Dashpot on quadrajet (merc 488)

[iliketodh]

Hi, I'm new here and I'm going to hit the ground running

I noticed while rebuilding my carb (winter projects) that I have a broken dashpot connected to the linkage for the secondaries (the ever popular and well loved mercruiser 488 haha) , also it looks like not the correct dashpot as the barb is way too close to the carb body

My questions are ;
what is it for ?
Does anyone have a part number or a picture of theirs?
Where can I find one and what happens if I don't put one back on ?

Thanks all ! Eventhough i wasn't a member , this forum helped me numerous times over the past 2 years

 

[Scott06]

Hi, I'm new here and I'm going to hit the ground running

I noticed while rebuilding my carb (winter projects) that I have a broken dashpot connected to the linkage for the secondaries (the ever popular and well loved mercruiser 488 haha) , also it looks like not the correct dashpot as the barb is way too close to the carb body

My questions are ;
what is it for ?
Does anyone have a part number or a picture of theirs?
Where can I find one and what happens if I don't put one back on ?

Thanks all ! Eventhough i wasn't a member , this forum helped me numerous times over the past 2 years

normally that is for the choke pull off, basically to use engine vacuum to open the choke. I suspect as long as the vacuum port is connected you can wire the choke open and run without it although you may have cold start or warm up issues. I ran my mercarb without a working choke for years in the summer its not an issue.

For Quadrajet parts and support Cliffs High Performance would be the place. https://cliffshighperformance.com/

Also mikes carb parts is very good as well. https://www.carburetor-parts.com/

I dont think either of this guys rebuild carbs anymore but they do sell parts

 

[iliketodh]

 

[iliketodh]

normally that is for the choke pull off, basically to use engine vacuum to open the choke. I suspect as long as the vacuum port is connected you can wire the choke open and run without it although you may have cold start or warm up issues. I ran my mercarb without a working choke for years in the summer its not an issue.

For Quadrajet parts and support Cliffs High Performance would be the place. https://cliffshighperformance.com/

Also mikes carb parts is very good as well. https://www.carburetor-parts.com/

I dont think either of this guys rebuild carbs anymore but they do sell parts

I have an electric coil choke and the linkages for the choke and the dashpot don't seem to be connected in any way , and thanks for the links , I'll deffinately save those

 

[Scott06]

I have an electric coil choke and the linkages for the choke and the dashpot don't seem to be connected in any way , and thanks for the links , I'll deffinately save those

I was just gonna edit my post as I think GM used dashpots on the throttle side - can you post a picture of what you are working with?

if you have a dashpot on the throttle lever I think that would indicate someone put an automotive carb on your engine. Fuel and electrical components are two types of parts where marine legitimately is different from automotive from a fuel and electrical spark safety standpoint. Probably the easiest way to tell if it is marine is if it has a 1/4" nipple on the carb to accept mechanical fuel pump diaphragm rupture line. Not sure where they are on quadrajets. Fast idle cam is another dead giveaway.

 

[iliketodh]

I was just gonna edit my post as I think GM used dashpots on the throttle side - can you post a picture of what you are working with?

if you have a dashpot on the throttle lever I think that would indicate someone put an automotive carb on your engine. Fuel and electrical components are two types of parts where marine legitimately is different from automotive from a fuel and electrical spark safety standpoint. Probably the easiest way to tell if it is marine is if it has a 1/4" nipple on the carb to accept mechanical fuel pump diaphragm rupture line. Not sure where they are on quadrajets. Fast idle cam is another dead giveaway.

Yes it is indeed a marine carb and the original to the engine (verified with serial number on carb) no fast idle cam, and the puke fitting for the fuel pump is on the side

 

[Scott06]

Yes it is indeed a marine carb and the original to the engine (verified with serial number on carb) no fast idle cam, and the puke fitting for the fuel pump is on the side

that to me looks like a choke pull off. I am not intimately familiar with Q-jets - maybe @kenny nunez is ?

I'm spit balling here- it looks like the small flat rod (2 holes in it) coming out of the pull off attaches to the perpendicular rod behind the choke stove housing. the other hole in it looks like it links up to the rod that connects to the secondary air valve? Im guess that inhibits secondary air valve from opening if choke isn't fully off?

on this it is listed as a primary vacuum kit? https://www.marineengine.com/parts/...-il4-19831984/6170297-thru-6916778/carburetor

Would think Cliffs would be able to tell you what it is , if you need it and sell you parts to fix it.

 

[iliketodh]

that to me looks like a choke pull off. I am not intimately familiar with Q-jets - maybe @kenny nunez is ?

I'm spit balling here- it looks like the small flat rod (2 holes in it) coming out of the pull off attaches to the perpendicular rod behind the choke stove housing. the other hole in it looks like it links up to the rod that connects to the secondary air valve? Im guess that inhibits secondary air valve from opening if choke isn't fully off?

on this it is listed as a primary vacuum kit? https://www.marineengine.com/parts/...-il4-19831984/6170297-thru-6916778/carburetor

Would think Cliffs would be able to tell you what it is , if you need it and sell you parts to fix it.

I've been screwing around with it for awhile and it seems to me you might have a point , under full vacuum it looks like it would prevent the secondaries from opening and if I bend the tang a little bit and play with the mount , under vacuum (engine running) it would somewhat crack open the choke a bit

I ran all year without it last year and didn't see any major problems , but I have an ocd with restoring things to their original design and I figure , if it was engineered to go there it must have a purpose

I am now 100% sure that the dashpot i have is not correct as there is no way to hook a hose to it since the barb fitting is about 1/32nd of an inch from the carb body , so someone must have bought a random rochester dashpot and slapped it on

 

[Scott06]

I've been screwing around with it for awhile and it seems to me you might have a point , under full vacuum it looks like it would prevent the secondaries from opening and if I bend the tang a little bit and play with the mount , under vacuum (engine running) it would somewhat crack open the choke a bit

I ran all year without it last year and didn't see any major problems , but I have an ocd with restoring things to their original design and I figure , if it was engineered to go there it must have a purpose

I am now 100% sure that the dashpot i have is not correct as there is no way to hook a hose to it since the barb fitting is about 1/32nd of an inch from the carb body , so someone must have bought a random rochester dashpot and slapped it on

I think you are right. I did some additional reading on it on some GM forums and one mentioned that it keeps the air valve from slamming open when you nail the throttle and also cracks the choke open a hair when you start, otherwise choke would be too far closed.

like you I like making it work the way it should before modifying or condemning it. I think you find out that the factory engineers knew a thing or two. I think the q jet gets a bad rap when you look at the range of engines it was on and how it is used for high performance it certainly is up there with any carb.

also agree it doesn’t look like the one in the parts breakdown . If you send your carb number to cliffs I bet you can get the right one.

 

[iliketodh]

Thank you i really appreciate the help , I would have never thought about the choke aspect until you mentioned it , and I will try and find a contact for Cliffs and see of he can possibly help

I think you are right. I did some additional reading on it on some GM forums and one mentioned that it keeps the air valve from slamming open when you nail the throttle and also cracks the choke open a hair when you start, otherwise choke would be too far closed.

like you I like making it work the way it should before modifying or condemning it. I think you find out that the factory engineers knew a thing or two. I think the q jet gets a bad rap when you look at the range of engines it was on and how it is used for high performance it certainly is up there with any carb.

also agree it doesn’t look like the one in the parts breakdown . If you send your carb number to cliffs I bet you can get the right one.