KA with sidedrafts

[Crashtd420]

26 minutes ago, datzenmike said:

Why is mechanical advance 'all in' by 3,000  when the engine continues to 6,000 and more? It would seem that as the time for the burn shortens you would need to keep advancing the start.

 

I have often wondered this too...

[Stoffregen Motorsports]

I think Jeff can answer that question better than I can. My fingers do work that sometimes my brain has a hard time translating into words.

[datzenmike]

Jeff... ? distributor guy?

 

 

I understand that time gets shorter as revs go up and the need to  start the fire sooner.

 

Mechanical advance is strictly RPM dependent.

 

Vacuum advance is strictly engine load dependent.

 

There's a big difference between a race car and a street car as far as ignition advance. Far and away the cars and trucks here are street cars and gain from having good mileage for the 99.999% of the time they are at part throttle. 

[Stoffregen Motorsports]

2 hours ago, datzenmike said:

Jeff... ? distributor guy?

 

 

I understand that time gets shorter as revs go up and the need to  start the fire sooner.

 

Mechanical advance is strictly RPM dependent.

 

Vacuum advance is strictly engine load dependent.

 

There's a big difference between a race car and a street car as far as ignition advance. Far and away the cars and trucks here are street cars and gain from having good mileage for the 99.999% of the time they are at part throttle. 

Yes, distributorguy.

 

Yes, it it RPM dependent, but that doesn't mean that higher RPMs give you more advance. By adjusting the spring tension on the weights, you can get all the timing in at whatever RPM you want.

 

There is a big difference between street and race, but as we start adding things like bigger cams, higher compression, dual carbs, we edge closer and closer to race, thus, the timing needs are going to be different.

[datzenmike]

I just wonder why.

 

I see chevs on the dyno and timing is say 38 and it's all in below 3K. The engine keeps revving to 6500 or w/e and the timing is still 38. So there is now half the time to get the cylinder fully lit and reaching maximum pressure at that 'sweet spot' about 17 degrees after TDC. If they increase the timing to 40 power suffers and there is risk of detonation. So something I'm not seeing here.

[wayno]

I have read in the past where someone drilled a vacuum advance hole in a  Weber side draft, it had to be drilled in exactly the right spot to work properly, but it was possible.

[datzenmike]

It would have to be on the atmosphere side of a throttle plate. As the plate opens past it, intake vacuum is applied more and more but drops off as the intake vacuum lowers from the huge opening at  half the full throttle.

[alexg89]

i think im just gonna not plug the vacuum part in and see how it works.. sounds like its gonna be more of a paint in the but to make it work or plum it than it needs to be ..

 

as for wiring the distributor it has 2 wires.. green and red.. im guessing green goes to the negative side of the coil correct.. where do i go to with red

[datzenmike]

 

This distributor?... no. You will need a remote igniter box OR easier is an HEI module from a GM distributor. All the green and red wires do is send a very small pulse signal to tell the module to fire the coil. I'll post the correct wiring for this tonight when I get home.

[alexg89]

8 minutes ago, datzenmike said:

I'll post the correct wiring for this tonight when I get home.

Awesome thank you so much 

[alexg89]

 

 

i believe i found it

 

[datzenmike]

Ignore that 1.6 ohm coil. That's the one but run a '78 or up L20B coil. It's 0.8 to 1.0 ohm if you want the best voltage output. 

[alexg89]

so just to add to all of this .. Saturday i had a delivery

https://xcessivemanufacturing.com/nissan-intake-ka-n-ka24e-tg.html 

 

Being my intake is a 2 piece design and will have the rubber boots that attach the 2, i dont believe heat will be to much of a problem but would you say that it still wouldnt hurt to run the thermal gasket?

[datzenmike]

As you like, but the greatest heat source is on the other side of the engine. The intake won't get that hot on this side.

[Stoffregen Motorsports]

There are two areas of carburetion that like to be kept cool: the intake air and the fuel chambers/float bowls. Since the exhaust is not directly under the intake (like on an L series), you don't really need to worry about keeping the bottom of the carbs cool, but having some sort of air box the keep the air charge cool isn't a bad idea.

 

I've never used one of those gaskets, but it seems like overkill. I even wonder if it will hold up over time. It says it's made from a heat resistant polymer...is that some sort of nylon? I would worry that it would not be firm enough to keep the manifold from tweaking when you toque the bolts down.

[alexg89]

I have used these on small engines.. Gopeds and such but themps are much higher on them .. especially at 14k rpms .. but over time they "squish" and become out of round 

 

These guys say their product wont do so .. guess its worth the 35 bucks to try 

[alexg89]

No turning back now i guess lol 

 

 

[Stoffregen Motorsports]

I really think you need to give than engine a bath.

[alexg89]

1 hour ago, Stoffregen Motorsports said:

I really think you need to give than engine a bath.

oh absolutely .. it will be getting the oven cleaner treatment, new freezeplugs.. the works pretty much .

 

I just through the intake on there to make sure it actually fit lol

[alexg89]

 

gonna have to hit it again and maybe with the pressure washer this time.. 

 

1 can and a hose didnt cut it all of it 

[Stoffregen Motorsports]

Definitely pressure washer time.

[alexg89]

Got it mocked up to make sure things clear and a few things dont.. welds on the intake have to be grounded down so the nuts can be tightened all the way down and where the carbs mount to their flange i think i need a spacer because the linkage comes in contact also

 

Any ideas on the spacer? 

 

[Stoffregen Motorsports]

There are companies that make carb spacers. I normally use Nissan rubber carb isolators, but you've already got the manifold cut in half and isolated with silicon tubes.

 

 

[Stoffregen Motorsports]

Or you could cut the manifold in the middle. Maybe only some of it needs to be machined away to clear the linkage.

 

For the nuts, you could use jet nuts like these -

[alexg89]

I actually went ahead and bought these for the carb.. as for the jet nuts what are they? is the built in washer smaller?

I was gonna pull the factory studs out of the head for the intake and buy allen head bolts to go in it so it looks a little cleaner and will clear.. Unless you see an issue with that