Pertronix question.

[Scott06]

I have messaged autoline about the jets in this carb. My book doesn't show jet sizes unfortunately. So I'll see what they say and if the have bigger jets I will order a few different sizes and go from there I guess

Mikes carb parts and Pontiac Tripower sells jets and small parts for 2 jets. There are others but have had goo luck with either for 2 jet parts

 

[Jakem]

Right o .when I find out what I got ill message Mike's.

 

[WIMUSKY]

Not sure what coil you're running. I installed a Pertronix module in a car and used a Accel Super Coil. I believe those modules like to be paired with a hotter coil....

 

[Jakem]

I'm using the matching coil to this dizzy. Here's a pic from autoline about jets

 

[WIMUSKY]

My Accel had a 45kV output.... Just for reference...

 

[Scott06]

I'm using the matching coil to this dizzy. Here's a pic from autoline about jets

If you are confident in your float level and fuel delivery i would look at going up from the 67 jets to a 69 or 71 Based off that last plug reading. Jets are cheap so if you are buying them i would get both sizes to have.

 

[Jakem]

The pressure is good. I just pulled my jets out and they have no number of course. Autoline did tell me .67 so hopefully that's what they are. Anyways I will get .68.69and .70

 

[Jakem]

My float bowl was half full and clean

 

[Scott06]

My float bowl was half full and clean

Would just verify the float level is correct while you have it open

This is a decent primer on 2 jets of course covers a lot of carbs over a lot of years GM made them.

https://www.carburetor-parts.com/assets/manuals/rochester-2gc-manual.pdf

I wouldn't bother with the 68 jets, normal rule of thumb is to go up 2 steps and there wont be that much diff between a 67 and 68... in the Edlebrock tuning guide going from a .101 jet to a .104 (.003 bigger dia) is listed a a 4% increase in richness of AFR. Different carb but may give you some idea of how much diff the changes will make.

The pressure is good. I just pulled my jets out and they have no number of course. Autoline did tell me .67 so hopefully that's what they are.

You can measure them with a pin drill - a 67 should be dia of .067"

the merc part number for the jet originally supplied is 1397-2450 but no where can I find the orifice diameter... and its a NLA part (#28 below), power valve #26 isnt listed https://www.marineengine.com/parts/.../3108723-and-up/carburetor-assembly-rochester

 

[Jakem]

Beings I have the top off the carb can I just take that to a carb shop and have them check and set the float. I've never done it

 

[Jakem]

I went to a carb shop and he doesn't sell parts. However he measured mine wich were 70. He happened to have a set of 77 and gave them to me. Shall I throw them in and see what happens

 

[Bondo]

I went to a carb shop and he doesn't sell parts. However he measured mine wich were 70. He happened to have a set of 77 and gave them to me. Shall I throw them in and see what happens

Ayuh,...... Absolutely,......

 

[Scott06]

I went to a carb shop and he doesn't sell parts. However he measured mine wich were 70. He happened to have a set of 77 and gave them to me. Shall I throw them in and see what happens

Agree with bondo put them in and see how it goes. if these re too rich and you cant get parts you can drill out the 70's to 72. of course you gotta be careful as they dont get smaller once you drill them out...

Strange the carb shop didnt know or control what was in there 67 vs 70's ...

Was the float height at least set correctly?

 

[Jakem]

He said to leave it

 

[Jakem]

It was autoline who said .67 the carb guy slid a peice of brass in and then used caliper and suggested it was .70

 

[Scott06]

It was autoline who said .67 the carb guy slid a peice of brass in and then used caliper and suggested it was .70

Yeah by carb shop i meant autoline. So bottom line they dont know what parts they are putting in their rebuilds …which is the knock on big carb rebuilders

 

[Jakem]

Ya it appears they don't.

 

[Jakem]

.77 installed...got it up to temp...seems abit boggy if I throttle up fast..if I ease in seems better. I guess water trial will tell the tale

 

[stresspoint]

I'm no xspurt . but from experience it sounds to me like the timing is retarded by a few degrees .
forget the timing light > advance the timing by small increments till you get a slight ping under acceleration from a full stop , once you get the pinging , retard the dizzy back to the last increment before it did the ping , that is where the engine needs to be.
DO NOT RUN THE MOTOR WITH IT PINGING only let it ping for a second > stop and correct the timing back a notch.

your cam chain or gears are worn and will need replacing in the near future.
or some xspurt has incorrectly dial the cam in. LMFAO

if the carb jetting was correct before you messed with the distributor ? why mess with jetting , 77 s are miles to big for that little motor and will only make it lug and use lots of fuel.
67 or 68 will be fine on a stock 302 motor with a 2bbl carb.

 

[Scott06]

I'm no xspurt . but from experience it sounds to me like the timing is retarded by a few degrees .
forget the timing light > advance the timing by small increments till you get a slight ping under acceleration from a full stop , once you get the pinging , retard the dizzy back to the last increment before it did the ping , that is where the engine needs to be.
DO NOT RUN THE MOTOR WITH IT PINGING only let it ping for a second > stop and correct the timing back a notch.

your cam chain or gears are worn and will need replacing in the near future.
or some xspurt has incorrectly dial the cam in. LMFAO

if the carb jetting was correct before you messed with the distributor ? why mess with jetting , 77 s are miles to big for that little motor and will only make it lug and use lots of fuel.
67 or 68 will be fine on a stock 302 motor with a 2bbl carb.

See post #10