Vacuum-Or Mechanical-Secondary Carburetor?

I just read this article in Motor trend - Vacuum-Or Mechanical-Secondary Carburetor?

Recently I purchased a Holley 4150, 750 CFM double pumper with mechanical secondaries and electric choke for my 1970 Buick GS 455.

The issue, should I have purchased a carburetor with vacuum secondaries?

What's everybody's opinion?

The car has been in an upgrade restoration process for the last 19 months (mostly waiting for parts with very long delivery times).

I had the opportunity the other day to test drive the car for 100 miles. Several time I went WOT. From an idle, foot braking it and rolling at 40 mph.
I didn't detect any hesitation or bog situations. It seemed to charge ahead with no rpm hesitation. But the highway gearing (2.93) did limit the torque rush feeling.

Everything thing I have read says I should have purchased a vacuum controlled carb.
Because the Skylark is heavy at 3800 pounds, it's an automatic, and has highway differential (2.93 posi).

However, I suspect that the below power add-on's may have created a situation where the mechanical secondaries are working just fine. BUT, that's just a guess on my part.

I'm a rookie when it comes to Buick BB engines.
I'm used the Chevy high revving small blocks with very little Torque feel.

It does have some performance add-on's.
(1) Bored .030 over.
(2) Kenne Belle pistons with valve reliefs (9.5 to 10.0 compression).
(3) Engine has been Ported.
(4) Has Stage 1 heads.
(5) Comp Cam little more powerful than the original Stage 1 cam.

 

I second the above recommendation. Put a WELL BUILT Qjet on it. (Don’t buy a parts store carb, don’t buy the chinesium ebay junk. There’s several ‘builders’ out there with a guarantee, and we all know what that’s worth).

Patrick

 

If it ain't broke don't fix it. You already dropped good coin on a carb and by your own words if doing everything you should. If you want to spend money and get more giggly up but some gears. But figure out how you plan to drive it most and if using a little fuel is worth the trade for get up and go.......

 

Now this isn't a direct apple to apples comparison but the point will ring true.

We put a set of 4.1 in a buddies 90s 5.0l mustang from the 2.93. It dropped almost a second st the strip with no other changes.

I dropped about .7 in my gs when I went from 3.08 to 4.10s. Point is a mid 3 gear would change your driving experience from day to night

 

Thanks to everyone re my question. Love your input.
I agree I have spent big bucks for a Holley, here's the main reason.

The shop that's working on my 70 Buick GS 455 ordered a 750 Qjet to replace the one on my car because previous owner had a heavy handed mechanic who wrench the carb to tight to the manifold and warped the carb.
The shop ordered a Qjet and right out of the box it was bad. Sent the Qjet back (I wouldn't be surprised if it wasn't made in China).

The engine mechanic asked me if I liked a Holley carb, I said yes, I've had super good performance from them in the past.
So he ordered from Holley a 4150, 750 cfm double pumper with mechanical secondaries.

I question him re the mechanical secondaries, he said with the current power adders.
(1) Bored .030 over.
(2) Kenne Belle pistons with valve reliefs (9.5 to 10.0 compression).
(3) Engine has been Ported.
(4) Has Stage 1 heads.
(5) Comp Cam little more powerful than the original Stage 1 cam.

He saw no reason why this 3800 pound Buick couldn't get up and go. He was right, no problem with power, the only issue is the 2.93 differential, it doesn't allow the huge Touque feel you get with the Stage 1 3.42 Differential that comes with the A/C cars.

I just forgot, yesterday it was close to 90 degrees, and I had the A/C on when I was doing the performance runs.
O'boy, bet that made a big difference. Well, it still smoked the tires and even got a little squirrelly, but easily controlled.

I'm not willing give up the highway gears because I plan on doing some long distance driving. I don't want to spin-up the engine revs to high.

The posted video by Brett is amazing, don't know what type of exhaust system you're running but it sound fantastic. VET (Navy)

 

Brett, I just played your entire video. I recognized your Black Stage 1, 4-Speed Buick.

I don't know what make of cam you have, but it sounds mean. You've got a ton of power adders on your Buick.

Your Buick is WAY beyond a standard Stage 1. Love your car, but I'm sure it would scare the S**T out of me.

I'm sure that's ever bit a 10 second car or faster. Thanks for the video. VET (Navy)

 

There is nothing wrong with your holley, they are great carbs, although the 750 may be a tad on the small side. A gear change to 3.23 may be in order, as you want to keep your rpms lower at highway speeds. If you really want to get crazy, put some 4.10's in it and switch to an overdrive transmission.

 

If you pulled up next to me and I heard that cam, I would turn off my car, lol.
Super nice car, don't see to many 4-speed Buick Stage 1's. VET

 

Overdrive trans might be doable. Great suggestion, thanks. VET

 

That’s the MTs singing away that is so alluring…

 

Vet - thanks for your service. I am not recommending you change your carb. My 2 cents, in general: should you ever need to change carbs: Testing has show the BBB like big carbs. You may find an 850 really helps in the upper RPM range. Also, a good Q-jet should give you as good performance and better MPG. Most Q-jets sold these days do have quality issues. It's not a reflection of the design that they don't work right!

 

Thank you Bill for the offer.

Just yesterday I noticed a JET Ad, JET sells their Qjets as "Remanufactured".
I know Qjets are not manufactured "new" anymore. However, they don't tell you who rebuilds or where the rebuilds are done (China?)
I purchased a Qjet, right out of the box it was bad.
Most of the Speed shops and Restoration shops in my area buy from JET, because there are very few Qjet vendors.

In turn, when the shops experience bad Qjets, they offer their customers Holley's and buy directly from Holley.
I'm not opposed to a Qjet I used them a long time ago in the 70's on a Corvette.

Now I have a Buick GS 455, and I'm on the V8Buick.com forum, I didn't know there are "expert" Qjet rebuilders on the forum I could have gone too.

The Restoration shop I'm working with, they almost never see a Buick, so their Buick experience is poor. They didn't even know about Todd Miller's Stage 1 Restoration company. Now they use him all the time for the few Buick projects they get. Currently a 70 GS 455 from Barret/Jackson and a 73 Buick GS 455.

If I had needed to have my engine rebuilt (which I don't) they have a very good engine machine shop that could have rebuilt a Qjet for me.

Most of my headaches have experienced, is a lack of knowledge with Buicks in general when working with automotive shops.

Thanks to all the help and advice. Regards VET (Navy)

 

I can help if you like, I have fixed a lot QJs for folks, Brett is just one of them.

 

If I had a nickel for every person who has a story like yours (with Buicks at shops, looking for parts, having machine work done, and with all GM products regarding Qjets), I’d have a big ass bag o’ nickels!

Next time someone posts a pile of the old GSXtras (GS Club newsletter), buy them and read them. There’s a wealth of info in them, some of it dated, but many of us on here are very wary of Brand X shops and builders because of their lack of that knowledge. They want to fire the Summit parts cannon at our cars and build them like they’re SBCs and set up clearances and oil pressure like that, too. Meanwhile, folks on here have cars that run 11s and 12s with Qjets, iron manifolds and factory ignitions.
Patrick

http://www.v8buick.com/index.php?threads/post-your-11-12-second-455-combos.275366/

http://www.v8buick.com/index.php?threads/post-your-12-13-second-455-combos.314631/

 

Rob, thank you so much for your offer.

Right now, I have a total of maybe 90 miles on the Holley and it seems to be working fine.
I need some more run time on it.

I have several issues the shop is working on my car.
(1) Replacing my "NEW" Delco Thermostatic HD clutch fan for one of Todds Thermostatic HD clutch fans.
For some unknow reason, I'm getting a roaring sound from the Delco HD clutch fan. I suspect its defective and is engaged all the time.
I purchased a Decimal meter to record the sound level (the shop Service manager didn't believe me). I even purchase a
laser temperature gun to record radiator heat. Everything I have read says the clutch fan does not rotate below 170 degrees.
When I started up the engine, I let it get to 92 degrees and the fan still rotated and still at 114 degrees too.
I don't know if the silicone is causing the fan to rotate. I'm having the Delco replaced with one of Todd Millers clutch fans.
I should know sometime next week.

(2) Ran into another issue. I had to buy a idle Solenoid Kit because when I turn-on the A/C, the rpms go so low that the engine stalls all the time.
Such a pain. Come to a stoplight and I have to two-foot brake and gas pedal. even in a parking lot, going from drive to reverse the engine stalls.
I called Holley and they have the kit for this issue.

(3) Had to upgrade my alienator (55amp) to a 150-amp model because I added some power drawing items, new A/C unit, Dokota digital dash gages. Modern (classic radio) upgraded dual speakers into the rear deck.
All these items were killing my battery. You would "think" the shop guys would have known this was going to happen? They waited until they killed two batteries, they paid for them, NOT me.

Haven't had a lot of fun working with a Restoration shop. VET (Navy)

 

Patrick, you are so "right-On".

I got back into the performance cars because I retired, my family are on their own. I'm very disappointed with the state of automotive suppliers.

Ebay and Amazon can't be trusted to deliver the parts we need. Amazon looks to be an supplier arm of China.

Every time I call TPP and ask a question, the guy at the desk doesn't know or is reading from the catalog.
The last guy I called at TPP, at least called Hdqs and got me the answer I was seeking. I appreciated that.

O' by the way, anybody know where to buy wiper refills for a 1970 Buick Skylark. None of the Auto part stores carry windshield wiper "refills" anymore.
That blew me away, guess there isn't enough profit to take care of the classic cars. VET (Navy)

 

Let us know how the repairs go. I’ve heard others say the HD clutch is noisy all the time. Thanks for posting.