?'s about replacing head gaskets

[BuickMike]

I blew out the drivers side head gasket awhile back and will finally be getting around to replacing it. Actually, I'm going to replace both. Given that this is just a mild street / strip car, what head gaskets should I go with? Also, should I replace the head bolts? If so, what should I get?

Thanks,

Mike

 

[blown okie]

cometics seem to be the gasket of choice, since the heads are off milling them for straightness and a valve job would be recommended, and as far as the bolts yes, arps are far superior to the stocks ones but just skip bolts and go to studs, not only are they better but they won't distort the cylinders when torqued as much as the blots will.jmo

 

[SouthernCal GN]

Based on your combo, I'd go with the Felpro gaskets. Also, do not re-use the stock head bolts, as they are TTY. Good thing aboout ARP (studs or bolts) is that you can re-use them- but the stockers are OK, too.

Don't know if I'd have the head milled, but I would have the springs replaced, and a good valve job done.

 

[turbofabricator]

Fel-Pro 9441-PT are the ones you need for your application. The Cometics need both the block and head milled smoother than the factory, or they may have problems. If you read the enclosed instructions, it requires a SUPER fine RHR finish (the actual finish requirement escapes me at the moment) The Stock repalcement head gaskets for Fel-Pro (9441-pt) are your best choice. If the head gasket is blown real bad, you NEED to remove the oil pan and clean the pick-up screen of all the "graphite" particles. I've seen guys loose their engines because they don't clean the screen. Run a thread cleaning tap through all the bolt holes. JEGS Thread Chasing Tap Set - JEGS Use ARP bolts, or studs. After torqueing the bolts in a four step increments (40,50,60,70 and then 75 on the long bolts) wait 20 mins and then loosen each bolt about 1/2 turn and then retorque. No sequence is needed for this step. Use ARP bolt lube under the washer and under the bolt head. I like GM thread sealant, permatex, or ARP bolt sealant on the treads. Use a quality torque wrench. For BEST results, after intitial torque (40 ft lbs) install and torque the intake manifold, then continue torqueing.

 

[SHADOWII]

I agree...

9441's and hd. studs!:biggrin:

 

[BuickMike]

Thanks for the replies! One more question. Will I be able to put the heads back on the motor with studs if it is still in the car?


The heads already have fairly new valve springs. I'd like to do more work to the motor, but money is tight and I'd like to get my GN running again before waiting another 3-4 years when I'll hopefully have the cash to get the motor rebuilt.

 

[SouthernCal GN]

Studs- yes, you will. There are studs with allen wrench receivers in them that go into the PITA bolt holes in the back of the block.

Heads- since you have the heads off, might want to look into some porting to get the most from them.

 

[BuickMike]

Studs- yes, you will. There are studs with allen wrench receivers in them that go into the PITA bolt holes in the back of the block.

Heads- since you have the heads off, might want to look into some porting to get the most from them.

I have my own head porting tool and am planning on at least doing some match porting.

 

[SouthernCal GN]

Be sure to research where and how much material to remove/smooth out. More isn't always better- you can actually hurt performance with a poor porting job.

 

[QuickBuick87]

Not to hijack thread, but who has the best price on Fel-Pro head gaskets?? TIA.........Ken B.

 

[BuickMike]

i was actually going to ask that too. Just wondering where is the best place to go for the gaskets and studs?

 

[turbofabricator]

First just check with the vendors on this board for gaskets. Support our SMALL community.
Second. Port matching isn't where the flow is. 80% of flow gain is in the valve seat and 1.5" into the bowl/port. Valve shape can make a difference. Flow benches do NOT tell the whole story, either. There are modifications you can do to your heads that show NOTHING on the bench, but make significant power on the car. Read about head porting BEFORE you attempt to make modifications. Here's one great source for head modification ideas. Speed Talk: Interviews - Racing Books - Racing Forum It'll take you YEARS to read half of the topics about head porting. Make your heads look like this and they will make good power. Have a GOOD machine shop do a three angle valve job. The stock valves can be made to work good by swirl polishing them. See pic. Just chuck the valve in a drill press, and take a flap sander to the back side of the valve face to make it look like the one in the picture. (keep away from the valve seat area) Then have the machinist do a 30* back cut on it to true up the face. Here is a picture of a cut away 8445 casting to show how much (or how little) material you can remove on the valve bowl before hitting water.

 

[BuickMike]

Wow! Thanks for all the info.

 

[84BuickGNYorkPA]

Turbofabricator,

In your first picture, I am looking down the exhaust port, is the wall for the valve stem ground down to the "floor" of the port? I bought a extra set of heads and they are on the workbench now, here is a link to some pictures. i did not take the exhaust stem hole down, I just shaped it into a cone like the intake port....Picasa Web Albums - Chuck - 8445 Buick V-...

Thanks,
Chuck

 

[turbofabricator]

Yes, I completely remove the valve guide boss in the exhaust port. If you look at the cut away section of the head you can see that the valve guide is plenty long enough to both support the valve and cool it. You have done a nice job so far. There is some flow to be had by widening the port where the head bolt hole is. There is a lump in the port wall for more material due to core shift in production heads. On engines that make big power, I move the wall INTO the head bolt hole and then seal it up with a thin wall brass tube and epoxy. (the brass tubes are available from a hobby store) I also take the port out to a Fel-Pro 1200 and then break into the push rod holes and then seal it up the same way. I have been doing that for 15+ years on the 8445/6293 castings and have never had problem. You don't need to take the port wall out to the head bolt hole, but try to straighten the port wall out. That's the wall that has all the high speed flow on it. (biased port)
The exhaust bowl and beginning of the port floor needs to be as wide as you can comfotabley make it (before you hit water) make the short side radius as smooth as you can get it. It take many years of porting to get the short side just right and to learn to handle the tooling. It's art work, really. If these are your first set of heads, then you are doing a FANTASTIC job. Keep at it. Buy yourself some good carbide and decent grinder(s) and you will enjoy the work even more. I put about 15-18 hours into a set of heads then to the machine shop for finalizing seat shape/guide work than back to the bench for finalizing port and chamber shape. The heads in the picture were about 90% complete when the pics were taken. Here's a good link for porting supplies. Cylinder Head Abrasives

 

[84BuickGNYorkPA]

Ken,

Thanks for the help, I will take your advice and run that exhaust valve guide boss down to the floor. I will also get the gasket sets to square up the ports. And that's probably where I will stop, with the heads, I think that what I did will give me a bunch of extra flow. I am a machinist, and a fabricator has let me borrow his grinder and a bunch of attachements, stones ect. I also have a dremmel tool that I used on the first head, today I used the air grinder(I just got it yesterday at work) and the second one is almost caught up to the first head already, it goes much faster with the air grinder, but now my air compressor on/off switch needs replaced.... it's getting there, just takes a lot of time, thanks again for the help.

Chuck