ok, since Aackshun gets away with these quite often, i'll try my hand at it...

the name of the game here is clearance.

rebuilding a severely overheated engine. *cough*Aackshun*cough* the heads were warped badly enough the shop had to take .010" off one and .013" off the other. i'll be taking the block in too, not expecting it to be as severe. presumably i think i can expect them to take approximately .005" or so off the block. i know the change in distances is so minute i could still throw everything back together and not have to worry about timing or valve clearance, etc, HOWEVER, i happen to have a VH sitting here... some of you know where this is going.

my question is how much room is there at stock tolerances between the valves and the piston and between the piston and the head? my concern is contact at speed. some have said the vh piston will sit slightly above the deck to the tune of .6mm (.023") or so as the piston's compression height is roughly 1.3mm taller than the 3.0's piston (it is dished much like the 3oh's, fyi). also, since i might as well do cams, i'd like to use the rev-up/hr cams but even those may prove to be too crazy as it's a gain in lift of approximately 2mm (.078). to remedy both of those may take a spacer head gasket, fly cutting/adding valve reliefs, or a combination of the two.

so the build will consist of:
stock block/crank/rods
either 3.0 or vh pistons
3.5 cams
new bearing/bolts/gaskets/etc
""Super Secret Intake Manifold" (not the one you're thinking)

this discussion may be for naught and i could end up back with stock pistons, but it's worth a shot. if nothing productive is gained, maybe i'll just assemble eveything and bend some valves for lolz. before i do that though, suggestions are welcome, haha.

EDIT: i would like to add that this motor will not be boosted. being that this is the all motor forum, i hope that would have been obvious. seems to have been the killing point of threads mentioning double head gaskets and other such possible solutions.

 

Ive got HR internals and cams for sale if needed.

In for enlightenment as well.

 

dang man, you couldn't even let the thread stew for 15 minutes, haha

yeah, this motor i'd like to get the most out of without investing a ton of time and money into it. the motor i'm pulling will either get the 3.3 stroker build or i may just go with my dream of a '09 3.5

 

its just like a stock rebuild witrh 3.5 cams???? do you have supporting mods?? or is it completely stock

 

finally, someone put down the turkey, lol

there will be supporting mods yes, intake and full exhaust, oil pump, etc. the VH pistons will increase the compression to 11.x:1 however there is talk of clearance issues. i may have technically been fine but since so much was taken off the heads in order to have a flat mating surface, my margin of error has lessened. adding to the equation that 3.5 cams will extend the valves another .5mm or so over stock (revup or hr even more), there will likely be problems.

the questions are:
how much room did i have to play with originally?
factoring in my losses do to the machining, how much do i have now?
will i need to flycut/add valve reliefs?
do i need a spacer type headgasket?

i definitely need cams to let the sucker breathe. compression isn't paramount but every little bit helps.

 

haha, engine pun

 

One of those extra thick cosmetic HGs should help out. Get some decent cams, IM and a properly sized TB.

 

well, the stock head gasket is .036". since i've lost .010"-.013" from the heads, plus i'm guessing at least .005" will be taken from the block, i'm gonna need at least a .050ish" (or about 1.27mm) HG. something thicker may be the ticket.

 

What is this? I don't even....

 

Ive got .045 Cometic HG's perfect for your project. Theyre BNIB.

 

A little too convenient, lol. 3.0 or 3.5?

 

What are your HP or ET goals with this setup?

Andy

 

Goals? What are those?

 

3.5. I was building a baby HR but changed it up so Ive got a slew of HR parts.

 

it starts

 

You dared to throw the word "Aackshun" in your build, it is the build anti-christ. The only thing worse would be throwing my SN in there.

 

I suppose that's fair.

 

And here we are posting in this thread.

Wanna know whats sad? His car has had time to die, revive and die again while the red car has been chillin

And he may even finish before I do....

 

because Teh Zombie!

EDIT: also, mine caught fire. Much more epic than the red devil or le white nightmare. :P

 

Plain and simple... I would like to beat Dandy. Or at the very least be in his ballpark. He did something awesome without going TOO overboard. Seems like a worthy goal.

 

Ok, block is apart, off to the machine shop early next week to get it checked out. I guess now I've got to recover my VH pistons, haha

EDIT: if anyone has measurements and/Mr pictures of how far below the deck the stock pistons sit, that'd be awesome. I was dumb and didn't look at that before I pulled the pistons. If not, I'll just find out when I reinstall everything.

 

Vq30 ftw!

 

I believe it should be a deck height of zero.

 

ok, just got a call back from the shop about 30 seconds ago, they took .006" (.15mm) off the block. including the .013" (.33mm) off the heads, that means i've lost about .019" (.48mm) of clearance compared to stock. that being so, my previous estimate of about a .042" or .5mm HG would just about right assuming i will still have enough clearance between the pistons, heads, and valves.

 

As stated above, Ive got the HG you need. BNIB.

 

i'd be all over that if i were using 3.5 head but i'm not. not yet anyway,

 

I guess I overlooked that

 

well, i've run into some time constraints so i may have to forgo the piston swap. doesn't bother me so much, was hoping for that extra little bit though.

 

Bish no you don't.

I'll take em out this weekend if I feel better.

 

Bump on the thread. Mightymax95, are you going to use HR cams or revups? If so are you going to tweak the cam timing at all or just PNP?

 

Well due to one motor's commitment to death by suicide, I'm going simple for the time being. Updates when the thing finally runs.

 

Since he won't update his own thread....


Rev limiter @ 2k because racecar.

 

So what pistons did you use for this engine?

 

Stock, got lazy and never dismantled the q45 motor he had.

 

t0rKz m0NstAr