I would spend the extra bucks and get stainless steel 428 valves. If he hasn't finished already, that is.

 

extra money in college does not exist...at this point i'm just trying ot get this thing running and running right w/o messing up my vavles and running on premium with the quench distance and so forth. My next worry up for talk is the .020 head gasket that i'm afraid of leaking. some say use copper spray and others have put them on dry...any recommendations?

 

My next worry up for talk is the .020 head gasket that i'm afraid of leaking.



which is why i don't use them. lots of the times they do leak if your heads are not 100% straight. i use the oem thickness. the loss of compression is minimal. the stock thickness is .052



also to save some money try buying a complete engine gasket kit or else you will be spending a lot on each individual gasket.

 

I have and have seen good luck the .041 Fel-pro's. They already come with a good silicone feel to them. For me I couldn't see putting goop all over the head gaskets and hope the work. It's a lot of work to replace them once they are in the truck and everything has to come off... ouch.

I too have and haven't used copper spray. Both works.

 

Spray the steel head gaskets with copper seal and put them on. They'll work good. The key is to torque down the cylinder head in the proper pattern and evenly. If you're worried about it, get a good steel ruler (or other straightedge) and a set of feeler gauges to check for straightness of the block and heads.

Loss of compression is not minimal. Take the average built up 390:
73cc chambers
TRW L2291 pistons, .012" deck clearance

With .020" steel shims: 10.2:1
With .041" Fel-pro's: 9.64

With the latter being more likely to ping.

If we're going to write off thin head gaskets, then we might as well write off the FE and go build small blocks. Without the advantages of quench, you might as well have an open chamber. 351m/400 here we come!

 

is that how you sealed yours kurt? how many miles have you put on yours?

 

Yes and I couldn't tell you. Haven't been keeping track of the odometer.

 

ok let me make sure about something, .012 deck clearance plus .020 head gasket equals .032 distance from the piston at tdc to the base of the head right? if so, what rpm do you start worrying about smackin a valve? i don't plan on ever going above 4500 at way most. sound in the ok range? and the other thing, what do you mean by an open chamber? thanks

 

If the valve is going to hit, I'm going to have to guess RPM's havent a thing to do with it..

 

ok talked to the machinist again today and he said a lean mixture is what burnt my seats. He's gonna put hardened seats in for me but he says i've gotta figure out where my lean mixture is coming from or my vavles will get it next. My thing is that i couldn't be lean b/c i was getting 8mpg!!! i'm think my vacuum advance was going too far b/c he said that'd do it too. i had my base timing set around 10-12 or maybe 8 at lowest i think. i think what i'm gonna do is buy a new advance motor and check to see what it advances to and adjust accordingly. no more than 38 degrees advance right? also what should my base timing be for a truck 390? how do i know if i have the right centrifugal weights?

 

Yep, .012" deck clearance + .020" head gasket = .032" quench distance.

During assembly, you're supposed to check piston to valve clearance. You're also supposed to run the recommended springs for the cam you'll be running. Valve float is what causes the pistons to contact the valves. Normally, the valves start to float about 500rpm beyond the maximum recommended RPM for the cam, assuming the correct springs are used and in good condition. This will also be well out of the power band of the cam, so you've got nothing to worry about.

Open chamber means a combustion chamber who's area takes up the whole area above the piston. It has no quench area. As you can imagine, this makes it harder to run higher compression ratios without pinging. You have to run a huge cam with a relatively low compression ratio, and the motor becomes an, as we say, "dog." Think 351m/400. This is why people go get the 2V 351c heads for their 400 motors. This same affect appears when you use closed chamber heads and leave the pistons too far away to take advantage of quench. In this case, you may as well have open chamber heads. With the FE, you dont have to worry about open chamber heads, there was never an open chamber FE head.

 

ok well my machinst said he's gonna match new springs to the 941 cam so everything will match perfectly. he said you can't just buy springs out of a catolog b/c the height of your valves are gonna be differnt for every motor depending on how much they've been ground and so forth so he's gonna do the measuring and get the proper springs so like i said...perfect. now ist here such thing as a say .030 or .025 head gasket b/c i really don't want to have to pull my heads after 10,000 miles just to change head gaskets and then have problems with pinging b/c i had to go to a thicker gasket b/c mine won't seal. i know my block is square b/c it's only got 5,000 miles ont he rebuild and everything has been torqued down by the book. my machinst has my heads now doing the valves again so he's gonna check the head for straightness. am i just worrying too much?? i want this thing done the first time!

 

You're worrying too much. If both surfaces are flat, they'll seal.

 

ok well as far as timing goes, how far do you adjust your advance module or do you just buy a new one and leave it from the store the way it is? also how do you figure what weights you need for your centrifugal advance weights? any ideas b/c i think they would be differnt now going from a 360 to a 390 b/c i've got more power.

 

It's more a trial and error thing. Every motor is different. Your 390 wont want as much timing as your 360. I think a good starting point would be 10 degrees initial, 38 degrees total, with some springs stiffer than the 360 had. Also, turn down the vacuum advance initially. Then you can slowly add timing and lighten the springs until it starts to ping, then go back to the last known good setup.

This is known as tuning. It's going to be a PITA. No way around it.