Builds The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[RWBeringer4x4]

Odd to get such a noticeable change without some known cause.
The challenge you're having with the SBC/Q-jet is the number of possible OEM manifold and gasket , add in the aftermarket manifolds and it gets more challenging.
I agree with @Weber Sarge that the manifold surface can be a factor if your leak is at the base of the carb and other possibilities have been eliminated.
Man, I don't miss my carb days.

Yeah...this is all making me very much consider finding a roller block and TBI manifold and just being done with it. If wiring all the computers and sensors wasn't such a pain, it would already be done. I do love the simplicity I get with a carb, plus I lack any and all chevy emissions pieces, but I have yet to have a Quadrajet run right for more than about 100-150 miles before I have to take it off and fiddle with it.

 

[RWBeringer4x4]

Update - walked outside at lunch, loosened the 4 mounting bolts. Then tightened them all back down to 15 ft. lbs. and now it idles fine again. a TOUCH of wander, but no longer responding to carb cleaner...Now it basically idles as good as it ever has, it kind of just picks a 50RPM range somewhere between 650 and 750 and floats around.

Sounds like I just have a REALLY tenuous seal between carb and manifold...Wondering is this is a job for wheel bearing grease...

Old hotrodder friend of my father-in-law greases his carb-to-manifold gasket, claims it seals better, and also makes the gasket more removable since the carb is on and off his drag car so frequently...Might be one of those old racing myths though...

 

[Norcalcruizer]

Update - walked outside at lunch, loosened the 4 mounting bolts. Then tightened them all back down to 15 ft. lbs. and now it idles fine again. a TOUCH of wander, but no longer responding to carb cleaner...Now it basically idles as good as it ever has, it kind of just picks a 50RPM range somewhere between 650 and 750 and floats around.

Sounds like I just have a REALLY tenuous seal between carb and manifold...Wondering is this is a job for wheel bearing grease...

Old hotrodder friend of my father-in-law greases his carb-to-manifold gasket, claims it seals better, and also makes the gasket more removable since the carb is on and off his drag car so frequently...Might be one of those old racing myths though...

How much vacuum are you pulling at idle? I have a Qjet as well on a Edelbrock performer intake manifold with a 1" spacer. I am also running a thicker gasket between the carb and spacer. My idle will change occasionally from 650-700 to 550 rpms, I notice my vacuum gauge at 20 idles perfect, when it does drop to 550 I then pull about 17. I have kinda given up on tracking it down, being that it is not consistent I really have no clue what could be causing the issue. It pretty much passes the carb spray test anywhere I spray it. A large majority of the time it idles fine at 650-700 rpms. One good thing about a Qjet is they are fantastic off road, they basically will run upside down which is why many guys run them for rock crawling because they do not flood out easily.

 

[RWBeringer4x4]

How much vacuum are you pulling at idle? I have a Qjet as well on a Edelbrock performer intake manifold with a 1" spacer. I am also running a thicker gasket between the carb and spacer. My idle will change occasionally from 650-700 to 550 rpms, I notice my vacuum gauge at 20 idles perfect, when it does drop to 550 I then pull about 17. I have kinda given up on tracking it down, being that it is not consistent I really have no clue what could be causing the issue. It pretty much passes the carb spray test anywhere I spray it. A large majority of the time it idles fine at 650-700 rpms. One good thing about a Qjet is they are fantastic off road, they basically will run upside down which is why many guys run them for rock crawling because they do not flood out easily.

Thanks for chiming in @Norcalcruizer - I'm running a semi-tired 283 at the moment, I pull about 14-15lbs of manifold vacuum on a good day. The fact that the quad won't flood out/is good offroad is about the only reason I haven't gone to a more simple system, like a Holley or something along those lines. Plus, the Quadrajet really is a marvel of engineering, it's just also (apparently) way over my head!

Not sure what would be causing your idle stumble - both Quadrajets I've tried to run so far have been a little flakey in that respect. Run great one day, stumbling the next. I'll go for a drive, at one red light it idles at 700, the next it idles at 900, after that it's back down to 500 and stumbling, and the one after that, 700 again. This one had been good for the past 100 miles or so, I'm kind of hoping it's just a manifold seal problem this time...it seemed to be a lot steadier today after I tightened everything back down.

 

[RWBeringer4x4]

Alright - confirmed, it was definitely the gasket leak causing the latest series of woes. I just drove it around town for about a half hour in rush hour traffic to give it plenty of opportunities to sit at idle and actuate the throttle. Ran for a half an hour and about 20 miles without so much as a hiccup.

And life with this finicky truck goes on...

 

[Weber Sarge]

I wish the Q-jet was built more like the AFB from Carter , or the modern 2-piece Edelbrock version - they tune out a lot better but their float design isn't the best off road . In the end , if you're going to stick with a SBC it would be easier to just bite the bullet and ditch the old engine - go with a newer throttle body for simplicity and run it - they are bone simple .
Sarge

 

[RWBeringer4x4]

I wish the Q-jet was built more like the AFB from Carter , or the modern 2-piece Edelbrock version - they tune out a lot better but their float design isn't the best off road . In the end , if you're going to stick with a SBC it would be easier to just bite the bullet and ditch the old engine - go with a newer throttle body for simplicity and run it - they are bone simple .
Sarge

The only thing that freaks me out about TBI is all of the initial re-wiring it would entail. I worry that the electric fuel pump, computer, and integrating all the emission control sensors (welding sensor bungs into the exhaust system and whatnot) would be a bit over my head, particularly integrating it into the stock harness without making a total mess of things. I completely agree that it's a superior system, and I've even priced out building up a TBI engine (from new parts) and it's not astronomically more expensive than replacing my existing carbed 283 with a carbed 350, especially if I can find a junkyard donor for the emissions and TBI pieces.

Even if I ditch the 283, I may just end up dropping in a basic crate, flat tappet 350 simply because it's a big tractor engine and something that even I can't screw up! I'd love to go to a 96-02 era roller-block vortec, with all the vortec fixin's but it's relatively expensive, and from my understanding, TPI was actually something of a step backward from TBI.

 

[Norcalcruizer]

CA smog is the problem, it's currently set at 1975. I heard rumor soon they are possibly bumping to 1977. If this happens I will more than likely drop a new fuel injected engine. It is a PIA to get a new CARB sticker with a new engine, you have to run cats, all sensors, etc. just not worth the headache.

Overall I am pleased with my Qjet, not a bad setup. Simple and easy to work on.

 

[RWBeringer4x4]

CA smog is the problem, it's currently set at 1975. I heard rumor soon they are possibly bumping to 1977. If this happens I will more than likely drop a new fuel injected engine. It is a PIA to get a new CARB sticker with a new engine, you have to run cats, all sensors, etc. just not worth the headache.

Overall I am pleased with my Qjet, not a bad setup. Simple and easy to work on.

Smog isn't really too much of an issue here - I literally mailed in my historic registration. It only needed to pass safety (horn, wipers, headlights, brakes, seatbelts). However, if I wanted it to be a daily driver, it would need to pass a smog inspection for the year it was built (1975). Although I think MD just moved the emissions test cut-off to 1977 this year (woohoo)!

I find it hilarious that California makes it so difficult to make your vehicle LESS smoggy by going to a more modern, more efficient engine, than the one currently installed.

To be honest - I'd consider going to 1975-era emissions controls just to get the smell down. My emission-less 283 is truly eye-watering. My wife doesn't like to drive in it because she smells like exhaust fumes for the rest of the day.

I'm sure patching the manifold exhaust leak and holes in the floor would help keep the fumes out of the cab, but it's still a pretty smelly vehicle, when all is said and done.

 

[RWBeringer4x4]

For what its worth - Delaware I think is the worst state for it. I had to register the truck there, initially. Whether you are tagging your car historic, or registering it as a daily use vehicle, you have to pass a curb idle test. The cut-off date is 1968...Only reason the clustertruck made it through the first time is because I knew a guy who knew a guy...

 

[Cdaniel]

Loose carb mounting bolts on new gasket after a few heat cycles is not uncommon.

 

[RWBeringer4x4]

Loose carb mounting bolts on new gasket after a few heat cycles is not uncommon.

Yeah, I guess what confused me is that the bolts were all snug...before I backed them off and re-tightened them, I checked them with a torque wrench, and they wrench clicked at 15 ft lbs before the bolts moved.

 

[Cdaniel]

Probably a dumb question, but are you using flat washers under the mounting bolt heads and/or nuts?

 

[RWBeringer4x4]

Probably a dumb question, but are you using flat washers under the mounting bolt heads and/or nuts?

Hey Cliff - I'm pretty sure I'm running a thick flat washer against the carb, and a split lock washer between the flat washer and the bolt head.

 

[Cdaniel]

Hey Cliff - I'm pretty sure I'm running a thick flat washer against the carb, and a split lock washer between the flat washer and the bolt head.

That's good. No flat washers could really mess with a torque reading. Split locks maybe a little, but .
Frankly I've never used a torque wrench on the carb. Just my calibrated elbow.

 

[RWBeringer4x4]

That's good. No flat washers could really mess with a torque reading. Split locks maybe a little, but .
Frankly I've never used a torque wrench on the carb. Just my calibrated elbow.

Normally, that's the approach I'd take (just snug it down by "feel") but I've heard Qjets are really prone to warping due to being over-torqued so I'm trying to be extra careful.

 

[SuperBuickGuy]

if you hear *snap* with a q-jet, you've tightened it too much and you'll need to find a new base.

 

[RWBeringer4x4]

if you hear *snap* with a q-jet, you've tightened it too much and you'll need to find a new base.

Har har har

 

[SuperBuickGuy]

Har har har

Just here to help. Don't forget to tip the waitstaff.

 

[RWBeringer4x4]

Today marks exactly 4 years of Clustertruck Ownership. Unfortunately not a lot to report, recently. It has been a VERY busy summer - and I'm still struggling to finish the garage renovations before tearing into the drive-line component of this refurb. In the meantime, I've been driving it, and fooling with "small stuff," Like putting a PCV valve back on it, trying to track down why the Quadrajet is draining its fuel bowl after sitting for a day and a half (AGAIN), and trying to track down why I haven't had driver side rear running lights. Of course, I'm enjoying every minute of it!

It turns out I have not one, but THREE old trailer hitch splices in my rear harness (one wired directly into the tail light). As such, I opted to just have Coolerman build me a new rear harness, and pick up some new OEM tail lights from Toyota. Can't wait to get it tested, and finally installed.

I just crossed the 1000 mile mark in my time of ownership. That's right - in 4 years, I've driven this thing 1000 miles. Probably 300 of those have been this summer. Given the sketchy clutch and oil leaks, I mostly tool around town, grocery shop, and take it to local mountain biking places, but it never gets old.

I had horse-care duty while the wife went on vacation, so it spent some time back in it's "natural habitat." The PO used this as a farm toy before I bought it...

I also ran a pseudo accurate fuel economy test. At 55-60mph highway driving, I get a surprisingly high 14MPG out of the 283 and Quadrajet. For a 50 year old engine pushing a 40 year old rusty, 2-ton brick, that'll do. It's actually WAY better than I thought.

Other than this, just saving my pennies and biding my time. The cruiser fund is prepped and ready for the parts onslaught to come. Maybe August?