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| | | Forums66 Topics128,050 Posts1,055,641 Members48,426 | | Most Online14,466 Apr 26th, 2026 | | AD Chevy Trucks Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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on the Internet for over 30 years! and not clogged down with Ads! Again, thanks! | | | | Joined: Jul 2012 Posts: 306 Shop Shark | | Shop Shark Joined: Jul 2012 Posts: 306 | i glued my base spacer for now just to get it back running ,, is there a gasket aslo that goes on and if so were ? on top of the base spacer ?
thanks
1958 chevy biscayne 235 6 cyl 1 barrel 2 speed PG tranny
| | | | | Joined: Aug 2011 Posts: 687 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 687 | Top and bottom I think. They come in a carb lit, or you can make your own pretty easy. | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | A lot of people put them top and bottom. Originally there was not one on the bottom. I do not like using one on the bottom because I feel that the squishiness of the gasket can cause the insulator to crack.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Jan 2009 Posts: 1,644 Shop Shark | | Shop Shark Joined: Jan 2009 Posts: 1,644 | I only use one on top also like Pre 68 Dave.
Pete | | | | | Joined: Jul 2012 Posts: 306 Shop Shark | | Shop Shark Joined: Jul 2012 Posts: 306 | Well got it all together and al is going well, , i did a gasket below and on top and ideling great i will tune it tomm but i was getting about 18 on my vac gauge is that good, i might be able to get more
Thanks
1958 chevy biscayne 235 6 cyl 1 barrel 2 speed PG tranny
| | | | | Joined: Sep 2001 Posts: 581 Shop Shark | | Shop Shark Joined: Sep 2001 Posts: 581 | 18" I think is OK at idle, though you'd like it higher - should be higher if the engine is recently rebuilt, I think, but it's still a healthy #. You may get higher if you tweek the timing, and check the idle mixture screw?
Most important thing would be to check carefully for any vacuum leaks around the base. "Common Wisdom" way to do this, is to spray carb. cleaner or some such around the base of the carb - if there's a leak, it will get sucked in, richen the mixture and the engine will speed up noticeably for a few seconds.
Personally, I don't like spraying anything on my engine if I can help it. I use an unlit propane bottle or acetylene torch for the same test. Use just enough flow so the engine speeds up some when you hold it near the air intake. Then, slowly move it around all sides of the base of the carb to see if there are leaks in the gaskets.
While you're at it, you can check for leaks around the intake manifold as well, not-to-mention the vacuum line to the vac. advance, and to the wipers and/or the hydrovac, if applicable.
My thoughts, anyway . . .
-Michael | | | | | Joined: Jul 2012 Posts: 306 Shop Shark | | Shop Shark Joined: Jul 2012 Posts: 306 | Well i think i only have 2 vac lines, 1 to the dizzy and 1that comes off the intake, this the one that is hooked to my guage, ,the wipers come off the fuel pump, were does the hose go that comes off the intake, the mod valve on tranny?
Thanks
1958 chevy biscayne 235 6 cyl 1 barrel 2 speed PG tranny
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | What is a mod valve on the tranny?
What kind of transmission do you have?
On small/medium trucks, the vacuum hole on the intake would have gone directly to the standard/stock vacuum wiper motor. With a dual-action fuel pump, that vacuum line would have gone into the "in" port on the bottom chamber of a dual-action fuel pump. Or, if the truck has an electric wiper motor, that vacuum-line hole on the intake manifold would have been plugged.
| | | | | Joined: Jul 2012 Posts: 306 Shop Shark | | Shop Shark Joined: Jul 2012 Posts: 306 | i have a 2 speed PG modulator valve on trany now goes stright to the intake port, i do have a duel action fuel pump , on that line you can feel it pumping thanks
1958 chevy biscayne 235 6 cyl 1 barrel 2 speed PG tranny
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