torque converter upgrade to avoid detonation? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 05-22-2005, 12:09 AM
Member
 
Last photo:
Join Date: Mar 2003
Location: Bakersfield, CA
Posts: 397
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
torque converter upgrade to avoid detonation?

Hi guys! I had another thread going on the topic. Basically, my 383 pings at around 2000 rpms with the th350 tranny in either 2nd or 3rd gear. This is with a 2000 rpm torque converter. I guess the engine is lugging causing the ping.

What if I bought and installed a 2400 rpm torque converter? This will shift my engine's power band into a more favorable position, right? Will this prevent the detonation? Or will the detonation start going at a different RPM range?

Here is the old thread with some details:
http://www.hotrodders.com/t61953.htm...383+detonation

Thanks!
Denis

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-22-2005, 03:41 AM
Siggy_Freud's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Dec 2003
Location: Portland, Oregon
Age: 29
Posts: 2,371
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Id combat the detonation via timing and tune before I started tossing torque converters at it. While yes, the engine will see less load due to the higher stall, I dont believe this to be an appropriate way to cure detonation.

What measures have you taken already to fix this?
__________________
Bringing history and technology together.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-22-2005, 08:19 AM
1BAD80's Avatar
The Smell of Nitro in the morn
 
Last wiki edit: How to adjust valves Last photo:
Join Date: Jun 2001
Location: Mich
Posts: 2,423
Wiki Edits: 2

Thanks: 0
Thanked 3 Times in 2 Posts
With your quench of 0.078in is your problem.
Why would you ever build a motor with that much is a guess.
There has been very much discussion about the topic.
Anything over .060 is asking for detonation.
Change the head gaskets.
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-22-2005, 08:57 AM
lluciano77's Avatar
Short changed on common sense
 
Last photo:
Join Date: Jun 2003
Location: california
Age: 37
Posts: 3,548
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The 2,400 stall will help, but you should fix the quench first. After you fix the quench work on the tuning.


2,400 is a good street stall. That is what I use in my everyday car. I have 3,200 stall in my all out fast car, but 3,200 gets annyoning after a while.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-22-2005, 09:06 AM
NXS's Avatar
NXS NXS is offline
wind & fire = guides to power
 
Last photo:
Join Date: Nov 2004
Location: Oklahoma
Posts: 1,534
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
i looked at your other thread.

Since you don't say it pings in Drive (3rd) i'll assume it doesn't?
If so it sounds like a VACUUM ADVANCE problem, with there being more load in Drive there will be less vacuum. B/C there is less load in 1st and 2nd that leads me to believe you can tune it out.

How does it run with the vacuum advance disconnected & plugged?

If that doesn't help get an adjustable MODULATOR VALVE for the transmission. They have a tiny screw inside the nipple the vac. hose plugs on. This will allow you to taylor your shiftpoints at the turn of a screw(2750rpm).

Also try retarding the cam. This will move the POWERBAND up in the RPM range.

And the idea of a stall is good also. In general these aren't just "band-aid" fixes, the system must be set-up to work together. If you do each of the above you will probably get away with 91 octane, despite your excessive quench.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-22-2005, 09:29 AM
just another car guy's Avatar
Member
 

Last journal entry: 50 chev p/u project
Last photo:
Join Date: Jun 2004
Location: Brightwood, OR
Age: 45
Posts: 70
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 1BAD80
With your quench of 0.078in is your problem.
Why would you ever build a motor with that much is a guess.
There has been very much discussion about the topic.
Anything over .060 is asking for detonation.
Change the head gaskets.
Ok Um what is a "quench" ? new one on me
__________________
Dan
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-22-2005, 09:36 AM
coldknock's Avatar
Member
 
Last photo:
Join Date: Feb 2004
Location: Social Circle, Ga.
Age: 43
Posts: 1,531
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Quench is the distance from the crown, or top, of the piston to the flat surface of the head. Generally speaking anything between 0.035" and 0.060" is acceptable for a performance engine. Less is better to a point, you don't want actual contact.

The idea is that the piston comes as close to the head as possible and sends the mixture shooting across the combustion area at a high rate of speed. This speeds up combustion and helps to cool localized hot spots. It reduces the chance of detonation.

Larry
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-22-2005, 09:37 AM
OddRodder's Avatar
CORNFED and INBRED !?!
 
Join Date: Jan 2003
Location: Springfield, MO.
Age: 53
Posts: 612
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
car guy, just do a search for "quench" from the tools at the top of the page. You will find something like 406 threads, many discuss quench in detail. Happy reading!!!
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-22-2005, 09:42 AM
just another car guy's Avatar
Member
 

Last journal entry: 50 chev p/u project
Last photo:
Join Date: Jun 2004
Location: Brightwood, OR
Age: 45
Posts: 70
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ok next question: How would you check/measure this when building? I've built 3 engines so far & never even heard of that, I know if there's contact you get the piston slap like if you were to over rev a tired engine.

thanks for the help

Dan
__________________
Dan
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-22-2005, 09:45 AM
just another car guy's Avatar
Member
 

Last journal entry: 50 chev p/u project
Last photo:
Join Date: Jun 2004
Location: Brightwood, OR
Age: 45
Posts: 70
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by OddRodder
car guy, just do a search for "quench" from the tools at the top of the page. You will find something like 406 threads, many discuss quench in detail. Happy reading!!!
ok thanks, you must have replied just as I posted the last one
__________________
Dan
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 05-22-2005, 09:57 AM
OddRodder's Avatar
CORNFED and INBRED !?!
 
Join Date: Jan 2003
Location: Springfield, MO.
Age: 53
Posts: 612
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
There are many variables to the "quench effect" and not everyone agrees what works best. The effect appears to be greater with flat-top or dish pistons when compared to pop-ups. And, some head designs don't have a quench area to speak of (HEMI)!!
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 05-22-2005, 01:27 PM
Member
 
Last photo:
Join Date: Mar 2003
Location: Bakersfield, CA
Posts: 397
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Guys, thanks a lot for your input. I will go over a few questions:
1.
Quote:
Id combat the detonation via timing and tune before I started tossing torque converters at it.
I've done it. Bought an adjustable distributor vac. canister, diff. weights and springs. The engine was retarted way down to 2* BDTC, ran hot, sluggish etc. Bought a new distributor Mallory HEI. Now my BDTC is 7* with total at 31* by 2800-2900* rpms.
2.
Quote:
What measures have you taken already to fix this?
- verified my TDC - checked right on the timing mark
- installed 160* t-stat
- alum. radiator
- colder spark plugs
- started mixing diff. octane gas (racing + 91), currently running avgas and 91 (50/50)
- richened up my 750 carb
3.
Quote:
Why would you ever build a motor with that much is a guess.
Change the head gaskets.
That was my first engine, I am a newbie. I wish I would have sincerely known the side-effects of the quench.
- My current gasket thickness is 0.026". Is there anything out there thinner than that?
4.
Quote:
Since you don't say it pings in Drive (3rd) i'll assume it doesn't?
If I take off in D (drive), the tranny shifts too quick, so I am going at 15-20 mpm in the 3rd, thus lugging the engine. At 2000 rpm I start hearing the rattling noise. That's why I figured to replace the t-converter with a higher stall.
5.
Quote:
How does it run with the vacuum advance disconnected & plugged?
I've tried that with the same effect. I replaced the springs with the most stiff ones to avoid the advance coming in too quick.
6.
Quote:
If that doesn't help get an adjustable MODULATOR VALVE for the transmission.
I rebuilt the tranny with a kit that had the adj. modulator. Right now the screw is turned all way in. This helped a lot with pinging, however in stop and go traffic it occasionally still happens.

Should I get copper(?) head gaskets that are thinner than mine?

I need another torque converter for a stock pickup truck I just bought. I will leave my current 1900-2000 rpm one for that and get a new one for Camaro. Should I aim for a B&M 2400 rpm t-conv. or go with a more radical one?

If I go with a 72cc heads, will quench cause the same problems I am having now with my 64cc heads? I am just trying to avoid to pull the engine out and rebuild it again with zero-decking etc.

Thanks again for helping me out. I really appreciate it.

Denis
'67 Camaro RS
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 05-22-2005, 02:25 PM
NXS's Avatar
NXS NXS is offline
wind & fire = guides to power
 
Last photo:
Join Date: Nov 2004
Location: Oklahoma
Posts: 1,534
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Oh, i gotcha now. It shifts too quick, lugs the engine then pings! Does your kickdown/TV cable have any adjustment in it? if not

--better get that stall--

and with .026" headgaskets you have .085" quench? are these the wrong pistons? did you use rosin core solder b/c it can expand.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 05-22-2005, 02:31 PM
wshinn's Avatar
Member
 
Last photo:
Join Date: Feb 2005
Location: Kansas
Posts: 80
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The 76cc head should lower your compression ratio and this would theoretically let you run lower octane fuel without pinging/detonation. I am not sure that the solder rod method for measuring quench height would provide a good measurement (assuming you pushed in through an open spark plug hole and cranked the engine). Standard deck height (distance from top of block to top of piston at TDC) on most engine rebuilds for SBC is about 0.025 inches. More than likely this is what you have. Adding about 0.038 inches (for the width of the head gasket) to the deck height would put you at about 0.063 inches which is reasonable.

Your basic problem is the compression ratio with the iron heads, as previously suggested. I ran into this same problem running 9.7:1 this past week with a 383 vortec setup I recently completed. It ran fine on 93 octane pump gas with the total timing (mechanical) at 35 degrees and with the Proform distributor factory vacuum advance. However, it wouldn't run without pinging on 91 octane even with the timing significantly retarded.

I solved the problem by disconnecting and plugging the vacuum advance canister and the vacuum port on the carburetor. I set the total mechanical advance to 34 degrees and have totally eliminated the detonation issue with running 91 octane gas. May not work for you, but itís worth a try if you haven't tried it already.

Good luck.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 05-22-2005, 02:39 PM
lluciano77's Avatar
Short changed on common sense
 
Last photo:
Join Date: Jun 2003
Location: california
Age: 37
Posts: 3,548
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
You need race gas unless you are running over 11.5:1 compression. Running more octane than needed is bad for your engine. It seems a lot of people run it just to be able to say they do.

9.7:1 is nothing. There were other issues other than compression if you were seeing detonation with 91 octane. The vacuum advance being one of them.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
torque converter IDENTIFICATION 327amc Transmission - Rearend 5 03-26-2005 07:23 PM
Is my jeg's brand torque converter a dud? elukas Transmission - Rearend 5 10-07-2004 12:08 PM
C5 or Torque Converter Bad? k2mooch Transmission - Rearend 2 11-30-2003 09:27 PM
Torque converter upgrade gpeak Transmission - Rearend 1 11-15-2003 09:58 PM
What Can I Really Expect From a High Stall Torque Converter ? white66coupe Transmission - Rearend 3 05-25-2003 06:21 AM


All times are GMT -6. The time now is 06:44 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.