WARNING: Edelbrock 1409 throttle linkage issue

WARNING: Edelbrock 1409 throttle linkage issue

Joined: April 5th, 2008, 6:00 am

April 28th, 2012, 8:59 pm #1

I bought a pair of 1409s for Giggity and installed one yesterday. As you can see from the picture the throttle linkage on the 1409 hangs down further than the Carter.



I could move the throttle back and forth at the helm and I verified the secondaries would open and more importantly completely close before the first test fire.

What I did not realize is the section of the linkage that hangs down below was hung on the intake manifold causing my accelerator pump to stick in the fully engaged position. Upon the test firing I got a major surprise when the engine rev'ed up quickly even though I pulled the throttle all the way back. I immediately killed the ignition and am happy to report I saved the motor from any damage but will need to modify the linkage to resolve the issue.

Anyone come across this issue before?

My TF will not allow carb spacers to be installed because the spark arrestor/air cleaners butt up against the cabin floor already so I am likely going to trim the bottom part of the linkage as it s not used in my configuration.

Thoughts?

Jim
Seattle

74 36' TF
69 19' SS


Last edited by 36TFisher on April 29th, 2012, 2:05 am, edited 1 time in total.
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Jeff Vail
Jeff Vail

April 28th, 2012, 11:44 pm #2

The plates that the linkage is made out of, the arms on the carb, are case hardened. To trim them you will have to use a cutoff wheel and a die grinder, a hack saw blade won't do much more than scratch them.

jeff
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Paul
Paul

April 29th, 2012, 12:25 am #3

I bought a pair of 1409s for Giggity and installed one yesterday. As you can see from the picture the throttle linkage on the 1409 hangs down further than the Carter.



I could move the throttle back and forth at the helm and I verified the secondaries would open and more importantly completely close before the first test fire.

What I did not realize is the section of the linkage that hangs down below was hung on the intake manifold causing my accelerator pump to stick in the fully engaged position. Upon the test firing I got a major surprise when the engine rev'ed up quickly even though I pulled the throttle all the way back. I immediately killed the ignition and am happy to report I saved the motor from any damage but will need to modify the linkage to resolve the issue.

Anyone come across this issue before?

My TF will not allow carb spacers to be installed because the spark arrestor/air cleaners butt up against the cabin floor already so I am likely going to trim the bottom part of the linkage as it s not used in my configuration.

Thoughts?

Jim
Seattle

74 36' TF
69 19' SS

Sorta been there. Here is a thread on my own linkage issues, and my issues were partially due to the fact that the linkage is actually a weighted dumbell that works partially with gravity and part with suction from the intake.

Read through this thread, it may give you some insight but for crying out loud don't take a hack saw to the linkage because I think you would totally toast the butterfly shaft. Also, you could use a 1/2" 4-hole spacer, that would give you some heat isolation if you used a phenolic, and it would (by some thoughts) give you some torque too.

http://www.network54.com/Forum/424840/m ... photos+%29

Regards,

Paul
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Joined: April 5th, 2008, 6:00 am

April 29th, 2012, 2:04 am #4

I will probably need to cut out a little insulation under my floor boards to allow the spacer to fit but after yours and Jeff's input I will try to avoid cutting the linkage...

Thanks guys!
Jim
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Paul
Paul

April 29th, 2012, 12:29 pm #5

Jim, there simply must be a better way than cutting the linkage to make this carb fit your boat, easy for me to say sitting here in Nashville. While you're at it, may as well either get a spacer that is already prepped for a PCV system, or drill the spacer for one yourself (hey maybe your carbs already had the PCV as I recall?). In any case, spacers come in several types and the open spacers seem to have a reputation for high rpm system (like a single plane intake manifold) and the 4-hole spacers seem to have a reputation for building torque. They both function as a volume builder in the intake and serve as a mini high rise intake manifold, if that makes any sense. The phenolic versions help keep the carb from heat soaking too, so cooler is always better with carbs and intake systems.

regards,

Paul
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Joined: April 5th, 2008, 6:00 am

April 29th, 2012, 7:06 pm #6

Thanks for heading me in the right direction Paul. The spacer will require me to trim a section of sound/heat insulation under my deck hatches but this looks to be the best solution with a cooler carb and the added benefit of not messing with carb linkage geometry have me sold.

The slightly longer runner will in theory build up a little air velocity resulting in "momentum" that may squish a bit more air into to intake valves when they open... however slight this may be. Porsche has a "Varioram" engine that increases the intake length as much as 9" which has a significant increase in torque at lower RPM. Above 5000 rpm the intakes are shortened by lifting off little trumpets inside the intake manifold Pretty nutty huh? It seems to work well and the low RPM torque is quite obvious.

Hey Paul how about an air cooled Porsche Chris Craft?

I will report my findings with the new carbs soon.

Thanks,
Jim

PS A Super Sport update is long overdue and will occur soon
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Paul
Paul

April 30th, 2012, 8:50 pm #7

Hi Jim,

Of course you could look for a lower profile flame arrestor too, and if so I would increase the overall diameter to compensate for the reduction in height, keeping the free air passage about the same or perhaps even greater. Oddly I've seen some of the Hardin type flame arrestors are only 5 or 6" in diameter and awkwardly tall looking, apparently just designed for open air applications on jet or drag boats, and those don't have much use with our classics. If you look around long enough you'll find some 8 and 10" diameter units that might be a lower profile that might help with a really tight clearance situation. If all you have to do is remove a little heat or sound insulation, that should not be a problem anyhow.

I think I'll pass on the air cooled boat motors! Not even Porsche had the guts to try to pull that one off, and they have done some pretty nutty things over the years from an engineering point of view. It still amazes me to see how the Germans can use 26 bolts to do the job of 4. I have thought about how much fun a 928 motor would be in a speedboat, now that would be quite the image pulling up the engine hatch and seeing a couple of magnesium overhead cam covers and an aluminum spider fuel injection manifold.

Regards,

Paul
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