77- stroker engine build

[da_mule]

So I recently found out that my blazer comes with factory 3.5" blocks for the rear. Is that correct? If that is the case then I have no lift with 35's. INTERESTING If so I am going to order the 4 inch shackle flip and take the blocks out until I can afford 8" lift springs form alcan.

Thanks

 

[76zimmer]

I don't think Chevy ever used blocks.

 

[the_mule]

still no rotating assembly

It's been awhile since I've updated this but still no rotating assembly, it will be here on Monday it has finally shipped. I installed ORD shackle flip, painted the front frame rails, built a rear bumper, and am now installing seats from a 2000 chevy truck. No pics of the seats installed yet just got the driver side bolted in, will finish it tomorrow.

 

[76zimmer]

I think you'll like those seats for an everyday driver....the inclusive seat belt system is a plus, makes for simple installation.

 

[Chevy305]

what is a dynamic compression ratio? i have never heard of that before

 

[Stomis]

what is a dynamic compression ratio? i have never heard of that before

Dynamic compression ratio is the compression after taking into affect how much pressure the cam bleeds off.

 

[Chevy305]

Dynamic compression ratio is the compression after taking into affect how much pressure the cam bleeds off.

what does the cam have to do with the compression cycle? the valves have to be closed to make any compression

 

[Stomis]

what does the cam have to do with the compression cycle? the valves have to be closed to make any compression

Well theoretically on a perfect engine yes but not in real world, especially not with performance cams when the valve overlap is greater. Your talking about hairs but it does affect things.

 

[Chevy305]

Well theoretically on a perfect engine yes but not in real world, especially not with performance cams when the valve overlap is greater. Your talking about hairs but it does affect things.

you mean to tell me that on the compression cycle the valves are open? even on the most radical cam I find that impossible

 

[Stomis]

you mean to tell me that on the compression cycle the valves are open? even on the most radical cam I find that impossible

Read.

http://www.empirenet.com/pkelley2/DynamicCR.html

I'm no expert on it. I'm not sure if its that the intake valve doesnt open soon enough to take in the maximum amount of air or what but the jist of it is that the timing of the cam isnt dead in sync with the stroke of the piston.

 

[Chevy305]

Read.

http://www.empirenet.com/pkelley2/DynamicCR.html

I'm no expert on it. I'm not sure if its that the intake valve doesnt open soon enough to take in the maximum amount of air or what but the jist of it is that the timing of the cam isnt dead in sync with the stroke of the piston.

I understand now that its the intake valve hanging open a few degrees after BDC. Once the valve closes then compression starts.

So I used an online calculator and my 355 has a SCR of 9.41 and a DCR of 8.71. A little high but I know I have to run premium anyway.

 

[76zimmer]

so if your cam card has measured lift and closing points @ .015, how do you convert that figure to .050 like the calculator asks?...actually measure the lift @ .050? or is there a commonly accepted conversion number to use?

 

[folkenheath]

so if your cam card has measured lift and closing points @ .015, how do you convert that figure to .050 like the calculator asks?...actually measure the lift @ .050? or is there a commonly accepted conversion number to use?

Zim I didn't read that whole speal on that page because I have done hours of research on that years ago and wrote my own excel spreadsheet that calculates dynamic compression, but why would you want to use the number at .050"? Unless you piston is traveling fast enough that is starts to squeeze the air before the valve is all the way shut (not likely, but possible), you want to use the advertised bumbers. I use the number at .006" or .015". I do understand that at .050 is more standard, because companies vary where they measure advertised duration, but the piston is not really moving super fast relative to the valve during the last bit of the closing sequence. For example, take the KB pistons calc...

http://www.kb-silvolite.com/calc.php?action=comp2

they use the cam timing @ .050 plus 15 degrees. That is to allow a little more time for the valve to close all the way. But that's just an estimate since different profiles close at different rates, roller cams open and close much quicker than flat tappets, etc.

I did notice that he is a little more lenient in the numbers, I have always used 8.0 as the limit for pump gas. But if you use the timing at .050 your dynamic compression will be a little higher than advertised numbers.

Anyway, Zim, depending on what your cam card says, the numbers at .050 are usually stated somewhere, maybe not all of them. But if you know the numbers at .050 and the lobe centerlines you can figure it out. It's not just a common number though.

 

[76zimmer]

Zim I didn't read that whole speal on that page because I have done hours of research on that years ago and wrote my own excel spreadsheet that calculates dynamic compression, but why would you want to use the number at .050"? Unless you piston is traveling fast enough that is starts to squeeze the air before the valve is all the way shut (not likely, but possible), you want to use the advertised bumbers. I use the number at .006" or .015". I do understand that at .050 is more standard, because companies vary where they measure advertised duration, but the piston is not really moving super fast relative to the valve during the last bit of the closing sequence. For example, take the KB pistons calc...

http://www.kb-silvolite.com/calc.php?action=comp2

they use the cam timing @ .050 plus 15 degrees. That is to allow a little more time for the valve to close all the way. But that's just an estimate since different profiles close at different rates, roller cams open and close much quicker than flat tappets, etc.

I did notice that he is a little more lenient in the numbers, I have always used 8.0 as the limit for pump gas. But if you use the timing at .050 your dynamic compression will be a little higher than advertised numbers.

Anyway, Zim, depending on what your cam card says, the numbers at .050 are usually stated somewhere, maybe not all of them. But if you know the numbers at .050 and the lobe centerlines you can figure it out. It's not just a common number though.

Heath, I'm going to take this to another thread:

http://coloradok5.com/forums/showthread.php?p=2879387#post2879387

 

[Stomis]

I understand now that its the intake valve hanging open a few degrees after BDC. Once the valve closes then compression starts.

So I used an online calculator and my 355 has a SCR of 9.41 and a DCR of 8.71. A little high but I know I have to run premium anyway.

You should not need premium w/ 9.4:1.

10:1 - 10.25:1 runs on 91 Premium

10.25:1 - 10.5:1 runs on 93 Premium

And thats with cast heads. Its another point up for aluminum...

 

[the_mule]

seats

I think you'll like those seats for an everyday driver....the inclusive seat belt system is a plus, makes for simple installation.

Yeah I like the seats now that they are in, it took more work than I expected for some reason I thought just drill some holes and good to go, but I ended up mounting them on pieces of 3/16" 2x3 and running 1/2" grade 8 bolts through the seat all the way through the floor through 3/16" flat bar pieces 3 ft long across the floor boards because with the seat belts I don't want them to move at all in an accident. I actually copied what someone else did on here (I had read the post then later bought the seats but couldn't find the post again to copy) I also fixed the floor while I was at it ( I had used rivited in the floor so I welded it in) so what I thought would be an afternoon job turned into 2 days.

 

[the_mule]

compression

what does the cam have to do with the compression cycle? the valves have to be closed to make any compression

You guys have it hammered out, just to add the incoming intake charge helps evac the spent gasses from the combustion chamber, and cams have the overlap because it changes the powerband and how the cc seals at different RPM's... those lumpy cams at idle have both valves open when the car is idling but it makes more high rpm power.


My Static compression ratio ends up at 9.55:1 and with the cam/rod combo I am running at approx 250 ft above sea level I end up with a dynamic of 8.06:1

 

[the_mule]

engine parts

I took some pictures not much to see though. Got the Cam and bottom end installed, everything is within tolerances (a little on the snug side but within), oil pump and misc bolts and plugs in the block, I am shooting for getting the motor in the truck on SAT. While under the truck messing with the seats I was looking at the front spring hanger and bushing, so new hangers and mounts for the front are on the way, as well as new bushings for the back springs this thing is like a big black hole in the garage that eats money. I just want to drive it again.

 

[the_mule]

long time

Well it's been a long time. I was about to make a build thread but remembered I probably had already started one. So after looking at where that left off I decided to just continue. Engine got installed, moved to GA, truck came along.


http://coloradok5.com/forums/attachment.php?attachmentid=151810&stc=1&d=1381893712


Ran truck for awhile.

http://coloradok5.com/forums/attachment.php?attachmentid=151811&stc=1&d=1381893770

Then converted to Propane, Removed Top, Built Roof Rack, Installed Side boxes , Built locking storage in rear of truck, Made Soft top, Installed lights, Installed Radio in water proof box, Installed Tuffy Center console, Installed Tuffy lock box under each seat. Cut off extra Sheet metal.

http://coloradok5.com/forums/attachment.php?attachmentid=151813&stc=1&d=1381893994


Decided to drive truck from GA to PA

http://coloradok5.com/forums/attachment.php?
attachmentid=151814&stc=1&d=1381894126

http://coloradok5.com/forums/attachment.php?attachmentid=151815&stc=1&d=1381894126

 

[the_mule]

and

Didn't need this much propane, but I wasn't sure how much I'd need, The truck gets about 10 miles to the gallon and this is 56 Gallons of pane. I filled up more than I needed to but was taking all back roads going for dirt roads as much as possible. I never used the two 8 gallon tanks at all. I planned to fill up at U-haul fill stations as they are all mapped but saw plenty of other places I could've filled up.