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Post by john442 on Dec 5, 2017 22:34:21 GMT -5
I have a question regarding quadrajets. I’ll try to be to the point. In the 60’s I had a 65 olds Cutlass with 67 400.
The car was a 4 speed like the 65 olds Cutlass I have now. The car I have now has a 455 with a quadrajet.
With the 400 I could gradually depress the gas pedal and as the secondaries began to open I would get a response
like that from an automatic car hitting passing gear. I don’t get that same response with the 455.
With both, there is great wot response with the secondaries opened fully. Difference in quadrajets, adjustment or ?
Thanks,
john
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Post by 65442 on Dec 6, 2017 8:10:57 GMT -5
John, I'm not sure your 65 quadrajet ever kicked in like passing gear (sometimes we remember things a little different from what really happen) I'm sure at the time (in 65) the 442 was the fastest thing you had ever driven so the memory is a little faded. But to the point you need to check out cliffshighperformance.com they have all the information you need. You can call them and they will help you on the phone (you usually talk to Cliff.)You can adjust the spring on the secondarys to open at different pressure which might make a bigger inpact but won't get you anymore power. Check out the site he has everythihg for the quad. Gary |
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Post by joepadavano on Dec 6, 2017 10:45:13 GMT -5
I have a question regarding quadrajets. I’ll try to be to the point. In the 60’s I had a 65 olds Cutlass with 67 400. The car was a 4 speed like the 65 olds Cutlass I have now. The car I have now has a 455 with a quadrajet. With the 400 I could gradually depress the gas pedal and as the secondaries began to open I would get a response like that from an automatic car hitting passing gear. I don’t get that same response with the 455. With both, there is great wot response with the secondaries opened fully. Difference in quadrajets, adjustment or ? Thanks, john If by "secondaries open" are you referring to the air valves on the top of the carb, or the real secondary throttle plates? You do realize that the air valves will barely open, if at all, if you are simply revving the engine in park, right? The actual secondary throttle plates at the bottom of the carb are mechanically operated. The air valves are opened by mass air flow through the carb (and NOT by "vacuum" as most people incorrectly assume). If you really do have a performance problem, yes, there are adjustments. The air valve wrap spring and the vacuum break both control the rate of secondary air valve opening. Of course, there are a LOT of other variables not related to the carb, like gearing, cam, etc, etc. |
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Post by john442 on Dec 6, 2017 11:27:34 GMT -5
Thanks for the information. I know we sometimes remember things bigger than they actually were but while my
description may sound like that, the effect I describe is not. It may not have been as powerful as an automatic
hitting passing gear but it was very similar. My guess was the secondaries were just starting to open before the
sound of them opening further became very noticeable. I will contact Cliff to see if my current carb needs adjusting
or something else.
thanks for all your help,
john
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Post by joepadavano on Dec 6, 2017 11:45:43 GMT -5
The "butt dyno" is a notoriously inaccurate measuring tool.
In any case, a properly adjusted Qjet should provide a smooth increase in power. If your older carb had a distinct step in the acceleration, chances are the secondary air valve was not adjusted properly on that carb, causing the big jump when it finally snapped open.
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Post by john442 on Dec 7, 2017 18:51:16 GMT -5
Joe thanks for your great information. My old car must have had something wrong with the carb for it to work as
it did. Coincidently I had a motorcycle that had a similar response when throttling up.
My current car seems to run just fine but I may end up replacing the rear end gears.
thanks again for your help,
john
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Post by fromthegrave65 on Dec 9, 2017 11:08:13 GMT -5
I think he's comparing a 4gc to a quadrajet. Not two quadrajets.
When the secondaries open on the 4gc it definitely feels like hitting a power band.
I think that's the distinction he's making. I'm unfamiliar with the quadrajets.
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Post by john442 on Dec 9, 2017 19:47:02 GMT -5
Thanks for adding information that may be the answer to what I described. I don’t know what a 4gc is. Is it a
carter AFB or an early quadrajet? My recollection is the carb on the motor was a quadrajet with the larger
secondaries. Whatever it was, your power band description. Is very accurate. That is exactly what it felt like.
many times when driving I would gradually depress the gas pedal in each gear until this response and then
shift to the next gear. Some times right after this response I would fully step into it by flooring it and get the
very powerful effect from the secondaries.
john
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Post by fromthegrave65 on Dec 9, 2017 23:00:05 GMT -5
The Rochester 4gc was the predecessor to the quadrajet and would have been the stock carb on a 65 in general.
I've never run a quadrajet.
You could have an issue with timing and/or your advance curve.
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Post by john442 on Dec 10, 2017 1:23:17 GMT -5
The car was a 1965 but the motor was from a 1967 442. I sold the car in 1972 . It ran great but at times it
would hesitate when floored.
john
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Post by joepadavano on Dec 11, 2017 10:07:48 GMT -5
I think he's comparing a 4gc to a quadrajet. Not two quadrajets. Go back and read his very first post 1967 motors DID come with a Qjet |
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Post by fromthegrave65 on Dec 11, 2017 19:39:33 GMT -5
I can read.....a little bit. Thanks though.
Having a 1967 400 block doesn't dictate the carburetor.
Just throwing out ideas.
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Post by john442 on Dec 11, 2017 21:10:43 GMT -5
I’m going to add some confusion but possible an answer. The car was a 65 olds cutlass, 330 4v and 4 speed. I
blew up this motor and installed a 67 400 motor from a wrecked 442 4 speed car. I don’t recall using the carb
from the 330 on the 400 but it is possible. I seem to recall the 330 had the power band like effect as well.
if the carb was a 4gc on the 330 and I reused it on the 400 would that offer an answer? Also, I’m pretty certain
that whatever carb was on the 400 it had the very large secondaries.
Thanks to all all for your help,
john
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Post by BR[] on Dec 12, 2017 9:19:02 GMT -5
" if the carb was a 4gc on the 330 and I reused it on the 400 would that offer an answer? Also, I’m pretty certain
that whatever carb was on the 400 it had the very large secondaries. "
If it had the large diameter secondaries, then it sounds like you simply dropped the 67 400 w/ quadrajet into the car. It would have made no sense to pull the manifold and small carb off of the 330 and install it onto the 400. The 66 & 67 400's have a totally different manifold than the 330 or even the 65 400 for that matter.
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Post by john442 on Dec 12, 2017 14:34:55 GMT -5
Bro,
If I had replaced the carb I wouldn’t have also replaced the manifold. It’s just coincidental that
both the 330 and 400 carbs had the same effect I mentioned. Whatever the reason, I really liked the
power band like effect before I floored it to fully open the secondaries.
thanks for all your information and help,
john
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Post by BR[] on Dec 12, 2017 15:25:59 GMT -5
Bro, If I had replaced the carb I wouldn’t have also replaced the manifold. It’s just coincidental that both the 330 and 400 carbs had the same effect I mentioned. Whatever the reason, I really liked the power band like effect before I floored it to fully open the secondaries. thanks for all your information and help, john My memories of the 60's are the same as your description...............when you punched it to the floor, sometimes the tires would break loose when the back two kicked in. I always ran 4:33's so that hard kick was amplified. |
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Post by john442 on Dec 12, 2017 21:17:13 GMT -5
Bro,
yeah, nothing like muscle car power. I’m sure the guys on this site could add some great stories about their cars.
If your car could break the tires loose when getting on it, you had a pretty powerful car. My 65 Cutlass could make
the tires squeal but that is because they were bald. Still, muscle cars ruled then and still do and my car then is the
reason I have one now.
john
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Post by joepadavano on Dec 15, 2017 11:33:43 GMT -5
Time to add some common sense here. The 1965 330 would have had a 4GC and matching intake. That obviously would not fit the 67 400 motor. Unless the OP searched out the one-year-only 1965 BBO intake, it is EXTREMELY likely that he simply dropped in a complete 1967 400 WITH the factory Qjet intake. The 4CG from the 330 would not have bolted up to this.
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Post by john442 on Dec 15, 2017 20:08:52 GMT -5
As I recall, I put the 67 400 engine in and it was complete. When I finished hooking everything up, I took the car
for a test run and found the power brakes felt funny. When I got back to the garage I discovered I forgot to
connect the power brake vacuum line to the manifold (or carb?). I do remember looking At the 400 manifold on
the engine and it appeared wider that the 330 manifold. Just one more question, do I understand that the 65 330
Could not not have had a quadrajet because the factory used a 4gc instead?
thanks to everyone for the great information and help,
John
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Post by joepadavano on Dec 16, 2017 9:12:27 GMT -5
Just one more question, do I understand that the 65 330 Could not not have had a quadrajet because the factory used a 4gc instead? Correct. The factory intake on the 1964-65 330 was a square bore for the 4GC. A Qjet would not bolt up.  The Qjet intake looks like this:  |
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