Mmmm....781 Heads w/Big Valves - Greg72's 496BBC Build Thread

[4X4HIGH]

I want a video clip when this thing is fired for the fist time!!!!!
Sweet A$$ build!

That will be Gregs job. Once i'm done here this engine will leave California heading for New Hampshire along with his 502.

 

[NoReGrEtS]

That will be Gregs job. Once i'm done here this engine will leave California heading for New Hampshire along with his 502.

Then i want 2 videos with them both roaring next to each other
sound like gregs got some wrench time coming

 

[4X4HIGH]

Then i want 2 videos with them both roaring next to each other
sound like gregs got some wrench time coming

That's a big under statement.

 

[MTChevy]

I just want to say that this is COMPLETLY bad ass... i dream of 496'ing one of my vehicles one day

 

[Greg72]

I just want to say that this is COMPLETLY bad ass... i dream of 496'ing one of my vehicles one day

Don't worry guys, once these engines arrive here I will take plenty of photos of the installation, and video of them running, etc.

I'm getting a little tingly thinking about fact that 998 cubic inches (16.3 liters) of Chevy BBCs will soon be sitting in my garage!!!

Thanks for the update pics Scott...

 

[Shawn]

Have to bring your thread up!

How did you figure the compression ratio on your engine? On my 496 engine I have flat top pistons and 116cc chambers and I get 9:1 CR. I'm assuming -2cc for the valve reliefs.
http://www.turbofast.com.au/Tfcomp.html

bore: 4.31
stroke: 4.25
gasket: .039
heads: 116cc (might be more with the larger 2.19 valves)
valve reliefs: 2cc

The piston may be in the hole .005 but I'll find out when I take my heads off.

 

[Greg72]

Have to bring your thread up!

How did you figure the compression ratio on your engine? On my 496 engine I have flat top pistons and 116cc chambers and I get 9:1 CR. I'm assuming -2cc for the valve reliefs.
http://www.turbofast.com.au/Tfcomp.html

bore: 4.31
stroke: 4.25
gasket: .039
heads: 116cc (might be more with the larger 2.19 valves)
valve reliefs: 2cc

The piston may be in the hole .005 but I'll find out when I take my heads off.

I'll let Scott answer the specifics....but I know that he physically measured the displacement of the cylinder heads with the burette and clear glass cover dealio... I can't recall from there how he calculated the effect of the valve reliefs on the piston itself. This may be something that the piston manufacturer has specs for??

Anyway....the heads have new guides now, and are getting larger seats installed....then the seats get blended to the ports behind them and the larger valves get installed. Once that's done, the heads go on and IT'S DONE!!!

Oh yeah.... I'm SOOO ready to fire this thing up it's not funny. Unlike you, I don't have experience with other large BBCs in the past...so this type of power is going to be a completely new experience for me.

 

[RGV72BLAZER]

would you trade your 502 for my 350, some cash...about 10 bucks..., and a cup of tea? lol. very very sweet. & this is just the motor...can't wait to see the thing with the Mogs and Link suspension.

 

[4X4HIGH]

The compression is calculated with a 115cc head chamber, zero deck clearance, .039" compressed head gasket with a 3cc valve relief on a flat top piston.

 

[Shawn]

The compression is calculated with a 115cc head chamber, zero deck clearance, .039" compressed head gasket with a 3cc valve relief on a flat top piston.

Should be around 9:1 correct?

 

[4X4HIGH]

Should be around 9:1 correct?

That is correct.

 

[4X4HIGH]

Just another update.

 

[thatK30guy]

Puuuuuuuuuuuurty!

 

[mofugly13]

Very nice!

 

[4X4HIGH]

Thanks guys. I'm having some issues coming up with the correct valve spring installed height. The Comp cam "KIT" didn't seem to come with parts that like to play nicely together.

I need an installed height of 1.900" but am only getting about 1.800-1.820" so i got some .050" keepers to give me another .050" installed height but i soon found that i can't use those without using a valve with a longer valve tip.

Seems like i may end up buying the proper sized spring seat cutter and having to cut the spring seats in the heads to make this come out correctly. I just finished another set of "781" heads but they used a different spring, retainer and locks and those heads came out perfect but i can't use that set up in this application because of the retro-fit roller cam. I need the valve spring pressure that i wouldn't otherwsie get using the other stuff that went into the other set of heads.

 

[dremu]

Thanks guys. I'm having some issues coming up with the correct valve spring installed height. The Comp cam "KIT" didn't seem to come with parts that like to play nicely together.

I need an installed height of 1.900" but am only getting about 1.800-1.820" so i got some .050" keepers to give me another .050" installed height but i soon found that i can't use those without using a valve with a longer valve tip.

Seems like i may end up buying the proper sized spring seat cutter and having to cut the spring seats in the heads to make this come out correctly. I just finished another set of "781" heads but they used a different spring, retainer and locks and those heads came out perfect but i can't use that set up in this application because of the retro-fit roller cam. I need the valve spring pressure that i wouldn't otherwsie get using the other stuff that went into the other set of heads.

(Hijacking Greg's build thread briefly) hey, I'm glad SOMETHING went RIGHT with my build

[/hijack]

-- A

 

[4X4HIGH]

(Hijacking Greg's build thread briefly) hey, I'm glad SOMETHING went RIGHT with my build

[/hijack]

-- A

There is something to be said about a "professional" assembling an engine versus a "novice" assembling an engine.

My knowledge is what you're paying for when i assemble an engine. I can look at something and tell you either it is or isn't correct or feel something and tell you as well. People forget sometimes that it is a learned art and that not all of us have the skills needed so that is why we need to be paid for our knowledge. Some people can read and learn and others just will never catch on. If you have a mechanical aptitude then you'll do fine otherwise give it up and let a professional handle things. I'm not talking about you personally either but just in general. This goes for any trade not just a machinist.

 

[dremu]

There is something to be said about a "professional" assembling an engine versus a "novice" assembling an engine.

My knowledge is what you're paying for when i assemble an engine. I can look at something and tell you either it is or isn't correct or feel something and tell you as well. People forget sometimes that it is a learned art and that not all of us have the skills needed so that is why we need to be paid for our knowledge. Some people can read and learn and others just will never catch on. If you have a mechanical aptitude then you'll do fine otherwise give it up and let a professional handle things. I'm not talking about you personally either but just in general. This goes for any trade not just a machinist.

Oh, amen!

The thing is, it's a balance of knowledge and aptitude. I have the latter, but not a clue what I'm doing ... I see something done or read how to do it even, I can pick it up ... but I feel bad asking you questions EVERY step of the way since you ARE the professional and should be paid for your time & knowledge -- more than just feeding you steaks now and again =))

OTOH, my budget (or lack thereof )and stubborn-ness led me into this, and dammit, they'll see me through!

[And yeah, next time I'm just gonna drop the motor on your workbench, in one piece, and say "Scott, fix it" ]

-- A

 

[4X4HIGH]

I don't mind answering any questions you have. That's the only way you're going to learn what's right and what's wrong. Don't feel bad about asking me questions as i'm sure i'll end up with a few more dinners before we're all done and believe me that is cheaper than "paying" for my knowledge. Greg may beg to differ but don't listen to him.

 

[Greg72]

There is something to be said about a "professional" assembling an engine versus a "novice" assembling an engine.

My knowledge is what you're paying for when i assemble an engine. I can look at something and tell you either it is or isn't correct or feel something and tell you as well...

Plus, a real machinist knows the difference between a framing hammer and a ball peen hammer!!!


Oh, I think we've all come a long way since Scott started helping us along.