stalls

[MN CJ7]

the advance on the hei can be corrected with different springs in the distributor, which is the same way that DUI corrects the advance curve. Summit Racing SUM-G5212 - Summit Racing® HEI Advance Curve Kits - Overview - SummitRacing.com a stiffer spring will lower the amount of advance.

Close... but do not agree

The springs will limit the mech/centrifugal advance to a higher RPM of the engine. The total amount of mech advance stays the same with spring change. This is true in duraspark stock distributor.

If heavier springs are used.... it could limit the mech advance amount the engine sees...... BUT ..... the mech advance will come in a too high a rpm range and will not work properly.....

Mech advance should be starting at 1000 rpms approx depend on needs and has range of 800-1200 early late. use would dictate

VAC Avance.....Health of engine, tune, carb will all affect vac levels of engine. So the vac advance will need to be made to work with your set up. Correct carb set up will have throttle plates closed and little vac/ ported vac at idle. Important on WEBERS. Vac levels pick up pretty quick at 850 on my VERY HEALTHY eng my eng is at 9" already and buids some with every 100 rpms up to 2400 rpms where it seemed to max out.

If the above is done correctly... will like 3-6 initial advacne... I am using 4-6 works great and set at 5. Lower initial if done right will also help in starts too.

In current state....
Hook up your Vac Advance and would guess you get harder starts and maybe even starter kick back.... pretty common on HEI use on AMC engines.

I do not recommed you change springs or anyting till the ... mech, vac levels, vac advance, and rpms are plotted. Then you can move and limit the and correct the advance to the Jeep Curve.

I did see on the summit kit... there are also plastic pcs..... I will guess... these are to slide on the mech advance limit slots to narrow the slot. This too would be trial and error but this would limit the mech advance AMOUNT TOTAL. The duraspark also have plastic bumper on the slot.... If I remember right I have seen a few with these.

The Jeep Field Service Manuals will have the correct curve. Select the one for I6, CJ. There are V8 and Full size versions as well as auto and manual Transmission . It will plot the advance with RPMs and vac levels. Poster is now a non computer operation... Take the advacne curve from 78, 79 , 80 FSM they have the proper curve for non computer for I6 and V8

The vac is used when cruise down road... the vac levels pretty high and can take more advance and get better ecnomy... Acceletate at hwy speeds and the gas goes up, vac level drops to 5/8/10 range and the vac advance comes out. The mech works with the rpm and has a range that it comes in and maxes out with a operational rpm range. Initial NEVER comes out and that is why a lower number is better adn better to use the mech/vac advance that work with engine needs.

Non computer Jeeps had 13 deg stock and if know how can change to 18 deg mech. I would expect the ebay HEI to have 10 deg or more than that and its too much. Have also be told if jeeper changes to 18 deg they need be very carefull with the mount of initial advance or could very likely have too much advance.

To do this work... vac gauge, Time light, Tac helps if on time light, and the box to limit the HEI vac / carb signal.


The stock duraspark is also fully adj too. The vac advance has a allen set screw to adj what level it comes in and ..... you match this to the carb level vac levels... it all works together...

Hope that makes sense.

Fred

 

[MN CJ7]

Here is a I6 Advance Curve for the 1979 Jeep FSM. Std Transmission .

Print this and the information above. Share and discuss with you shop... should be even better and much much safer.

you will have to test your HEI GEAR with std drill bit.... I strongly suggest...and you can see I have done this a few times.

Best of luck,

Fred

 

[MN CJ7]

Re: New HEI

maybe good idea to stay on your other thread.

The ans to you question is there, along with corrective info.

 

[IOPort51]

This is interesting, very interesting.
What are the two variables represented by the two lines on the graph??
You are saying that with the vacuum connected to the distributer advance it should be 10 deg. or less before TDC ??

 

[WAXER]

Re: New HEI

Yea, Sorry bout that MN. Just another thought that popped in my head. Please do not reply to THIS thread (go to "stalls").
Thanks
WAXER

 

[WAXER]

OK, So I need to take the advance curve chart for a non-computer I6 AMC 258 i6 / 4.2l to the shop and have them set my distributor (mech and vac) to those parameters? I wish I would have researched the HEI a little better (lesson learned). I think I'll hold on to the old dizzy, just in case!

What would be the long term effects if I just run like it is without vacuum advance?

Thanks,
WAXER

 

[Petescj]

Threads merged. It would be better to keep all your information here.That way people can answer your questions in this thread till the original problem is solved.

 

[Rescue Diver]

Re: New HEI

OK, its the weekend and I will not talk to the mech who installed my HEI until Monday. But, in the mean time, why do you think he capped my vacuum advance? From what I read, vacuum advance would help increase MPG (for what its worth on a CJ) and help with longer engine life? I'm thinking I should have him hook it back up?

Your vaccum advance hooks to ported vaccum and kicks in coming off idle through mid range throttle. It falls back at wide open throttle because the vaccum drops when the butterflies are all the way open. It's a good idea to use it, but it's not absolutely neccessary if your mechanical advance is tuned properly. I use mine.

 

[Rescue Diver]

OK, So I need to take the advance curve chart for a non-computer I6 AMC 258 i6 / 4.2l to the shop and have them set my distributor (mech and vac) to those parameters? I wish I would have researched the HEI a little better (lesson learned). I think I'll hold on to the old dizzy, just in case!

What would be the long term effects if I just run like it is without vacuum advance?

Thanks,
WAXER

It's not just the HEI. Any replacement distributor you could use would need tuned for your engine. The nice thing about the HEI is that the mechanical advance and springs are located under the rotor where they can be accessed more easily than on a lot of other distributors. Advance Auto sells a curve kit with different weights and a variety of springs for less the $5.

Let us know how things go with the mechanic!

 

[Rescue Diver]

you will have to test your HEI GEAR with std drill bit.... I strongly suggest...and you can see I have done this a few times.

Don't worry about testing the gear Waxer. Since you have an I-6 AMC 258 i6 / 4.2l instead of an AMC V8, you won't have the soft add on cam gear so no worries mate!

 

[Rescue Diver]

There is big issue with hardened gears on the HEIs that ARE MADE FOR THE AMC JEEP ENGINES.... petty wide spread on I6 and V8. The test is try to drill with std drill bit... if you get dimple it is good. If does not touch its going to eat you cam gear.

Please don't take this as me starting an argument.

The cam gear problem only applies to the V8 AMC motors. I hate to keep repeating myself, but the I-6 has a hard cam gear that's milled as part of the cam. It will not be eaten by a hardened distributor gear. This is not an opinion, it's fact. I've built a AMC 304 and a couple AMC 258 i6 / 4.2l engines with my own hands and have personally seen the different cam gear designs.

 

[MN CJ7]

Please don't take this as me starting an argument.

The cam gear problem only applies to the V8 AMC motors. I hate to keep repeating myself, but the I-6 has a hard cam gear that's milled as part of the cam. It will not be eaten by a hardened distributor gear. This is not an opinion, it's fact. I've built a AMC 304 and a couple AMC 258 i6 / 4.2l engines with my own hands and have personally seen the different cam gear designs.

Sorry... STRONGLY disagree... issue for V8 and I6

has been for several years and have been involved in 75 engine failures and have the quotes to prove it. This has been all over the web with dozens and dozens of posts with same feedback.....

I guess one of is going to be wrong

 

[MN CJ7]

This is interesting, very interesting.
What are the two variables represented by the two lines on the graph??
You are saying that with the vacuum connected to the distributer advance it should be 10 deg. or less before TDC ??

I am glad you liked it....


FUNNY.... NO THANK BUTTONS HIT?????
NOTE>... all you X computer guys that is what is messing you up.... Distributor needs to be modified or changed to refurbished with larger limit slots for mech advance.... Now wonder you like the HEI... you stock distributor cannot work with engine once you take away the computer and all the parts that talk and make up the system.

NOT sure what you are asking???? so you may have more??

The first graph is the centrifugal advance / mechanical advance. AS the engine rmps increase so does the advacne amount... it works with RPMs and help your engine effeciency.

The second graph is vac advacne and works with ported vac source above the throttle plates. As the work load, acceleration change on the engine so does the vac levels and so does the vac advacne the engine sees. VERY IMPORTANT.... Run a vac line and gauge to the dash and drive around for a few days... Max Out the Vac Levels as you drive and you will get 3 mpg better fuel economy on average. This is the load portion of ADVANCE.

If anyone tells you the do not need vac advance on a road vehicle or trail vehilce.... do not listen... they do not understand. Regards to another suggestion/post.

Waxer.... vac is very important... also shows me you have way too much advance if they could not hook up vac advance.

All out race vehicles will forgo the vac advance. THAT IS NOT US HERE ON THIS FORUM.... even if it was used then ... it would still work.

The charts do not use TDC.... so not sure what your reference is... Please explain further and see where it goes.

 

[MN CJ7]

OK, So I need to take the advance curve chart for a non-computer I6 AMC 258 i6 / 4.2l to the shop and have them set my distributor (mech and vac) to those parameters? I wish I would have researched the HEI a little better (lesson learned). I think I'll hold on to the old dizzy, just in case!

What would be the long term effects if I just run like it is without vacuum advance?

Thanks,
WAXER

I would take prints of all what I posted... and the JunkyardGenius thread also. Test drill the gear to make sure not hardned like the test shows. Take you old distributor and ck lenght, gear location, and the stuff in that thead.

Yes you need vac advance so your advacne curve works with your engine. Engine RPM/Mech Advance and Engine Load Changes VAc Levels/that will change Vac Advance. They work together so you do not rattle you engine apart.

If the shop seems to understand, use your judgement... and needs a bit more I can speak with them. What you and the need pretty much covered.

 

[Petescj]

Heres a great place for info on AMC engines. Happy hunting fellows. Remeber to post your replies tactfully please.

Bulltear.com - Home

 

[MN CJ7]

I think the MOST BENEFIT FOR JEEPs is that your stock ignition can be tweeked (distributor) and used with a stock ignition modaul and work very well great actually. Once the computer is taken out, the computer system and feedback carb. or any pc removed.... the jeep ignition is no longer whole and needs correction. Another words once the nutter is done, further work will make it work like new.

Ignition modual will need a aux ground and the head should be grounded at min. There are a dozen things to ground on your CJ with aux grounds. Grounds will keep the modual from death..... yep that is why some do no live. MINE is 1978 and still lives, its my back up.

YEP..
Poor grounds of cylinder head or duraspark ignition modual can kill and over heat your ignition modual
Leave you key on RUN w/o the engine running can kill you ignition modual... it will over heat... black potting will flow out.

Ignition modual can be replace with an iexpensive modual and work fine also.

Ignition modual can be replace with a MSD and give you the best ignition 500-600% better than stock or any HEI and the math does not lie and is spelled all over the internet.

If a jeeper has a hard time hooking up say a MSD vs a 1 or 2 wire HEI than maybe a CJ is not the best choice. MSD can be hooked up in 20 min and does not require a TDC and Distributor insertion that alone can / should take 20 min and needs a helper.... but no one ever says this here on Jeep CJ Forum.

I mean the battery neg is there, the soleniod on/off + is there, coil is right there, the distributor fire signal is right there. They give you connectors so its plug and play (optionals).


I know BullTear here in MN and JeepHammer have gone at in great lenght. At one time BullTear had problem gears also. I am not sold on the BullTear hardened gear set either.... but have not studdied in detail... nor do I intend to.... because I am years away from haveing a V8 CJ if ever. I know for a fact at one time there were issues and had facts and quotes from users... its real... and was at BullTear too. BullTear invited me to come up and look 2 yrs or so.... and have not and may not.

Often gears have one soft and one harder. On wear the soft one the easy one gets replaced. See this on snow blower augers.... Ariens has bronz/steel, went to steel/steel for while and big failure.... Went back to bronze/steel and larger gear set to spread out the load.... Just as example do not know the ans... just know at one time there were issues with the gears above too.

I am amazed how many things are out there that can do great harm to our little CJs. From Gear Lube in Transmission /Transmission , motor oil that does not protect flat tapet engines, Clutch Kits, Wrong Oil Pick ups, Faulty power steering hose kits, fram oil filters not good/ faulty anti drain backs, water pumps assembled wrong/pully on too far..... I found 12 or more.... major bo bos..... and I do not do this weekly, monthly, or even quartly.....

I can assure all that have read this far.... The HEI thing is not over.... It will not be ended on this Forum.... it will not be solved on this forum... It has a few more years to play out yet... and even if it gets settled......

If you understand what you have DuraSpark.... there is little reason to change it.... and its free and if you have to change it..... it cost $50 to get a refurb.... and its lifetime warranty.

I have been and JH has been too collecting info on the DuraSpark Distributors dimensions so they can be modified safely to have the correct curve. If you curve your HEI, the curve on DuraSpark is much easier and built in options that make it on of the easiest to adjust to advance curve.

Just be carefull

 

[IOPort51]

the timing curve graphs you display and the ones in the FSM have two lines with different profiles. What is the variable, what is the reason for two lines on each graph??

 

[MN CJ7]

the timing curve graphs you display and the ones in the FSM have two lines with different profiles. What is the variable, what is the reason for two lines on each graph??

Here is a I6 Advance Curve for the 1979 Jeep FSM. Std Transmission .

Auto and Std Transmission .... see first graph legend

Just to clear..... This is the JEEP Field Service Manual, FSM, page from 1979 CJ.

Confused.... this is the FSM page... if you have a computer year of FSM it will not have this curve. The car is tuned at 1600 rpms and the computer will TAKE TIME ADVANCE OUT..... OUT ONLY..... as it sees fit from knock sensor, O2 sensor, temp and adj carb meter rods at same time.... Good at that is you have whole system.

I think you maybe saying your FSM has two lines also as does MY FSM chart scanned and shared above.... if that is the case than we are covered.

 

[Rescue Diver]

Sorry... STRONGLY disagree... issue for V8 and I6

has been for several years and have been involved in 75 engine failures and have the quotes to prove it. This has been all over the web with dozens and dozens of posts with same feedback.....

I guess one of is going to be wrong

Respectfully, please provide links, pics and any other info you have to show that the I-6 has the soft cam gear problem because that goes contrary to everything I found on the internet and from personal experience. If I am proven to be wrong by you showing any example of an I-6 vcam gear being eaten by a hardened distributor gear, I will gladly admit it.

 

[MN CJ7]

sure...

see post #19 this thread.

also posted on your thread on the HEI

Has pics and user name... I was also involved when the user had his engine failure.