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  #16 (permalink)  
Old 10-06-2008, 11:14 PM
j.d.brown.042964's Avatar
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If you are changing converters this weekend, then it wouldn't make sense to try my idea. I thought you were going to have to live with situation for an extended period of time, so that's why I suggested it.
If you were curious as to how one could implement such a system, you need only to know that you would supply "ignition switched" power from the fusebox feeding to the limit switch (many different types and sizes available from electronics supply house, probably even Radio Shack) to be activated either thru floor or column linkage, or even off input selector itself on trans. Circuit continued thru the switch ("normally open type") on to the solenoid (smallest you could find that, you would fab. your own mounting bracket for) which would ground thru switch body. For reverse you would run a second feed, or split-off from power feed going to backup lamps. Anyways... you won't be requiring it, but that would be one way to boost idle speed , only when in gear. A simple remedy from a simple mind -MINE! Have fun with your tq swap this weekend, and be sure to run a good tranny cooler with that high of stall. -Jim

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Old 10-07-2008, 12:20 AM
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stall

Jim,
So the looser converter swap will fix my problem? This is what i've been trying to find out all along. I was told that it wouldn't make a difference what converter I had in it that it would still lose idle and vacuum when i put it in gear.
Also Techinspector ain't on or just no reading this right now so How much HG do you think I'd gain by switching to a dual plane Intake like one of the 3 performer rpm intake's i have. Should i use the regular performer rpm, or the air gap??
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Old 10-07-2008, 12:27 AM
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converter

ya know now that I think about it. Who knows what the stall of the stock converter is thats in there?? I know that most stock converters are around 1500, but this one feels like it locks up right away.
Just so you know it came out of a 87' chevy 3500 dually. It was a jasper factory exchange tranny set up for towing not racing. Would something like that have an even lower stall than say a passenger car's stall and that could explain why my idle is dropping so much when put in gear?? just a thought. its getting changed regaurdless but I'd still like do find out what it is.
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Old 10-07-2008, 06:18 AM
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Quote:
Originally Posted by eatonde
FBIRD,
So let me make sure i understand you right
First I wrap the tape around the balancer marking both ends, then find 1/10th of that and mark it on the tape.
Put the tape back on the balancer lining up the 2 circumphrence marks that i made on the tape with the TDC slit that in machined into the balancer.
Then with a timing light i can line up the mark I made on the tape that is 1/10th of the circ. with the 0 degree mark on my timing tab scale that will put me at 36 degrees.

Unless I'm misunderstanding you, Isn't that a little much for the base or do you mean 36 total?? I'm not questioning you, just trying to make sure i understand. This should be mechanical only with the vacuum unhooked and the hose plugged right???

No it is not too much. It is exactly what the motor requires to idle correctly with that cam. The exhaust delution caused by the increased cam overlap slows the combustion speed down so much at idle and low rpm that you need much more timing at idle to compensate. Lock out the mechanical advance and set the timing at 36deg BTDC. It will not move with rpm.
Vacuum advance is a separate thing and is in addition to the fixed 36deg mechanical advance. (10 to 15deg additional cruise vacuum advance)

Mechanical 36deg fixed..... Vacuum 10 to 15deg at part throttle hiway cruise.
Use ported or full timme vacuum source, which ever works best for your.
I use ported.

If the car is hard to start when hot with fixed 36deg timing, install a ignition power interupt switch on the HEI distributor power wire to disable the spark during initial hot cranking. it will fire easily.

This is the correct way to set up the engine with this camshaft for an automatic trans car. You still need the converter.
You'll need a 3.5 or 4.5 power valve and will need to reset the carb throttle blade opening at idle to expose just .030" of idle transfer slot on both the pri and sec throttles. Remove the carb and flip it over and have a look.
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Old 10-07-2008, 06:31 AM
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Sorry about that. Yes the 3000+ stall will fix the idle issue. You should be able to idle at 1000 rpms in park and in gear. I doubt you will feel the car go into gear from park.

And yes, you need a bunch of timing (at least 20 degrees at idle) and a lower power valve number. (like 4.5). Total mechanical timing should be around 38 or 40 degrees with old iron heads.

Vacuum advance may not even work with that cam. You need to check the vacuum while driving down the road. It would help mpg if the vacuum advance would work.

I would use the RPM intake. Much better low rpm torque.

Don't expect too much power with that 3.08 gear. And be careful not to over heat the trans with that loose convertor on the street (try to run it above the stall).
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Old 10-07-2008, 08:42 PM
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carb and timing

OK, please forgive me but when you say lock it out, what exactly do you mean? Like I said, I have built 8 stock motors basically back to stock and 3 mild performance motors in my young career in this field. The most cam I've ever used is a comp 280 magnum. I never really had to learn this termanology or put it to use before, I could always just slap the dist. in find were it ran best and take off.
This one is proving to be much more difficult, but i love it. I learn something new every day.

anyway can someone fill me in on how to do this.
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  #22 (permalink)  
Old 10-07-2008, 08:48 PM
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Dizzy

Do you just mean lock the distributor or are you refering to something inside the dist??
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  #23 (permalink)  
Old 10-07-2008, 09:33 PM
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If you are going to put the stall converter in this weekend I would wait to do any setup additions until after the converter goes in it will make all the difference in the world. Even if you don't put the gears in till later. After the converter goes in then work on the idle. Your chasing you tail otherwise. As far as the timing tape idea you could also consider buying a inexpensive timing light with advance dial on the back. Just keep in mind that if you fix your mech advance and set it at 36 deg it may be hard to start when its hot. sometimes you have to limit your mech advance say to 8 deg then set the base at 28 deg which will help with hot starts. But I agree with the previous post that you need more.
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Old 10-07-2008, 09:36 PM
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Sorry I should have added when he said lock the dist he meant lock the mech advance so it is fixed and does not move. so you set your timing at 36 deg and it stays there. Then refer to my previous post.
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Old 10-07-2008, 10:26 PM
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timing

OK, I have been doing a lot of reading and I am starting to understand the terms that everyone keeps using. Mechanical and centrifugal are the same thing right?? thats what was confusing me....

Aside from that, how do I get the mechanical section locked?? Do I need to remove the weights and springs and find a way to lock it OR is there something I'm missing.

Also, I like the Idea of being able to still start my car when its hot, so if I just want to limit it as you said MEZ how do I do that???

Also, even if i lock the mechanical advance out at 36, If I'm using Manifold vacuum on the canister, provided Its working, wouldn't the 15* supplied by the vacuum advance at Idle put me up to like 51* at Idle making it to much?? This is whats confusing me too.. My brain is telling me that if I'm attaining 15* vacuum advance (provided its working) on full manifold vacuum, then wouldn't I only need 21* to attain the 36 total, OR is it the 51 that I really need, Or are you saying just don't use the vacuum advance or what???????????????? can someone please explain exactly which way this should be???????????
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Old 10-07-2008, 10:31 PM
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2 different methods

Guys the reason I think I'm gettin confused is cuz 454C10 says to set initail to atleast 20, but F-BIRD88 Is saying 36 Initial. Are these 2 different methods or am i misunderstanding F-BIRD88????
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  #27 (permalink)  
Old 10-08-2008, 08:26 AM
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At least 20 but you could run 36. But, I have my doubts it will start with 36 degrees at start up after it is warmed up.

Yes you are right, when driving down the road the vacuum advance will add to the mechanical (centrifugal) advance. And 50 to 55 degrees during light loads (high vacuum) is good for mpg.

However, your cam will not make much vacuum, so the vacuum advance may not even work. you should drive down the highway and measure the manifold vacuum.

You can connect the vacuum advance to a manifold source or a ported source.

Ported sources do not have vacuum at idle and a manifold source has vacuum at idle.

When the throttle is opened, both sources will have the same vacuum. And the more the throttle is opened, the lower the vacuum will be on both ports, so the vacuum advance will fall off (go away) under load. And revving up the engine in neutral is not an engine under load.

There are a number of ways to lock out or limit a distributors advance. Welding up the advance slots to reduce movement, or weld the slot closed to lock, or use straight wire instead of springs on the advance to lock.
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  #28 (permalink)  
Old 10-08-2008, 12:28 PM
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Stop trying to think about how it will work and do it.
This is not a stock motor now. it does not require the same timing curve as a stock motor.
it needs the correct timing curve fora motor with a big cam.
mechanical advacne is not nessessary.
A fixed mechanical timing setting (36degBTDC) combined with some vacuum controled cruise advance for efficient part throttle cruise is what this motor needs for timing.
When idling in gear there will be very little manifold vacuum less than 5".
When idling in gear you need 36deg of timing that does not drop off with manifold vacuum. Therefore fixed mechanical advance at 36deg.

When cruising down the road at part throttle at say 60mph you will have much more manifold vacuum near 18". vacuum advance will add approx 10 to 15 deg of additional timing at cruise when set up right.
Concentrate on the mechanical timing and idle set up.
Lock out the disributor mechanical advance by removeing the weights and springs and wrapping the mechanism locked fully advanced using two plastic eleictrical cable ties around the advance mechanism. Orient the tie wrap knots down under so the rotor can go back on.
Reset the distributor to 36deg BTDC at idle without vacuum advance.
This is not that hard.
If you install a dash mounted 10 to 15amp rated SPST spark cut off switch to interupt the spark during initial hot cranking it will fire easily and surely when hot with 36deg of timing.

You will have little manifold vacuum at idle and less while idling in gear with this cam. Therefore manifold vacuum controled vacuum advance will not provide a stable idle timing in and out of gear like on a milder cammed motor.

Set it up and get your car idling properly and then you can make up all the theory as to how things work etc etc later.
I've been tuning and setting up high performance street driven and drag cars with big racey cams for over 35 years.
This method provides the best, most stable idle quality in and out of gear with a auto trans and quick throttle response with the cam you have.
once you get into long duration cams this big, this is the spark timing that is required.
This is how you do it.
You'll need to install the high stall torque converter also.
Yes you'll be employing a slightly different method to start the motor when its hot by using the dash mounted spark power control switch combined with the ignition key.
Some people use a add on MSD electronic start retard box "starter saver" to reduce the spark timing during hot starter cranking. The simple cheaper effective cutoff switch serves the same purpose. It also serves as a cool anti theft device. Mount it somewhere that you can use it while starting yet won't bump it while driving.

Don't throw away the distributor weights and springs.
When you finally figure out that having the meanest cammed motor does not suit your situation and get a more reasonable camshaft setup that actually works for your daily driving purposes, you can easily reinstall the weights and advance springs in your distributor.

To get the power from that cam in a 350 you need:
a high rear gear ratio 4.11 4.56
a 3500 4000 stall converter
A 9.8 to 10.5:1 compression ratio. (premimum pump gas) 10.5:1 or more for race gas.
If you're not going to be running 110+ octane race gas don't build it with more than 10.5:1 cr.
a 750cfm carb with a 3.5 or 4.5 power valve
big valve high flow high performance heads or fully ported stock heads.
A hi rise dual plane "RPM" manifold or a streetable single plane (vic JR)
LONG TUBE headers with dual exhaust or a 2.5" into 3.5" 2 inot 1 exhaust
A modified distributor spark advance curve as I outlined.
preminum 92+ octane gas
A lot of money for gas.

Last edited by F-BIRD'88; 10-08-2008 at 01:09 PM.
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  #29 (permalink)  
Old 10-08-2008, 08:35 PM
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loked advance

Thanks F-BIRD, that last post really elucidated the situation. I am goin to lock it out and set it to 36*initail. I am gonna see if any of the local auto stores carry a timing tape I can fix to my balancer.
I wasn't tryin to beat around the bush about doing it, I was just confused as to whether I was comprehending everything right. I can be a tad dense at times. I was reading some of your other posts about this subject via the search function and I see that you recomend the crane cams adjustable vac advance canister to a few folks in similar situations. Would this piece benifit me or should i leave well enough alone?????? I am planning on porting another pair of the stock 76cc heads I have at home to use until I buy my new ones. I have already completed the 416 305 HO heads that I talked to you about but that would make my CR around 12:1, whick Is waaayyyy higher than i wanna go. Does anyone make a plate speifically for locking the mechanical advance?? I have read about several guys using a plate with thier MSD's to lock it. I will just do it as you described for now but I was wundering for future reference. Thanks
Danny

Also If not the crane cams Vac can, I hear that NAPA has one for lower HG motors that will allow full vacuum advance between 9-11HG. Should i get this??
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Old 10-08-2008, 08:54 PM
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The crane (and various other branded) adjustable vacuum advance is the way to go.
http://store.summitracing.com/egnsea...=KeywordSearch
pick one...
It is adjustable for both the amount of vacuum advance. And the rate that it comes in based on variable manifold vacuum and engine load.
Needs some experimentation to get it dialed in right.
You won;t have to depend of vacuum advance for idle quality, just for efficiant part throttle cruising. What ever little vacuum advance you get at idle is just a bonus.

There is no mechanical advance lock out plate commonly available for the HEI distributor.
The two simple plastic electrical cable ties work just as well at locking out the mechanical advance on a HEI. If you install them right they are on there for good unless you want to remove them. Some people drill thru the advance mechanism and run a sheet metal screw down thru the advance mechanism to lock it. Why spend money you don't need to.
Why make this more difficult than it needs to be.
If you're using smogger heads that use a stock R44TS or R45TS spark plug (.460" reach),
use a Champion RV8C spark plug or a AC delco R42T spark plug.

The R44TS is too hot a plug for hi performance work. gap at .035"

Do not use 87 octane gas.

Last edited by F-BIRD'88; 10-08-2008 at 09:01 PM.
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