Tunnel ram bogs - Page 4 - 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
  #46 (permalink)  
Old 05-07-2013, 06:24 AM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
It did no like that jetting change at all,, WOT.
it is way too rich now @ WOT.
So try 98 primary jet 70x.042 pri rod and 95 secondary jet.

try that...

Overdrive.... This big cammed motor won't be very happy cruising at a low rpm.
Do not force the engine to run in overdrive.. it wants to rev. Let it rev.

Why is the idle AFR so lean... Are you setting the idle correctly for best idle quality using a vacuum gauge?
Are the header gaskets leaking?
I don't have a 70x42 rod. Got 2 tunning kits. 1 for a 1407 and 1 for a 1406 but no 70x42 rod. lol Go figure! LOL I'll do some math and see how close I can get between the 2 kits. Maybe I can get the rods from summit or ?

Was just checking OD. Usually run round 2500+ RPM when using OD on interstate.
Idle was set with a vacuum gauge to best vacuum 9.5-10". Any hints on setting idle with twin carbs? Have 2 vacuum gauges if needed. Been using one off manifold below carbs. Vacuum is same when using 2 gauges.
Header gaskets are pretty new and show no evidence of leaking. 1600 miles on them.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #47 (permalink)  
Old 05-08-2013, 06:48 PM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
When the idle is set up correctly and set for best vac at idle,,, the resulting air fuel ratio should be in the 12.5 to 13.5:1 zone. 14.5 and leaner is too lean at idle Engines idle richer than 14.7:1 normally.

This indicates to me that there is a air leak somewhere on the exhaust system creating false lean O2 sensor reading which throws off all AFRs on a gauge.
Headers and gasket joints can be very pesky.

600carb jetting: well try what you thing will help for your next test.
maybe try stock default jetting as the WOT was very rich.

I have never been big on the 600cfm carbs. The 750's will work better overall in my experience.
One reason is the pri an and sec throttle s are near the same diameter. More even flow on a tunnel ram.
The fuel curve will be better too. No they are not too big.
It would be nice to get that 750cfm carb back in service.
But I guess for now you are stuck with working with the 600's.
Let me know how you next test works out.

tell me something: when setting up the idle mixture and adjsuting the idle screws while watching the vacuum gauge, tach rpm and AFR gauge are you able to shift the gauge AFR rich with the 4 mixture screws counterclockwise is "richer" or is it always leaner than 14.7:1 at idle, reguardless of mixture screw adjustment?
As you should end up in the 12 to 13.5:1 area at idle.

Possible intake manifold gasket leak....probable exhaust leak even at the O2 bung.
Oh yes, always been able to shift the AFR at idle with the IMS screws. Poured marvel mestry oil down carbs at high idle to make smoke looking for an exhuast leak but didn't see any.
AFR looking better? Still looks rich to me at normal cruise and way rich at WOT. I did some math on the jetting and rods looking for as close to setting you suggested last: 95 & 70x37, 98 last log run, u suggested 98 70x42, 95 sec. not having a 70x42 I went with 101, 73x42 and 95 sec. Way i did the math was deduct the rod sizes from the main jet sizes:
95 - 70x37= 25x58 and 98 secondary
98 - 70x37=28x61 and 95 secondary
98 - 70x42=28x56 and 95 secondary
101 - 73x42=28x59 and 95 secondary
Hope this makes sense?
Bout what AFR differance would be in, say, a 3point differance in sizes as in
98 - 70x37=28x61 and 95 secondary (61)
98 - 70x42=28x56 and 95 secondary (56)

Just hit me! I was looking at the rods backasswards! Will try a 101, 73x52 and 95 sec tomorrow.

Last edited by Fang16; 05-08-2013 at 06:58 PM.
Reply With Quote Quick reply to this message
  #48 (permalink)  
Old 05-08-2013, 07:00 PM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Guess the logs would be nice.

Here's the logs I forgot in above post.
Attached Files
File Type: txt 05081300-Session 1.txt (121.2 KB, 30 views)
File Type: txt 05081300-Session 2.txt (124.2 KB, 28 views)
Reply With Quote Quick reply to this message
  #49 (permalink)  
Old 05-08-2013, 10:23 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 57
Posts: 9,664
Wiki Edits: 0

Thanks: 448
Thanked 1,024 Times in 969 Posts
fyi.there are 3 step rods available.something to consider when you get closer to tune.They work good on the street when you do a 2/3 throttle.(Brisk take off while just hazing the tires)
Reply With Quote Quick reply to this message
  #50 (permalink)  
Old 05-08-2013, 10:35 PM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by vinniekq2 View Post
fyi.there are 3 step rods available.something to consider when you get closer to tune.They work good on the street when you do a 2/3 throttle.(Brisk take off while just hazing the tires)
I have the tunning kit for the 1406 and also 1407 carbs.
Reply With Quote Quick reply to this message
  #51 (permalink)  
Old 05-08-2013, 11:55 PM
1Gary's Avatar
Registered User
 

Last journal entry: 383 dyno sym
Last photo:
Join Date: Oct 2010
Location: Roch,NY
Age: 67
Posts: 1,552
Wiki Edits: 0

Thanks: 201
Thanked 156 Times in 142 Posts
Fang.I get it.You like figuring out this.Yep-I get that.My question to you knowing this manifold was never designed to run at part throttle and no matter what there are trade-offs,is it really worth it??.

I mean how often are you going to buzz this from 5,500 to 7 grand where this tunnel ram comes alive??.

Do take a third party look and think long and hard about that.Guys respect you for the car alone.Ya know.Nothing like a long pleasurable cruise too.

Just think about it some.
Reply With Quote Quick reply to this message
  #52 (permalink)  
Old 05-09-2013, 08:53 AM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
You cannot do that.... you have to calc the area of the jet and area of the rod.
Subtract rod area from jet area.... not diameter.
AREA..

set the idle for best vacuum and idle quality ... should be 12.5:1 to 13.5:1 ish... you got it too lean at idle.

area of a circle is Pi x (radius squared) Pi='s 3.1416 radius is diameter /2

You cannot find an exhaust leak by dumping junk down the carb and looking for smoke.
Get a grip.
How do you find an exhaust leak if there are no visable signs of one?
Reply With Quote Quick reply to this message
  #53 (permalink)  
Old 05-09-2013, 08:57 AM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by 1Gary View Post
Fang.I get it.You like figuring out this.Yep-I get that.My question to you knowing this manifold was never designed to run at part throttle and no matter what there are trade-offs,is it really worth it??.

I mean how often are you going to buzz this from 5,500 to 7 grand where this tunnel ram comes alive??.

Do take a third party look and think long and hard about that.Guys respect you for the car alone.Ya know.Nothing like a long pleasurable cruise too.

Just think about it some.
Thanks Gary! Seems I lost site of the big picture. Hit the track 6-8 times a year and was just concentrating on that. We lives and we learn. Thanks again!!
Reply With Quote Quick reply to this message
  #54 (permalink)  
Old 05-09-2013, 10:31 AM
spinn's Avatar
Reviewing the situation
 

Last journal entry: This makes a huge difference
Last photo:
Join Date: Oct 2004
Location: here
Posts: 2,555
Wiki Edits: 0

Thanks: 14
Thanked 88 Times in 85 Posts
A exhaust leak can be found by listening . Stuff a shop rag in the tailpipe with the engine running. Follow the exhaust piping. It will increase the backpressure sos that you hear the leak better.
Reply With Quote Quick reply to this message
The Following User Says Thank You to spinn For This Useful Post:
AutoGear (05-09-2013)
  #55 (permalink)  
Old 05-09-2013, 11:04 AM
1Gary's Avatar
Registered User
 

Last journal entry: 383 dyno sym
Last photo:
Join Date: Oct 2010
Location: Roch,NY
Age: 67
Posts: 1,552
Wiki Edits: 0

Thanks: 201
Thanked 156 Times in 142 Posts
Quote:
Originally Posted by Fang16 View Post
Thanks Gary! Seems I lost site of the big picture. Hit the track 6-8 times a year and was just concentrating on that. We lives and we learn. Thanks again!!
Yeah.We have had a number of 9.90 cars over the yrs.I do think we are sharp tuners.Some of the cars did have tunnel rams.Talk about learning,what we found is they where not as consistent and where more susceptible to minor climate changes.We have been using weather stations for yrs.We did get a data log on them and somewhat had a handle on it,but at the end of the day the raiser single 4 worked overall better.So we left that chapter behind us and never returned.
The tune on these is not static where you are going to be making adjustments on it long term.One thought I always have is where I see a car at a car show that is outlandish just setting there,well really two,that guy really knows his sh**t and most of the crowd passing by don't know the back story to the car to get there(maybe the week before of prep work)not like the articles in a fan car magazines.
Reply With Quote Quick reply to this message
  #56 (permalink)  
Old 05-09-2013, 11:17 AM
Registered User
 
Last photo:
Join Date: Jun 2010
Location: Syracuse, NY
Posts: 2,641
Wiki Edits: 0

Thanks: 1,208
Thanked 325 Times in 279 Posts
One of the fastest hot rods I ever saw was a 56 chevy with twin turbos mounted underneath the car. This thing was absolutely quiet at idle...like Targetmaster crate motor quiet. Blow through carbs on it...TONS of time on the dyno to tune it. And MAN would that thing come on after about 150ft....just freight train people. He had 3.08s and an automatic.

If you go unconventional, there will be some give-and-take. But for some people, the theme, or just taking the road less traveled is worth it. In the end thats what makes this hobby great.
If you want the tunnel ram; keep it, just know that on the street a guy with a purpose built dual plane single 4bbl is going to probably beat you.
Theres always more compression and E85 LOL
Reply With Quote Quick reply to this message
  #57 (permalink)  
Old 05-09-2013, 02:50 PM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by spinn View Post
A exhaust leak can be found by listening . Stuff a shop rag in the tailpipe with the engine running. Follow the exhaust piping. It will increase the backpressure sos that you hear the leak better.
You haven't heard my car. (loud) lol Headers, 20" pipe, flowmaster 10's. HUH? Will try the shop rag trick though. With them in the exhaust should be a lot quieter.

Last edited by Fang16; 05-09-2013 at 03:00 PM.
Reply With Quote Quick reply to this message
  #58 (permalink)  
Old 05-14-2013, 09:45 AM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by 1Gary View Post
Yeah.We have had a number of 9.90 cars over the yrs.I do think we are sharp tuners.Some of the cars did have tunnel rams.Talk about learning,what we found is they where not as consistent and where more susceptible to minor climate changes.We have been using weather stations for yrs.We did get a data log on them and somewhat had a handle on it,but at the end of the day the raiser single 4 worked overall better.So we left that chapter behind us and never returned.
The tune on these is not static where you are going to be making adjustments on it long term.One thought I always have is where I see a car at a car show that is outlandish just setting there,well really two,that guy really knows his sh**t and most of the crowd passing by don't know the back story to the car to get there(maybe the week before of prep work)not like the articles in a fan car magazines.
Went to Tulsa last Saturday, ran 1/8 mile (didn't know they were only doing 1/8 mile) Not geared for that but using your advice and F-bird's, looking at the big picture, jetted the carbs to what I thought was needed, knocked over a second off 60' and ET, turned a 7.37@89+ n a 7.39@89+. Wanted to thank you and F-bird big time for all the help!! Came out of the hole at idle and just put the peddle to floor, no bog, just go like he**!!!! Still some tunning to do but well on my way now.
Reply With Quote Quick reply to this message
  #59 (permalink)  
Old 05-14-2013, 09:47 AM
Registered User
 
Last photo:
Join Date: Jun 2010
Location: Syracuse, NY
Posts: 2,641
Wiki Edits: 0

Thanks: 1,208
Thanked 325 Times in 279 Posts
YEE HAW! feels good don't it
Reply With Quote Quick reply to this message
  #60 (permalink)  
Old 05-14-2013, 09:52 AM
Fang16's Avatar
Registered User
 

Last journal entry: A little cancer
Last photo:
Join Date: Mar 2010
Location: Rogers, Ar.
Posts: 314
Wiki Edits: 0

Thanks: 9
Thanked 13 Times in 13 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
The flow master mufflers are not your best bet.
Every car I have worked on that had flowmasters picked up significant performance by removing them or replacing them with a different high performance muffler design.
Louder than they need to be. There are better design mufflers that are both quieter and more powerfull.

Any exhaust leak 25" to 30" fore or aft of the O2 sensor on the pipe will throw off the O2 sensor reading.
Next I'll be trying open headers. lol What mufflers do you like? Could quite it down a little to keep piece with the neighbors. lol
Here's the same Thank You I posted to 1Gary.
Went to Tulsa last Saturday, ran 1/8 mile (didn't know they were only doing 1/8 mile) Not geared for that but using your advice and F-bird's, looking at the big picture, jetted the carbs to what I thought was needed, knocked over a second off 60' and ET, turned a 7.37@89+ n a 7.39@89+. Wanted to thank you and F-bird big time for all the help!! Came out of the hole at idle and just put the peddle to floor, no bog, just go like he**!!!! Still some tunning to do but well on my way now.
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:
Insurance
Please select your insurance company (Optional)

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: 2 (0 members and 2 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
To tunnel ram or not to tunnel ram maverickmechanic13 Engine 107 03-04-2012 07:33 PM
tunnel ram blazinlow Engine 3 05-21-2011 06:31 AM
sbf hi ram tunnel ram 72fordlb Engine 9 04-13-2009 04:15 PM
Tunnel ram? HemmiGremmie Engine 5 09-02-2003 05:40 PM
a tunnel ram? jboxcar818 Engine 2 12-11-2002 09:04 PM


All times are GMT -6. The time now is 11:00 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.