Think of the intake manifold as a wind instrument (Flute, etc...), by changing the size of the plenum it changes the 'note', this will change the reversion to a different rpm, it also changes the mid-range a bit on the long ram manifold (in essence if using as a daily driver, it will make it more manageable). One other fun aspect is that you can now tune the engine as two separate 3 cylinders (if you have a split exhaust), allowing finer tuning of the fuel mix (this is more interesting in cars where the front runners are near the radiator and fan, and the rear runners are near a 'heatspot' before the air runs into the firewall and has to duck under).

-D.Idiot

What is your initial mechanical advance again? Any chance you have a vac leak at the carb or intake somewhere?

Lou

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Home of Slant6-powered fun machines since 1988

thanks DI, now i have another project. already have the primaries to the left.

Lou, i have initial at 10* (advance disconnected, plugged) and doesn't change when hose connected so i'm not into the advance at idle. doesn't like anything much over 12*. i have had this thing apart enough times to be pretty positive there are no vac leaks. holds about 10 inches at 800 -1000 now. earlier on i plugged all ports on the carb which had no effect and sprayed carb cleaner.

i will have a better assessment on how it does after the recent changes this weekend. snowing and sleeting right now. bad time of year to tune a new engine.

thanks again guys, for all the help, andy.

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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

OK. You really want 15 deg or a bit more at idle with that cam/comp. I did a lot of trail and error and found that 10 was not enough, and Doc found the same. That should improve your idle quality and pull more vacuum. Try 15 deg and unplug the vac adv and plug it at the carb and drive it to see what that does. If the vac adv is starting to actuate around idle vac levels, that will really screw up idle quality.

Lou

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Home of Slant6-powered fun machines since 1988

i will hopefully get some time this weekend to tinker. i'll throw 15* at it and see what happens. i did drive it around the block today and the character has definitely changed, as expected, less bottom end but pulls strong, better idle.

and now something completely different.

as i was sitting here while the ice melts browsing the oregon cams list from the FAQ, i noticed that my cam card and the list give different numbers. the 346 grind is 102 intake lobe center and 110 exhaust on the list. my cam card says its 104 intake and 108 exhaust and shows the ocg part #DO-226MP. something amiss here?

more to come, andy.

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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

hello. set initial to 15, valves at .026/.024 i have good idle down to 600. with the cam timing change i lost alot of the 1200-1800 rpm torque. i think i could put a little of the advance back in and get to the sweet spot. its been a blast finally driving it daily.

in general, how much of a change would be expected by doing the manifold split?

thanks again for all the input.

andy.

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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

Fantastic. I bet you can put the cam timing back at least part of way (split difference?). You should get a stall converter too (2500-2800). That will really improve your life.

Lou

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Home of Slant6-powered fun machines since 1988