[eric32]

Hello guys I had to take out my distributor HEI today and get some new parts for it cause it had seen better days.

Engine is 350 sbc 9.5 to 1 compression Quickfuel 650 cfm race carb, edelbrock rpm performer air gap, Iron eagle 200 cc heads ported and gasket matched, Comp cams big mutha thumpr hydraullic roller cam 531/517 lift ( will be replacing soon with lunati voodoo 60112 cam ). Be for I did anything the distributor has given me a miss here and there and it seemed like it would mis a fire here and there but worked ok I never had any pinging with my vacuum hooked up or anything also I did not have any kick back when starting.

Ok I got a Mr Gasket advance curve kit for it. It had originally Heavy springs for the centrifugal weights. The weights on it where worn out etc so I put all the new advance weights that came with my kit and also I went with the lighest springs wich are black and start to give me mechanical advace at 500 rpm. It was set at estimated 12 degrees initial timing wise before I did all this. I marked where the distributor was set at before I took it out and put it back the same way. When I tried to start it the first time it kicked back like it had too much advance so I loosend it up and retarted it a little and still got some kick back but not as much.

I now have it slightly retarted more then where the old mark is and it still wants to kick back here and there but not as bad at first. After it was running it seemed the miss was worse then before and does not run quit as smooth as it did but I do know with the lighter springs and weights I am getting more time in more quickly as to before with the stock springs it would not be fully timed till 5000 rpm or more. So what should I do now to get things going good? I just ordered a new HEI Distributor from Skip White on ebay and it comes with a vacuum adjustible canister. I will be replacing my above roller cam with a Lunati Voodoo Hydraullic roller cam with 231/239 @ 50 with 535/550 lift.

I need some help so I can get this thing timed right and running good for the best power and streetability and clean burning mpg all in one. I know it won't do excellent mileage but I want to get the most this engine can make. I don't have a timing light to use and I don't know what kind the autoparts stores have and what to look for if renting one. I know a lot of you guys on here have excellent experience with HEI's. I want to be able to have around no more then 12-14 degrees initial for a total of 32-34 total and around 48-50 with vacuum advance. I don't want to have a bunch of kickback and have to hoop up more stuff to get this to work good.

I don't know how this all works a hundred percent and how vacuum works in relation to initial timing and advance. Hope someone can help me with some pointers.
Thank you guys appreciate it.
Eric

 

[DoubleVision]

You can`t set the timing without a timing light, estimating it won`t cut it.
Get a timing light and set it properly, don`t guess and take the chance of ruining a bunch of high dollar parts. I know you wouldn`t be happy and then you`ll be asking yourself why you didn`t buy a timing light so don`t let it happen like that.

 

[ericnova72]

The cheap Actron?Sunpro lights are just as good as some of the more expensive ones. DoubleVision is right, you CANNOT set timing without a light. I would be foolish to try to, you are just guessing at this point.

Two light springs is not the way to go, as you have found, because the advance has started at too low of an RPM. The MrGasket weights typically don't work well either. You will probably end up with a mixed combo of springs(one light, one medium or one medium, one heavy) to get a curve you can use. I wouldn't bother with your old distributor, just wait until the new one gets here. Go buy yourself a timing light while you are waiting! You will use it for the rest of your life.

 

[eric32]

Hi thanks guys. I will get me a timing light soon. I was looking at the ones that go for around 30 bucks or so that will give you advance timing as well. Also I only did the light springs cause I have read that you want all timing in my 3000 rpm for a performance motor. I used two light springs in my other 350 but it was pretty much stock but it did make an improvement and ran much better so that is why I went this rought with this one. I am now second guessing my other one but I will have to see how it comes out once I get it running.

I wil get my timing under control I just don't know how much is too much and how much is too little. I want to get the most I can without too much. I know how mechanical advance works as it depends on what springs you use along with the rpm range but what about vacuum advance? How does it work along with mechanical advance?

I know with the distributor I am getting it has adjustible vacuum timing as to where you can set it. When does vacuum advance kick in and when does is stop? sorry for all the questions just tring to do it right. Thanks again guys appreciate all your help. It has all come in handy this past year.
Eric

 

[DoubleVision]

Vacuum advance is operated by vacuum, as you know, vacuum drops as more throttle is applied. On street bound small block chevy`s I always set the base timing to 12 degree`s BTDC with the vac advance disconnected and plugged. After setting it at 12 I lock the distributor down and connect the vacuum line to a manifold vacuum source (Manifold vacuum - Any port that pulls vacuum full time, even at idle)
Next I use the tach at different RPM levels and check the advance curve until I get it like I want it. If your vacuum advance is adjustable still set the base at 12, connect the vac advance and test drive, if it rattles or detonates take 2 degrees at a time out of the adjustable vac advance until the ping disappears.

 

[eric32]

Thanks double vision I do thank you for your help. How do you get correct initial timing when your mechanical advance starts to kick in at 500 rpm by just a few degrees? I installed the lightest springs cause I want all of my total timing in by 3500 rpm but if I go to medius springs it will not be until after 2500 rpm to get just a few degrees of advance timing.

I went all this time with the heaviest springs on my distributor and with just 12 initial I did not have hardly anything for timing wise just with the vacuum advance hooked up. What should I be looking for to time my engine to have all in by 3000 rpm and no more then total of 36 degrees and I will adjust my vacuum to add no more then what you recommended. Right now the vacuum canister in my hei is a stock one and I adjusted my timing with everything hooked up.

This was only the second time doing this and I did the same to my other truck but the engine is a mild performance one nothing like this one and I put the two lightest srings on to bring all of my timing in by 3000 rpm and it runs like a charm. The one I have now it went from bad to worse.

The old weights where so loose it was pitiful and the stock type springs kept me from any reall good timing for my big cammed motor. I will get a timing light but still don't know what all I should be looking for. Sorry for so many questions but I am searching as much as I can and cant come up with what all I need to do. I find on how to chang things but not get the correct amount with still keeping the light springs. If I go back to medius or stock then that defeats the purpose of recurving my HEI to a performance curve.
Thanks
Eric