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#51 |
Registered User
Join Date: Nov 2012
Location: santa rosa,california
Posts: 650
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Re: Help! 454 bog/die on accel
Dylan
Sorry about that there are two caps held by a couple torx head screws and the springs are called step up springs. |
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#52 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
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#53 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: Help! 454 bog/die on accel
So you built the motor!!
Did you do all the assembly yourself? Did you put the cam/lifters and timing chain in? |
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#54 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
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#55 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: Help! 454 bog/die on accel
I'd bet you got your timing gear off a couple teeth.
Did you align the dots at 6 and 12 or at 12 and 12? |
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#56 |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
When you buy the step-up springs, you get all five sets in one package. Vacuum pulls the pistons down against the spring pressure. Stiffer springs will push the pistons up (and richen the mixture) sooner on throttle application. Go to the max step-up.
I talked to an engine tuner buddy tonight. I asked him about your situation, and his diagnosis is that you are way lean. Backfire through the carb is the giveaway to him. Having the engine heat up quickly and having a hard time cooling it is another sign. When you pop the throttle plate and air rushes in, the mixture goes way leans and the fire goes out. Fiddling with the accelerator pump can address that somewhat, but not if you are tuned too lean. Do you have any idea what your mixture is? What jets and rods are in the carb?
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Rich Weyand 1978 K10 RCSB DD. |
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#57 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
I have build over a dozen old chevy blocks. There is no chance it is wrong without any doubt.
Last edited by Dylan86; 04-28-2014 at 12:45 AM. |
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#58 |
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Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: Help! 454 bog/die on accel
So!
6 and 12 or 12 and 12? |
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#59 | |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
Quote:
The Max step up is the blue springs? Last edited by Dylan86; 04-28-2014 at 12:48 AM. |
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#60 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
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#61 |
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Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
No, blue is the minimum, 3#. You want the maximum, 8#, which is plain metal. This will kick in the power circuit (richer mixture) soonest as the throttle is opened.
For tuning my Edelbrock, I got an air/fuel ratio meter (AFR meter). This allows you to see the AFR as you drive, and how lean or rich you are. They're not free, but it really lets you get the mixture nailed down. ![]()
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Rich Weyand 1978 K10 RCSB DD. |
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#62 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
Why does everywhere I look say to switch to the blue spring?
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#63 |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
Dunno, other than that it is easy to get turned around on vacuum and how the system works. So here's the long explanation.
The springs are rated in pounds, from 3 (blue) to 8 (bare metal). The bigger the number, the stronger the spring. The way they work is: manifold vacuum from the underside of the throttle plate pulls a piston down against the spring. If the vacuum is strong enough, it overcomes the spring, the piston moves down, and with it the metering rod moves down. The end of the metering rod is narrower than the middle, so as the rod moves down, it blocks more of the jet and the mixture leans out. The vacuum can overcome a weaker spring easier, so the piston will spend more time in the down (lean) position if the spring is weaker (3# blue) than if the spring is stronger (8# bare metal). At idle the engine pulls a lot of vacuum and the pistons are down. As you open the throttle plate, the vacuum decreases until the spring wins. The stronger spring will win sooner, where the weaker spring will keep the needles in the lean position longer. I run the 8# springs on my 350. I have bogging problems at mid-range throttle settings with the weaker springs.
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Rich Weyand 1978 K10 RCSB DD. |
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#64 | |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
Quote:
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#65 | |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
Quote:
One thing that may help is a heat insulator between the carb and the manifold. Read this thread: http://www.hotrodders.com/forum/edel...gs-199736.html
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Rich Weyand 1978 K10 RCSB DD. |
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#66 |
Registered User
Join Date: Nov 2012
Location: santa rosa,california
Posts: 650
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Re: Help! 454 bog/die on accel
Dylan
You set the idle mixture with a vacuum gage attached and adjust until you get your highest reading.The throttle plates need to be closed so if you set the idle up lower it back down. Once you find your maximum vacuum you divide it by 2 and put the proper spring in it.You pick the spring by halving the vacuum reading. If your plugs are gas fouled you want the secondaries to kick in sooner. |
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#67 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
I ordered the spring kit. Richer metering rodd and bigger accel pump squirter. I'll play around with those and see if I get an improvement. Anyone know how to replace the accelerator pump jet/squirter?
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#68 | |
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Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
Quote:
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Rich Weyand 1978 K10 RCSB DD. |
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#69 | |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
Quote:
The accel pump jets are screwed to the underside of the top of the carb, so you need to order the gaskets, too, for putting the carb back together. They come in a five-pack. While you are in there, make sure to adjust the floats. They will not be right.
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Rich Weyand 1978 K10 RCSB DD. |
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#70 |
Registered User
Join Date: Nov 2012
Location: santa rosa,california
Posts: 650
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Re: Help! 454 bog/die on accel
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#71 | |
Registered User
Join Date: Nov 2012
Location: santa rosa,california
Posts: 650
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Re: Help! 454 bog/die on accel
Quote:
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#72 | ||
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
Quote:
Quote:
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Rich Weyand 1978 K10 RCSB DD. |
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#73 |
Registered User
Join Date: Dec 2012
Location: Lloydminster, Alberta
Posts: 88
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Re: Help! 454 bog/die on accel
Thank you Rich you have been a huge help. I should be getting all my carb components in soon. I'll update you on how it goes.
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#74 |
Registered User
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
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Re: Help! 454 bog/die on accel
Yeah, keep us posted. I'll help out if I can: I can take that carb apart in my sleep.
You really, REALLY should consider springing for the NGK A/FR meter, though. You'll be able to dial it in exactly, which will save the purchase price on gas in the first year.
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Rich Weyand 1978 K10 RCSB DD. |
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#75 |
Registered User
Join Date: Nov 2012
Location: santa rosa,california
Posts: 650
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Re: Help! 454 bog/die on accel
Dylan despite what you might read here Edelbrock knows how to tune there own carb.They want you to measure your vacuum so you get the right spring for your engine.If your engine has 16 pounds of vacuum the 8 spring is what they want you to use.
On free flowing heads creating more vacuum I have been building engines since most of the posters here were in diapers and I have never heard that before.Most engines built with free flowing heads have very large duration camshafts in them to take advantage of the extra flow and have very little vacuum at idle. That is exactly why big cams cause problems with power brakes. I would do a google search for Edelbrock carb bogs on acceleration and read 50-75 posts on what actually fixed the issue. You can do the same thing on You Tube. Good Luck with your motor. |
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