Quadrajet question

"Hello, I have a set of 1982 C

"Hello, I have a set of 1982 Crusader 454's with Quadrajet carbs. Unfortunately, the carbs are not marine units and need to be replaced anyways. Is there a difference in marine Quadrajets made for a Crusader versus a Mercruiser or other marine engine? One company I found said there is a difference and wants $650 for a reman. Another place (flyingfishcarburetors) says they have a universal upgrade carb for $220. Can anyone shed some light on this? Thanks."

"The difference is how the Mar

"The difference is how the Marinizer specs the 'tunable items'. The basic castings are all the same. For the most part, a carb off a merc 330/340 BW inboard (same vintage) will behave ok on your big blocks.

How did you find out your's were NOT marine types?"

"The current ones don't ha

"The current ones don't have the overflow tube that runs back down to the fuel pump.

My mechanic was saying he didn't think you could properly tune the carbs unless they were the ones specifically for the Crusader.

ebaycarburetors has one listed for $270 that supposedly fits a Crusader, but I didn't get a real confident feeling after talking to them.

The other thing that muddies the water is that some of the places are offering an electric choke as an upgrade to the OEM style. I don't know what is the best way to go."

"Shawn, we recently had a disc

"Shawn, we recently had a discussion about these carbs and a few others. I have the Edlebrock 1409's. What a breeze to rebuild, setup, tune and adjust for performance. I AM trying to get a set of quadrajets for this boat as I enjoy tinkering with the outcomes and experimenting. BUT, I think since I have had the 3 years with these 1409's...I would buy them again. Of course they were $300.00 then

Regarding the chokes, In nearly 4 seasons, I have not yet connected the electric chokes. Never really have a problem in NJ from April to December"

"The hose barb is easily added

"The hose barb is easily added with a drill and pipe tap....assuming the casting is the marine "flavor".

If your mechanic said what you posted, don't let him touch your carbs - new or old.

The "fit" is called the spreadbore bolt pattern. You need to worry about the choke style match what you have if you need it and don't want to modify it. Linkage connections are another area of concern. The divorced choke uses the V in the carb model. The electric conversion kits I've seen are ~ $50. For that, I think my leanly adjusted bimetal springs are very adequate.

You may want to check with Cliff at cliffshighperformance.com to see if he has any available. He does custom tuning work and restorations and is well respected. Last I heard his rebuild backlog was running thru the summer of this year (6+ months lead time). he may be will to mod yours if there are the proper 'flavor'."

"Mark, in your first reply you

"Mark, in your first reply you mentioned that the difference was in the "tunable items". What does that mean? Sorry to be ignorant but I'm still confused on this issue of what (if anything) is different about a Q-jet specifically for a Crusader.

Part of my confusion comes from conflicting stories from some of the carb suppliers. At marineengineparts.com they list a reman Q-jet for all GM 454 (except Crusader) for $436. Then they have a reman Q-jet just for the Crusader that is $650! The guy I talked to didn't know for sure what was different to warrant the huge price difference.

On the other hand, the guy at flyingfishcarburetors.com says their reman Q-jet is something unique as they start with a Q-jet that is a newer vintage and then modify it for marine use. He said it will work on any 454 and that this version is an upgrade from the older vintage I have. Their unit sells for only $200 + core).

I would like to think I could spend $200 for this "upgrade" and it would work great, but I'm hesitant since I don't know if either of these places is right. Any thoughts to clear this up? Thanks."

tunable items are metering com

tunable items are metering components you select to match the casting to deliver the desired amount of fuel at a given rpm. the mmajor ones are the metering rods (two pairs) and the primary jets. The castings have air bleeds and the whole thing is 'matched' to the engine.

"Shawn,

Basically the main

"Shawn,

Basically the main "tunable" parts of a Q-jet are the primary jets, primary metering rods and the secondary metering rods. There are several other small things that can be tweaked but really isn't necessary for a marine engine. If you get into carb performance more, than you can consider some other modifications later down the road that can save fuel and round out engine performance. If the current carbs you have run well then you want to maintain the same jet size and metering rod combos. Those items can be removed easily and put into another Q-jet. You could rebuild what you have (not that difficult) and add the overflow nipple as Mark suggested or get the specs for what your carb should be from Crusader (carb number) and do a little research. My guess is the carbs from flyingfish will work just fine. Not sure about their "upgrade" claim though since it is the same carb. Marineengineparts are basically selling Sierra parts and are not totally knowledgable about carbs. More than likely you need carb number 17082403 (check me on this), which I believe is generally more expensive on Sierra's listing. Why, I don't know."

Maybe this is what my mechanic

Maybe this is what my mechanic was referring to when he said the carb needed to be spec'd for a Crusader engine so it would have the correct fuel flow for the given engine rpm of that motor. I will send an email to Crusader and see if they will tell me what was the OEM carb part number for my motors. I'll let you know when I get a reply. Thanks guys.

"Don't be surprised if it

"Don't be surprised if it comes back with a 70 primary jet, 42 primary rods, and CL secondary rods. The most common power piston spring if fully on at 8" vacuum.

I'm pretty sure all these data are in the Factory Service Manual.

The newer castings have an APT (adjustable part throttle) adjustment. It allows you to tune the primary rods' position with the power piston in the economy (down) position. Consider this a "fine tuning" feature focused more for emission issues than an essential function for a marine application."

"Unfortunately, I still haven&

"Unfortunately, I still haven't got a reply from Crusader. I did get the part number from my current carb. It is 17059293. However, I didn't really run the boat enough before this renovation to tell if this setup works well or not (regarding the tuning). I guess I'm going to try the unit from flyingfish carburetors and go from there."

"Shawn,

I second Mark's

"Shawn,

I second Mark's numbers as that is what is in my carbs. Just FYI. 1705 desigantes decade date of 1975-1979; 9 is the manufacture date (1979); 2 designates carb type, for yours 2 = quadrajet (4 bbl) Federal standards; 9 designates the GM division (i.e. Chevy, Pontiac, etc.), for yours 9 = "Special" and the 3 designates transmission type, for yours 3 = manual transmission. The last two numbers in the carb code can really be anything for a marine carb and don't necessarily track.

I don't know off the top of my head when they started requiring fuel pumps to have the safety overflow feature built into them. I am sure someone here knows the date. (Someone feel free to jump in here.) Your year engine might be before the requirement. If so, your carb may not have the overflow nipple (I am not sure if you mentioned that or not) and your fuel pumps may not be configured with the overflow port and the clear tube running from the pump to the carb. You might want to check and see what type of fuel pump you have and whether or not they have the overflow port with the clear tube running up to the carb. Your new carb will have the overflow nipple. My point being in the end that everything matches up...right pump and right carb."

That infers they are NOT the O

That infers they are NOT the OEM carbs.

I've found the 'decoder info' available isn't good for much more than the year when it come the the marine stuff.