Holley 6210 (650 double pumper) and 454

[Bill C.]

Hey all ...

I am doing the following and need some help....
I purchased a Holley 6210 650 spread-bore replacement for the QuadraJet.
I want to use the Holley for driving/daily use and keep the 7042217 for NCRS shows only.

I have the carb mounted and running - no issues there.
I can not use my stock dual snorkel air-cleaner, it sits to high and the breather plumbing (bent tube from air-cleaner) hits the accelerator pump lever on the secondaries.

I ordered an air-cleaner kit/assembly from Paragon, but ordered the kit for 66/67 BB application. I did this hoping that the base would have the correct drop and elbow/tube fit necessary. Plus the 425HP 427 used a big ass Holley and it fits under it okay.

Does anyone see any issues with this?
Should I have ordered the 68/69 427 kit instead?

ANY INSIGHT is really appreciated with this!!

[Joe L.]

Re: Holley 6210 (650 double pumper) and 454

Hey all ...

I am doing the following and need some help....
I purchased a Holley 6210 650 spread-bore replacement for the QuadraJet.
I want to use the Holley for driving/daily use and keep the 7042217 for NCRS shows only.

I have the carb mounted and running - no issues there.
I can not use my stock dual snorkel air-cleaner, it sits to high and the breather plumbing (bent tube from air-cleaner) hits the accelerator pump lever on the secondaries.

I ordered an air-cleaner kit/assembly from Paragon, but ordered the kit for 66/67 BB application. I did this hoping that the base would have the correct drop and elbow/tube fit necessary. Plus the 425HP 427 used a big ass Holley and it fits under it okay.

Does anyone see any issues with this?
Should I have ordered the 68/69 427 kit instead?

ANY INSIGHT is really appreciated with this!!

Bill------


As far as the "drop down" is concerned, the 66-67 and 68-72 bases are the same. So, as far as this goes, you should be fine. The difference in the bases has more to do with the angularity and configuration of the breather tube. I think you'll be ok with the 66-67 base but I'm not 100% sure. There may be some slight fitment problems with the breather tube, but I think you'll be able to overcome it.

[Bill C.]

Re: Holley 6210 (650 double pumper) and 454

Thanks Joe.

[Jim T.]

Re: Holley 6210 (650 double pumper) and 454

Bill I installed a Holley spreadbore 6210 650 double pumper on my original owner 1970 350/300 many years ago, 1974.
I used my original dual snorkel air cleaner, did not change bases. The installation of the Holley spreadbore used the original choke pull off.
You may not want to do it, but I just made a indention in the fresh air metal tube on my 70's dual snorkels air cleaner base which worked for me. NCRS was not around then for C3's.
I also installed the Holley 6210 650 spreadbore double pumper in 1974 on my 1968 327/350 L79. I used the original open element air cleaner base, still do. Did something different, reclocated the fresh air tube to not interfere with installation and use of the Holley. Not a complicated change, but again no NCRS for C3's in 1974.

Did you make up a new steel fuel line from the fuel pump to your new Holley?

I also use full time vacuum from the Holley 650 base plate to the vacuum advance. Better gas mileage in town/city driving and cooler operating temperatures in stop and go traffic.

[Bill C.]

Re: Holley 6210 (650 double pumper) and 454

Jim,

I was able to use the factory fuel line, it fit/aligned without any issues.
I still use ported vacuum, however I did run it full time to the distributer. I bypassed the TCS selonoid.


The dual snokel base, when used with the Quadrajet, sat flush with the ignition sheilding. When I sat the base on the Holley, it was elevated about 3/4 of an inch. The clearances under the BB hood are tight, and was worried it would hit.

The pumper arm on the secondaries is really big compared to the one on the front fuel bowl. I would need to rotate the breather tube some and raise it up about an inch to clear the pump arm.

I want it to look nice, so I figured I get a aircleaner kit from Paragon.
I may need to modify the breather tube on the new unit, that I be okay with.
I want to leave my original alone, and then it is always ready for NCRS shows etc..

Thanks for the great insight!!

[Mark E.]

Re: Holley 6210 (650 double pumper) and 454

Years ago I trial fitted an 800 cfm 4165 (mechanical secondaries) and a 650 cfm 4175 (vacuum secondaries) on my '70 454. As you shared, there was interference with the PCV inlet on the dual snorkel air cleaner with both carbs as I recall. Plus there was either no or very little hood clearance (don't recall which).

I also tried the open element air cleaner used on early '70 454. That interfered with the Holley's rear fuel bowl as I recall. So instead I boxed up the original 7040205 Q-Jet and installed the California version (7040505 for 1970 454) which features both manifold and ported vacuum connections.

If you make the mods required to make this fit, would you share what you did on the forum?

Regarding Jim's comment about manifold vs ported for vacuum advance: I encourage you to experiment with each. Every engine I've had was much more responsive with ported vacuum. It's not unusual to encounter an initial stumble at full throttle with manifold vacuum because the VA immediately retards timing due to vacuum drop just when the engine wants the opposite.

The trick with using ported vacuum is to advance static timing as needed. This may require limiting total centrifugal advance. For example, with ported vacuum, my LS5 likes 12 degrees BTDC initial/38 degrees total centrifugal (instead of the factory 6 degrees initial/38 total). So in my experience, using ported vacuum and advancing static timing typically increases responsiveness, mitigates the problem of running hotter at low RPM, and smooths out the idle.

[Patrick H.]

Re: Holley 6210 (650 double pumper) and 454

Silly question - any reason you didn’t take a different Quadrajet, install the same size jets/rods/springs used on the 7042217, and use that?
It would really cut down on the issues regarding fuel line, air cleaner, etc.

[Joe L.]

Re: Holley 6210 (650 double pumper) and 454

Silly question - any reason you didn’t take a different Quadrajet, install the same size jets/rods/springs used on the 7042217, and use that?
It would really cut down on the issues regarding fuel line, air cleaner, etc.

Patrick-----

I agree. Also, I consider the Quadrajet to be the best 4 barrel STREET carb ever available. And, when you get right down to it, the STREET is just about the only place where any of us here ever use our cars.

[Justin S.]

Re: Holley 6210 (650 double pumper) and 454

I guess I should've revived the 14 year old thread against popular edict after all.

https://www.forums.ncrs.org/showthre...rmarket-Holley

Does anyone know of an aftermarket air cleaner base that will work on a big block '70 with a 6210 single feed?

[Mark E.]

Re: Holley 6210 (650 double pumper) and 454

I guess I should've revived the 14 year old thread against popular edict after all.

https://www.forums.ncrs.org/showthre...rmarket-Holley

Does anyone know of an aftermarket air cleaner base that will work on a big block '70 with a 6210 single feed?

My bad replying to this old thread. I read you thread from the other day, followed its link here and reflexely replied here.

[Justin S.]

Re: Holley 6210 (650 double pumper) and 454

Zip item# AC-58 worked.

[Duke W.]

Re: Holley 6210 (650 double pumper) and 454

Ported vacuum advance is an emission control technique. By reducing total idle advance below the ideal range, EGT increases, which helps initiate oxidation reactions to reduce HC and CO. It also increases idle and low speed driving fuel consumption, and the increased EGT throws more heat into the cooling system as the exhaust gas traverses the exhaust ports, which can increase coolant temperatures in low speed driving, especially if all cooling system components are not up to snuff.

Emission controlled engines have very different spark advance maps than pre-emission engines. The former typically have short, lazy centrifugal curves and long, lazy vacuum advance curves. When converting emission-controlled engines from ported to full time vacuum advance, in most cases a different spec VAC is necessary in order to meet the Two-Inch Rule, and often more centrifugal is needed to get close to the optimum WOT advance range without excessive initial timing that can lead to detonation.

Closed chamber head big blocks don't like as much low speed, low load advance as small blocks, and this is why pre-emission big blocks have VACs that only provide a maximum of 12 degrees instead of the 16 typical of small blocks. They also have longer centrifugal curves than most small blocks, so need less initial timing to achieve the optimum 36-40 degrees total WOT advance.

I recently helped an owner who was having idle speed issues with his '66 L-36, It turned out the OE VAC was "sticky" and wouldn't always fully advance at idle. So we installed a new B26 VAC that has 16 degrees @ 12". (There are no longer 12 degree VACs available.) This resulted in some low speed roughness with 6-8 degrees initial. Rather than limiting the VAC max advance we installed a '67 L-36 cam assembly that offers 32 degrees total centrifugal ('66 L-36 is 30) and set the initial at 4-6. With lighter springs to bring full centrifugal in at about 3500 instead the OE 5000. The result was idle behavior of 15" @ 600 with just a hint of lope and a noticeably stronger mid-range to top end.

When converting an emission controlled engine to full time vacuum advance and optimizing the entire spark advance, one should look at the optimized map for the antecedent non-emission controlled engine. The antecedent for the '70 - '74 454s is the L-36, so in addition to selecting a proper VAC when converting from ported to full time vacuum advance, one should look at increasing total available centrifugal into the 30-32 range.

The early 454s used the L-36 cam, but the last year or two or two they had a different cam that increased overlap, which was effectively a full time EGR system to meet new NOx standards, but it also hurt idle quality and low end torque.

Theoretically open chamber head big blocks should like and tolerate more advance under low speed, low load conditions than closed chamber head versions, but I've never had an opportunity work on an open chamber 454 in search of an optimum spark advance map.

There is more information on this subject in my tuning seminar that is in the restoration documents thread near the end of the sticky section.

Duke

[Mark E.]

Re: Holley 6210 (650 double pumper) and 454

Ported vacuum advance is an emission control technique. By reducing total idle advance below the ideal range, EGT increases, which helps initiate oxidation reactions to reduce HC and CO. It also increases idle and low speed driving fuel consumption, and the increased EGT throws more heat into the cooling system as the exhaust gas traverses the exhaust ports, which can increase coolant temperatures in low speed driving, especially if all cooling system components are not up to snuff.

Emission controlled engines have very different spark advance maps than pre-emission engines. The former typically have short, lazy centrifugal curves and long, lazy vacuum advance curves. When converting emission-controlled engines from ported to full time vacuum advance, in most cases a different spec VAC is necessary in order to meet the Two-Inch Rule, and often more centrifugal is needed to get close to the optimum WOT advance range without excessive initial timing that can lead to detonation.

Closed chamber head big blocks don't like as much low speed, low load advance as small blocks, and this is why pre-emission big blocks have VACs that only provide a maximum of 12 degrees instead of the 16 typical of small blocks. They also have longer centrifugal curves than most small blocks, so need less initial timing to achieve the optimum 36-40 degrees total WOT advance.

I recently helped an owner who was having idle speed issues with his '66 L-36, It turned out the OE VAC was "sticky" and wouldn't always fully advance at idle. So we installed a new B26 VAC that has 16 degrees @ 12". (There are no longer 12 degree VACs available.) This resulted in some low speed roughness with 6-8 degrees initial. Rather than limiting the VAC max advance we installed a '67 L-36 cam assembly that offers 32 degrees total centrifugal ('66 L-36 is 30) and set the initial at 4-6. With lighter springs to bring full centrifugal in at about 3500 instead the OE 5000. The result was idle behavior of 15" @ 600 with just a hint of lope and a noticeably stronger mid-range to top end.

When converting an emission controlled engine to full time vacuum advance and optimizing the entire spark advance, one should look at the optimized map for the antecedent non-emission controlled engine. The antecedent for the '70 - '74 454s is the L-36, so in addition to selecting a proper VAC when converting from ported to full time vacuum advance, one should look at increasing total available centrifugal into the 30-32 range.

The early 454s used the L-36 cam, but the last year or two or two they had a different cam that increased overlap, which was effectively a full time EGR system to meet new NOx standards, but it also hurt idle quality and low end torque.

Theoretically open chamber head big blocks should like and tolerate more advance under low speed, low load conditions than closed chamber head versions, but I've never had an opportunity work on an open chamber 454 in search of an optimum spark advance map.

There is more information on this subject in my tuning seminar that is in the restoration documents thread near the end of the sticky section.

Duke

Consider ported VAC as a tuning option that often improves responsiveness, especially from idle and high vacuum conditions.

When using ported VAC, you’ll dial in a lot more static timing than when using manifold VAC. So the difference in total timing (static + VAC) at idle is minimal. This mitigates concerns about increased temperatures. The centrifugal advance curve will often need to be shortened to limit total advance.

So what happens at WOT from idle with manifold VAC?
Vacuum drops ==> VAC retards timing just when the engine wants more ==> reduced responsiveness and sometimes a stumble as the engine recovers.

And what happens at WOT from idle with ported VAC?
Vacuum drops ==> VAC advance remains zero; static timing is more advanced from the start; centrifugal advance immediately increases ==> timing immediately and smoothly advances ==> improved responsiveness (often much improved).

Try each and see which makes your engine happier.