Author Topic: Do i need to swap jets and rods?  (Read 5350 times)

Offline Jl2556

  • Newbie
  • *
  • Posts: 3
Do i need to swap jets and rods?
« on: July 04, 2017, 06:35:00 PM »
I have a 17057204 that's on a stk 1977 305. Being that carb came on a 350, do i need to change the jets or rods? If so, what sizes do i need. Only thing ive had to change was the accelerator pump rod location. Was bogging on take off really bad till i did that. Set idle with a vac guage and tach. The truck has been rebuilt by an online carb rebuilding site, cant remember who it was, got it off ebay all ready rebuilt, but never ran.

Offline Ethan1

  • Moderator
  • Qjet Hero
  • *****
  • Posts: 1148
Re: Do i need to swap jets and rods?
« Reply #1 on: July 05, 2017, 04:20:52 AM »
I have a 17057204 that's on a stk 1977 305. Being that carb came on a 350, do i need to change the jets or rods? If so, what sizes do i need. Only thing ive had to change was the accelerator pump rod location. Was bogging on take off really bad till i did that. Set idle with a vac guage and tach. The truck has been rebuilt by an online carb rebuilding site, cant remember who it was, got it off ebay all ready rebuilt, but never ran.

 Welcome to CHP!

 What cam is being used in the 305? Stock? Mild? Performance?
Ethan

1972 Chevelle

(oo______oo)

Offline Jl2556

  • Newbie
  • *
  • Posts: 3
Re: Do i need to swap jets and rods?
« Reply #2 on: July 05, 2017, 12:16:48 PM »
Welcome to CHP!

 What cam is being used in the 305? Stock? Mild? Performance?
Thanks......

Cam is stk.

Offline Ethan1

  • Moderator
  • Qjet Hero
  • *****
  • Posts: 1148
Re: Do i need to swap jets and rods?
« Reply #3 on: July 05, 2017, 02:29:22 PM »
 I just reread your post. You said you bought it off of eBay already rebuilt. Commercially remanufactured? Is there a white sticker on it somewhere?
Ethan

1972 Chevelle

(oo______oo)

Offline Jl2556

  • Newbie
  • *
  • Posts: 3
Re: Do i need to swap jets and rods?
« Reply #4 on: July 06, 2017, 06:42:37 AM »
I just reread your post. You said you bought it off of eBay already rebuilt. Commercially remanufactured? Is there a white sticker on it somewhere?
I'll have to check, it might be on the back of the carb. I know it had one when I got it. I looked and looked through my gmail account for the winning ebay email to see if I could find who made it but no luck. I know it was a known commercial reman company as I looked up the name on the sticker when I 1st got it 2 yrs ago.

The quad I have on it right now is a 17057204. Here's the spec from another post off this site:
17057204 CHEV 77 CHVL, VETTE 350 AUTO A/C 77 52 7029529 CH

The old quad I took off (was missing some pieces) is a  17058213, specs are:
17058213 CHEV 78 GMC HD Truck & '79 Canada HD 63 40 7036019 CP

77/52 vs 63/40 is a big difference. I wonder why the rod and jet sizes are so different even though both carbs came off 350 engines. Maybe the cam profile is way different in the vette vs the hd truck.

Here's what the cylinder head code comes out to be on  the truck:
UTT   1978   305   van & bus hp 145   2 barrels   C-10 & 1500

So, some one added a 4 barr intake to it. Maybe the cam profile needs the 64/40 or slightly larger, say a 72/40 or 71/40 from a 305 setup, and moving the accelerator pump shot linkage back to the original position?
The only thing I haven't verified is that someone hasn't put 305 heads on a 350 block. Sigh......this poor truck(64 c10) has had the most backwoods, jacked repairs/patch jobs I've ever seen so anything is possible.....lol. Such as wrapping the end of a stripped wire around a washer, then sliding the washer down the starter solenoid post and putting the nut on.....:;

Just wanted to give you as much info as I can, thanks for your help so far...

Offline Ethan1

  • Moderator
  • Qjet Hero
  • *****
  • Posts: 1148
Re: Do i need to swap jets and rods?
« Reply #5 on: July 06, 2017, 09:23:24 AM »
I'll have to check, it might be on the back of the carb. I know it had one when I got it. I looked and looked through my gmail account for the winning ebay email to see if I could find who made it but no luck. I know it was a known commercial reman company as I looked up the name on the sticker when I 1st got it 2 yrs ago.

The quad I have on it right now is a 17057204. Here's the spec from another post off this site:
17057204 CHEV 77 CHVL, VETTE 350 AUTO A/C 77 52 7029529 CH

The old quad I took off (was missing some pieces) is a  17058213, specs are:
17058213 CHEV 78 GMC HD Truck & '79 Canada HD 63 40 7036019 CP

77/52 vs 63/40 is a big difference. I wonder why the rod and jet sizes are so different even though both carbs came off 350 engines. Maybe the cam profile is way different in the vette vs the hd truck.

Here's what the cylinder head code comes out to be on  the truck:
UTT   1978   305   van & bus hp 145   2 barrels   C-10 & 1500

So, some one added a 4 barr intake to it. Maybe the cam profile needs the 64/40 or slightly larger, say a 72/40 or 71/40 from a 305 setup, and moving the accelerator pump shot linkage back to the original position?
The only thing I haven't verified is that someone hasn't put 305 heads on a 350 block. Sigh......this poor truck(64 c10) has had the most backwoods, jacked repairs/patch jobs I've ever seen so anything is possible.....lol. Such as wrapping the end of a stripped wire around a washer, then sliding the washer down the starter solenoid post and putting the nut on.....:;

Just wanted to give you as much info as I can, thanks for your help so far...

 Is it a SMAB (single main air bleed) carb? Or dual? If single, I would go with 75/52M/DA rods or if dual 72/42K/DA rods. Do you have, Cliff's, book? What is the casting numbers on the heads?
Ethan

1972 Chevelle

(oo______oo)