AMC 406 Stroker build

[Ristow]

those are forged pistons? i thought keith black was hyperyou whatsit only?

[BA_051]

Hyperyou whatsit... lol Hyper-Eutectic... KB does sell some forged, just not many... Cast and forged pistons are eutectic, 12% silicon... Hyper-Eutectic castings have more silicon in it, about 18%...

Yea the ones I ordered are Hyper-eutectic instead of forged... the hypers are a lot stronger than regular eutectic cast pistons, but not as strong as forged... They have a much lower coefficient of thermal expansion (because the melting point of the alloy is higher) so the tolerances can be much tighter then with forged or even regular cast pistons so the cold start noise will be very little...

[BA_051]

Alrighty! Well the crank is done, just need to go pick it up... Turns out the mains were already turned 0.020" under so they are now 0.030" and the rods are STD 360 size... I'll get pics up tonight when I get it!!

[BA_051]

Here are the pics of the reworked 401 crank...
Vat cleaned, magnafluxed, offset ground to 3.8" stroke with standard size 360 rod bearings, straitened, shot peened, mains turned from 0.020" to 0.030" under and oil passages chamfered. Cost... $275... And ready to go!

I decided to add the additional cost to magnaflux it just to make sure the crank had no cracks and sure enough, there were none...

[Ristow]

i woulda nitrided it too.

you got rockers?

[BA_051]

Yea I was looking into nitriding it, but they quoted me another $325 for that... My budget is already $350 over for the rockers/pushrods/cam kit...

And yes I got the rockers! Will be sweet! 2 of them had a little binding on the roller tip so no worries since you sent extras!!

If my new 0.030" under mains come in by next Friday or Saturday, then I'll take PTO the following Monday-sunday to get it built and running

[Ristow]

well,at .030 you're about at the limit on the crank,on a crank that is getting hard to come by. nitriding will save it if an issue arises. but yah,it aint' cheap.

[BA_051]

Well, Its been a while since I posted, its been very busy the past few weeks... This past Tuesday, I got the motor pulled, checked valve clearances, cut the valve reliefs for the intake valves (exhaust clearances were over 0.150" and 0.060" radially), and took the rotating assembly to be balanced on Wednesday. I did get pictures so I will try and get them posted as soon as I can. I should get everything back on the 7th or 8th so I can finally get it assembled and fired up!

Well I guess they got a late start on the balancing so I'll get everything back the end of the week. After months of planning it all coming together...

[BA_051]

Well I checked everything over and getting everything prepped for assembly and I hit another snag... I forgot the 390/401's had a smaller width rod journal than the 290-360...

Correct me if I am wrong...

The 401 rod had a pin diameter of 1.000", width of 0.995" and a base width (rod journal) of 0.916"
The 360 rod had a pin diameter of 0.930", width of 0.995" and a base width (rod journal) of 0.995"

So I will need to narrow my rods to the 401 rod journal width and everything will bold together! It ticks me off that even the shop did not pick up on the difference on rod thickness and will rebalance my assembly for free when i get the rods cut down...

[BA_051]

Well I finally got the rods back from being narrowed at the big end from 0.985"-0.987" to 0.920"-0.923" and everything finally bolts right together!

Here are a bunch of pics as assembled everything.















As of right now, The valve covers are on and the engine is bolted to the transmission and motor mounts. I am getting a replacement water pump tomorrow and will finish putting the accessory belts and such on. So hopefully it will fire tomorrow!

I fooled a few guys at work when I stored the block there next to my tool box... I painted it "aluminum" and they actually thought it was an aluminum block! lol. It will make fluid leaks a little easier to spot and it looks quite sweet with the black pan and powder coated valve covers.

[Ristow]

looks good. them pushrod slots long enough? looks awful close.

[BA_051]

Indeed they are. I checked all of them before I put the covers on. There is about 0.030" in both the seated and max lift positions and more at half lift.

Have he motor in and accessories on, just need a day to start it up and begin the break in...

[Ristow]

sounds like its good. what are you running for valve springs. i'd like to see dual springs or a damper spring setup on those heads.

[Husker77]

I would love to see this with mpfi.

[BA_051]

I'll have to go digging around for my receipt for the heads when I had them done. They are not stock since I'm running 4 groove keepers and they moved the retainers lower on the valve stem. They are running 120lbs seat pressure vs the stock is 90lbs.

I'm pretty sure they are comp cams springs..

I heard quite a few people having issues with the exelbrock mpfi setup... But I'm using my 2" bore TBI with the 16197427 PCM with the 46lb injectors at 30-32 psi with a vacuum referenced regulator.

going to fire it up tomorrow morning since I don't have to be at work until noon...

[BA_051]

Well... After priming the oil pump with a drill and installing the distributor and dumping about 2oz fuel down the tbi... It fired right up! No knocks, no pings, no issues! Idle oil pressure is 70-72 lbs and after running down the highway for 30 mins it idles at 650 with 40lbs at 195 degrees. Never had such good oil pressure...

Also added an oil cooler and use an FLA-1 oil filter... Took 7 quarts to fill from bone dry to top of the hash on the dipstick...

Smooth idle, no where near the lope of the k8600 and not 1 drop of any fluid anywhere...

Now to get rid of that leaky 7/8" CJ clutch slave cylinder and install the 1" ford cylinder... Looked it up under a '58 ford f100...

[Ristow]

very nice.

[wiley-moeracing]

great to hear, how does it feel? more torque/power?

[BA_051]

Ohh yea... Real snappy throttle, revs real quick and the truck rocks when I do lol... I need to be careful in 1st and 2nd now or the back end is all over lol... Now it's time to save up for the 5 speed and 4.56 regear...

[wiley-moeracing]

sounds good, keep us updated on it