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  #16 (permalink)  
Old 12-20-2012, 04:14 AM
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Also did some reading on compression. Apparently it doesn't raise hp as much as i thought it would. Plus with the effeciency i'd gain from flat tops might be a halfway decent idea.

using
Compression Calculator - SummitRacing.com
w/ a 3.48" stroke, 4.03 bore, +5 pistons, .04 quench i'll have about 10.38:1
vs 11.54:1 w/ -3.5cc pistons.
So looks like maybe 15hp/tq lost? according to different threads and articles its not much of an area to gain unless you are literally trying to make a pure drag engine. While I would like to spending 200-400$ more doesn't seem worth it for forged pistons to gain that much. Well I learned something new.

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  #17 (permalink)  
Old 12-20-2012, 05:47 AM
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355 build check up

Deathmunchy, I am recommending this calculator because it computes static compression and dynamic effective compression ratio. United Engine & Machine Co. Incorporated. The DCR is an effective way to know if your engine will use 91 octane pump gas or not. All you need is the intake valve closing @.050 which is listed on the cam card. Here is an article that explains DCR. Dynamic CR
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  #18 (permalink)  
Old 12-20-2012, 03:05 PM
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Quote:
Originally Posted by cdminter59 View Post
All you need is the intake valve closing @.050 which is listed on the cam card.
Crane and Lunati will give you that info on the cam card. Comp will not, they only give you timing at 0.006" (on a flat tappet hydraulic such as we will deal with here.) You have to figure the intake closing point @0.050" for yourself from the intake centerline and duration @0.050 tappet lift.

Here, I'll show you how to do it.....
We'll use this cam since I already have it copied.....
12-246-3 - XTREME Energy
Draw a circle on a piece of paper, about 1" to 2" in diameter. Size doesn't matter (in this case, LOL). Visualize the circle as an analog clock face. Make a mark on the circle line at 11:00 O'Clock. Mark it IVO. This will be the intake opening point @0.050". Make a mark on the circle at 4:00 O'Clock. Mark it IC. This will be the intake centerline, or highest lift point of the lobe. Make a mark at 8:00 O'Clock. Mark it IVC. This will be the intake closing point @0.050".

You see on the cam card that the intake duration @0.050" is 230 degrees. Write 230 in the middle of the circle so you can reference it. Draw a line under the 230 and write 115 (half the 0.050" duration) so you can reference it.

Now, beginning at IC, move counter-clockwise around the circle until you reach 115 degrees from the IC. You will be using up 106 degrees to get back to top dead center and will have 9 degrees left over. Write in 9 at the 11:00 O'Clock mark you made on the circle. Now we know that the intake valve opens @ 9 degrees before top dead center. We can prove this by adding 9 plus 106 to equal 115. See, that's why I had you write 230/115 in the middle of the circle, so you could prove your work.

Now, we know that the intake valve will not close before the piston gets to the bottom of the stroke and heads back toward top dead center. Therefore, going clockwise from the intake opening point, we can add 9 and 180 and find that we have 189 degrees of 0.050" duration from the time the intake valve opens to the time the piston gets to bottom dead center. (180 degrees in a half-circle). Referring to the middle of your circle and using the 230 you have written there, subtract 189 from 230 and find 41 degrees. That's the intake closing point @0.050" tappet lift. Prove your work by adding 189 and 41 to produce 230.

After you have done this a number of times, you can do the math in your head without the circle.

One of you guys could do a good deed by posting this on the wiki. I don't need any more wiki credit, let's get someone else started......
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Old 12-21-2012, 02:24 AM
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Yea thanks tech. Thats reassuring so I am doing that right. I typically draw the lines to represent the TDC and BDC cycle. This seems to get me the same answer so I'm going to assume it works right?

Also yea Minter I had to read that guide a few times when i first saw it before I finally grasped it. I got the idea of a DCR I do believe. Also like I said at one point. I believe with my compression and the cam and 6" rods I'd have about a 9.2 DCR.

just to check though basically the longer the cam is open ABDC the less of your stroke is actually used. But at higher RPM's the Inertia of air actually comes into play and this is what affects your VE and different RPM's?

Oh also I went by comp cams today. They said a custom ground solid roller w/lifters will be "about five hundred".

Last edited by Deathmunchy; 12-21-2012 at 02:35 AM.
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Old 12-21-2012, 08:52 AM
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tell comp that the cost of a custom cam should be similar to a shelf cam. If not then ask another cam grinder the same question.Comp cam sells a lot of custom grinds to crate engine builders so I doubt its a custom grind. My cam is a comp custom grind,buts its also a shelf grind for Jeff Lukovich
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  #21 (permalink)  
Old 12-21-2012, 04:42 PM
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Quote:
Originally Posted by vinniekq2 View Post
tell comp that the cost of a custom cam should be similar to a shelf cam. If not then ask another cam grinder the same question.Comp cam sells a lot of custom grinds to crate engine builders so I doubt its a custom grind. My cam is a comp custom grind,buts its also a shelf grind for Jeff Lukovich
Ageed. Comp sells at the exact same price as you can find on Summit's site. I bought one about a month and a half ago. It was a custom grind but using their standard lobes. No extra cost and they got it to my door in three days.
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  #22 (permalink)  
Old 12-22-2012, 02:07 AM
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Went to a machine shop today. Apparently to have the block bored decked and the assembly balanced its going to be about 375. This doesn't seem too bad.

To get a valve job is 180 for the pair. So if the brodix heads do come with the valve job like you were saying then neat I'll save money. but would it be worth it to look into a 4 or 5 angle valve job?

They said they'd inspect the crank and rods during balancing because they might not need resizing and if they don't why waste money? I don't remember if there was a charge or not but would it be safer to resize them anyways? Is there any benefits to resizing or just safe vs sorry?

Lastly, they said they recommend locaters (i think thats what they said) vs valve cups. So that you don't have to resize the spring pockets(if you would have to). What do you guys think/recommend? I don't remember if I mentioned wether my heads were aluminum or not so I don't know if theres a difference.
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Old 12-23-2012, 03:57 AM
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Ok I'm really confused now.

Yes I would think that resizing would be followed by balancing. I would think though it would be best when bringing the assembly in to have this done on the same trip.

They wouldn't resize only a couple of rods right? (your statement makes me think maybe this could be the case. I do have a tendency to over think things. I would imagine this would cause instability if someone did this.)

When I asked about spring cups, he said something about most after market heads coming with big enough pockets. I think it was something like 1.5" pockets. If you use wide springs they pockets have to be expanded if you use cups as they take up space. But if you use locators most of the time this is not the case. This is what I got out of that.
Is this correct? I could have mis interpreted what he was saying.

I'm confused as to what makes people think I'm trying to cut corners. I'm not. I may have to wait till I'm healthier before I post as my brain seems to be kind of addled.
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  #24 (permalink)  
Old 12-23-2012, 11:53 AM
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let me throw in some confusion:

you dont drop parts at the machine shop,get work done,take home and then assemble them.

You become like best friends with the machinist for a couple weeks:::

you need to bore the block before you can trial assemble the engine to check deck height,usually you bore and hone to custom fit each piston,,,,
any engine that is raced or looking for maximum power will have as much blue printing as the assembler is willing to put into his efforts. block needs to be alighn honed and squared,final decking cannot be done until at least one trial assemble(partial). Your block will be machined at least 2 times.not counting final piston to wall honing,each piston will be hand fitted. crank is also custom polished for final bearing clearance. Crank is checked for straightness,polished to fit each bearing set,checked for rod side clearance.(another trial fit),,,,block can probably go back for decking. test fit after decking(after measuring piston to valve clearance) machine pistons if requires,crank,rods,pistons,balancer,flywheel etc can go for balance check. we weigh all the rings and bearings in extreme cases(for each set) another trial fit assembley,double check P to V,
take it all apart( good idea to recheck crank for straightness after balancing) any fine adjustments,do now. clean everything like you are going to do surgery with the engine parts,get all the parts in order,clean dust free shop,,,

this is just a very mild hint of the details involved. 40 hours to assemble an engine is a fast build imo. dont make any mistakes,have someone else take measurements to confirm yours are all correct.fix any differences. every part is trial fit before final fit. short blocks are often assembled more than 4 times.If you assemble the parts after you get them with out checking them and its a one time thing I doubt the engine will be all that great

maybe oldbogie can detail my post better as he seems pretty good at this kind of articulation
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  #25 (permalink)  
Old 12-24-2012, 05:20 AM
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Vinnie that wasn't confusing. That sounds fun. I've found these in regards to blue printing and have them bookmarked.
4g63 Blueprinting Basics - YouTube
Engine Blueprinting (Part 1) Precision Engine
Blueprint Your Motor For Mere Dollars-Super Chevy Magazine
Like the second guide states I've found I can only do so much at home but I think I grasp the fundementals relatively well. Still going to take it to the machine shop.
This is to give you guys an idea of what I've been doing. Lots and lots and lots of reading. And this is just the favorite ones. I haven't watched the videos yet.

Also just so you guys can further understand. If it was 1000$ for all the machine work OR I could rent the equipment/tools for 24 hours for 2000$. I'd choose the latter. I think I'm giving the impression I'm doing stuff to save money. I'm not.

Yeppers going to follow your initial piece of advice f-bird. Kind of disappointed I can't find any of those rebuilds for 6" rods. But basically lets take my original build. Use your idea for the bottom end. I REALLLLLYYYYY like that cam. and thats the engine itself.

If this seems solid then I'm going to start buying more stuff. Like I said, I have the intake and carb pistons are next so I can start the block machine work.
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  #26 (permalink)  
Old 12-24-2012, 04:16 PM
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Quote:
Originally Posted by F-BIRD'88 View Post

Set the valve lash cold at .004" tighter than the cam card specs.
[/url]
.004 Tighter? I ve been doing it wrong? Who taught me looser? I thought clearance would close up when hot?
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  #27 (permalink)  
Old 12-24-2012, 06:04 PM
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.004 Tighter? I ve been doing it wrong? Who taught me looser? I thought clearance would close up when hot?
Lash the valves HOT on a couple cylinders and use them as your standard to set the cold lash. Let the engine cool completely- like overnight-plus. Then check the lash on the valves you lashed hot- this is the correct cold lash that you can use from that point onward, knowing it was based on the correct hot lash to begin with.
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Old 12-24-2012, 10:55 PM
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Originally Posted by F-BIRD'88 View Post
On a push rod engine the block grows more than the valves do.

try it.
Damnit!! I learn something every day here!
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  #29 (permalink)  
Old 12-25-2012, 02:53 AM
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http://www.cranecams.com/pdf-tech-tips/mech-lift.pdf
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  #30 (permalink)  
Old 12-25-2012, 05:33 PM
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Quote:
Originally Posted by cobalt327 View Post
Lash the valves HOT on a couple cylinders and use them as your standard to set the cold lash. Let the engine cool completely- like overnight-plus. Then check the lash on the valves you lashed hot- this is the correct cold lash that you can use from that point onward, knowing it was based on the correct hot lash to begin with.
Heh I was just talking to my dad about doing this. Lash them to the factory/camcard spec followed by heating the car up. He said we could probably mess with the temp a bit to bring it a little warmer than typical operating temperature just so we could have some wiggle room for the finished thing. I hate lashing valves though but every little thing counts...right?
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