Jump to content

Photo

Basic Cam Timing Question

- - - - - Camshaft Timing Cam Timing Timing Belt Cam Position Sensor

  • Please log in to reply
7 replies to this topic

#1
luvin_the_rings

luvin_the_rings

    Member

  • Members
  • PipPipPip
  • 204 posts
  • Location:Los Angeles, CA
  • Car Year:1990

Hello All,  

 

I want to thank you all for your continued support for all us new SM'ers.  I know its repetitive to keep answering the same ole' questions from us youngins who are too lazy or broke to buy the Advanced Autosport Ultimate Constructors book.  

 

This brings me to my question.  I want to make sure, without a shadow of a doubt, that my Cam timing is correct on my 1.6. The manual that I have gives a picture of how the cam gears should be oriented, but there is too much room for error in my opinion.   I was thinking that I could put the engine at TDC with my dial indicator, then measure the valve lift on the intake and exhaust side on Cyl 4.  This combined with counting the teeth on the belt between the two arrows on the cam gears should ensure that it is correct.  As I know, there are supposed to be 19 teeth between the arrows on the cam gears.  This I already know is correct.  Does anybody have a measurement on exhaust valve lift on cyl 4 at TDC?  If you could include your measurement for valve lash also that would help even more, although it is not necessary.  

 

If anybody knows a different  way to directly measure cam timing so we know it is correct, any help is welcomed.   

 

Just want to make sure before we really start shaking the car down.  

 

Thank You, 

 

-Z



#2
Bench Racer

Bench Racer

    Different strokes for different folks : )

  • Members
  • PipPipPipPipPip
  • 5,508 posts
  • Location:Wauwatosa, WI
  • Region:Milwaukee
  • Car Year:1990
  • Car Number:14

Welcome and have fun.

 

If you have a 1.6 Mazda Factory Shop Manual, please follow the picture/written instructions, they work very well.


Broken record - You are starting to sound like a broken record. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver

#3
davew

davew

    Veteran Member

  • SMembers
  • PipPipPipPipPip
  • 2,297 posts
  • Location:Beloit, Wi
  • Region:Chicago
  • Car Year:1999
  • Car Number:72

Valve lash should be zero. Your 1.6 has hydralic lifters (technically called "hydralic lash adjusters" or HLA's).

 

Insert a long stick (screwdriver or 1/4" drive extention) into #1 spark plug hole. Turn engine and watch for stick to reach the top of its travel. This will not give you exact to the 0.001" of measurement, but works fine for setting the timing belt

 

dave


Dave Wheeler
Advanced Autosports, the nations most complete Spec Miata shop
Author, Spec Miata Constructors Guide, version 1 and 2.0

Building Championship winning cars since 1995

4 time Central Division Spec Miata Champion car builder 2012-2013-2014-2017

Back to Back June Sprints Spec Miata 1-2 finishes 2016 and 2017

5 time June Sprints winner in Mazda's

6 Time Northern Conference Champion Car Builder

2014 SCCA Majors National point Champion car builder

2014 SCCA Runoffs winner, T4 (Bender)

2014 Central Division Champion, ITS (Wheeler)

2013 Thunderhill 25 hour winning crew chief

2007 June Sprints winner, (GT1, Mohrhauser)

Over 200 race wins and counting.
www.advanced-autosports.com
dave@advanced-autosports.com
608-313-1230

Survive the 25, NASA Thunderhill - Survive the 25, NASA Thunderhill We have a Winnah! - Won their 1st race... Congratulations! Sponsor / Advertiser - Site sponsor / advertiser... support these guys! Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver

#4
ScratchRob13

ScratchRob13

    Member

  • Members
  • PipPipPip
  • 22 posts
  • Location:CT
  • Region:NER
  • Car Year:2001
  • Car Number:13

Valve lash should be zero. Your 1.6 has hydralic lifters (technically called "hydralic lash adjusters" or HLA's).

 

Insert a long stick (screwdriver or 1/4" drive extention) into #1 spark plug hole. Turn engine and watch for stick to reach the top of its travel. This will not give you exact to the 0.001" of measurement, but works fine for setting the timing belt

 

dave

That's what I do for most of my 4 bangers.


'01 Miata SM #13

SCCA NER

 


#5
luvin_the_rings

luvin_the_rings

    Member

  • Members
  • PipPipPip
  • 204 posts
  • Location:Los Angeles, CA
  • Car Year:1990

thanks guys, 

 

we took it to Buttonwillow, CA and realized that the "freshly rebuilt" trans we purchased is actually "freshly blown"

 

motherf**kers on craigslist i swear...

 

-Z



#6
Jamz14

Jamz14

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 1,310 posts
  • Location:California

.


Broken record - You are starting to sound like a broken record. Donor - Made PayPal donation Sponsor / Advertiser - Site sponsor / advertiser... support these guys! Novel Approach - When a paragraph simply won't do... Make it Rain - Made Paypal donation of $100+ Bona fide - A bonafide Spec Miata driver

#7
RWP80000

RWP80000

    Member

  • Members
  • PipPipPip
  • 161 posts
  • Location:Phoenix
  • Region:SoPac
  • Car Year:1999
  • Car Number:2

-Z,

 

Your are correct in thinking you can use a dial indicator to measure the intake and exhaust valve lifts as a method to accurately verify the cams are positioned correctly.  Also, even though your engine has HLA's, the measurement you make using this method is valid regardless whether or not the HLA bleeds down while performing this measurement as you are measuring what is happening at the cam/lifter interface independent of actual valve movement.  

 

I use this method but rather than measure each cam lobe separately at TDC, I measure both the intake and exhaust lobes at the same time on the overlap stroke (where the Exhaust valve is closing and Intake valve is opening).  The dial indicator reading to observe is where the lift of both the Intake and Exhaust valves are exactly the same. This is commonly called "split overlap" position.   When measuring this way, you see exactly where "split overlap" occurs with respect to TDC.  Split Overlap is normally referenced as happening at TDC (also considered as cams being installed "straight up"- a position where the cams are considered to be neither advanced or retarded).  You will find for Miatas' that split overlap happens more like 2 or more degrees after TDC and the split overlap lift measurement value will be in the range of .014 to .020 inch on the dial indicator.

 

Rich Powers



#8
luvin_the_rings

luvin_the_rings

    Member

  • Members
  • PipPipPip
  • 204 posts
  • Location:Los Angeles, CA
  • Car Year:1990

Rich, 

 

Great info.  Thanks.  So, if the marks on the head are dirty, hidden or otherwise not visible, I can just set the engine to 2 degrees ATDC and set the cams to split overlap on Cyl 4; then put the timing belt on?

 

Thanks, 

 

-Z







Also tagged with one or more of these keywords: Camshaft, Timing, Cam Timing, Timing Belt, Cam Position Sensor

1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users