Mpls Funk

Hi All,

I have a 1970 350/350 that has a modified cam (previous owner, so I'm not sure what it is) with a Edlebrock Torker intake and Holley 650cfm double pumper carb. I have not driven the car much at all over the past five years, and the last couple of times it ran like total CRAP, to the point that I couldn't even get it started last fall.

I rebuilt the carb over the winter and installed it last weekend...and it fired right up! The carb was a total mess. So, now I think I need to tune the carb...and re-time the car, etc. My understanding is I should get the timing/dwell set first before I tune the carb.

Can anyone point me to an easy to understand guide as to how to set the timing, and what it should be? I don't understand what the configuration of my engine (carb, intake, cam, etc) might have on what the timing should be...so any guidance there would be appreciated as well. I have purchased a timing light, but I have never done this before.

The previous owner was racing the car...I am not...I am street driving it. Of course I want it to go fast at times...that's why I bought a Corvette, right?! But I'm not trying to get 1/4 mile times, etc.

Any advice would be greatly appreciated!

MelWff

regardless of any modifications if you have points the dwell is set for 30 degrees. As far as timing, do you know if you have the stock distributor and whether the timing curve has been modified? Did you buy a dial back timing light? If you just want to set it to stock specifications, disconnect the vacuum line at the distributor and set the timing for 8 degrees BTDC.

Mpls Funk

Thanks - unfortunately, I don't know. I'm assuming it's the stock distributor...I have not changed it, but I don't know if the previous owner did? He was racing it...would that be a common change for someone that wants to race it? Is there an easy way to tell?

The timing light I have is pretty basic...so not sure if it has the feature you are mentioning? Sorry - I wish I had better answers to help you help me!

MelWff

can you post pictures of the outside of the distributor and with the distributor cap and rotor removed. This way we can tell if it is the stock distributor with the stock weights and springs.

MelWff

Do you own a dwell meter?

hugie82

If you have the access door in your cap and the car runs. You can stick your Allen key in while it's running. Turn it until it sputters, then go back the other way until it shudders . Then you can center it between the two points. It's usually less than 3/4 of a turn between the to points of studdering.
Timing, advance it (counter clockwise ) until it cranks hard or pings when hot. Then back off until it stops. Of coarse this is backyard wrenching until you can get the right tools.

Easy Mike

You're gonna want one.

7t9l82

id say if it won't start you may want to run a piece of fine sandpaper across the point contacts. they get a film or corrosion on them and the car won't start or just run crappy.

Paul L

Or just replace them for less than $20.00. Why fool about.

Peterbuilt

Post #1 by Barry K explains a lot about timing.
https://www.corvetteforum.com/forums...long-post.html

7t9l82

its just a way of confirming that as an issue without spending "less than 20 dollars", and finding out that wasn't it.

Mpls Funk

ok guys, I'm back. Sorry for the delay. Here are some pictures of my distributor with the cap installed/removed, and with the rotor removed. I hope this helps answer the questions posted above? with this, I would be happy to have any help in how to properly set the timing. Again, I know the previous owner put a different cam in it, but I have no idea what the cam is? The car also has headers on it along with an Edelbrock intake and a Holley 4150 carburetor (freshly rebuilt and tuned by me!).






Also - here are pictures of the timing light I have...there are no buttons/displays on it at all...just the light and a red clamp, a black clamp and another black clamp.


Here is the picture of the dwell meter I have...it is integrated into this DVM that I have.


I do not know how to hook up either of these meters and I don't know what to adjust to get the results that I want...and I'm not sure what results I want, other than the previous post that I want 30 degrees of dwell.

Last - I noticed when I took the rotor off, there was a light red dust/smudge in one area...see picture. This dust came right off when I wiped it with my finger...but any idea what this is? Or if it's a potential problem? There also appears to be similar red dust on the two pieces of metal (that I think are the weights?) under the rotor. Any ideas?

toobroketoretire

When the points are new set them to .019" with an ordinary feeler gauge.

MelWff

the dust is rust, lubricate the pivot points of the weights, hold on tight to those springs when you remove them. Also the rub spot under the weights. The negative of your gauge goes to any ground and the positive of your gauge goes to the negative side of the coil. You will need an allen wrench and with the engine running open the little window, insert the allen into the horizontal screw you see on the points and turn to set dwell to 30 degrees. On the timing light the black again goes to ground and the red goes to any 12 volt source, could be the alternator output or the horn relay to name two. The clamp goes to the number 1 cylinder plug wire, first cylinder on drivers side. You loosen the clamp at the base of the distributor and slowly turn it while shining the timing light on the timing marks found on the timing chain cover tab. The springs look stock so you would set timing to stock numbers for now. Disconnect the distributor vacuum advance while setting the timing.

Mpls Funk

thank you for your response! dumb question...what should I use to lubricate the parts?

MelWff

just a very very thin coat of wheel bearing grease, others will tell you clean it and place nothing on them

hugie82

YouTube is a great source on how too. It's very hard to describe and talk about function without pictures or prior knowledge. If you set the points wrong and then change the timing, you'll have a mess on your hands until you learn how to set it up. For most of us, it's easy because we've been doing it for 30-40 years. Watch some videos on how to set points on any GM vehicle and then timing. The guys here can fill in the blanks if you have questions.

kanvasman

Wow,dwell meter, points, gap… I shure feel old. Like when I opened the hood on my '78 and then had to explain to my 27 yr old son what that thing in the middle of the engine was. He had read about carburetors but had never actually seen on before! But as stated, those of us who have messed with them for 30 yrs find it all so simple compared to today. Previous experience, for example, shows that a match book cover will get the points close enough to get you home…oh, try and find a match book! Sorry.

kdlp

I was out on a "Rod Run" with a "younger" club member earlier this Spring... After easing away from a stop light on a 55mph highway I got into the pedal and then floored it engaging the four barrel. He looked at me with a shocked expression and said, "what was that?" After we arrived at the picnic I conducted "Carburetor 101" class.

kdlp

Mpls Funk

So - should my order be:
1. Set point gap
2. Set dwell to 30 degrees
3. Set timing to xx (need to look this up somewhere)

Is that the right order?