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Hey, gang. Working through carb adjustments (4GC) on my new-to-me ‘63 Cutlass (choke and high idle now good... still have a bog/hesitation going into the secondaries...) and was wondering about alternatives to the Rochester.
I like Quadrajets and I’m sure I’ll get this little 4-Jet tuned... but time under the hood makes one ponder. Joe P has chimed in on another thread about his 500cfm Edelbrock... and that seems a reasonable option. I’m curious about the 390 Holley and Carter AFB. Hell, I’m curious about dual two-barrels, tri-power, downdraft or side-draft Webers, Strombergs, 4-71 Jimmy blowers...
Car is running a rebuilt Buick 215. Yeah. Auto RH5... which is doing just fine at the moment, and any carb option has to play nice with the Roto.
When i rebuilt my qjet, i followed the FSM set up there was a whole page dedicated to secondary spring wrap, adjustments factory dimensionetc.
im no carb expert and certainly not a qjet guru, but i can stomp the peddle to the floor ar any speed and it just goes no hesatation no burble just roars.
only took about halfan hour. When i got my car there was an e brock carb on it. It ran fine but the qjet is definetly more responsive.
Yeah... I have the Qjet on my ‘78 Suburban tuned so there’s no bog. The carb on the Cutlass is a 4GC and a bit different. I’m getting my head around it, but some of the adjustments are a bit different.
Any carb other than that 4Jet is going to create transmission problems unless you are very good at fabricating and adjusting tvr and linkage.
How long since that carb's been disassembled and properly cleaned? You have to make sure the correct throttle body to bowl gasket goes back in on reassembly and there are 3 different ones. A misadjusted secondary air flap can create a bog when the secondaries open (it's buried in the secondary side of the carb). A weak or poorly adjusted accelerator pump can cause it. Also don't discount the distributor mechanical advance.
The 4GC is not my favorite carb but it's no worse than any other once dialed in, and like a QuadraJet they are tailored for their engine. An Edelbrock or Holley by design will be a compromise unless you get into supertuning it.
Any carb other than that 4Jet is going to create transmission problems unless you are very good at fabricating and adjusting tvr and linkage.
How long since that carb's been disassembled and properly cleaned? You have to make sure the correct throttle body to bowl gasket goes back in on reassembly and there are 3 different ones. A misadjusted secondary air flap can create a bog when the secondaries open (it's buried in the secondary side of the carb). A weak or poorly adjusted accelerator pump can cause it. Also don't discount the distributor mechanical advance.
The 4GC is not my favorite carb but it's no worse than any other once dialed in, and like a QuadraJet they are tailored for their engine. An Edelbrock or Holley by design will be a compromise unless you get into supertuning it.
Thanks, raider. Completely understand that TV linkage is an issue. That’s my hesitation.
No idea on the maintenance history of the carb. This car is new to me and the guy I bought it off of pulled it out of a garage in April, where I had been stored for nearly 30 years. A legit, survivor barn find. Seller told me the only thing done was a replacement of the accelerator pump. No other info about what was done or when. It’s generally pretty clean and runs ok now that I have the choke adjusted.
The bog definitely has the characteristics of the secondary air valve not being correctly adjusted. Easy enough to fiddle with on the Qjet and fine tune the adjustment. The spring being buried in the carb on the 4GC is a bummer... Guess every time I’d want to adjust an 1/8 turn means tearing down the carb.
Could be the accelerator pump... wouldn’t be the first time a new part failed or was installed/adjusted improperly. I’ll see if I’m getting a good shot tonight.
The carb will get a rebuild over the winter. It’s missing it’s tag, so I’m not sure which 4GC I have... compounded by the Buick 215 in the Cutlass, adjustments may definitely be off. Still... other than the temp bog going to WOT, it runs strong.
Haven’t gotten into the spark side yet, but ignition and timing/advance may be in play. This does feel like the secondary valve being maladjusted though...
Been thinking on it and as long as this motor remains basically stock, I’ll run the Rochester. If/when we start to hop up the little Buick, we’ll take a closer look at carb setups.
So much to learn on this little car with the cool little Buick under the hood...!
Spray some carb cleaner down the secondary side just in case that long storage left some goo in there. Secondary side jets or transfer passages could be partially plugged as well. I think a teardown, soak and rebuild will help much as anything.
Lurk on Rover forums too. It's insane some of the stuff the Brits have come up with for these engines. 'Course there's a little matter of shipping it from UK...
Last edited by rocketraider; Oct 19, 2020 at 11:11 AM.
Oh I lurk on the Rover sites. Once I learned that the Rover mills are the legacy of the 215 I started to snoop around. Such impressive work and creativity with a high level of quality. I sorta want a second car to build up something nutty.
Ya know... ya’d think a guy would have thought to blast the carb with some cleaner... I’ll do that the next day we don’t have rain. I’ll definitely do a thorough clean and rebuild sometime this winter.
Anyone have any other first hand experience with different car set ups on the 215?
I've had some experience with the 4gc accelerator pumps being bad or going bad quickly. Make sure your parts are new as there were 4 different runs of different cup material of which only two worked worth a damn.... Tedd
Can anyone suggest a good rebuild kit for the 4GC? Time to tear it down and do it right. It’s definitely not getting a pump shot. Not sure if the accelerator pump is bad, it’s missing a check ball, or the passages are blocked. I’m at my limit without taking the carb off the car and getting into it.
Unless I can take the air horn off without taking the carb off the car…?
Also… anyone ever swap a Quadrajet onto a 215? I wonder what would be involved with that… Might be time to call Cliff Ruggles…
There are no Qjet intakes for the 215. The spreadbore-to-squarebore adapters create flow disruption. If you want a different carb, get a 500 CFM E-brock. It bolts on. You just have to fabricate linkage (as you would for any carb swap).
I run a quadrajet on my 215 with an open(3/4” or 1” I can’t remember) spread bore to square bore adapter on an edelbrock intake. I have seen a 215 intake that excepts a quadrajet but I don’t believe they are produced anymore. I still have those parts boxes up waiting for you if you still want them.
Thanks, fellas! I think the Mike's kit comes with all the various throttle body to bowl gaskets... Since I really don't know what carb I have until I tear it down, I'll make sure I all the items to cover my bases. What are you guys jetting at for ethanol-laced fuel?
There are no Qjet intakes for the 215. The spreadbore-to-squarebore adapters create flow disruption. If you want a different carb, get a 500 CFM E-brock. It bolts on. You just have to fabricate linkage (as you would for any carb swap).
Every time I see that linkage I get confidence that I can make it work. I think I have a lead on a good 500cfm Eddy...
) and was wondering about alternatives to the Rochester.
