (9.000") and use a conventional 0.040" composition gasket that is punched for steam holes. That will put your squish at 0.040". You have a nice flat portion above the ring pack on your pistons that will come up to meet the underside of the cylinder head as the piston comes to TDC, to "squish" the mixture out of that area and jet it across the chamber. The turbulence will homogenize the mixture and eliminate rich and lean pockets in the chamber that might or might not burn when the spark plug tells them to. Motors with a tight squish have shown to be more tolerant of low grade fuel.
Personally, if I were building this motor for a daily driver truck, I'd build it 9.6:1 with a 0.040" squish and be able to burn a lesser grade of fuel. If you build it right up against the wall and then take on a bad load of fuel, you'll have to open the hood and take some of the ignition timing out of the motor to prevent holing a piston or breaking the ring lands off the crowns from detonation. 9.6 is within the range that Crane recommends for the cam you have, so it should all come out smelling like roses.
I'd use a set of 1 5/8" long-tube, tuned length headers and install an H or X pipe before the mufflers. If looking for max power from the combo, I might use 1 3/4" primaries instead of 1 5/8". Recommend an Edelbrock Performer RPM intake manifold with carb of your choice and a 14" x 4" air filter arrangement. Let 'er breathe. If you get any cold weather where you are, recommend the regular RPM intake, not the Air Gap model. The RPM, especially on a 406, will make more power from idle to max revs than any other manifold you could bolt onto the motor.
Almost forgot....begin by checking the roundness and parallelism of the main bearing bores. If they're out, align-hone or align-bore back to spec, then jig the block up on the main saddle to cut the block decks.
The 5.7 rods will need a little grinding at the bolt head area to miss some of the cam lobes, or you can buy a real nice set of Scat forged rods for about $260 that have already been manufactured with clearance. Look for Scat Pro Stock 5.7" SBC rods.
Using a flat tappet cam can be risky, please read and follow these instructions carefully......
The Scat 5.7 rods:
Wow - thanks! This gives me great info to get started! I do have a set of old rods in the box, but not sure if they would require clearancing or not. I'm sure the response is better safe than sorry.
Are there any views on an FI setup v carb? We are in a colder climate (Calgary, Alberta. A couple of hours north of Great Falls, Montana). Anything to keep the drive good in the mountains.
Thanks again for the great information!
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