SStrokerAce

Defection as the old man said is mostly happening in other areas.

A Billet core is going to take more spring load. At 400lbs over the nose or less a billet core is probably a good idea, even though a cast core and do the deed sufficently in some applications.

Jon, think about the placement and accuracy of the lifter bores. If the block is off in that area then the valve timing is off also and probably more than the cam twist cam play into it. There is a solution to this, it's to have the lifter bores bushed and "trued" by a engine shop with the BHJ fixture to do this. It's around $500 and is something a very high end race motor should have done to it. Most CNC machined blocks will have this spec accurate so they are also a option, just not for LT1 blocks unless you have a 5 axis big enough to take a block and have the accurate programing.

As for books........ hmmm that's a hard one. David Vizzards book on cam timing is decent, and about the only one I know of, the rest is just experience and understanding the relationship that changing a certain spec is going to do for you. Acutally most good engine design is understanding what a change in x will do and what other parts you can change to adjust y to make more HP and TQ. The rest is understanding the parts and what makes them good and bad, engine building is interesting since it takes a lot of different things into account, machining, metulurgy, fluid dynamics, thermodynamics basically stuff that ME's learn in college. The bad thing is that it's so far from being applied in that setting that it gets extremely boring. One way around that is to learn what you need to know to make a correct choice concerning engine parts. For example your 4340 vs 4130 post, it's not entirely necessary to understand the metalurgy of those two materials as much as it's important to know that the 4340 is a stronger piece. When you get into pistons and pins there is more that just knowing x is better than y but different applications need different things. Connecting rods are some of the most complex in understanding their manufacture. A billet might not be as strong as a forged rod and such, things like that are the little details that you learn over time.

Bret

jonaddis84

Thats a good point, I never thought about that before, something to the degree of a hundreth or thousandth even off could throw valve timing off a bit. Especially if it is angled like that. That seems a little steep of a price, but I guess if you are searching for every last ounce of power (like Im trying to do) it might be worth while, although I will probably not end up doing that.

Kindof on the same point, I would assume its possible, to check valve timing with the top end assembled, and with a degree wheel...by turing the crankshaft and knowing exactly what valves should be opened and how much, you could "test" the accuracy of your valve events correct?

SStrokerAce

Actually $500 for that is not bad considering the work and tools needed.

First you need a $1,500-$2,000 fixture to start with, then a Bridgeport Mill (common thing in a machine shop, most guys don't have one in their garage) and a operator who can do the work properly. Then you have about one full day of work to accomplish this task. Around 10 hours, that and at about a normal shop rate for some high quality machine work, $50 an hour you come out to $500. I would imagine that some large named shops would almost double that figure based on a $100 an hour labor rate.

Once you throw that into the mix getting a LT1 block to a CNC Bowties spec is almost the same price.

$200-$300 For a good LT1 Core to start with
$500 to True up the Lifter Bores
$250-$350 for Front and Middle Billet Main Caps
$250-$350 for 4 Bolt conversion
$250 for line Bore and Line Hone

Around $1500 and you still have to do the same work you would have to do to a Bowtie block at this point. Oil prep, bore/hone, deck etc....

As I said good race motors and street motors are different creatures, or are they? I would say 600hp+ no matter which way you cut it is going to need serious prep work if you want it to live. 700hp+ needs serious considerations on a block that was designed to hold 330hp max.

Yep that's called degreeing in a camshaft. Go look up Comp Cams tech section on valve timing tutorial, it's going to give you a good foundation.

Bret

jonaddis84

Actually I have three of them

Quote:

Once you throw that into the mix getting a LT1 block to a CNC Bowties spec is almost the same price.

$200-$300 For a good LT1 Core to start with
$500 to True up the Lifter Bores
$250-$350 for Front and Middle Billet Main Caps
$250-$350 for 4 Bolt conversion
$250 for line Bore and Line Hone

Around $1500 and you still have to do the same work you would have to do to a Bowtie block at this point. Oil prep, bore/hone, deck etc....

Yeah, Im not arguing with that, once you get into that stage of doing things, a bowtie block IMO is definitely worth it, especially once you want to get away from LT1 heads. Just sayin in my case thats expensive!

Quote:

Yep that's called degreeing in a camshaft. Go look up Comp Cams tech section on valve timing tutorial, it's going to give you a good foundation.

Bret

Yeah, Ive read that thing about 10 times, think I finally totaly understood it, the first time i read it was before I knew the first thing about valvetrain and how a 4stroke engine works.

that doesnt talk much about degreeing cams though, just a little bit, I think they sell cam degreeing videos, but I think I could figure out how to do it myself now that I understand how everything works, just dont know at what cam degrees puts what cylinders open and how much and so on. Guess it should be pretty to figure out if I record what pistons come up when while I have the heads off. You wouldnt happen to know that order off the top of your head would ya, starting with piston 1 at TDC?

OldSStroker

Try page 413-414 of the Comp online catalog. At Step 7 with the dial indicator installed you can measure valve events. I'd suggest weak valve springs a solid lifter, zero lash and only one cylinder with pushrods. You can check advertized duration (comp uses .006 lobe lift) by multiplying by rocker ratio and checking at the retainer. .006 x 1.6 = .0096 or about .010. Similarly check .050 (@ lifter) or .080 at retainer with 1.6 rr, etc. Also check .200 (lifter) duration for a good way to compare lobes.

You aren't asking firing order are you? 18436572 for std SBC.
Not sure what you meant otherwise.

jonaddis84

Thanks Jon, thats exactly what I was thinking, just explained way better than I couldve.

Not firing order, but...hmm...how to explain. Ok, with the heads on, you cant tell what piston is going to be where exactly, unless you do it for a living. so with the heads on, say you do the above on piston one one its way from BDC to TDC through both the intake and exhaust events.
Well, I think I just answered my own question, it doesnt matter, you just have to keep installing the pushrods on each cylinder and go through all the valve events by turning the crank.

Sorry, I am really bad at explaining what goes on in my head, just good at doing it and showing it that way.

Jon