L28 Stroker Build - I need your advice :-)

[german240]

Not all events are advanced. And putting it in hole #3 would advance it even further..or are you kidding 

I left it like it is and finished the engine. I will upload some more pictures this week. 

Edited December 3, 2017 by german240

[siteunseen]

17 hours ago, german240 said:

Not all events are advanced. And putting it in hole #3 would advance it even further..or are you kidding 

Well sort of kidding but hoping to learn something as well. 

If your cam card says open at 8 degrees before TDC and it's opening at 11 degrees before TDC I was thinking that's 3 degrees too soon?  If each higher hole on the cam sprocket is 4 degrees advance and you put it on #2 wouldn't that get you opening at 7 degrees before TDC?  

I'm trying to take in all I can before I put my E31 together with the .490 cam kit.  After reading madkaw's post and now yours I'm thinking I MUST get the cam "degreed" with that paper wheel and the bent paperclip.  My machinist could do it quicker than me and I won't need to buy that stuff for a one off cylinder head rebuild (hopefully).

Cliff

[madkaw]

Don’t think of it as “too soon” , but advanced 3 degrees Cliff. It’s already ADVANCED , so moving sprocket would advance it more . 

[madkaw]

I would personally shoot for getting the intake closing as close to card as possible, even slightly advanced to make other numbers to come out

[siteunseen]

3 hours ago, madkaw said:

Don’t think of it as “too soon” , but advanced 3 degrees Cliff. It’s already ADVANCED , so moving sprocket would advance it more . 

Here's where I'm confused. 

The motor turns clockwise, 11 comes before 8 going clockwise towards TDC.  Does that not mean 11 would open sooner?

 

[Zed Head]

Actually it is "too" soon if you're comparing to the cam card.  I just look at the B or the A in BTDC (before top dead center) and ABDC (after bottom dead center), and the like.  If the B number is bigger than the cam card, then it's sooner, more advanced, more early, more "before".  But if the A number is bigger then it's later, more after.  The numbers are in relation to the "dead center" point chosen. You can recalculate them in other terms if you want.

The ATDC number is the one that's not early.  It's a bigger "after" number.  I missed it.  Two bigger B's, one smaller A, and the bigger A (the later than the card timing event).  Edited (again) - don't know my A's from a hole in the ground.  Original version in madkaw's quote.

Delta cam must have large tolerances in their specs, or sloppy equipment.  Most people wouldn't check the quality of the job like german240 did.  Disappointing that they couldn't give a good answer to the question.

Edited December 5, 2017 by Zed Head
typo dang it

[madkaw]

3 hours ago, siteunseen said:

Here's where I'm confused. 

The motor turns clockwise, 11 comes before 8 going clockwise towards TDC.  Does that not mean 11 would open sooner?

 

Simple answer is yes 

[madkaw]

4 hours ago, Zed Head said:

Actually it is "too" soon if you're comparing to the cam card.  I just look at the B or the A in BTDC (before top dead center) and ABDC (after bottom dead center), and the like.  If the B number is bigger than the cam card, then it's sooner, more advanced, more early, more "before".  But if the A number is bigger then it's later, more after.  The numbers are in relation to the "dead center" point chosen. You can recalculate them in other terms if you want.

The ATDC number is the one that's not early.  It's a bigger "after" number.  I missed it.  Two bigger B's, one bigger A, and the smaller A (the later timing event).

Delta cam must have large tolerances in their specs, or sloppy equipment.  Most people wouldn't check the quality of the job like german240 did.  Disappointing that they couldn't give a good answer to the question.

ISKY sent me the wrong card with my cam. I spent a day turning my engine over and over and rechecking numbers to try and make them come out. I finally got him on the phone and we cleared it up. It’s frustrating if you don’t do this a lot or are not confident of your skills- you swear your doing something wrong when your not. Not easy telling Mr. Iskerdian his cam card doesn’t make sense . 

I also never hit my numbers exact. Lots of slop in rocker arm ratios and other variables. If the cam grinder says they are good numbers then go with it

[Zed Head]

Fixed my error in #102 about the smaller "A" being the "later" event.  Confused myself this morning.  

german240 ended up with more duration on both valves so might be better off in the long run.

 

 

[german240]

I left it like it is. Double checked valve-piston clearance (it is >2mm) and piston-head clearance (1.5mm) using a strip of solder. The engine is complete so far, I just have to fit the Zstory race manifold and the fully refurbished SUs. 

BTW: Some cam grinders like ISKY supply two completely different cam cards. One as reference (advertised), one for actual numbers that can be measured with a degree wheel. I found a similar (advertised) spec cam card, the "workshop specs" come out like my measurements did. 

@siteunseen I just realized that you uploaded those cam cards.  

 

Better pictures will be added next week Just some quick shots. 

 

 

DIstributor shaft alignment..shifted it around many times, hopefully it is right now

Header

 

 

Aaaaand.... Engine before I started working on it

This was the Ebay ad..

Edited December 5, 2017 by german240

[Patcon]

That's a good looking motor! I don't know why but a sexy motor stirs something deep down in side me...

[Jason240z]

Thats a great transformation.

 

Nice looking header also.