Do not use aftermarket weights out of a kit. Use the stock factory weights and tune the curve with springs.
Timing question
Drifting
Joined: Jul 2004
Posts: 1,695
Likes: 64
From: Kissimmee fl
Finalist 2021 C3 of the Year - Modified
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St. Jude Donor '07
Another option is to lock tite the proper length studs into your new intake. Then when servicing under there, you will not be threading into the aluminun all the time. 
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Just a follow-up thought.... You indicate that max timing isn't coming in until after 4000 rpm. Did it increase smoothly, or did it "jump" at times? The interior of the mechanism is so full of rust powder, I suspect that the flyweights aren't operating freely. Lars could advise you better, but I think it might be wise to clean and lube the appropriate areas before trying to do any more adjustments. If the weights are hanging up at all, your adjustments might be worthless. Hang in there! Just remember that everything you are encountering is providing you with future "knowledge"....it is a good learning experience for you. Think of it like that, instead of just being a big headache. 
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 936
Likes: 0
From: Tulsa OK
It was jumpy. It'd hold pretty steady from around 30-3500 then jump up again as I got closer to 4000.
I figure since I've got to pull the distributor anyway to make way for the new intake, I might as well try my hand at cleaning it up. The advance kit came with new weights and nylon bushings. I'll see if I can't get things working more smoothly.
I figure since I've got to pull the distributor anyway to make way for the new intake, I might as well try my hand at cleaning it up. The advance kit came with new weights and nylon bushings. I'll see if I can't get things working more smoothly.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
It was jumpy. It'd hold pretty steady from around 30-3500 then jump up again as I got closer to 4000.
I figure since I've got to pull the distributor anyway to make way for the new intake, I might as well try my hand at cleaning it up. The advance kit came with new weights and nylon bushings. I'll see if I can't get things working more smoothly.
I figure since I've got to pull the distributor anyway to make way for the new intake, I might as well try my hand at cleaning it up. The advance kit came with new weights and nylon bushings. I'll see if I can't get things working more smoothly.
BigBlockk
Later.....
Advanced
Joined: Aug 2006
Posts: 90
Likes: 0
From: Cumming GA
interesting thread..... I've been over timing a few times on these threads, but would like opinions on using either manifold or ported vacuum. I've been told ported (have an '81), but Lars suggests manifold???
Please give opinions on what works well for you- thanks again!
Please give opinions on what works well for you- thanks again!
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Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
If you have to comply with smog standards you'll have to use ported vacuum. Some engines with big camshafts do better with ported vacuum. Manifold vacuum will help a milder engine provide very good throttle response.
BigBlockk
Later.....
BigBlockk
Later.....
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
That's correct. Manifold vacuum will help a low compression engine build cylinder pressure earlier in the power stroke. This helps driveability by improving throttle response.
BigBlockk
Later.....
BigBlockk
Later.....
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
BigB is correct. The additional timing from running manifold vacuum will also help the engine run cooler at idle and in stop-n-go traffic. But bottom line is that you just need to try both sources out and see what your engine likes: Use the vacuum source that produces the best quality idle (which is not neccessarily fastest idle). Keep in mind that the advanced timing condition from using manifold vacuum will increase hydrocarbon emissions, if emissions are a concern.
Melting Slicks
Joined: Apr 2002
Posts: 2,337
Likes: 14
From: Norfolk VA
Lars, If possible, could you write a tech paper specifically geared for the HEI distributors. I do know that these same principles can be used for HEI but your pictures use the points stlye distributor? What type of ignition box would work best with an HEI unit or is it not necessary. Btw, do you set up new in the box carbs? I have a new in the box Demon 750cfm carb I would like you to set up to sit atop my 383 which I will begin building when my crankshaft arrives. I was thumbing through old posts and saw a thread with a NOVA member earlier this year. Will you be able to come out to NOVA this year for a TFB? (I will bring the Vette instead of the Jaguar)
Last edited by Oldguard 7; Apr 3, 2007 at 03:09 PM.
Safety Car
Joined: Jun 2004
Posts: 4,652
Likes: 80
From: Lakeland Florida
What is the plastic/nylon button on the weight base cam? Is it to give the weights some clearance and help keep them from riding on the base plate itself? Would these need to be replaced also.
And, do these distributors have a stop bushing on the mainshaft that will limit the total timing advance.
kdf
And, do these distributors have a stop bushing on the mainshaft that will limit the total timing advance.
kdf
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
V8FastCars@msn.com
The HEI distributors do have an advance slot that limits the length of the advance. However, the shape of the weights is what actually limits the length of the curve: The weights are shaped so that they run out of mechanical leverage at a certain point, thus limiting the length of the curve. For this reason, you cannot set the total timig on an HEI with the springs removed - this will allow the weights to advance further than they can ever advance with the springs in place.
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 936
Likes: 0
From: Tulsa OK
