TOYOTA, more than ever before... (2 Viewers)

[OSS]

I don’t think the exhaust pressure is very high at those air injection nozzle block off plugs. It certainly is hot there though.
That black crap on top of the head could just be burned dirt too so it’s hard to guess what’s causing it.
Yeah just clean that area up real good and take another picture of it - then keep an eye on it. It’s probably nothing.

Optimistically- maybe the fuel wasn’t so good that was sitting in the tank all that time and the Sniper had issue with it. It’s really hard if not impossible to pinpoint a problem if it only happens once or very rarely.
Maybe the Sniper just needed to wake up!

 

[cps432]

I don’t think the exhaust pressure is very high at those air injection nozzle block off plugs. It certainly is hot there though.
That black crap on top of the head could just be burned dirt too so it’s hard to guess what’s causing it.
Yeah just clean that area up real good and take another picture of it - then keep an eye on it. It’s probably nothing.

Optimistically- maybe the fuel wasn’t so good that was sitting in the tank all that time and the Sniper had issue with it. It’s really hard if not impossible to pinpoint a problem if it only happens once or very rarely.
Maybe the Sniper just needed to wake up!

Thanks! Yeah it’s kinda frustrating when it only happens intermittently. I was thinking it was fuel related or perhaps the sniper was tryin go to figure out what to do when I’m hauling that heavy load. It fires right up and runs great otherwise. I’ll clean it up and post a pic for posterity’s sake. Will monitor from here. Maybe there’s a tiny leak in the valve cover?

 

[cps432]

Here are some pics of that area cleaned up as best I can without disassembling the sniper.

@g-man I don’t see any cracks where you pointed. I believe that was dirt build up that was scratched at some point. I did the carb cleaner around the manifold trick and didn’t experience any rpm changes so I don’t have any vac leaks to note. I have found a few vac port plugs that have cracked due to heat. I’ll go find some new ones for high heat applications just to make sure there’s no leaks. I’m wondering if there’s just not enough air flow when I’m really asking her to work hard. I can hear the sniper sucking like crazy through this edelbrock air cleaner.

 

[cps432]

Well, this certainly might cause a hesitation when I’m really getting on it… doesn’t the advance kick in around 2000 rpm? I forget… this little rubber cap had the smallest hole in it…. I wonder if that’s it… lol

 

[g-man]

that rubber cap on the advancer isn't doing anything. Having a hole in it means .... it's still doing nothing. That diaphragm isn't moving without a vacuum line connected to it.

 

[cps432]

that rubber cap on the advancer isn't doing anything. Having a hole in it means .... it's still doing nothing. That diaphragm isn't moving without a vacuum line connected to it.

But is it open to atmosphere if not plugged? I’ve not pulled my diaphragm apart or seen the internals of one to know for sure. I have several other caps that are in the same condition. I’ll replace them all with silicon this afternoon just for peace of mind.

Do you remember reading about what rpm range the advance kicks in? I’m wondering if I have a bad diaphragm and I’m not getting advance under heavy load, but when I ease on the throttle and let the truck gradually gain momentum it overcomes the 2000 rpm range without kicking in the advance. If throttle is wide open it seems to have trouble keeping up. Hmmmmm…

 

[g-man]

It's not that complicated. Its a rubber bladder. When you apply vacuum it moves....pulling the arm that is linked to the breaker plate. The VSV probably has more to do with delay. But it will gradually pull the arm with the increase in rpms

when you set the timing the 2f engine fsm says to pull the vacuum lines and plug them. Doesn't say anything about plugging the advancer ports. Because it wouldn't matter. No vacuum line means diaphragm not moving...arm not moving, dizzy not advancing.

 

[g-man]

this is all the fsm says about testing the vacuum advancer:

you really can't see the diaphragm move because it is enclosed. You can see the arm move that is attached to the diaphragm.

 

[g-man]

And here about the timing:

 

[cps432]

this is all the fsm says about testing the vacuum advancer:

View attachment 2982385

you really can't see the diaphragm move because it is enclosed. You can see the arm move that is attached to the diaphragm.

I definitely checked it when I was re-curving the dizzy last year. I wonder if it’s failing now. I ought to check it again.

 

[cps432]

The inner port in the diaphragm is for the HAC correct? I haven’t looked at all this since October and I no longer have any of that equipment.

 

[g-man]

I wonder how much less the arm pulls when applying vacuum only to the secondary. Compared to the primary. Yes, the outer is the secondary ...for the HAC and what desmogged instructions say to use instead of the primary.

 

[cps432]

I wonder what happens if I switch the vac line?

 

[g-man]

try it, if it's too much advance the engine will ping.

 

[OSS]

The larger inner vacuum advancer diaphragm on the distributor pulls about 12° advance when it gets full vacuum.
The outside smaller diaphragm pulls about 6° advance with full vacuum.

The common “hack” when disabling the EGR system without recurving the distributor timing is to place the vacuum hose that normally connected to the inner (big) diaphragm to the outer (small) diaphragm. Doing that will knock back the vacuum advance.

But if your distributor is recurved and EGR is disabled, the vacuum advance from the Sniper should connect to the big inner vacuum advancer diaphragm on the distributor. (I think).

But listening for pinging and noting power however it’s hooked up is important.

 

[cps432]

The larger inner vacuum advancer diaphragm on the distributor pulls about 12° advance when it gets full vacuum.
The outside smaller diaphragm pulls about 6° advance with full vacuum.

The common “hack” when disabling the EGR system without recurving the distributor timing is to place the vacuum hose that normally connected to the inner (big) diaphragm to the outer (small) diaphragm. Doing that will knock back the vacuum advance.

But if your distributor is recurved and EGR is disabled, the vacuum advance from the Sniper should connect to the big inner vacuum advancer diaphragm on the distributor. (I think).

But listening for pinging and noting power however it’s hooked up is important.

Ah! The rabbit hole goes deeper! So, I re-curved my dizzy and then installed the vac advance to the wrong port on the diaphragm effectively retarding the re-curve…

 

[OSS]

Yes

 

[g-man]

I think you need to make sure your vacuum source is coming from above throttle plates or whatever opens up inside the sniper to allow air to rush into the intake. In other words make sure you vacuum source is not hooked up to intake or you will get the opposite ...high vacuum at low rpms and low vacuum at high. The inverse happens inside the carb and I assume sniper.

 

[cps432]

I think you need to make sure your vacuum source is coming from above throttle plates or whatever opens up inside the sniper to allow air to rush into the intake. In other words make sure you vacuum source is not hooked up to intake or you will get the opposite ...high vacuum at low rpms and low vacuum at high. The inverse happens inside the carb and I assume sniper.

This I have a vac advance port on the sniper body but I think maybe I tapped the intake… I’ll go double check.. that combined with the inadvertent retarding of the recurve…. May just be my problem.

 

[cps432]

Well, I had the vac advance connected to the correct port on the sniper all along so that wasn’t an issue. Switching the vac advance line from the outer to the inner port on the advance diaphragm really made a difference. Like, holy smokes! It feels like a Camaro now! Lol That did it!

I’ll check all the valve clearances this weekend and double check the timing. I’ll re-run the Sniper wizard just to be sure it’s all copacetic. Man… did that ever make a difference. Wow! Thanks a lot @OSS and @g-man! Ya’ll rock!