adjusting timing

[fabjunkie]

Hi Guys, I have a 92 auto with a 4.6 stroker. I have done all the usual stuff, adj map sensor, 24 lb injectors, open air filter, comp 232 cam, etc.

The motor is running 9.3:1, and I have 91 octane in it, but the motor really is begging for some more timing. It's real strong, but it's got a lot more in it, I can tell..

Is there some way to put some more advance into this thing? From what I've read the only way is to fiddle with the sensor on the bellhousing... any other ideas??

Thanks

 

[cruiser54]

Get a high altitude CPS is one way. Moving the intake air temp sensor from the manifold to the air intake is possibly another way. I know moving the IAT sensor helps on the Renix but I'm not as familiar with the Chryco injection system. How did you determine it is begging for timing advance? Have you monitored your air/fuel ratio with a wide band?

 

[fabjunkie]

Well, it's a seat of the pants thing. I know that sound from my 5.0, and this sounds like it doesn't have enough timing in it.. I put my light on it, and at idle it reads 14 deg... I'm not pinging, or hard to start, so it could take more. it just feels a little choked off. I know that's a bizarre description, but it

Now all those other things you mentioned, wide band O2, IAT, Map, etc, are for additional fuel if I'm correct, my fuel situation looks good according to the plugs, but I'm looking for a way to put some more advance in it..with my adj map I can get the thing to run white on the plugs, or run real dirty, so I have that dialed in pretty good.

Im thinking there has to be a way to adj the timing from the CPS...or maybe we need to figure out a way??:rtm:

 

[jeeperjohn]

It seems like Hesco makes a crank trigger that mounts in the front and is adjustable.

 

[stroked88]

you cant just turn the distributor like on the chevy small blocks? idk never looked at it or tried

 

[techno1154]

you cant just turn the distributor like on the chevy small blocks? idk never looked at it or tried

No.. The distributor is non-adjustable. It have a bolt hole in it to secure it to the block. If you were to modify it, the ECM would re-adjust the spark timing to match the fuel timing which (I think) uses the CPS in the bell housing.

A high altitude CPS if they are available for the HO engine or a modified ECM are your only options.

 

[cruiser54]

I have modified the CPSs on the Renix but I've never seen a ChryCo sensor so I can't help you there unless I see one. Post a pic if you can. Even if modifiable, it won't add alot of advance since it only moves about 3/4" and that's out at the flywheel diameter..

 

[fabjunkie]

sure, I got ya. Thats what I was afraid of.

 

[winterbeater]

Yeah. Move the sensor. A rough calculation would be from the calculation of 0.017" per inch radius per degree. So, if the sensor is at a 10" radius from the flywhell center (which I do not know, you need to figure that out), every 0.17" you moved it toward the direction of rotation would advance your timing 1 degree.

 

[ehall]

how was that number obtained? how rough?

 

[ChiXJeff]

Pi(d)=circumference, divided by 360 will give you the linear distance of a 1 degre angle at the rim.

 

[ehall]

Yeah I know but I am wondering if that's how he did it or if his rough number was derived some other way

 

[gradon]

The high alt cps is only for the renix. Pick up a used Jet2 chip--it woke my 94 up real nice with the timing advance. Another $ option is a Unichip from hesco, since they have tuned multiple strokers with it--hornbrod over on jeepstrokers saw more than a 50hp&lb-ft increase on his 91 obd1 stroker.

 

[nmcommando]

I had to do this when i installed a new motor before and just unbolt the distributor and pull it out and rotate the teeth the way the timing needs to be adjusted it worked perfect on my 94.

 

[Talyn]

I had to do this when i installed a new motor before and just unbolt the distributor and pull it out and rotate the teeth the way the timing needs to be adjusted it worked perfect on my 94.

You did not adjust timing by doing that.

Another option for timing is the SCT Tuner. I believe MarineJRM on JeepForum sells them

 

[winterbeater]

Yeah I know but I am wondering if that's how he did it or if his rough number was derived some other way

The sine of 1 degree is 0.017xxxxxxxxxxxxx.

Opposite leg of triangle / hypotenuse = sine.

You would not be moving it exactly as a straight line, more along the circumference, but that is close enough for horseshoes (and quick mathematical estimates).

 

[fabjunkie]

Ok , I did a quick experiment tonight while i was trying to figure out the solution to the puking transfer case problem....

I cut the crank sensor loose from it's bracket and jury rigged it so I could slide it back and forth.... YAHOO!!!!! ADJUSTABLE TIMING!!!!! works like a champ.

I'm going to work drawing up a cleaner bracket setup tomorrow ( I run a water jet machine for a living so I'll make some prototypes) and will report back..we will still have to climb under there and loosen the bolts to slide the sensor, but it's worth it, it works!

 

[winterbeater]

It seems like once you get it advanced a little too far, that it could be retarded electronically. I think Kastein is the electronics guru. Try PM'ing him.

 

[techno1154]

It seems like once you get it advanced a little too far, that it could be retarded electronically. I think Kastein is the electronics guru. Try PM'ing him.

The Renix version have a knock sensor that will retard the timing if pinging is detected. The HO do not have a knock sensor. The timing will have to be retarded manually if knock/ping is detected.

 

[fabjunkie]

Ah very cool. Well today I made a sliding bracket mock up for the crank sensor, I test fit it and all looks cool so i will make a final version tomorrow and let you guys know how I make out:clap::clap:. What I'm trying to do is make it so I can use the stock sensor (it will be modified by cutting it loose from the stock bracket), just making the mount adjustable.

From what I saw tonight, the movement (advance/retard) is going to be limited by the mounting bolts cause there's not a whole lot of room, but it ought to be plenty for what we are trying to do.

Thanks for the continued help!!eace: