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| fuel pump https://slantsix.org/forum/viewtopic.php?t=28134 |
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| Author: | notmy6 [ Sun Mar 30, 2008 9:54 pm ] |
| Post subject: | fuel pump |
will the factory fuel pump keep up with aluminum intake, 4 barrel carb, headers and dual exhaust? Installed all of this and the does not run much better that a 1 barrel and single exhaust. Just wondering the customer is not impressed.I will install a wideband o2 mon and see what is happening Thanks Mike |
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| Author: | 70valiant [ Mon Mar 31, 2008 2:11 am ] |
| Post subject: | |
It does a fine job on mine. |
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| Author: | LUCKY13 [ Mon Mar 31, 2008 5:49 am ] |
| Post subject: | |
What have you got the timing setup to do, it makes a big diff on these engines. They need a lot of timing at the base, but most of the distributors let it advance to much and the advance is to slow. About 12 to 15 degree base, but no more than 28 to 31 total at higher RPM. Advance weights need to kick in pretty quick so it helps at lower RPM & midrange because ofter that you done anyway with a stock slant. It needs to come in by around 2500 RPM at the most... Any latter and its to late to help, any earlier and it can cause problems at a cruize. Most of the time I go by highway cruizing RPM, what ever that is set the advance to swing in right after that RPM. Then be sure the vacuum advance is working and hooked up on a timed vacuum port. This will help tip in and part throttle alot but go back to only machanical advance when at WOT so it doesnt advance the timing to far. You want it hooked up to a vaccum port that has vaccum after you open the throttle. If its a pure stock slant six all this may be over kill, its hard enough to get a built slant to take a four barrel carb and at this stage of build a Holley Two Barrel 500 adapted to the aluminum intake would be a much better choice. Even a 500 Two Barrel is a little big for a stock slant so you can guess what a four barrel is doing. What size exhaust did you put on it and what mufflers did you use? What type header did you put on it? The Clifford Shorty, or a long tube header. A long tube header will do much better until he gets the head ported with bigger valves & a bigger cam to work in the higher RPMS. The long tube headers will work uptil around 5000 RPM so unless your running a bigger cam the short tube headers could kill to much torque. You can extend the collectors if its the short tube header, infact they need this even if higher RPM is the goal. A long tube header on a stock slant likes around a 25" long collector, this would be measured from the end of the primaries to the end of the collector.. My collector was only 6" and I added pipe of the same size to get the lenth, then stepping down to the exhaust size. I dont know how this would work with a shorty header but even when tuning for 6000 RPM with short headers it takes around a 17 to 18" collector. All the slant six headers I have seen have way to short of a collector. After changing the collector lenth on mine the midrange torque incress was very noticable. If this is a old stock engine there is a good chance carbon is built up around the valves and restricting the head even more. A lot of upper intake cleaner run through the engine by putting it down through the carb will soften this stuff up. Then follow up with a spraying of water while the engine is running and up around 2500 RPM when hot will clean alot of this stuff out and help it breath. Follow up with a heathy dose of running the crap out of it down the highway to clear it out even more. Be sure and go over the rocker arm ajustment. Many times people have these to tight from trying to get them to run quiter. They need to be no tighter than factory specs and most of the time run better just setting them about .001 looser. Ofcourse getting the A/F right can make a big diff and will probably be way off with that four barrel. Jess |
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| Author: | sandy in BC [ Mon Mar 31, 2008 6:56 am ] |
| Post subject: | |
A 4 bbl and headers and duals on a stock slant is possibly the most money spent for the least result. (unless visual effect is paramount) If you want the car to do better you need cam , compression and a timing curve to match. Converter and gears go with that. The stock fuel pump will get you into the 15s. |
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