Don't think valves were too far out. This engine seems to be more sensitive to carb./timing adjustment than I was used to. You always think new carbs will be close to 'good to go'. Mike has told me new carbs are good, but usually need fine adjustment or mods to make them run 'perfect'.
Low engine vacuum?
- Thread starter VortecZ
- Start date
First off, glad you got it figured out VortecZ.
There's a certain "feel" required to lashing valves, be it solid or hyd., and everybody has a "different" feel so to speak, not to mention how to get there. I have done many GM hyd., many are set at 1/8 from "Zero", the question is what is Zero to one, may be 1/8 of a turn already to another...just saying.
I've had some brand "NEW" carbs that were so bad internally they had to be returned for full refund and exchange....and not talking about the "economy" line carbs from large volume warehouses or blems being cleaned up and re-sold. Pretty bad when old greyed out 35 yo zinc kicks the new billet/anodized stuff in some cases.
They all need fine tuning, some just need lots of it to get them just "right".....but then when you do, the payoff is worth it.
Some think carbs are dead....not around my parts, maybe I just attract fussy customers LOL.
There's a certain "feel" required to lashing valves, be it solid or hyd., and everybody has a "different" feel so to speak, not to mention how to get there. I have done many GM hyd., many are set at 1/8 from "Zero", the question is what is Zero to one, may be 1/8 of a turn already to another...just saying.
I've had some brand "NEW" carbs that were so bad internally they had to be returned for full refund and exchange....and not talking about the "economy" line carbs from large volume warehouses or blems being cleaned up and re-sold. Pretty bad when old greyed out 35 yo zinc kicks the new billet/anodized stuff in some cases.
They all need fine tuning, some just need lots of it to get them just "right".....but then when you do, the payoff is worth it.
Some think carbs are dead....not around my parts, maybe I just attract fussy customers LOL.
annamartino
New Member
- Jan 18, 2023
- 3
If you've done all the testing for leaks externally, Speed Test pull the intake manifold and inspect the gasket. Good luck and welcome to NastyZ.
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vatedome04
New Member
- Jan 9, 2023
- 1
A vacuum reading at idle that is much lower than normal might indicate leakage through the intake manifold gaskets, manifold to carburetor gaskets, vacuum brake booster or the vacuum modulator. Low readings could also be caused by very late valve timing or worn piston rings
Good to hear, sounds like your next steps is carb tuning, keep us posted what you find out with the carb come springtime.
Good eye....that's my R&D "house" carb....over 75k in cash winnings and 3 track championships in 2022, with one customer, he's happy LOL.
Me likes the shiny gold one on the red carpet...
Good eye....that's my R&D "house" carb....over 75k in cash winnings and 3 track championships in 2022, with one customer, he's happy LOL.
Resto_Paul
New Member
- Sep 28, 2022
- 2
Hey VortecZ how have you made out with your most recent tuning? I'm back at it with mine trying to tune the backfire out of my lake header exhaust. I still have the tripower on my engine and found the front carb pulling air past the closed throttle blades today. It seems like I have an intermittent misfire on cyl 1 at idle and I'm guessing that's also the one giving me the big backfire. All ignition components have tested good....even upgraded to a new MSD distributor. Also put a brand new plug in that cylinder yesterday. Was pulling plug wires at idle to see what made the biggest or smallest change. Cylinder 1 caused the least change to idle but damn thing lit me up like a Christmas tree when my hang got to close to the end of the wire....plenty of spark on that cylinder. Relashed all the valves on that side yesterday after inspecting the pushrods and springs too.
My idle is probably similar to yours....vacuum floats between 15 and 16hg. Idle will go from fairly steady to a little rough but never like it wants to stall. May be from the misfire. That header primary is still the coolest on the engine too but not cold. Putting blockoff plates on my end carbs tomorrow and going after the tune of the single 2bbl again. Hoping that fixes my backfire and I can move on from there. Truck pulls fairly well with current jetting but the backfire out that side with flames is obnoxious.
My idle is probably similar to yours....vacuum floats between 15 and 16hg. Idle will go from fairly steady to a little rough but never like it wants to stall. May be from the misfire. That header primary is still the coolest on the engine too but not cold. Putting blockoff plates on my end carbs tomorrow and going after the tune of the single 2bbl again. Hoping that fixes my backfire and I can move on from there. Truck pulls fairly well with current jetting but the backfire out that side with flames is obnoxious.
Whoops. Can't find your number.
