Ignition/Carb Help Please

ratlee2

I am trying to chase down an annoying hesitation on my newly rebuilt 262 with twin H.  I am trying to narrow down between an issue with the carbs or an ignition issue.  Car idles really smooth at 500rpms and revs up great, but seems to have a hesitation under load between 30-45mph.  Hesitation goes away after transmission shifts into 4th gear.

I installed new spark plugs, wires, cap and rotor, and coil after the rebuild and I am running a crane fireball electronic ignition in my 12volt system (rewired car about 8 years ago). I also replaced fuel with fresh 92 octane gas as it was a couple years old.  Since breaking in the engine, I tuned the twin h with a unisync and adjusted the hydramatic kick down linkage to shift into 4th gear at 45 mph.  The hesitation was still there.

I rebuilt both carbs with kits from Daytona carb since the car sat a few years before the rebuild. I readjusted and balanced the carbs and verified both accelerator pumps are working correctly. The hesitation was still there.

I installed a timing tape on the balancer and verified I have 6 degrees of initial timing and I am all in at 20 degrees about 2000 rpms.  The vacuum advance also moves and holds vacuum when I pull a vacuum.  If I am reading the manual correctly the 20 degrees should be correct.  6 degrees initial + ~4.5 vacuum + ~9 mechanical.  20 seems low to me as the Small block Ford engines I am used to are usually 36 degrees total advance.  The distributor number is #IAT4009B, is that correct for a 53 with 262?

Is my issue more likely a carb issue and I need to adjust the metering rods since it smooths out at cruising speed?  I saw someone on this site sells a metering rod tool.  Are they the same between the 262 and 308 and will they work with the 990S carbs?

Sorry for the convoluted post, but not sure where to go next on this.

Rich   

  

iceblade10

IAT 4009B is what I have in my 54 Hornet 308.  My gut tells me that it's probably NOT what was stock for a 53 262, but I don't know that for sure.  Nor do I know if that would cause your problem.  

iceblade10

I read some older posts and found conflicting info.  Some people say the 4009B will fit "any" wide block stepdown engine.  Others say the 4009 is for 232, the 4009A is for 262, and the 4009B is for 308.  If that last bit were true, that might cause a problem?  The advance and centrifugal bits are different between a 4009 A vs. B, apparently.  But it sounds like a lot of people are running these 4009Bs in different engines, so I dunno...

Jay_G

My guess is the carbs.  Although you could put a little more advance in to see if it helps.  Just listen for pinging. Does your hesitation happen at the same RPM range no matter the gear? or only when you are accelerating at a slow pace?  (very little to no accelerator pump action).  Also is the Twin H original to the car or purchased as an add on?  I say this because I have purchased Twin H setups with "matching carbs" and they are not.  I would take the carbs apart and look at the jet and metering rod numbers.  If they are not the same, there is your problem.  The Carburetor Shop (on the web) can supply you with matching jets and rods.  On all my purchased Twin H setups the carb insides never matched nor were they what the book said they should be, someone has always messed around before I got there.

The guy at The Carburetor Shop purchased all the Carter NOS stock as well as the prototyping equipment for the metering rods and jets.  So he will make a matching set if he does not have them in NOS.  You must start with matching carbs in order to get the system working correctly.  Also check for wear around the throttle plates and rods as they can let air pass and create a lean condition and other issues.

Hope this helps. Jay 

Glowplug

Long distance trouble shooting is a SHOT in the DARK... 
My suggestion is to take a close look at the vacuum during all phases of the engine operation.  I should point you to the appropriate offender.  The hesitation you note at a specific speed under load had the characteristics of several things... the vacuum gauge will focus you.    Good Luck
 

ratlee2

Thanks guys.  After reading the comments and looking at Ken's website.  I am going to pull out the vacuum gauge and see what I have and set the timing with the gauge. 

ratlee2

Thanks for the help guys.  I made some progress with the car yesterday.  When I went to install the vacuum gauge on my manifold inlet I found out that the hard pipe connections from the manifold to the fuel pump were loose.  After installing the gauge I had a steady 17 " hg.  I advanced the timing and it came up to 20" hg.  After reviving the engine a couple times I noticed it would not always return to the exact same reading.  I pulled the distributor cap and found the shutter wheel sensor on my electronic ignition was loose and causing the sensor to move.  I re-phased the sensor and took it for a test drive.  The hesitation appears to be gone, but I will need to retune the carbs again.  It seems to like 8-10 degrees initial timing with 92 octane which puts it slightly past the timing marks on the flywheel.  Does that sound right to you guys?  I realize fuel octane ratings and quality has changed over the years, but don't notice any pinging under load.

Glowplug

On the correct path!  Great progress and when you get the unisync on those carbs your tune should set at the best place.