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Hey guys,
So the rebuilt Quadrajet I bought to match the 200-4r linkage is junk. I can't get the bog adjusted out, the idle screws don't have any effect, and it's leaking gas from the accelerator pump for sure, and maybe the air horn gasket.
The builder is going to replace it but I would like to know what you think I should request for the innerds.
1. Primary rods and jets
2. Secondary rods (CV?) and hanger (G?)
My motor:
A. 350 small block
B. 7A heads with new valves, seals, springs, etc.
C. Aftermarket cam:
*0.448 lift in and out
*overlap 60.00
*duration 280
D. Roller-tip rockers
E. One-inch phenolic carb spacer on Edelbrock 3711 intake
F. Duel exhaust with H-pipe
G. New stock mechanical fuel pump
H. High-flow in-line fuel filter (no filter in carb).
I. 3.73 gears with 200-4r trans
Lastly, which quadrajets were matched with the 200-4r? Mid to early 80s Olds 307s and same year Buicks but what about same year chevy trucks? Pontiacs?
Lastly, which quadrajets were matched with the 200-4r? Mid to early 80s Olds 307s and same year Buicks but what about same year chevy trucks? Pontiacs?
By the time the 200-4R came out, both Buford and Pontiac had stopped building V8s. I think the only V8s bolted to a 200-4R were the 307 Olds and the 305 Chebby. Both of those used the CCC Qjet. The Buick V6s in front of the 200-4R used the DualJet or EFI.
THanks for the replies, fellas. The current (leaking) carb supposedly has #72 main jets but I've forgotten which rods (which makes knowing the jets pointless I guess). Could I check my plugs to see where I'm at now or does the leaking carb negate that? I haven't seen puddles of fuel but it is definitely leaking, enough to coat the area around the pump shaft with a glaze, and down around the carb body from there. COuld that be the cause of the bog? Or maybe the guts were just not put together well.
Ahh, CCC, computer controlled. Well that won't do. So it seems I won't find the perfect linkage unless I find a CCC and swap the throttle plates/linkage. Well then, the current linkage model will have to suffice. Which btw is an '81 Checker or Marine unit. What motor did the Checker cabs run?
Last edited by Macadoo; July 28th, 2016 at 03:44 PM.
Just some pics of the leak. We went to a cruise-in the other night and when I opened the hood a few guys standing there exclaimed "whoooweee, smell that gas!"
IDK what hanger those ran i dont think i ve seen a source that lists that, the info i posted was from the 70 csm.
that leak looks like the acc pump maybe the cup is no good and gas is getting by it?
ive taken my carb part so many times in last couple weeks ive gone from newby to off the car and dismantled in about 40 mins, im currently waiting on gaskets to put it back together for the last time (i hope LOL)
So I checked a few plugs to see what I could see. This looks a wee bit lean, don't it?
I don't suppose a carb that leaks air would show up on a vacuum gauge hooked to manifold vacuum (assuming that can happen). It doesn't seem like the lean secondary hanger could do this either. And the builder claims #72 jets. Something's not adding up.
IDK what hanger those ran i dont think i ve seen a source that lists that, the info i posted was from the 70 csm.
that leak looks like the acc pump maybe the cup is no good and gas is getting by it?
ive taken my carb part so many times in last couple weeks ive gone from newby to off the car and dismantled in about 40 mins, im currently waiting on gaskets to put it back together for the last time (i hope LOL)
Oh man, that's a "knock on wood" comment if I've ever heard one! Lol.
Both my original carb and my first rebuild had a "J" hanger. However, another member suggested the "G" hanger to make the secondaries a little richer. A=richest while Z=leanest. This current rebuild came with a "U" hanger! I swapped in a "J" and that made it better but something is definitely amiss.
If the carb is leaking air spray a little water with a spray bottle around it and watch the rpms change. Depending on where the air leak is i guess. Also cant see the plug very good. Bit of glare on the pic. It could be lean at idle. You mentioned you where running a little hot on your long drive. A lean running engine will run hotter but it will also surge while crusing. if you idled longer than a few minutes the plug will read diffrent. I know because my idle is a bit lean but if i check my plugs after a run and shut it down while pulling into the pits it will read diffrent than it would at idle.
The late 70's Olds 350 and 403 carbs have the proper linkage for the 2004R. The 77-80 carbs, are ones I am talking about and a stock 403 carb should be close. My 78 403 carb came with 44K primary rods, 73 jets and CV rods with an I hanger, I believe.
Actually, there is very little glare on the pic. That plug is bright-white, lol. There's a little glare but not much.
No surging at cruise. Came home from Chi town yesterday, ran around town a little today, made the 15 mile drive home this afternoon and parked it. Very little idling involved and none before final shutdown.
I'll try the spray bottle, thanks. Maybe a piece of cardboard to block the throttle blades.
Retro, where did you find the rod/jet specs in the CSM? I've been looking in my '71 but can't find it. I doubt, however, that it's different than yours.
Looked like a glare in my screen lol. If you ever want to go back to a th350. I can take care of that for ya lol. Good luck Mac car looks great in person. If all else fails you can go to a holley . You can borrow mine in the fall when I do the body work to the 72 if you want to try that out
If you wold have asked me a month ago, yeah, I was ready to go back to the 350. But I just drove from Bloomington to Elk Grove Village, to St. Charles, back to Elk Grove, and back to Bloomington on just a little more than a single tank of gas. I'm digging the lockup, lol. Right now it's completely manual though, just a rocker switch. I'll get the vacuum switch hooked back up but I'm keeping the rocker switch! Haha.
Thanks for the carb loan offer but your double pumper on my motor would be like using a flame thrower to light the dinner candle
I found this on a Chevelle forum. Sounds reasonable.
"The main air bleeds of a Q Jet are what determines the stock primary jetting and metering rod sizes more than anything. Some engines with small air bleeds have jets as small as .067. Later Q Jets with huge main bleeds have jets as large as .076-.077. Yes engine size and emissions tuning entered into it but the stock jetting and metering rods FOR THAT PARTICULAR CARB is the best starting point. Maybe one step richer for stock and two steps for mild to moderate mods. Carbs (mainly later Qjets) can have the bleeds resized to use smaller jets/rods if desired. That makes them easier to tune."
As per my above post, I ordered the replacement carb. I asked that they go two steps richer than the stock setup for the M4MC and to double check the accelerator pump. I'll report back when I have it on and adjusted.
Question: is the accelerator pump a common weak spot on the QJ? My two previous Quadrajets both leaked at the pump, but just a tiny bit. Nothing like this one. Is it the Ethanol?
It could be ethanol if the accelerator pump cup is not alcohol resistant. The ethanol compatible ones I have seen are blue instead of the traditional black.
I'm a big, fat, stupid, idiot. Okay, okay, I'm not fat.
So, when I first built this engine and had the first replacement Q-jet I decided to put in a hi-flo, inline fuel filter. And of course I removed the filter from the carb. Guess what I forgot to do when I replaced the carb
I pulled the filter out of the new carb, undid everything I did to solve the problem and started from scratch. It's running pretty good now. No bog, initial timing 22*, 22* mechanical (coming in a little slow and late maybe). It's not perfect, I still think it's under jetted but it's cruising great and I can stomp on it.
Last edited by Macadoo; August 8th, 2016 at 04:06 PM.
Just to verify, I pulled a few plugs after some cruising and they're a nice light tan instead of snow white. I guess there's such a thing as over-filtered.
Copper, how much mechanical are you running? I know you have the MSD kit, one medium and one light spring (right?) but how much total mechanical and how soon is it all in?
I had to go with the heaviest springs (stock weights) but if I'm seeing it correctly, I have 22* mechanical. In my opinion, it's too much. That's why I put the heavy springs on. With two mediums I had to back initial off to the point where the car was sluggish and was backfiring through the carb when I stomped on it.
I have 20 mechanical 14 initial. Its all in around 3000 rpm. I think the msd wheights are heavier than stock. I think the only curve kit that was deisgned to be used with the stock weights was the old crane cams kit. The springs are designed to be used with the weights. Im runnin the msd kit on pops car and im using the heavy springs because i had set the curve for a dog assed 2.41 gear. Went to the 3.08's and you can literally feal the advance kicking in lol. Im yet to change the springs since i changed the rear gears.
Last edited by coppercutlass; August 8th, 2016 at 07:48 PM.
I think 22 mechanical advance is about right. I find 36 or 38 total in before 3000 rpm works best with a lot of vacuum advance right off idle. I say leave one light and medium spring with the stock weights or play around with the MSD weights. I would add another 4 degrees base over Copper's numbers with MSD weights. A 10 to 1 350 with a large cam is totally different than an 8 to 1 350. I found 36 was fastest at the track but 38 felt stronger on the street. Glad your carb is fine, you could pick up a G hanger and try that as well. I once put leaner secondary rods in a 307, the only time a 307 has ever pinged on me.
Im not running the msd weights on my 355. they are in my old engine in my dads car which is a 9 to 1 350. I run 36 at the track but on the street keep it lower between 32 and 34 just to be on the safe side since im running 10 to 1 on 93 on the street. performance on the street is not my priority. Just as long as i runs good and is reliable.
My mechanical isn't coming all in until, well, I don't know for sure. I chickened out around 3500 rpm and it was still coming in. I also limited my vac advance to 12*. Should I increase that a little?
BTW, the stock weights are a lot larger (and I assume heavier) than the MSD weights.
No reason to limit your mechanical advance and run full vacuum advance on a 8 to 1 350. I have the same specs as you on my 9.5 to 1 350 with too small of a cam, way too lazy but will ping with an agressive curve. Throw on lighter springs, 2-4 degrees more initial and try full advance from your vacuum can. Unless a solid stop is put in, there will always be a couple of degrees added in higher rpms. It won't be an issue, you won't have vacuum advance at that point.
Last edited by olds 307 and 403; August 11th, 2016 at 05:31 AM.
I'd set it up to run 16 initial, 34 total. All-in 3000-3200. Check timing at 2000, should be about 24-26 degrees.
12-15 degrees vacuum, attached to manifold source when you're done tuning. The less vac you have at idle, the less vacuum advance you use. 8-10 degrees vac advance on a high compresison street engine (well over 10:1).
This is all for a 9.5:1 motor BTW. a low compression smog motor you can throw buckets of timing at to get it to run properly.
Last edited by distributorguy; August 10th, 2016 at 01:09 PM.
My mechanical isn't coming all in until, well, I don't know for sure. I chickened out around 3500 rpm and it was still coming in.
From your earlier post:
Originally Posted by Macadoo
I had to go with the heaviest springs (stock weights) but if I'm seeing it correctly, I have 22* mechanical. In my opinion, it's too much. That's why I put the heavy springs on.
Be aware that the springs are not what limits the amount of mechanical advance, it is the contact surfaces of the weights/center bar. The springs change the rate of advance.
What I did was install the lightest springs, run the engine to 3500, then turn the distributor to achieve the total advance (34-38 or whatever you are wanting). This ensures the distributor is advancing fully at 3500 RPM. Then swap out the light springs for the ones you want to give the correct rate of advance.
Last edited by Fun71; August 10th, 2016 at 12:39 PM.
No reason to limit your mechanical advance and run full vacuum advance on a 8 to 1 350. I have the same specs as you on my 9.5 to 1 350 with too small of a cam, way too lazy but will ping with an agressive curve. Throw on lighter springs, 2-4 degrees more initial and try full advance from your vacuum can. Unless a solid stop is put in, there will always be a couple of degrees added in higher rpms. It won't be an issue, you won't have vacuum advance at that point.
I fabricated the vac stop myself. I can always take a little off but I won't be able to put it back on so I want to be sure.
Originally Posted by distributorguy
I'd set it up to run 16 initial, 34 total. All-in 3000-3200. Check timing at 2000, should be about 24-26 degrees.
12-15 degrees vacuum, attached to manifold source when you're done tuning. The less vac you have at idle, the less vacuum advance you use. 8-10 degrees vac advance on a high compresison street engine (well over 10:1).
This is all for a 9.5:1 motor BTW. a low compression smog motor you can throw buckets of timing at to get it to run properly.
I chambered my heads back when they are off. I calculated something like 8.4-8.6 to 1. So I think I understand that the vac advance compensates for lack of centrifugal at lower RPMs but what happens when cruising at 3000 PRM (which I don't, but just sayin') when all three are all in? Isn't that a lot of advance?
Originally Posted by Fun71
From your earlier post:
Be aware that the springs are not what limits the amount of mechanical advance, it is the contact surfaces of the weights/center bar. The springs change the rate of advance.
What I did was install the lightest springs, run the engine to 3500, then turn the distributor to achieve the total advance (34-38 or whatever you are wanting). This ensures the distributor is advancing fully at 3500 RPM. Then swap out the light springs for the ones you want to give the correct rate of advance.
Vac can disconnected, yes?
Yeah, I understand that. It was just a bandaid so I could run more initial. I've seen where I can put a screw in the spinny-plate-thing and grind it down until I limit the mechanical to where I want it.
Originally Posted by oldcutlass
After its set, I run it up to 4500-4800 just to make sure its not advancing any more.
4800?! You're a braver man than I!
So here's what I really want to know: I get the most grunt, seat of the pants acceleration with high initial timing, say 22-26*. But that gets me some detonation when getting on it. Maybe I need less initial and faster mechanical with a little more vac. Am I over-depending on initial when I should be concentrating on the correct mechanical curve?
July 28th, 2016, 11:49 AM
