dist0rtion_69

I purchased afr 190cc aluminum heads and i'm interested on how i am suppose to torque them down ?? what steps what procedures? is the pattern the same as an iron head? and how many ft lbs?

Thanks
Josh

Damon

Yes, same torque as iron heads- 65 ft/lbs. Please note that stock 6-point head bolts won't work with AFRs (I know- I have them on my motor right now). The 5/8" socket won't fit down into some of the head bolt recesses (namely the 2 end bolts sitting way down deep at either end of the rocker deck area). I went with 12-point bolts that use a smaller socket - problem solved.

Tightening Procedure......

1. Clean out ALL the head bolt threads in the block by running chase down EVERY DAMNED ONE OF THEM before you put on the gaskets/heads. You will go bonkers by the time you're done with both sides of the block but this is CRITICAL to getting proper torque on them. No shortcuts. Do it right.

2. Drop on the gaskets and heads. Make sure that your gaskets are installed right-way-up if they have a "top" and "bottom" side. Some do, some don't- check and be sure.

3. Drop head bolt washers onto every head bolt. Aluminu heads require the use of washers under the head of every head bolt so you don't gall the soft aluminum of the head you are tightening them against. Put a thin smear of oil on the washers so you aren't tightening down against them "dry" metal-to-metal. I don't recall if AFR supplies these head bolt washers- I don't think they do. You can buy them anywhere you buy head bolts or other performance parts.

4. Put a thin, even smear of thread sealant on the threads of every head bolt before installing them. The exact kind of sealant isn't hyper-critical. Liquid Teflon is all the rage these days. I have used non-hardening RTV, Gasket Shellack, even just Anti-Seize lubricant. Never a leak yet. The exact sealant used isn't as important as USING ONE! It's needed to seal the threads AND to give some lubrication to assure proper torque readings.

5. Speaking of torque..... do them in steps. I do 35, 45, 55 and 65 ft/lbs. Do ALL of them to the same spec before bumping up the torque to the next level.

6. Tightening pattern..... different manufacturers often specify different torque sequences. If in doubt it's always a good starting point to do them "from the center to either end". Do them evenly so, in a criss-cross pattern working from center out to the edges. You might think that the exact pattern is hyper-critical from what you read on the internet. Not true. I've done plenty of heads never knowing the exact recommended torque pattern. Haven't blown a head gasket yet becuase of it. If you know the right pattern for sure- use it. If you don't- follow my recommendations. Either way, you won't have a problem.

7. You have now spent more than an hour just prepping and installing the heads. Take a break. Have a smoke, drink a soda. Come back in 2 hours and RETORQUE the bolts at 65 ft/lbs AGAIN. You'll be surprised to find that the bolts will probably all move another fraction of a turn when you do this. That's because the head gasket has "settled" a little under torque. This final round of torqueing will assure that's it's really "home" and that you've got proper pressure applied to the gasket.

Follow this and you'll have the best possible shot at NEVER having to replace those head gaskets every again. This is one area of engine assembly where I get very "****" about assembly. Onle becuase I hate doing a job like this more than once.

dist0rtion_69

hey,
the head bolts i bought do not have a 5/8 inch head, they have a 1/2 inch 6 point head. you think they'll be ok?? im going to lowes tommorow to purchase some washers. as for all the surfaces and head gaskets they are prepped good. i've did quite a few head gaskets before

thanks
Josh

Black6SpdTA

They should be fine, I don't see 1/8" making a difference provided you get the correct size/depth washers.

Damon man Awesome post, I'm going to have to bookmark that!

Z28SORR

All stock SBC head bolts are 5/8" head or smaller, ie. use a 5/8 socket. Are these after market?

DO NOT use hardware store washers. These washer are special. They are parallel ground and radiused on one side. This side goes toward the bolt head. You can get them from Chevy or aftermarket.

The torque sequence is easy to remember. Start from the center bolt and spiral out to the ends. Center bolt, right top, right bottom, left bottom, left top, next right top, etc.

Damon

If the head bolts you have take a smaller 1/2 socket to turn them then you'll be fine. It's the large diameter of a 5/8" socket that you just can't get on top of some of the bolts to tighten them down. They hit the valve spring shims if you can believe that.

My 12-point head bolts also used a smaller 1/2" socket to turn them- that got me the socket clearance I needed.

Also, agreed that the head bolt washers are not hardware store items. They're a special washer used exclusively for head bolts. And yes, they do have an UP and a DOWN side.