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1968 Z28 RS Camaro 302 British Green M.O.
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Discussion Starter · #1 ·
Read this and let me get your thoughts on it.....Dianna
The Following is a partial List of Holley's List numbers for some of their most popular carburetors. (It is not a complete liat)

LIST # CFM STOCK JETTING POWER VALVE TYPE
_
1850-2 600 (F)66,(R) PLATE 134-9 6.5 4160
1850-3 600 (F)66, (R) PLATE 134-9 6.5 4160
1850-4 600 (F)66, (R)PLATE 134-9 6.5 4160
2818 750 (F)65,(R)76 6.5 4150
3124 750 (F)70, (r076 8.5, 8.5 4150
3247 750 (F)70,(R)76 8.5, 8.5 4150
____
*3310 780 (F)72, (R)76 10.5, 8.5 4150
3310-1 780 (F)72, (R)76 10.5, 8.5 4150
____
Yes, Kinda! The original 3310 was a 780. When Holley came out with the updated version 3310-1 it was now a 750cfm carb. Same goes for all the 3310-numbered carbs. Only the 3310 was a 780. These carbs are dual feed, not double pumpers.
Edit, There were some 3310-1 that were still the 780 cfm rating. The easiest way to know for sure on the 3310-1's if it as rated at 780 cfm it had the secondary metering block (one with changable jets). whereas thee 750 cfm only had a secondary metering plate (thin plate that you have to change the "jetting" as they do not have actual jets in the secondaries anymore. I f you look at the carb, it should have a block between the bowl and the main body on the rear just like the front (except no mixture screws) that will be rated 780cfm. If the rear bowl looks like it is just attached to main body without the block between the bowl and main body, this is a 750 cfm rated.
The 780 was the only vac carb with 2 metering blocks. I was debating with this guy who is trying to sell me a carb that Isay Holley didn't makea 780 DP and he say they did....Well, he sent me a pic and now I'm confused. As you can see it does have 2 squirters and a DP bas plate. What I'm confused about is that I thought only the 780 had that little tab on the one down leg boodter....and this one does. It sure looks like a 780 main body to me, but what's up withthe 2 squirters. and this one does.
My guess...That was a 3310 series carb, but could have been an after market dedicated carb for a Z28 302 or 396/427, and most likely had both a List number and a GM number. The 1969 Z!- camaro's were all delivered with a 780 vacuum secondary carb to the dealers, but, all those carbs were changed by a FDM (Factory Directed Modification) to an 850 double Pumper. before
Actually on model 3310 Holley's using either the 750 or 780 rating is correct and depends on what you want to call it.
The original 4150 series (ie- with the secondary metering block List 3310AAS....carbwas a oem Chevy carb used on 375 HP 396 Chevelles and Holley rated it at 780 cfm. Later when Holley came out with a aftermarket versions of the carb- both in 4150-series versions and the cheaper 4160 series (ie with secondary metering plate) they still rated it at 70 cfm. However, the carbs never changed- the early and later versions (both 4150 and 4160 versions) flow * exactly the same * and the supposed 30 cfm reduction in airflow rating was merely done for marketing reasons. to simplify catalogimg and to make carb better fit into the Holley lineof Carbs in nice even cfm inccrements.
___
They are different. I have both carbs. First ones rated 780 had downleg boosters. 750 ones have straight boosters. Downleg boosters restrict the airflow less, thus the different rating.
The dealers were allowed to release them to the buyers.
An example of the dual numbering would be thus, Holley LIST-4053, G.M. Ident 3929289DZ, 780 cfm, Vacuum secondary, standard transmission only, fitment: 1968 302/290/DZ, 396 l-78/L-89, 427 L-72, 1969 302/290/DZ. BOTH those identification numbers would be located stamped into the driver's side of the choke tower.
The metering block markings would be Holley LIST only, wouldn't have an OEM number.
____
Well guys, you tell me what you think...Dianna
271845
 

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1968 Z28 RS Camaro 302 British Green M.O.
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Discussion Starter · #6 ·
Thank you Everett. your always so nice.
I'm confused now, when the camaro ran the 12.97 in 1/4 mile it had a List Holley Carb. 4776-2 DP 650 on it. Crower (David) back then said that was a racing carb, now Chris has put a Holley 3310 780 on it. It likes it better because its getting more gas. But with that 650 on it we would race it every weekend and it ran really good. Not that it doesn't now. but I am very confused with the stuff the write about the 3310-1, -2, etc being a 750. and the only 780 was the 3310. I do a lot of research on the internet on just our car. what do you think. Plus I read the 68 Z28 came with a holley 4053?
 

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LIST-4053-AAS, "1968-69, All Chevrolet Products, 302, 340 (350), 427 & L-28 (Print error) Engine, All Transmissions"

LIST-4054-AAS, "Corvette, 427 (425 H.P.) Std"

Dual feed bowls, single accelerator pump (primary only), Vacuum Secondaries, THESE ARE NOT "MECHANICAL SECONDARIES, DOUBLE PUMPER" STYLE CARBS.
 

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I'm confused now, when the camaro ran the 12.97 in 1/4 mile it had a List Holley Carb. 4776-2 DP 650 on it. Crower (David) back then said that was a racing carb, now Chris has put a Holley 3310 780 on it. It likes it better because its getting more gas. But with that 650 on it we would race it every weekend and it ran really good. Not that it doesn't now. but I am very confused with the stuff the write about the 3310-1, -2, etc being a 750. and the only 780 was the 3310. I do a lot of research on the internet on just our car. what do you think. Plus I read the 68 Z28 came with a holley 4053?
Hopefully I can clarify a bit.
1. A larger carb does not give more fuel, it gives more air.... the jet size adjusts the fuel ratio to match the air.

2. A 302 does not need 780CFM, but since it is a vacuum secondary carb, the secondaries open based on air flow demand as measured by the velocity through the primary venturi's. This prevents you from over carbing the engine.

3. A 650 DP (or any DP) has mechanical secondaries & all 4 barrels are wide open when your foot is on the floor. This can make the carb respond faster & make more power if correctly sized. A 302 can only flow approx 650CFM at 7500rpm, so you see it is of adequate size. If you install too large of a DP carb, the engine can hesitate if you apply full throttle at too low of an RPM. This is because there is not adequate velocity through the carb to pull the fuel it needs to match the available air. Hence a vacuum secondary carb is more forgiving (and typically more street-able), but may not make the most power.

4. Also there was another vacuum secondary Holley carb that had a secondary metering block. It was a 950CFM 3 barrel made in the late 60's early 70's. Currently many of the newer offerings also have rear metering blocks available.
 

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Used in 68 / 69, list 4053 is a 780 vacuum secondary known as a DZ carb, it was used in DZ302 the L78 396 375 hp. the L89 396 375hp. and 427 450 hp.
Here's a pic showing the stampings on one for 1968, the 704 is the date code, 67 year 10th month, 4th week.
272548
 

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1968 Z28 RS Camaro 302 British Green M.O.
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Discussion Starter · #11 ·
Read this and let me get your thoughts on it.....Dianna
The Following is a partial List of Holley's List numbers for some of their most popular carburetors. (It is not a complete liat)

LIST # CFM STOCK JETTING POWER VALVE TYPE
_
1850-2 600 (F)66,(R) PLATE 134-9 6.5 4160
1850-3 600 (F)66, (R) PLATE 134-9 6.5 4160
1850-4 600 (F)66, (R)PLATE 134-9 6.5 4160
2818 750 (F)65,(R)76 6.5 4150
3124 750 (F)70, (r076 8.5, 8.5 4150
3247 750 (F)70,(R)76 8.5, 8.5 4150
____
*3310 780 (F)72, (R)76 10.5, 8.5 4150
3310-1 780 (F)72, (R)76 10.5, 8.5 4150
____
Yes, Kinda! The original 3310 was a 780. When Holley came out with the updated version 3310-1 it was now a 750cfm carb. Same goes for all the 3310-numbered carbs. Only the 3310 was a 780. These carbs are dual feed, not double pumpers.
Edit, There were some 3310-1 that were still the 780 cfm rating. The easiest way to know for sure on the 3310-1's if it as rated at 780 cfm it had the secondary metering block (one with changable jets). whereas thee 750 cfm only had a secondary metering plate (thin plate that you have to change the "jetting" as they do not have actual jets in the secondaries anymore. I f you look at the carb, it should have a block between the bowl and the main body on the rear just like the front (except no mixture screws) that will be rated 780cfm. If the rear bowl looks like it is just attached to main body without the block between the bowl and main body, this is a 750 cfm rated.
The 780 was the only vac carb with 2 metering blocks. I was debating with this guy who is trying to sell me a carb that Isay Holley didn't makea 780 DP and he say they did....Well, he sent me a pic and now I'm confused. As you can see it does have 2 squirters and a DP bas plate. What I'm confused about is that I thought only the 780 had that little tab on the one down leg boodter....and this one does. It sure looks like a 780 main body to me, but what's up withthe 2 squirters. and this one does.
My guess...That was a 3310 series carb, but could have been an after-market dedicated carb for a Z28 302 or 396/427, and most likely had both a List number and a GM number. The 1969 Z!- Camaro's were all delivered with a 780 vacuum secondary carb to the dealers, but, all those carbs were changed by an FDM (Factory Directed Modification) to an 850 double Pumper. before
Actually, on model 3310 Holley's using either the 750 or 780 rating is correct and depends on what you want to call it.
The original 4150 series (ie- with the secondary metering block List 3310AAS....carb was a oem Chevy carb used on 375 HP 396 Chevelles and Holley rated it at 780 cfm. Later when Holley came out with an aftermarket version of the carb- both in 4150-series versions and the cheaper 4160 series (ie with secondary metering plate) they still rated it at 70 cfm. However, the carbs never changed- the early and later versions (both 4150 and 4160 versions) flow * exactly the same * and the supposed 30 cfm reduction in airflow rating was merely done for marketing reasons. to simplify cataloging and to make carb better fit into the Holley line of Carbs in nice even cfm increments.
___
They are different. I have both carbs. The first ones rated 780 had down leg boosters. 750 ones have straight boosters. Downleg boosters restrict the airflow less, thus the different rating.
The dealers were allowed to release them to the buyers.
An example of the dual numbering would be thus, Holley LIST-4053, G.M. Ident 3929289DZ, 780 cfm, Vacuum secondary, standard transmission only, fitment: 1968 302/290/DZ, 396 l-78/L-89, 427 L-72, 1969 302/290/DZ. BOTH those identification numbers would be located stamped into the driver's side of the choke tower.
The metering block markings would be Holley LIST only, wouldn't have an OEM number.
____
Well guys, you tell me what you think...Dianna
View attachment 271845
Well, its Dianna, we had a Holley List 4777-2 650 DP on the camaro a year ago and had it on there for 9 years with minot problems. But today we put Dart Sportmen heads (400) oin the 68 camaro Z and changed yhe carb to a Holley 4346 780 cfm. Chris rebuilt the 4346 as its been in cupboard wrapped for 10 yrs. Got a Trick kit from Holley of courrse they put 6.5 power valves in the lit but called them and they sent free 2- 8.5 power valves. The camaro didn't like the 8.5 P.V. so he put the 6,5 in it and we have a crower cam, the dart heads were porte and that cost as much as the car when it came out. But it likes it. The 3310 780 we tried and liked it too. But the 3310-1 you have to modifty it yo be a 780 cfm. anyhow thanks Dianna
 

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Put a 750 DP on,
get a Holley jet kit,
some squirters and
pump cams and
dial it in.

There is no magic part #.
 

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1968 Z28 RS Camaro 302 British Green M.O.
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Discussion Starter · #13 ·
Put a 750 DP on,
get a Holley jet kit,
some squirters and
pump cams and
dial it in.

There is no magic part #.
well, what I was saying is the 4346 carb works real good now, I was just wondering if any one else has used it and what they thought of it. Thanks so much, Dianna Here's a pic of the Dart sortmens heads after porting.
277325
 

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My 302 ran like crap with the 780. Went with the 750 DP. The car was very happy after that. I have since ditched the 302 for a 409 small block. Still using the 750 DP though. The only place I have found that the 780 works well as a doorstop.
 
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Discussion Starter · #16 ·
My 302 ran like crap with the 780. Went with the 750 DP. The car was very happy after that. I have since ditched the 302 for a 409 small block. Still using the 750 DP though. The only place I have found that the 780 works well as a doorstop.
Thanks for the information . Dianna(y)😎
 
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