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406 build
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cmarr6
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PostPosted: Sun Feb 10, 2013 10:24 am    Post subject: Reply with quote

I will definitely go back and do it again. it will have to wait til next weekend. I work 12 hr days, sun thru thurs, so don't have much time during the week to do anything. I have a stright edge I can use to measure for tdc and then down to the top ring to get the piston height. I will have to find a piece of plexiglass and use that instead of eyeballing it. The stock heads were 76cc, that's why I figured I could just use a small cc head and get some decent compression. Really appreciate all your help. This is a great learning experience.
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clay
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1972 Chevrolet Nova

PostPosted: Sun Feb 10, 2013 10:33 am    Post subject: Reply with quote

You can get more compression with the heads that are available today. However you have to ask do you want to run premium fuel full time or do you want to run on 87 ocatane? Heads are available in the mid 70cc range, mid 60 range and RHS makes a 49cc head. Also you can run a 0.039" gasket or either the 0.015" steel shim gasket. With the cam you have you can't get carried away with static compression or you'll get in trouble. There are several variables you have to get figured out but we'll be happy to help you work through it. Clay
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cmarr6
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PostPosted: Sun Feb 10, 2013 11:08 am    Post subject: Reply with quote

No, I want it to run on pump gas. Like I said, it's just a cruiser, not a 1/4 miler. Don't want so much compression that I can't run on pump gas. Just want it to make some good power and sound nice. Do you thing that is a good cam choice? I did a lot of reading and tried to figure out what I needed. Didn't want to overcam it. Thought that would be a good choice. The numbers started to overwhelm me, and it was time to decide. So I had to go with what I thought was right.
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Paul P
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1971 Chevrolet Chevelle

PostPosted: Sun Feb 10, 2013 1:21 pm    Post subject: Reply with quote

I guess I made 2 assumptions that were missed. My bad you did say you were new to this. Clay did make these points.

1. Positive stop with a bridge or a dial indicator to find true TDC.

Bridge bring the piston up until it hits the stop. Mark the balancer. Go back in the other direction of rotation and hit the stop again. Mark the balancer. The mid point is True TDC.

Dial indicator find a spot down the bore slightly that you can zero the dial indicator. Use the same method mark the balancer then go in the other direction until the same point is met on the indicator. The mid point again is TDC.

Piston rock as long as your measurement is made with the piston coming up takes care of this factor in doing this so just be aware of it.

Once you find TDC you can use the dial indicator zero'd out on the deck to see how far you are down the hole the piston is. This is likely affecting the cc'd volume you are seeing.

2. Plexiglas with grease sealing around the top of the cylinder.

This is industry standard practice which I am sure now that you understand you will use it. One thing you might want to check is the volume at both ends of the deck. You might find out that the deck is higher on one end than the other. Something that can be corrected by tearing it down and having it decked. Not sure that is what you want to do as it is a complete turn around.

This should be fun so keep it that way no worries this site is a good place for information as most of us have been there and will gladly share what we have learned.

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6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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cmarr6
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PostPosted: Sun Feb 10, 2013 4:52 pm    Post subject: Reply with quote

Yes, I am new to the technical aspect of all of this. I have put some pretty good running motors together in the past, but it was mostly just guessing. I have always been interested in learning the technical side of things. This is a slow build so I thought I should do it right this time. I have a weeks vacation next week so I will spend some time getting the numbers like you guys suggest. Will get a piece of plexi and use a straight edge and do it the right way. It will be awhile before I can afford a good set of heads, so I am as far as I can go without the heads. I can still disassemble and replace the pistons if I decide I want something better. I saw in another thread that there were some books that were suggested by David Vizard. Which one of these is the best at explaining cams and valve timing and such?
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clay
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1972 Chevrolet Nova

PostPosted: Sun Feb 10, 2013 9:03 pm    Post subject: Reply with quote

This is from another post I did a while back with some good book information.

Quote:
Here is the information on some of the better books I have.
1. How To Build Max. Performance Small Blocks On A Budget
By David Vizard ISBN# 1-884089-34-8
2. How to Build And Modify Chevrolet Small Block Cylinder Heads
By David Vizard ISBN# 0-87938-547-2
3. How to Build Horsepower Vol. 1
By David Vizard ISBN# 0-931472-24-5
4. How to Build Horsepower Vol. 2 Carburetors and Intake Manifold
By David Vizard ISBN# 1-884089-14-3
5. How to Build and Modify Chevrolet Small Block V-8
Camshafts and Valvetrains
By David Vizard ISBN# 0-87938-595-2
6. Small Block Chevy Engine Buildups
From Chevy High Performance ISBN# 1-5578-400-5
7. Horsepower Handbook
From Hot Rod Magazine ISBN# 0-7603-1814-X
The first two I listed are to me the most beneficial to you right now. #3 repeats a lot of what is in #1. #4 is beneficial if you plan to extensively modify a manifold or carburetor - I haven't really used much out of it. #5 is pretty good to read - it talks a good bit about camshaft selection for specific uses and setting up the complete valvetrain. #6 and #7 are made up of articles from the magazines. I like them because they get all the best articles in one place - you don't have to try to find them in a 5 year old stack of magazines. Good to look at and get ideas.


You are going to find it's kind of a the more I learn the less I know type thing with engines. For heads look into the factory Vortec's - impressive head for very cheap. Since you are running a smaller flat tappet you shouldn't have any problems with their main limitation - retainer to seal clearance. Since it sounds like you want to build a high torque engine that's the way I would go - especially if on a budget. Personally I would change the cam also but you can do that later if you want. Clay

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cmarr6
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PostPosted: Mon Feb 11, 2013 7:52 am    Post subject: Reply with quote

Yes, I have already found that out, the more you learn, the more you realize how much more there is to learn! I was thinking more along the lines of an aluminum AFR head or something like that. I will look into the vortec heads. They will bolt right on to the Gen 1 without any mods or other concerns? Yes, I was aiming at more low end power and torque, you don't think that was a good cam choice? I know, maybe a little small, but I read Lingenfelter's book on building small blocks and in it he said the worst thing you can do is overcam an engine for it's intended use. And it's basically just a stock bottom end, I didin't want to overdo it and end up breaking things.
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clay
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1972 Chevrolet Nova

PostPosted: Mon Feb 11, 2013 10:16 am    Post subject: Reply with quote

You're right about not overcaming and I'm not talking about a huge change in the cam by any means. It's not bad for your intended purpose. Everybody has an opinion and personally I would go with just a little more duration and a tighter lobe seperation - maybe something in the mid 220's in. and ex. at 0.050" and a 108 or so seperation. Here is my reasoning. The cam you currently have is listed for up to 5200 rpm. Generally for a sbc this rpm range is listed for a 350 since it's the most popular. Since you have an additional 50 ci. its effective rpm range will be slightly lower. In Vizard's books one rule is if head flow remains the same as displacement goes up lobe seperation needs to tighten up. The tighter lobe seperation should help with midrange power / torque. It will also give a little lope which everybody likes Very Happy . Shouldn't be anything radical at all though. Also I would recommend degreeing it. It's not hard and it makes sure it's installed where it should be. I've had some be dead on and some I had to move 4* to get it installed where it should be. You will have to drill the steam holes in the Vortec heads but you will in the AFR's also. All the Vortec's require is an intake to match their different bolt pattern. If you don't already have an intake then cost is a wash. You also are correct on not turning a lot of rpm's. Seems like I remember the 400 rods have the pad that the rod bolt head seats against milled a little lower for camshaft clearance. This results in a thinner area on the rod that is a little weaker than a 350 or 5.7" rod but for your intended purpose I wouldn't worry about it. This is just my opinion and the final camshaft pick is your decision so you have to take information from any source you can find and make the best educated decision you can. Clay
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cmarr6
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PostPosted: Mon Feb 11, 2013 3:02 pm    Post subject: Reply with quote

I will definitely look into the vortecs. I don't have an intake yet so that's not a problem. I am going to get that book by Vizard and do some reading. I think I'm going to run this cam first and see if I like it. Can alway do a cam swap later. Thanks for the advice on the cam. I thought this was a 110 LSA cam when I ordered it, come to find out its 112. I kinda misjudged the duration, too. That "advertized duration" @.50 always throws me off. I was looking at actual duration of 288/298 and thought that was pretty good. I will definitly degree it when I get the heads on. I want to try to do everything right on this motor as a learning experience. Might run like s___ when I get it together, but hey, I learned something, right. Sometimes, learning how not to do it is just as important.
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clay
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PostPosted: Tue Feb 12, 2013 9:59 am    Post subject: Reply with quote

Advertised duration is the hardest to compare so I don't look at it too much. Reason is that different manufacturers don't use the same checking height. Some use duration at 0.006" lift, some 0.004" and if you get to mechanical flat tappets I think they throw in valve clearance too so you can't use advertised to compare much. That's why duration at 0.050" lift is normally used to compare cams. By all means run what you have - it's paid for and it's a learning experience to change to something else. On the Vortecs as far as flow numbers they are very close to a Dart Sportsman II before any work and can make some power. Main thing on the cam is break in lube, the correct oil for break in, checking spring pressures and keep the rpm's up. I would absolutely get the first book I listed - it's by far the easiest to read and full of information on exactly what you're doing. Clay
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cmarr6
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PostPosted: Tue Feb 12, 2013 4:33 pm    Post subject: Reply with quote

I have already read a few books about building SBC's. One was by John Lingenfelter i think and the other I can't remember the author. Both were pretty good, all about building SBC's. But neither got too specific about cams and valve timing. I was thinking of getting the one on cams and valvetrains. I want to learn more about that area. I have used alot of break in lube, I bought a big tube of it and put it on everthing that moves! I have always just used a cheap mutiweight oil for breakin. I have heard about specific "breakin oil", should I be using something like that? And keep the R's up around 2 grand for 15 mins or so? Got me a piece of plexi and will be cc'ing it again first thing friday morning. will post the numbers.
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cmarr6
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PostPosted: Wed Feb 13, 2013 12:16 pm    Post subject: Reply with quote

A couple of quick questions, what sort of compression ratio should I be shooting for? I want it to run on pump gas. How high of compression can I go and still run on pump gas. Been thinking of just going ahead and replacing the pistons with a flat top or a smaller dish. If I do, what should I be looking for.
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cmarr6
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PostPosted: Wed Feb 13, 2013 12:21 pm    Post subject: Reply with quote

I forgot to post my other question. Maybe this isn't the place to be asking, but you guys know a hell of a lot more about motors than I do. I have a chance to buy a completely stock 75 L82 out of a vette. His dad owned the car and pulled it and swapped in a crate motor. His dad passed away several years ago and he inherited the car and the old motor. Has been in the crate in his garage since. I have him checking the numbers, but, if it checks out, would this be worth my while?
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PostPosted: Wed Feb 13, 2013 2:28 pm    Post subject: Reply with quote

I'd pass on the L82. Get a newer roller block and/or make the switch to an LS motor.
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cmarr6
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PostPosted: Fri Feb 15, 2013 10:52 am    Post subject: Reply with quote

Okay guys, here are the numbers. I got a piston height of .15" and 34 cc's of volume. Does that sound right? I'm new to all these numbers so I don't know what they should be. It does sound better than the 41 cc's I got before. What size of chamber should I be looking for in a head that I can get decent compression and still run on pump gas?
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