Dial Indicator w Magnetic "arm" base or deck bridge? - CorvetteForum - Chevrolet Corvette Forum Discussion

Go Back  CorvetteForum - Chevrolet Corvette Forum Discussion > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Reload this Page >

Dial Indicator w Magnetic "arm" base or deck bridge?

Notices
C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

Dial Indicator w Magnetic "arm" base or deck bridge?

Old 10-12-2018, 07:34 PM
  #1  
NewbVetteGuy
CF Senior Member
Thread Starter
 
NewbVetteGuy's Avatar
 
Member Since: Jun 2016
Location: Woodinville WA
Posts: 2,118
Thanked 160 Times in 141 Posts
Default Dial Indicator w Magnetic "arm" base or deck bridge?

I'd like to be able to use a CHEAP dial indicator to be able to fairly accurately measure how far down the hole my pistons are AND to be able to more accurately measure ACTUAL top dead center when degreeing in my cam.

I'm unclear on whether I can use a magnetic base with the arms on them like this:
Amazon Amazon

Or whether I have to use a deck bridge like this:
Amazon Amazon


My understanding is that the kind with the arm is useful for more tasks than just measuring how far down the hole the piston is and when the piston's at TDC.



Thanks,
Adam
NewbVetteGuy is offline  
Old 10-12-2018, 07:54 PM
  #2  
Milan454
CF Senior Member
 
Milan454's Avatar
 
Member Since: Sep 2017
Location: Westlake Ohio
Posts: 127
Thanked 15 Times in 15 Posts
Default

The magnetic base is the better option ONLY if you get a good one. Try Craig's list. I got a name brand one for cheap. The cheap ones on Amazon move and wiggle way too much. If you need to go cheap a bridge and using a piston stop method is the most economical accurate method.
Milan454 is offline  
Old 10-12-2018, 08:14 PM
  #3  
Rodnok1
CF Senior Member
 
Rodnok1's Avatar
 
Member Since: Sep 2016
Location: NC
Posts: 2,032
Thanked 75 Times in 66 Posts
Default

I have several of the arm versions, much more versatile and cost effective. Not sure the brands of mine as one is super old and others have no markings but were not cheap when bought them(not too expensive though).
Rodnok1 is offline  
Old 10-12-2018, 09:37 PM
  #4  
427Hotrod
CF Senior Member
 
427Hotrod's Avatar
 
Member Since: Jan 2000
Location: Houston, Tx
Posts: 11,208
Thanked 535 Times in 377 Posts
2017 C2 of Year Finalist
Default

A bridge is best for measuring deck height. But you can use a magnet if it's real steady in the arms. It takes a little care to measure. best to be right over pin..but you can also measure 90* to it by rocking piston all the way down and then all the way up and splitting difference.

For degreeing cam you want to use a piston stop to get true TDC and a very steady dial indicator to measure lobe movement.


For general all around use...I use these flex type. Easy to setup and work well vs all the pivot arms.

https://www.bing.com/shop?q=ball+joi...03B0BD5FDDBB18


JIM

Last edited by 427Hotrod; 10-12-2018 at 09:39 PM.
427Hotrod is offline  
Old 10-13-2018, 07:49 AM
  #5  
derekderek
CF Senior Member
 
Member Since: Jul 2015
Location: Westville NJ
Posts: 3,436
Thanked 417 Times in 388 Posts
Default

There is also a vise-grip base indicator mount. Harbor freight cheapie.
derekderek is offline  
Old 10-13-2018, 09:10 AM
  #6  
jim2527
CF Senior Member
 
jim2527's Avatar
 
Member Since: Apr 2003
Location: Tampa Florida
Posts: 15,099
Thanked 131 Times in 115 Posts
Default

I have a magnetic type base from HF. IMHO its extremely difficult to work with, But better bases are $$$$$ so balance it against how often your going to use it. I'll be trying a flex arm style next time around.
jim2527 is offline  
Old 10-13-2018, 09:15 AM
  #7  
GTR1999
Tech Contributor
 
GTR1999's Avatar
 
Member Since: Aug 1999
Location: New Haven CT
Posts: 11,024
Thanked 219 Times in 163 Posts
Default

As any toolmaker, machinist, and operator will tell you cheap and good quality measurement tools really don't go hand in hand. If you are going to work on your car you will find a quality 0-1" indicator and a good mag base will pay for themselves over time. I only use Starrett, I think they have been one of the best for the past 100 years or so but I have the cheap ones tool. There is a big difference- I have a couple of those mag arm bases but the magnetic pull is weak on them all compared to my push button Starrett. The Chinese indicators have weak springs in them and often loose position without you knowing it. The few that had all broke in short time, the last one I have I use for a travel indicator for rough lathe work.

I would spent the money and get a good used set of ebay, they are always on there or I can sell you the fancy looking arm base sitting in my cabinet the past 5 years taking up space.
GTR1999 is offline  
Old 10-14-2018, 11:34 PM
  #8  
NewbVetteGuy
CF Senior Member
Thread Starter
 
NewbVetteGuy's Avatar
 
Member Since: Jun 2016
Location: Woodinville WA
Posts: 2,118
Thanked 160 Times in 141 Posts
Default

Originally Posted by GTR1999 View Post
As any toolmaker, machinist, and operator will tell you cheap and good quality measurement tools really don't go hand in hand. If you are going to work on your car you will find a quality 0-1" indicator and a good mag base will pay for themselves over time. I only use Starrett, I think they have been one of the best for the past 100 years or so but I have the cheap ones tool. There is a big difference- I have a couple of those mag arm bases but the magnetic pull is weak on them all compared to my push button Starrett. The Chinese indicators have weak springs in them and often loose position without you knowing it. The few that had all broke in short time, the last one I have I use for a travel indicator for rough lathe work.

I would spent the money and get a good used set of ebay, they are always on there or I can sell you the fancy looking arm base sitting in my cabinet the past 5 years taking up space.
Iím building one motor EVER then Iím getting rid of the tools, so cost effectiveness trumps most else. If the tool works for 8 cylinders and deferring the cam, Iím happy. If I could borrow the tool from OíReilleys for two days and return it, I would but they donít loan dial indicators. Iím not an engine builder; this will be my one and only old car and engine that I rebuild / restore/ mod myself.


Adam
NewbVetteGuy is offline  
Old Yesterday, 02:16 AM
  #9  
theandies
CF Senior Member
 
theandies's Avatar
 
Member Since: Jun 2001
Location: "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants."
Posts: 16,903
Thanked 254 Times in 211 Posts
Default

Adam,
Let me look at my mag base setup and get back to you. I'm at work right now. I had no problems checking my flywheel with my setup. Worked great and I think it's just what your're looking for. Decent performance and not too expensive.
theandies is offline  
Old Yesterday, 07:45 AM
  #10  
69L46vert
CF Senior Member
 
69L46vert's Avatar
 
Member Since: Jul 2006
Location: Buxton Maine
Posts: 470
Thanked 10 Times in 10 Posts
Default

I used Starrett mag bases daily for 30 years but now very much favor the Noga base.

Amazon Amazon
69L46vert is offline  
Old Yesterday, 08:31 AM
  #11  
jim2527
CF Senior Member
 
jim2527's Avatar
 
Member Since: Apr 2003
Location: Tampa Florida
Posts: 15,099
Thanked 131 Times in 115 Posts
Default

Originally Posted by GTR1999 View Post
I have a couple of those mag arm bases but the magnetic pull is weak on them all compared to my push button Starrett. The Chinese indicators have weak springs in them and often loose position without you knowing it
I'll agree on the weak bases, you need a nice solid mounting surface. The hardware is sketchy at best, I have hard time tightening down the *****...even after lubing the threads. But as Adam said, I'm never going to use it more than a handful of times so there's zero reason to buy something high end.

There're a bunch a youtube videos comparing Chinese dial indicators and other measuring devices to high end U.S. made and Japanese instruments. The imports are just as accurate. One guy compared spring strength and the import was actually stiffer than the high end model. I've check the accuracy of my 'Chinese' measuring tools and they're dead on....

I truly believe you get what you pay for, if I were a professional I'd have a set of high end instruments and tools. But I'm just a garage mechanic with one project car, entry level, but accurate instruments will work just fine.
jim2527 is offline  
Old Yesterday, 05:10 PM
  #12  
theandies
CF Senior Member
 
theandies's Avatar
 
Member Since: Jun 2001
Location: "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants."
Posts: 16,903
Thanked 254 Times in 211 Posts
Default

This is what I have and it works fine for light duty work.




I found these pictures on Harbor Freight but I don't think I bought them there as it came in a kit and these are listed separately on HF.
theandies is offline  


Thread Tools
Search this Thread
Sponsored Ads
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: