Carburation Ideas

[WaltZ]

If I were to change from my original 780 Holley on my stock 302 69 z, what would be suggested.
Would like to keep it looking proper when air cleaner is on it.
no computer or elect pieces.
Thanks in advance.

[firstgenaddict]

Why change from the 4053? Are you having issues?

[WaltZ]

yes, not totally sure if I will change or keep putting $$s into it until it's off idle hesitation is gone. I have exhausted everything, including sending it out 2 times to a highly recommended carb shop in New Jersey.
Timing spot on and adjusted with vacuum gauge and checked for leaks.
Just looking for a carb recommendation.
So much help offered here on this site and tried just about all of it.

[crossboss]

Use the very common 'aftermarket' Holley and very similar in the looks department would be a 750 cfm 3310 model. Summit Racing and others can sell you one in the mean time while getting the OEM 780 version working properly.

[WaltZ]

thank you

[bertfam]

1. Send your carb to Jerry.
2. The newer 3310 carbs are not the same as the original 3310. The newer 3310 carbs are a 4160 model (instead of the original 4150 model) with a primary metering block but a secondary metering plate. If you plan on using your original fuel lines, they won't fit (Some great info HERE). Not only that, but your automatic choke won't work. The original 3878261-EH 3310 used a hot air choke and the later 3310's use a manual choke, or an electric.
3. Send your carb to Jerry, or find a good used 3878261-EH (3310) or aftermarket 3310-1 core and send it to Jerry if you don't care about the choke.
4. Buy a new reproduction 3923289-DZ.
5. Send your carb to Jerry.

Ed

[WaltZ]

I am thinking about sending it to Jery, but want to be able to put something on to use while he has it, hopefully using the existing fuel lines,
thanks
Walt

[Tinkerr]

Have you checked the points gap. I used to set mine at 30 degrees with a dwell meter. Had a issue with a hesitation turned out to be the points were off. Corrected to 30 degrees and solved the problem.

[WaltZ]

using a pertronics

[GMAD_Van Nuys]

If your valve clearances are set too tight, it can cause a rough idle.

[crossboss]

using a pertronics

Thats most likely a high percentage on your issues. Pertronix has a failure rate of over 50%. 'I' would never use it.

[MO]

I agree with Ed's numbers 1,3 and 5. Let him know the issues you're having and I'm sure you won't be disappointed. As for the Pertronix, I think it's a good choice. I've used it on several cars as well as friends using them without any issues. Then again, some may find problems, but over 50%?

[crossboss]

I agree with Ed's numbers 1,3 and 5. Let him know the issues you're having and I'm sure you won't be disappointed. As for the Pertronix, I think it's a good choice. I've used it on several cars as well as friends using them without any issues. Then again, some may find problems, but over 50%?

Yes, over 50% failures. Other car sites/owners report the same. Many engine builders hate it. Many have failed with in minutes, some failed in weeks. Check the online chat boards...its not good for Pertronix. Remember the ill failed Mallory Unilite? Same as Pertronix. That said, IF you like it, use it. I wont.

[69Z28-RS]

If your valve clearances are set too tight, it can cause a rough idle.

I agree with Ed's numbers 1,3 and 5. Let him know the issues you're having and I'm sure you won't be disappointed. As for the Pertronix, I think it's a good choice. I've used it on several cars as well as friends using them without any issues. Then again, some may find problems, but over 50%?

Yes, over 50% failures. Other car sites/owners report the same. Many engine builders hate it. Many have failed with in minutes, some failed in weeks. Check the online chat boards...its not good for Pertronix. Remember the ill failed Mallory Unilite? Same as Pertronix. That said, IF you like it, use it. I wont.

Where do you get that failure rate Cross?   Do you have the raw numbers you used to calculate it??

[jdv69z]

yes, not totally sure if I will change or keep putting $$s into it until it's off idle hesitation is gone. I have exhausted everything, including sending it out 2 times to a highly recommended carb shop in New Jersey.
Timing spot on and adjusted with vacuum gauge and checked for leaks.
Just looking for a carb recommendation.
So much help offered here on this site and tried just about all of it.

Is your jetting stock 68/76? How about accelerator pump cam? 72/76 jetting works well for my Z, and I changed the accelerator pump cam to initiate the fuel shot sooner. I think the Z had this issue from the factory originally as a result of the emissions tuning requirements. Mine also reacts differently depending on air temperature. Definitely more off idle hesitation when it is colder outside, cold air density is higher; so mixture is leaned somewhat. The carburetor is a compromise of settings trying to cover the different conditions encountered during different driving situations, idle, cruise, accelerate, etc. I believe drag racers are constantly making adjustments to their carbs depending on air temp, humidity, etc. This is what today's fuel injected, computer controlled cars are able to do, make constant adjustments for changing engine requirements.