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Am I at the limit of my ignition?

CRASH

CRASH

NAXJA Forum User
NAXJA Member
Location
Foresthill, CA
I think I'm getting weird performance when revving past 5,000 in the new stroker. Is the Renix distributor prone to spark scatter/wander at high revs? Do I need something better to fire this thing off while in race mode (5,500 RPM shifts)?

CRASH

P.S. Don't want to lose a desert race to the likes of Goat and Dave Taylor now that we are all on bling-bling suspensions.
 
Can you describe the weird preformance?

I dont know about the spark scatter other than an old cap can cause problems from carbon build up and such.

What coil are you running? I guess the question is can the stock coil handle 5500 rpm? It may not have a big enough duty cycle to provide constant spark at that RPM. Have you tried a hotter coil such as the MSD coil or a MSD ignition box?

AARON
 
MrShoeBoy said:
Can you describe the weird preformance?

I dont know about the spark scatter other than an old cap can cause problems from carbon build up and such.

What coil are you running? I guess the question is can the stock coil handle 5500 rpm? It may not have a big enough duty cycle to provide constant spark at that RPM. Have you tried a hotter coil such as the MSD coil or a MSD ignition box?

AARON
Click to expand...

It feels erratic at that RPM, though the A/F ratio is still the same WOT 13.0 to 1, so it's not starving for fuel. The cam should be OK, up to about 5,500 or so.

I'm running a stock coil because of the miserable luck I had with Jacobs. I vowed to never use aftermarket again, perhaps I need to re-evaluate.....what is the hot setup from the aftermarket? I need bullet-proof dependability most of all.
 
I had the same wierd erratic missing thing through my whole rev range, I installed an msd 6 and it runs smooth now. I also run mopar performance wires. I think the higher compression of strokers brings out the weakness in the stock ignition system.
 
Andy, don't compare Jacobs with MSD......how many serious racers run MSD gear? Most of them.
 
Thread hijack

[/quote]
CRASH

P.S. Don't want to lose a desert race to the likes of Goat and Dave Taylor now that we are all on bling-bling suspensions.[/QUOTE]

With you and Richard running strokers ,I need to start airing up for the for the fun stuff. I might need to go hyd-bump stops this summer. Also I might need new valving in the rear shocks. It's so light back there now. Further
testing will be going on at JV this weekend.
 
XJEEPER said:
Andy, don't compare Jacobs with MSD......how many serious racers run MSD gear? Most of them.
Click to expand...


So throw a dog a bone, what's the hot MSD ignition to run? MSD Offroad?

I don't like wiring stuff, so the simpler the better.

Bulletproof, waterproof for those Fordyce crossings.....


CRASH
 
The offroad would probably be the way to go. I haven't had a problem with my 6a but I have to send it into msd to have it upgraded so I can use a rev limiter. Wiring takes like 15 minutes and it is all plug n play if you spend the $15 on the instal kit. The install kit is only two spacers and some jumper wires and two small bolts. I have a writeup on my install that I will submit to the repository.
 
CW said:
The offroad would probably be the way to go. I haven't had a problem with my 6a but I have to send it into msd to have it upgraded so I can use a rev limiter. Wiring takes like 15 minutes and it is all plug n play if you spend the $15 on the instal kit. The install kit is only two spacers and some jumper wires and two small bolts. I have a writeup on my install that I will submit to the repository.
Click to expand...


Well get on it, damnit!

Thanks, I'll look into the offroad.....

CRAS
 
Yeah, I'd say you are. From what I've found so far (I've still got to set up my RENIX gear on the bench...) the computer system itself is highly adaptable, but the ignition can only do so much.

I'd most likely want to run the MSD 6-Offroad - with the option of a 6-Offroad Rev Limiter box if you're worried about such things.

There are adapter harnesses to connect the 6-Offroad to both RENIX and HO ignition setups, so you shouldn't have any trouble connecting it up.

MSD P/N 8813 is the adapter harness for RENIX. I'd have to look up the P/N for adapting to HO (I haven't gotten that far just yet - and I've got more letters to exchange with MSD yet...)

5-90
 
My Renix stroker pulled 5300 RPM on the chassis dyno and will go higher. Stock coil, MOPAR Performance cap and wires, Autolite platnum? plugs.
If all your ignition components are good (high speed miss is often spark plug boots leaking to head) what about valve float? what cam and springs are you running?

I have a MSD 6AL on the drag MJ and it goes 6500 with hydraulic lifters (spaced out to .005 clearance) but a production cam may valve float at 5500 or so - depending on ??
 
rsalemi said:
My Renix stroker pulled 5300 RPM on the chassis dyno and will go higher. Stock coil, MOPAR Performance cap and wires, Autolite platnum? plugs.
If all your ignition components are good (high speed miss is often spark plug boots leaking to head) what about valve float? what cam and springs are you running?

I have a MSD 6AL on the drag MJ and it goes 6500 with hydraulic lifters (spaced out to .005 clearance) but a production cam may valve float at 5500 or so - depending on ??
Click to expand...

Standard stroker issue 5.9 magnum springs, 5249464.

Isky 133125/26 Cam .450, 256 duration intake, .465, 262 duration exhaust.

I'm missing some torque at the bottom end, so I'm thinking of playing with the cam timing a bit to get some back (I have an adjustable cam gear setup).

The old motor would float valves badly over 4500, but then it had over 200K on it. This doesn't seem like valve float, but weak ignition or inaccurate timing. The cap, rotor and wires are new, but they are just parts store specials.

CRASH
 
Is there wear in the distributor shaft?? side play can cause high speed miss...
excessive end play can cause unstable timing...I would hook up a good timing light and check to see if the timing "walks" around...this is assuming you have the cam thrust pin and spring installed...if it is missing,the cam can move around...altering timing.
 
CRASH said:
I need bullet-proof dependability most of all.
Click to expand...


Everything that I have read online and and talked with the old school crusty mechanic that lives down the street from me said that MSD is the way to go. I havent had any problems with my MSD 6al box but then again I have had it on for a month or so on my XJ but it was used on 2 vehicles previously. Can you say village bicycle? :)

The only thing I have herd about the Offroad box is that since its sealed, only MSD can repair it where as the regular boxes can be rebuilt/fixed in your garage. Does anybody else know any more about this?

AARON
 
Indexed the distributor??? Many rebuilds - stock and strokers - have had to index the distributor to solve ign problems. If you haven't done this you need to.
 
Well I don't have a storker, but....

a few things sparked my interest here....

I have a stock 98 4.0 with MSD 6A and blaster 2 and I have seen 6000+ r's a bunch of times and never once have I heard a misfire.

You might wanna lookinto more spark.

Also... being you have a stroker... why on earth would you wanna be up that high in the R's for?! its a low end torque motor.... not a 10000rpm nascar motor!

Your not makin any power up there are you?!?!

I like my stock powerband thankyou very much!
 
Actually, I make a ton of power all the way to 5,500.

I'm curious to see why you think a stroker has to be a torque motor? You realize, don't you, that a stock 4.0 is an under-square motor? It has a shorter stroke than it's bore diameter, making it a very friendly motor to revs. My stroker is perfectly sqare, equal bore and stroke, and is still very friendly to revs.

CRASH

XJRubicon said:
Well I don't have a storker, but....

a few things sparked my interest here....

I have a stock 98 4.0 with MSD 6A and blaster 2 and I have seen 6000+ r's a bunch of times and never once have I heard a misfire.

You might wanna lookinto more spark.

Also... being you have a stroker... why on earth would you wanna be up that high in the R's for?! its a low end torque motor.... not a 10000rpm nascar motor!

Your not makin any power up there are you?!?!

I like my stock powerband thankyou very much!
Click to expand...
 
I have the MSD 6 offroad box. Actually my 3rd one now, I keep killing them, when I talked to the guys at MSD they told me the offroad box was there cheapest guts put in a fancy box. What they told me to do was buy any anylog box and send it to them and they can add "humiseal", the epoxy looking stuff that seals the box.
I love the performance increase, but it would last about 3 months then die.
We (MSD Tech and i) finally decided that a combination of heat and voltage spikes was the culprit (besides bus service and offroading my cherokee is also a roadside rescue truck) and the voltage spikes where coming from the constant jump starts to other vehicles.

If i was do do it again i would use a digital box and mount it inside. away from most of the heat and water.
Call MSD and see what they recomend.

Dingo
 
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