My 1971 521

[datzenmike]

I would say that a cam with similar opening and closing times but with increased lift would be best for street. Moving the cam events around tends to move the power making RPM around, (usually up) at the expense of low RPM drive-ability. Huge overlap at TDC destroys intake vacuum and a very poor idle is the result but at the same time also favors very high RPM cylinder filling and power.  Retaining stock timing events but increasing the lift keeps the engine drive-able but allows more breathing when revved up. The last thing you want is to be driving around town at 3,000 but power doesn't come on till 5,000-7,000. 

[Crashtd420]

18 minutes ago, d.p said:

Ok great Mike but I have racer brown cam which someone has referred to as a "very good street grind."

 

 

 

This might be the setup spec sheet for degreeing the cam not necessarily the actual cam specs.... 

 

This is the cam sheet from mine so you understand what I meant...

[banzai510(hainz)]

16 hours ago, d.p said:

How do I confirm the alt is charging again?

 

How many times?  just look at your volt meter !!!!!!!!!!!!the cig lighter volt meter you have I know you have it!!!.  or just use a regular volt meter across the battery and when the light is on measure then rev up the motor. But the cig lighter  does it right in the cab. How can you forget this its simple.

 

Only other thing maybe this is a self exciting type alternator like GM uses but Im wingin it here. If light on its a reason . Measure at idle , then rev up motor then rev say to 1500 and put lights and heater on.

I assume this is a Intervolt reg alternator and you put the jumpers in where the old volt get goes. Or this is the stock External and external volt reg?

 

also people sayin is it wired right??? WTF if he put the power to the case it would short out and pop a fuse /spark. Then he never changed any wireing so why or how it be backwards? The T connector?   The alt to me is weak and it looks like a chinese clone of some sort as it dont have a Hitachi or Mitshibishi diamond on the back.

 

Those carb numbers are close to what it needs to be as a baseline  and was used on the other car/motor  . How about try more advance on the distributor like 12 up to 15 and this might help it.  If you cant get to 15 cause the dist is all to one side and no more movment then the dist spindal isnt lined up right on the oil pump your off a tooth. But Im hoping you go this.

 

as for being LOUD!!!!!!!!you serious?

well you can go back to stock Hitachi carb and put the other motor back in

 

 

44s are big and I would stick with 40s on the street but 44 are fine and just drive it at a higher RPM as the carbs need airflow. hitting the gas to fast will just equal out the pressure and gas dont get sucked in.  New cars this is all done for you .

SU carbs did this also with the plunger on front of the butterfly flap to keep the airflow correct. But they didnt have a power valve to squirt gas.

Edited March 9, 2021 by banzai510(hainz)

[Crashtd420]

10 minutes ago, d.p said:

Lol my bad, you are right.  I mistyped that...bottom is MAIN jet not AIR jet. 

 

I read it online and was told by the guy who rebuilt my crabs that its not needed because Mikunis 'have a very week vacuum signal.'    I trust the dude and he has come HIGLY recommended.  

 

 

Good enough reason for me...

[thisismatt]

13 minutes ago, banzai510(hainz) said:

 

 

also people sayin is it wired right??? WTF if he put the power to the case it would short out and pop a fuse /spark. Then he never changed any wireing so why or how it be backwards? The T connector?   The alt to me is weak and it looks like a chinese clone of some sort as it dont have a Hitachi or Mitshibishi diamond on the back.

 

 

Calm down, didn't know if he had switched to a newer alternator that required a different plug like a newer Nissan alt, in which case he would have had to rewire the T plug. I already talked to him and it's working fine other than needing to be blipped to get it going

[thisismatt]

26 minutes ago, d.p said:

Lol my bad, you are right.  I mistyped that...bottom is MAIN jet not AIR jet. 

 

I read it online and was told by the guy who rebuilt my crabs that its not needed because Mikunis 'have a very week vacuum signal.'    I trust the dude and he has come HIGLY recommended.  

 

 

Crabs for weeks

[d.p]

Ill get it, just might take some time to do so.  Dual carbs is a learning process for sure but between here, church of L and Taka I am sure I will get it running.  

[mainer311]

High lift cam with shorter duration moves the powerband lower in the RPM, so it should make good torque and be great for around town. Very "streetable." Knowing that, you can kinda figure out how to tune the Mikunis. What diameter venturis did Taka install? If the cam is setup for lower RPM, it makes sense to install smaller diameter venturis. 

Edited March 9, 2021 by mainer311

[d.p]

Just now, mainer311 said:

High lift cam with shorter duration moves the powerband lower in the RPM, so it should make good torque and be great for around town. Very "streetable." Knowing that, you can kinda figure out how to tune the Mikunis. What diameter venturis did Taka install? If the cam is setup for lower RPM, it makes sense to install smaller diameter venturis. 

 

Cool, that is what I was hoping for, something street able. 

 

Whatever I sent them to him with which I never checked.  I wish I would have checked all the jetting prior to get a sense of what was what but my own fault for not doing my homework.   

[d.p]

35 minutes ago, banzai510(hainz) said:

 

How many times?  just look at your volt meter !!!!!!!!!!!!the cig lighter volt meter you have I know you have it!!!.  or just use a regular volt meter across the battery and when the light is on measure then rev up the motor. But the cig lighter  does it right in the cab. How can you forget this its simple.

 

Only other thing maybe this is a self exciting type alternator like GM uses but Im wingin it here. If light on its a reason . Measure at idle , then rev up motor then rev say to 1500 and put lights and heater on.

I assume this is a Intervolt reg alternator and you put the jumpers in where the old volt get goes. Or this is the stock External and external volt reg?

 

also people sayin is it wired right??? WTF if he put the power to the case it would short out and pop a fuse /spark. Then he never changed any wireing so why or how it be backwards? The T connector?   The alt to me is weak and it looks like a chinese clone of some sort as it dont have a Hitachi or Mitshibishi diamond on the back.

 

Those carb numbers are close to what it needs to be as a baseline  and was used on the other car/motor  . How about try more advance on the distributor like 12 up to 15 and this might help it.  If you cant get to 15 cause the dist is all to one side and no more movment then the dist spindal isnt lined up right on the oil pump your off a tooth. But Im hoping you go this.

 

as for being LOUD!!!!!!!!you serious?

well you can go back to stock Hitachi carb and put the other motor back in

 

 

Yeah ALT is wired right for sure and it is and ACDELCO hat I got from RockAuto for $60. 

 

https://www.rockauto.com/en/moreinfo.php?pk=999525&cc=1208540&jsn=8

 

Spindle and dizzy is lined up FOR SURE....I think lol.  Assuming that is the right end of the rotor but my son helped me with that and like to believe we did it right.  Taka said to try some more timing which I will once I get the carbs synced and figure out what is what.  

 

 

Yeah its loud man, lol never really knew how loud they were.  Lol I chucked the stock Hitachi in the river (trash) a long time ago.  

[banzai510(hainz)]

OK photo shows if anything lined up for Zero on the crank which looks correct.

 

now use a timming light and see if you can get to 15deg BTDC with that set up. be honest you should be able to go to 20 deg EZ in the timming plate slot .

 

my 44s on my car I didnt use the vacuum advance as it had not ports for them anyways my Banzai car with 40s has a port and I use it.If it even really works on One cylinder pulsating

[demo243]

In fairness I am still pretty green when it comes to engine specs, and tuning carbs... So most of my info is just what I ran and know worked...

This is the cam I was running in my L20b
Comp Cam's # 79-131-6 Grind # 280S . 
2000-6000rpm; Adv. Dur. 280 Int./Exh.; Valve Lift .460 Int

As I posted in mainers thread- when I spoke to Todd at WolfCreek about Mikunis based on that cam profile and my intended use (AutoX, Track day, very spirited street use) he recommend I bump up to 44s and choke them down a little bit.  Prior to my Mikunis though I had Weber 40s with no problem on the same setup. 40's should help keep it a bit more lively lower in the power band.

End of the day my settings probably wont help to much since I was on 44's. 

Definitley stick with it though! My Mikunis have been much simple and more reliable to run then my Webers were. The mikunis are basically just set it and forget it. As you mentioned the only real adjustments are mixture screw and idle stop - the rest is done with jetting. Definitely get an airflow meter to synch the two carbs up.

I was running and MSD ignition and I think a Mallory? distributor, with no vacuum advance. 

As I mentioned Ive been very lucky running my Mikunis... Todd got the jetting correct just from shear experience and guessing on my L20b and Duke did all the trial and error for the KA...

 

[d.p]

27 minutes ago, banzai510(hainz) said:

OK photo shows if anything lined up for Zero on the crank which looks correct.

 

now use a timming light and see if you can get to 15deg BTDC with that set up. be honest you should be able to go to 20 deg EZ in the timming plate slot .

 

yes zero on the crank is where its lined up I think? Or whatever this mark is on the crank pulley (off an L16):

 

 

I put a timing light on it, set the gun to 12 degrees and advanced the dizzy until he light hit that mark on the nose.  And still have room to go on the timing plate.

 

Edited March 9, 2021 by d.p

[d.p]

1 hour ago, Crashtd420 said:

 

This might be the setup spec sheet for degreeing the cam not necessarily the actual cam specs.... 

 

This is the cam sheet from mine so you understand what I meant...

 

 

yeah then I got nothing, Racer Brown or the guy who bought that name is local to me in Baltimore.  I called him up before but not even sure what I should be asking him lol.  

[d.p]

Welp went to mess with the truck and it seems like my battery is dying or my starter is.  Will start sometimes and other times click once and other times nothing at all. Voltmeter shows 12.1 with the truck off.  If i turn the key everything loses power even the voltmeter.  
 

It wasn’t doing this on Sunday so not sure what the problem is. Battery had been sitting for 5 months or inside but I put it on the charger a couple days before firing it up.  

[d.p]

Weird if it sits for a couple minutes it will try to turn over then loses all power.
 

When I turn the key to OFF power comes back but super low like 8.x volts then works its way up to 12 slowly.  Like 11.6 11.7 is that indicative of a battery going south? 

[Crashtd420]

3 minutes ago, d.p said:

Welp went to mess with the truck and it seems like my battery is dying or my starter is.  Will start sometimes and other times click once and other times nothing at all. Voltmeter shows 12.1 with the truck off.  If i turn the key everything loses power even the voltmeter.  
 

It wasn’t doing this on Sunday so not sure what the problem is. Battery had been sitting for 5 months or inside but I put it on the charger a couple days before firing it up.  

Did you have an electric choke on the other carburetor or manual....

I'm not sure what year started it but my 72 has the electric choke relay, that needs to be disconnected if you have it...  

[d.p]

Nah manual choke and it’s completely disconnected.  

[demo243]

5 minutes ago, d.p said:

Welp went to mess with the truck and it seems like my battery is dying or my starter is.  Will start sometimes and other times click once and other times nothing at all. Voltmeter shows 12.1 with the truck off.  If i turn the key everything loses power even the voltmeter.  
 

It wasn’t doing this on Sunday so not sure what the problem is. Battery had been sitting for 5 months or inside but I put it on the charger a couple days before firing it up.  

Check the ground - My 620 had a bad ground when I got it. New battery cable and ground made all the difference. Had similar issues, sometimes it would start fine, other times it would be really slow to crank or not crank at all.

[Crashtd420]

Just now, d.p said:

Nah manual choke and it’s completely disconnected.  

Ok so that shouldn't be the issue... 

[d.p]

Yeah I have two ground strap cables. One to the block and one to the firewall both connected to the negative battery terminal. Same ones I had on the my l16. 

[d.p]

Battery is 6 years old if that matters.  

[d.p]

Alright well fuck me I simply swapped the ground cables so that the one from the block was on the bottom of the negative battery terminal and that fixed it. 

Edited March 9, 2021 by d.p

[datzenmike]

Six years old is getting old. Should charge up once a month. A discharged battery is not good for it. I though of bringing in my brand new battery for the winter but easier to just start the car once a month and warm it up.

[banzai510(hainz)]

DP maybe also run the carb with the filter this might help a little in adding extra vaccum.

 

try running at 12 then adjust to say 15deg intial advance and see how this runs.NOt positive if a L20 needs thats much. My L18 I think i had that much.

 

setting cam from 1 to 2 or 2 back to one isnt going to be a huge difference as this is a low gear ration truck.

just learn how to drive it and run it more like a 2 stroke(more rpms and see if that works out.

 

i PERIODICALLY CHECK TO MAKE SURE THE JET BLOCKS DONT BACK OUT ALSO!!! mine does this acting like its loosing power /going out of time. then I open the carb tops and one block usually works its self loose. so I alwasy have a screw driver with me.

Edited March 9, 2021 by banzai510(hainz)