That cam is a mild ''performance'' cam. The main reason for vac.advance is better drivibility and mileage when cruising around.In the case of your engine,the mileage will be improved by 2-3 mpg. once the tune is dialed in.You'll have longer plug life as well.TThere's a reason why Chevrolet ditched the no vac.advance deal starting with the 63 model year and never went back to it.If you were running very high compression and over about 240 degrees at .050 then no on the vac.advance.
A few q's RE: 348 3X2 set up
- Thread starter reastman
- Start date
I found this last nite, regarding accel pumps and check balls:
www.trifive.com
This would be pertinent for anyone using Rochester 2GC and 4GC carbs.
I looked at my pump wells again today, and they [all three] have each a blind hole in the pump well, and a blind hole adjacent to the well in the bottom of the bowl - no check balls, no cross-drilled holes - nothing. If the pump well slot is above the pump seal, how does the well receive fuel? The pump plunger body, with a check ball in it looks like the only way to get fuel to the well bottom according to the Tri Five thread. The thread addresses hesitation, flat spots and bogging. It's worth the read.
BTW, I rec'd my end carbs plungers, and they have the "garter" spring under the cup seal lip. The center plunger I got earlier this week did not
Dick
Accelerator Pump Rochester 2GC
I am bumping this post this with some modifications. It was kind of silly to post this on Christmas eve as I am sure most Tri-vers had other things on their minds. So, here goes! So my newly rebuilt Rochester 2GC performed great for a couple of weeks - No flat spot upon acceleration. Then...
www.trifive.com
This would be pertinent for anyone using Rochester 2GC and 4GC carbs.
I looked at my pump wells again today, and they [all three] have each a blind hole in the pump well, and a blind hole adjacent to the well in the bottom of the bowl - no check balls, no cross-drilled holes - nothing. If the pump well slot is above the pump seal, how does the well receive fuel? The pump plunger body, with a check ball in it looks like the only way to get fuel to the well bottom according to the Tri Five thread. The thread addresses hesitation, flat spots and bogging. It's worth the read.
BTW, I rec'd my end carbs plungers, and they have the "garter" spring under the cup seal lip. The center plunger I got earlier this week did not
Dick
You are saying there is no passage open at bottom of pump well. So if fuel does seep through check ball on accelerator pump then fuel has no where to go. That makes no sense. I would split carb pour fuel in bowl and pump well and take a accel pump and pump it in the well see if anything comes out somewhere.
Gofish
Well Known Member
I feel we’re getting hung up on the check ball issue. Maybe watch this from Mike’s Carburetor.
John
Rochester 2 Jet Check Ball - Mikes Carburetor Parts
Rochester 2 jet check balls. Where do the check balls go and which check ball do you put in the main discharge.
www.carburetor-blog.com
John
That could be, so there has to be a escape route for fuel being forced by the accelerator pump is what I was saying also.I feel we’re getting hung up on the check ball issue. Maybe watch this from Mike’s Carburetor.
Rochester 2 Jet Check Ball - Mikes Carburetor Parts
Rochester 2 jet check balls. Where do the check balls go and which check ball do you put in the main discharge.www.carburetor-blog.com
John
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Gofish
Well Known Member
I feel we’re getting hung up on the check ball issue. Maybe watch this from Mike’s Carburetor.
Rochester 2 Jet Check Ball - Mikes Carburetor Parts
Rochester 2 jet check balls. Where do the check balls go and which check ball do you put in the main discharge.www.carburetor-blog.com
John
lets see some pictures of the float bowl and accelerator pump well.…..
John
When I rebuild a carb I fill bowl and accel pump well and then use accel pump by hand to go in well to make sure passage is open.
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Here are some pics, #1 rear, #2 ctr, #3front. Different lighting, #4 rear, #5front, #6 ctr. #7 is Show Cars chrome timing cover. First off, I had to cut out lip at bottom of seal opening - it was tapered, and tapered the oil seal as I pressed it in. It ruined the seal; Secondly, when I set the crank TDC, compression #1 cyl, with my TDC adapter, and indicator, #8 pic, the timing tab was off 4 degees. The true engine TDC is 4 deg ATDC on the tab. BTW, the tool is made from a plug, with the porcelain knocked out and reamed for a 3/8 drill bushing. I still need to let Show Cars know, and see if they will give me a new seal, too.
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That center carburetor need a pump that looks like this, well only put together with now parts.
I've made several inquiries about leather plungers. I've had leather disks in my rebuild kits, but they did not look to fit anything. The plungers were plastic and no provision for check ball. I talked to Mountain Man Carbs and he gave me a name of a company that makes leather seal plungers: https://daytonaparts.com/m/findyourkit.html?opt=make
I don't know if they use the metal bodies w/ check ball, as shown above.
I also installed the Echlin plungers to replace the kit ones that ended up with torn cup seals. The Echlin tech I talked to said the secondaries have a different p/n, because the length is different. The ctr is 2.530" lg, the two ends are 2.485" long. The replacement secondaries also came with the Garter springs, the ctr did not. Also the ctr plunger had 2 less spring coils, and was noticeably lighter.
They must have a reason for this
I'll talk to Daytona parts Monday. They never showed up on any searches, had to hear it from another carb shop.
Thanks for the pic, Don
Dick
I don't know if they use the metal bodies w/ check ball, as shown above.
I also installed the Echlin plungers to replace the kit ones that ended up with torn cup seals. The Echlin tech I talked to said the secondaries have a different p/n, because the length is different. The ctr is 2.530" lg, the two ends are 2.485" long. The replacement secondaries also came with the Garter springs, the ctr did not. Also the ctr plunger had 2 less spring coils, and was noticeably lighter.
They must have a reason for this
I'll talk to Daytona parts Monday. They never showed up on any searches, had to hear it from another carb shop.
Thanks for the pic, Don
Dick
Speak to Jon at The Carburetor Shop, he makes his own leather accelerator pumps, he only sells full kits and will want your original carb tag numbers. He only sells quality kits and they are not cheap in price either. Eldon, Missouri.
I just got 3 kits from Jon, pricy yes, did I get what I payed for yes.
Took about a week to get them.
Took about a week to get them.
3 X 2 kits? What were the pump cup seals made from?
No, one kit was for a 1950 Plymouth B&B the other two are for a pair of 750 AFBs
All three kits have leather accelerator pump cups.
That was the reason for using his kits.
Jon knows the rubber pumps won't stand up to the crap gas they sell today, plus he builds the kits with the parts that they came with from the factory.
All three kits have leather accelerator pump cups.
That was the reason for using his kits.
Jon knows the rubber pumps won't stand up to the crap gas they sell today, plus he builds the kits with the parts that they came with from the factory.
Here are pics of pumps I got in kit. The seals tore, so I bought three more that looked same, except ctr carb had no garter spring. The blue ones are from kit 27 years ago, and the cup seals shrank. But, notice difference in spring length, as well as plunger length. The white ctr plunger is about 3/32 longer than the end carb plungers flanking it. The short springs were from kit 27 years ago. Also, is the leather disc pictured for perhaps the old plunger style w/ check ball, as shown above that LAHR posted? The long springs are much stiffer, too.
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Maybe I missed it, but are you getting parts according to your tag numbers???
I have one of those leather pieces, I'll try later today and see if it will fit.
I think I may know where this car is located. It was in Toledo and a friend of mine bought it from him around 2000 2001 it is a black car red interior SS 350 HP 4sp when he got the car someone had put in different interior pieces some were still red some aqua he bought it with a 283 in it and the 348 was in pieces. we put the 348 back together and it ran fine but was tired. He had the car verified by Verne Franze. He sold the car to another friend of ours before his passing in 2020. I wish I could of bought the car but didn't know he was selling. The car is now in Michigan in storage. I know its the same car.