[64speed]

This is my first engine that has deviated so far from stock that I couldn’t use the factory manual for timing guidance. I have the Summit ready to run distributor and I am about to drop it in. My builder said I need 32 degrees all in by 2800. How do I achieve that with these springs and the vacuum advance?

[tom s]

Forget the vac advance for now.You need to know how it is setup from the factory?It did not come with a sheet showing the curve built into it?If not find someone with a machine and have it spun to know.Adjust it from there.Tom

[HoovDaddy]

I always refer to this article written by Lars Grimsrud. You can do this in your driveway.
http://http://corvette-restoration.com/wp-content/uploads/technical_papers/Engine_Timing.pdf

[amcmike]

If the camshaft has a lot of overlap, it'd probably like a decent amount of initial. The R2R comes with the 21* limiter installed. So, I'd go ahead and install the black limiter (18*) along with 1 blue and light silver spring. because that's likely going to be where you end up at. If you set the initial to 14* with that combo, you should get to 32* at 2800rpm or if not, it'll be really close.

With the vacuum advance disconnected (and the carburetor port blocked), set the initial idle timing to 14*. Dial in your carburetor idle setting. Rev the engine up to 3500rpm and verify the total timing. You want to rev past the point you want it to come in, to verify it's not adding more than expected.

Adjust as necessary to achieve 32* total max by 2800. Change the springs if it comes in too fast or too slow (this can can be done while it's still installed). Adjust the initial if the total is off slightly.

Then let the engine get up to full temperature. Restart the engine. If you get a slow crank, then you probably have too much initial. Otherwise, you're ready to move on to adjusting the vacuum advance.

If you do get a slow crank, dial the initial down in 2 degree increments until it cranks at a normal speed. That's your new desired initial. Then you need to remove the distributor, install a different bushing and spring combo so that you get the 32* total by 2800rpm again. After that's all set, then hook up your advance and tune that for part throttle.

[64speed]

Ported or full vacuum?

[67Fbird]

ported usually.....depends on your vehicle set up.....fat car with NO converter or gear....PORTED for sure

[Cliff R]

Not enough information to really help out.

What are the engine specs, CID, compression ratio, heads used, and cam specs?.......

[amcmike]

Originally Posted by 64speed

Ported or full vacuum?

As mentioned, a lot more engine and torque converter details would be needed to understand if ported for manifold may work better.

Get it setup without the vacuum first. How it runs and what combination works best for initial and mechanical settings will also give an indication what vacuum source to start with. Tuning the vacuum advance is a final step after everything else is adjusted first.

[OCMDGTO]

64, didn't you have this all figured out on the dyno?

[64speed]

Originally Posted by OCMDGTO

64, didn't you have this all figured out on the dyno?

Yes, my builder said 32 at 2800. I didn’t set it up on the dyno. He did

[tom s]

So this is because you changed dizzys?Tom

[64speed]

It was ran with a regular HEI and carb provided by the engine builder, then I started it with the sniper which of course was set with a handheld. Now I am on my own

[Cliff R]

Without providing all the details on the engine build it's impossible for anyone reading this to help out with recommending how to set-up the timing curve or how much VA to add, etc.

I will say this that switching to another distributor woln't make any more power compared to what it was tested with. I've back to back tested stock HEI's against MSD billet units with a 6AL box and have never saw any increases anyplace. Not familiar at all with Summit Ready to Run as for the most part I avoid anything like that having rejected every single off-shore HEI clone or attempt at a "high performance" electronic distributor that's ever been sent here to evaluate and re-curve it. Some are OK, some are hopeless and the best sound they will ever make is when i "tink" them off the dumpster outside the shop.

The biggest problem with most starting with junk distributor gears (soft) is that by design the mechanical advance mechanism has to much leverage to keep some of the curve out at idle speed when you start using the lighter springs sent with them to improve the advance curve. This causes NOTHING but tuning issues and idle speed problems, and too much RPM drop when the auto trans is placed in gear. Many engines using them start fine, but the first time you rev them up they will not return to idle speed as some of the curve stays in. Then you back off the speed screw, idle RPM drops, re-set to the desired RPM, and the very next time you rev it up it happens all over again. So you go in and increase the spring tension to fix all that and you end up with a delay in the curve more than you are shooting for.

So basically nothing but a huge PITA to set most of those up. The MSD units are typically better, but the internals rust pretty heavily as they fail to effectively zinc plate the associated parts under the cap withing a few months they look like it just came off the bottom of the Coral Sea!.......

[wbnapier]

I really think this a neat idea:

https://progressionignition.com/

Curious what you all think. Sorry to hijack thread, but it seams pertinent. You only set the base cranking timing, then the rest follows the map you make/select.

In theory, you can have the perfect curve for your engine and driving objectives.

[grivera]

Originally Posted by wbnapier

I really think this a neat idea:

https://progressionignition.com/

Curious what you all think. Sorry to hijack thread, but it seams pertinent. You only set the base cranking timing, then the rest follows the map you make/select.

In theory, you can have the perfect curve for your engine and driving objectives.

That sure sounds slick but hard to imagine RFI wouldn't affect communication

[wbnapier]

From what I read, you only communicate to the dizzy when you want to change / upload a new timing map. The connection is done by bluetooth.

[64speed]

The Summit RTR is an MSD RTR with vacuum advance

[grivera]

Originally Posted by wbnapier

From what I read, you only communicate to the dizzy when you want to change / upload a new timing map. The connection is done by bluetooth.

I wonder if it maintains settings if car battery dies or is removed.

[64speed]

That looks pretty slick

["QUICK-SILVER"]

Originally Posted by OCMDGTO

64, didn't you have this all figured out on the dyno?

Originally Posted by 64speed

Yes, my builder said 32 at 2800. I didn’t set it up on the dyno. He did

David,
I completely missed your post/thread on the dyno session. All I remember was break-in on a run stand.

So what RPM's did this engine make peak torque and peak horse power? And what were them peak numbers?

"32 at 2800" sounds like generic numbers, to me, for an automatic car with a 3,000 ++ RPM stall converter. Not ideal at all for a stick shift daily driver.

I don't get it
Clay