Lifter tap?
#41
I've tracked the " whistle " down to the drivers side vacuum secondary butterfly.
Get the engine hot ( properly hot not warm) let it tick over and no whistle, rev the engine up properly and the whistle appears, I put a rubber stethoscope down the centre tube of that venturi ( which confirms the noise is from there)  onto the butterfly and it stops.
So something is blocked/stuck/loose  Huh

Anyway I see a carb rebuild on the cards.
Any thoughts?

Thanks
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#42
You can try opening the secondary's a little.  There is a small set screw in the base plate on the right side of the carb that is accessed from the bottom.  Sometimes the carb has to be removed to get to it.  That will increase the idle speed.  So you will have to slow it back down with the idle speed screw on primaries and maybe readjust the A/F screws.

There is a procedure with Holley carbs to set the idle speed.  Many mess it up then complain about performance.  On the primaries the idle screw is adjusted so 0.020" to 0.040" of the transfer slot is exposed below the primary throttle plates.  That is typically done with the carb off and upside down.  There is a little adjustment room to keep it in the 0.020" -0.040" range.  After that stop tinkering with the primary side idle speed screw to set idle speeds.  Instead fine tune the idle speed with the secondary's.  Then readjust the A/F screws if needed.  For those with very aggressive cams additional measures of holes in the throttle plates are needed to let more air into the motor without messing up the idle speed screw setting.
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#43
(07-21-2021, 02:15 AM)1969_Mach1 Wrote: You can try opening the secondary's a little.  There is a small set screw in the base plate on the right side of the carb that is accessed from the bottom.  Sometimes the carb has to be removed to get to it.  That will increase the idle speed.  So you will have to slow it back down with the idle speed screw on primaries and maybe readjust the A/F screws.

There is a procedure with Holley carbs to set the idle speed.  Many mess it up then complain about performance.  On the primaries the idle screw is adjusted so 0.020" to 0.040" of the transfer slot is exposed below the primary throttle plates.  That is typically done with the carb off and upside down.  There is a little adjustment room to keep it in the 0.020" -0.040" range.  After that stop tinkering with the primary side idle speed screw to set idle speeds.  Instead fine tune the idle speed with the secondary's.  Then readjust the A/F screws if needed.  For those with very aggressive cams additional measures of holes in the throttle plates are needed to let more air into the motor without messing up the idle speed screw setting.
Fair enough, I'll give it a go thanks
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#44
Holley has a video on their website discussing what I mentioned about adjusting idle speeds.
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#45
(07-23-2021, 01:16 AM)1969_Mach1 Wrote: Holley has a video on their website discussing what I mentioned about adjusting idle speeds.
I've taken the carb apart to fit a rebuild kit and have found the screw you talked of for the secondaries ( shame it's so hard to get to when the carb is fitted) I'm going to clean everything up and then start putting it back together then I will watch the video and try and set it.
To be honest I never intended to "adjust or alter" any settings as it has always run and started very very well it was just to stop a couple of very very small leaks ( seeping through the gaskets rather than leaks) and also to make sure it was clean inside  which it is, no crud whatsoever.
I've got a new choke arm, a red one ( all I could get at the time) but it's an amber ( old dirty brown) fitted, will the new one be ok do you think? I assume its the "steps" on them that make them different.
I've modified the new 1/2" spacer by fitting the PCV metal pipe from my original spacer in it so at least it cant be a cracked spacer making any noise etc.
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#46
Rebuilt my Holley yesterday and the rear bowl had a "normal" 3 piece needle and seat but the front bowl has a one piece "This solid type of needle & seat was used on some industrial and truck applications" one fitted!
My rebuild kit had 2 "normal" ones so I had to put the solid one back in, can anyone suggest why I've both types and where can I get a replacement for the solid one?
I forgot to say I can't swop it for the normal one as the solid one has a larger dia thread.
Someone changed the front bowl at some time?
Thanks
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#47
Sounds like you got a one piece at a time carb. LOL!

JTS
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#48
Do you have any pictures of the carb.  It sounds like it has some mismatched parts.  A float bowl was probably replaced at some time.  Does the carb have the correct List Number for your motor?  What brand rebuild kit did you use?  I try to use Holley brand on Holley carbs.
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#49
More of a "one piece at a time car"  Huh
I always knew the carb wasn't right for the car ( 4 barrel on a 2 barrel block) but I've found a place in New Jersey that has 7/16" dia needles instead of the 3/8" ones
The kit was a cheap one from Rock auto and did the basics ( gaskets good ) everything I buy is a risk as it never pays to try and return anything ( shipping is often 50 / 70% of the parts) so I have to weigh up "wastage" and bite the bullet if it's no good.
On the good side I reset the primary slot ( squared it off with the butterfly) and she started up easily and smoothly, problem was she wouldn't tick over so I cheated and opened the primaries as I was more interested in if my rebuild had upset the settings too much but I went for a 40 mile run and she was fine, smooth, no hesitation so I suppose I have to ease back on the primary and try and open the secondaries with that horrible little screw  Exclamation
The A/F screws have plastic type seals which I put back in as I didn't realise the thick cork washers in the kit were replacements so thats a future job as they aren't leaking but are old and will need changing sometime.
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#50
Adjusting the secondary's for idle is so common and needed, for the mechanical secondary carbs Holley a lever that attaches to the secondary shaft and has an adjustment screw that's easily assessable from the top.
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