Rod and Jet for 350 Truck - 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 04-09-2008, 05:21 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 665
Wiki Edits: 0

Thanks: 1
Thanked 3 Times in 3 Posts
Rod and Jet for 350 Truck

Does anyone know what a good rod and jet combination would be for a 72 Chevy 350 in a truck? I am having a little problem towing my 5000lb trailer. I would like to try some different rods before I go to the expense of putting on a Qjet. The truck runs fine except for some pinging when towing. Initial timing is at 12. MSD ignition headers Carb is a 1406 with EPS manifold. Plugs are clean and to the white side.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-09-2008, 06:10 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Do you know what rods and jets are in it now?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-09-2008, 06:57 PM
Member
 
Last photo:
Join Date: Nov 2004
Location: Lakeland FL
Age: 65
Posts: 4,110
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
hey Mertz...been awhile...

stock rods in the 1406 are for "economy" .075/.047 aka:"lean"

yes, it is likely that a thinner rod for richer will help when towing...and put in the stiffer springs so that the rods will pop up to the richer position when there is less load on the motor (pop up at a higher Hg) ....

I don't have the kit or book handy but try the .070/.037(?) rods and which ever colored spring is rated the strongest (silver?)...

unless you have really tall rear gears and tall tires that should fix it with the stock 98 jets...
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-10-2008, 03:26 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,025
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
try a 68x42 rod pair Edelbrock #1446
If your cylinder heads use a 5/8"hex .460" reach spark plug (AC R44TS stock plug)
Change the plugs to a AC R42T or Champion RV8C, Autolite #144

Just a bit cooler heat range to hold off detonation while towing.

Last edited by F-BIRD'88; 04-10-2008 at 03:32 AM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-10-2008, 01:48 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 665
Wiki Edits: 0

Thanks: 1
Thanked 3 Times in 3 Posts
I have be gone awhile working some other projects. Last year I was changing my stock carbs on my 260Z to webers. Everything went fine and didn't need any help. I also built a couple of wind generators, something a bit different than hot rods. This year I will be rebuilding the top end on my 66 Catalina convertible with a 428. It has always overheated and I have tried tuning, etc to fix it. It is hard to start when hot even with the new starter. The thing that worked the best was a tube of alumaseal which confirmed the possibilty of a leaky head gasket. I am sure my carb is to small as well. Running a swap meet Carter AFB of unknown size but assume it is 600 cfm.

I am sure I will be here for that project. I also have had a few questions on Qjets lately. I intend to put one on my truck for sure and hopefully will have the funds to put one on my Catalina. I have 3 rebuildable ones laying around the house (one is a built by Carter version) but I think I would be better off buying a rebuilt and tuned carb. I had a terrible time rebuilding the carbs on my Corvair. I had an expert help me. When I gave up and sent them to him he returned them with a long list of things I did wrong even though I followed all the directions.

It's good to be back. I will try the rods you suggest on the Edelbrock until I find my Qjet.

Anyone want to trade a Carter AFB and an Edelbrock 1406 for a couple of electric choke Qjets?

BTW the rod change is just for the primary right? Do I need to change the secondary as well?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-10-2008, 03:42 PM
Member
 
Last photo:
Join Date: Nov 2004
Location: Lakeland FL
Age: 65
Posts: 4,110
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
CRS is so much fun!

went and got the label out of the tune up kit to scan into my computer...."found" my Edie book I've been looking for high and low...."in the scanner"

anyway, .070/.037 is about 10-12% richer and you may not need that much

try the .073/.042 rods and silver springs in the kit....it will save a buck or two on gas...

so that's how you do it!!!
build wind turbines to have a lower electric bill to have pocket money for all your car projects!!!
glad to hear your doin' well
Attached Thumbnails
Click image for larger version

Name:	Edie tune up kit.jpg
Views:	71
Size:	129.1 KB
ID:	29161  
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 04-10-2008, 04:10 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Red65 and F-Bird

Do you think he would be better off with this combo jets and rods?

104 jets and 7342 rods Edlebrock #'s 404 and 1455

I don't have a desk top program to figure this out for me, if either one of you do punch it in and let me know. Please!
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 04-11-2008, 01:56 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,025
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
There are no rods on the sec side. Just a jet. if you are not towing on the secondaries, hen no sec adjustment should be nessessary. Try the rod change I listed, Saving the pistons is a lot cheaper than saving a bit of fuel. You need to burn fuel to make power. "White" is way too lean for towing.
Brown/tan/redish is good.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 04-11-2008, 10:52 AM
Member
 
Last photo:
Join Date: Nov 2004
Location: Lakeland FL
Age: 65
Posts: 4,110
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
car savvy,
no DD needed, its a simple arithmetic compare

F-bird recommended a .068/.042 rod

stock .098jet - .068 rod obstruction = .030 "donut shaped opening" thru the jet for fuel to pass thru

your .104 jet - .073 rod = .031 "donut shaped opening"

.031/.030= your high Hg cruise opening is only 3% bigger than F-birds so it's not worth changing the jet....potential fuel flow for either is basically the same

stock is .098-.075=.023
so F-birds .031 hole is .031/.023=34% bigger hole than stock (that's alot) at high Hg

(same arithmetic compare applies to the low Hg thinner rod section "rich" step)

F-bird is saying .098jet-.042=.056 opening when the Hg is below 5Hg...
your .104 jet -.042 rod=.062 opening
.062/.056=your combo has a 10% bigger opening than F-bird
stock is .098-.047rod=.051 opening in the rich position
your .062/.051 stock= 21% larger opening than stock

to find the net actual metering % changes results...do the same "hole size" math compare on some of the examples in the tuning book....(the chart saves a PIA step, it calculates the jet sq"s area (pi r squared) minus the rod obstruction sq"s of area)
EX:
I said use a .070/.037 rod for rich low Hg
.098jet-.037rod=.061 opening
.098jet-.047rod=.051 stock opening

.061/.051=19% bigger hole = 12% richer on the chart= basically it's a 2/1 ratio for hole size % change to net mix % change

so now you can calculate the expected mix results with your "not on the 1406 chart" .104 jet and 21% bigger hole low hg opening .....it's about 12% richer mix same as the .098 and .037 rod combo I posted (when the Hg is below the stock orange 5Hg rated spring)(silver spring goes to the richer rod step at 8Hg aka:"sooner" as the motor load increases

the simplicity of adjusting the mix and knowing it won't change is why I do like the Edelbrock

I used to bracket race my car at the strip (a lot of fun playing "mind" games change the ET numbers on the windshield)...I could predict within about .2 sec what my ET would be by just changing the base timing and the rods to richer or leaner between rounds (make it too rich on purpose and/or not enough timing)

hope that helps

ps: do measure the rod steps with micrometers...they aren't exact as marked....
and you can hand sand a rod step to whatever diameter you want to get a custom combo for just say very lean cruise and very rich WOT total 4V gas supply ...600 grit paper and some rubbing compound....
EX:
the kit doesn't have a .068/.042 rod....Mertz could sand the the .073/.042 rod down to .068 if it still pings at high Hg with the .070 rod that is in the kit
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 04-11-2008, 11:29 AM
Member
 
Last photo:
Join Date: Nov 2004
Location: Lakeland FL
Age: 65
Posts: 4,110
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
car savvy,

here's the 1406 tuning chart and rods and jets pages

grrrr...300k board limit so I had to re-scan to post as 2 pic's

hey Mertz,
mount your vac guage so you can read it driving so you can tell us what the Hg actually is when it pings....above or below 8Hg?
"if" richer doesn't fix it...it's telling you there's not enough TQ available at that rpms...what cam and gears are in the truck

F-bird,
LOL
some parts of Washington state are flat...some are beautiful mountains...he didn't say where he is lugging around that 5,000 lb trailer...flat=maybe 73/42 is enough....mountains needs probably 70/37 (or sanded to 68/37)
Attached Thumbnails
Click image for larger version

Name:	1406 tuning chart.jpg
Views:	68
Size:	199.6 KB
ID:	29182   Click image for larger version

Name:	1406 rods and jets.jpg
Views:	62
Size:	210.4 KB
ID:	29183  
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 04-11-2008, 01:41 PM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 665
Wiki Edits: 0

Thanks: 1
Thanked 3 Times in 3 Posts
I am on the east side of the state and take my trailer to the St Joe River near St Maries, ID. Some great fly fishing for cutthroat trout. Most of the driving is flat but there are several grades. The one I am having trouble with is a long climb out to the plateau from the lake. It is about a 7% grade. Other than the pinging on this last trip, I don't have any trouble except on that grade. I think part of the problem was in the trans rebuild. The guy that did it fixed my shift rod and found lint on the filter. It pulls better now that I have a new filter. I did use high octane gas to stop the pinging and cut back my timing about 2 to 12 initial.

I think I am going to try the 7342 rods and a silver spring. Edelbrock said I can go half my vacuum reading. I have a vacuum gauge in the car and it read 0 as I was towing the trailer up the grade. I try to drive by the gauge to get the best fuel economy. It idles at about 17 which I think is ok for my 2500 foot elevation. I would like to get more but that is the best I have been able to do. The cam is stock so are the gears. Its a 3/4 ton but the gearing is good for the highway. I am pretty sure that the pinging was above 8 hg when driving on the flat but I can't remember for sure.

Remember I want the best fuel economy I can get during normal driving but have enough torque to pull the trailer.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 04-11-2008, 02:27 PM
Member
 
Last photo:
Join Date: Nov 2004
Location: Lakeland FL
Age: 65
Posts: 4,110
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
Mertz,
your killing me...
any chance of buying me a round trip ticket to "test and tune" drive it on a fishing trip!!!! "no charge" for the rods!

on the Edie, idle Hg is only idle Hg and has no effect on mpg when the primaries are actually working....
dial in the vac advance to show max Hg possible at 65mph with the trailer for best mpg....
that may be as little as 42*TT b+c+v

"0"Hg basically means do downshift for that grade....the carb needs minumum about a 10Hg pulse signal to make a decent "atomized" mix into the intake to make TQ...."0"Hg would be like only one Clysdale horse pulling the Budweiser wagon up that grade....sweating and panting to beat hell!
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 04-11-2008, 02:55 PM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 50
Posts: 4,021
Wiki Edits: 0

Thanks: 0
Thanked 23 Times in 23 Posts
maybe getting too much advance from the vacuum advance. Try running it without the vacuum advance connected. If that helps then get a crane adjustable vacuum advance canister for your hei.

Measure how much the stock vacuum advance is adding to the total timing by checking the timing before and after plugging into a manifold vacuum source. Then reduce the stock advance by 5 degrees with the adjustable canister and run it again. keep reducing until it doesn't ping.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 04-14-2008, 08:53 AM
Mertz's Avatar
Member
 
Join Date: Jun 2002
Location: Reardan, WA
Posts: 665
Wiki Edits: 0

Thanks: 1
Thanked 3 Times in 3 Posts
Hey red, I fished locally this weekend and caught a 26" 5 lb brown trout with a 4wt rod and my wife nabbed a 22" rainbow. I have pictures.

I installed the new rods and the truck screams. I went with the .073/.042. I haven't driven it for about 5 months so I don't really remember how fast is was before making thw switch. I finally was able to burn a little rubber on our chip seal road. It's hard to turn the tires on chip seal especially with truck tires. It sounded and ran fine. I won't be pulling anything until this summer's fishing trip. There was no pinging on my short test drive. I haven't checked the plugs yet.

Vacuum still reads 17 to 18. I could go to the silver spring. The one in it looked silver but the paint probably came off. I am still looking for the qjet although I think the truck is running much better. I will be checking timing again but I thought I was pretty high with mechanical and vacuum plus initial. I am checking it at 2500 rpm. I think I am close to 50 all in now but can't remember for sure.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 04-14-2008, 10:53 AM
Member
 
Last photo:
Join Date: Nov 2004
Location: Lakeland FL
Age: 65
Posts: 4,110
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
mertz,
hell I don't want pictures!
FEDEX me the fish!!!.....it would be 1,000,000,000 "brownie points" with the wife!
(last time she had fresh caught trout was many moons ago in Leadville CO...mentions it constantly)

yes, due to the weight of the truck, the 73/42 rods are likely better....and ....if you bump up the base to 14* it will likely be better yet!!!
(oem recommended base timing is a "compromise" so the car can run at least "decent" anywhere in the world regardless of altitude and ambient temp and gas quality and maybe drag a trailer)....
having a bit more base builds alot more TQ at low rpms aka: better pedal response for a given amount of pedal....
you will need to test for ping on a steep grade dragging the trailer to be sure 14*'s base is not to much to soon timing added with more base....

illustration/example...I don't drag a trailer but:
my intake and dist are marked for 10* and 12* (sbf timing is different)...
in the hot summer I have to back off to 10* or burn 89 octane for no ping at 9.3/1 CR (170psi comp test at sea level))...(stock base is 8*)
(honest, there are hills in central FL)
for in town my .071 hand sanded rod is fantastic for "pep" with the 3.55 gears...
if I am going to my daughters in Boca Raton (500 miles round trip) I do stick the 75 rods in it for a bit better mpg (3500=70mph) but mainly to clean the cylinder heads with a max lean burn because 90% of my miles are stop and go in town...

you need to be thinkin' like that for "with" and "without the trailer"
no trailer= 14 base and about 50TT and 7342rod????
with trailer=12base and about 46TT and maybe the 70/37 rod???

only takes a few minutes to test and have the best for both...

sidenote:
do make a home made exhaust cross over as a "putzin" project for your straight back duals...it is a worth while project to help make abit more TQ for mpg and performance....(the H pipe kit is about $34 if you want quick and simple)
CRS=I haven't recalled (yet) where the O2 sensor and volt meter article is... with the specifics for how to!
CRS= the other day I did remember something I forgot to post on this thread...but now it's gone
(likely because the 2 grandkids totally wore me out this weekend...had a blast with them...one made the Honor roll and one is student of the month so grandpa "treated" "big time"!)

pps: some motors do respond to a carb spacer....buy one for $5? at a yard and try it...or a couple of 3/8" thick heat insulator gaskets from a local store...50/50 shot at it will or won't help
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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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
Re: Ram Jet Motors 1ontokid33 Introduce Yourself 2 09-21-2006 03:16 PM
Crate motor- Carb. or Ram Jet 37Rodder Engine 2 10-05-2005 07:56 PM
Ram Jet, Ramport, or StealthRam EFI? Blownolds Engine 0 12-16-2003 08:47 PM
ram jet 350 engines mike bryan Engine 4 01-23-2003 04:37 AM


All times are GMT -6. The time now is 09:52 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.