Ok, I have been told that 32-34 degrees total timing is nominal, but the best total timing that I can get is 27 or 28 degrees.

Here's the thing, my base timing now is at 18 with no problems. Is there any advantage to upping my base timing to like 20? If it doesn't ping, is it better to go as high base timing as possible before it pings. And how could I get my total timing higher?
I have the weight and spring kit in the distributor. I've heard of grinding the weights to get more timing out of the distributor, but I don't know how.

 

timing depends on what the engine needs..this is where you need to take it to the track or dyno..it all depends..Some heads flow so good that it doesnt need a lot of timing..

Daz

 

It's also important to consider what RPM the timing comes in at.

 

I'm amazed to see that you can get 18 degree initial on an 11:1 motor, with stock heads, and not have any pinging.

To add more total timing to the distributor, you need to grind out the openings on the advance slots in the distributor. When you have the rotor off the distributor, you should see the posts the springs attach to. If you look at the posts furthest from the center of the distributor, you'll see that they go through an oval shaped hole. If you use your hand, you can twist the assembly and see the post hit the far edge of that oval slot. This is the area you need to grind out to get more total mechanical advance (I'm not including vacuum timing here).

If you find that grinding out the advance hurts the car's performace, most of the timing spring kits come with little bushings you can put over top of the posts. These will reduce the total amount of timing available, or just weld or braze the slots back to the original position.

 

lol Kaboom!!!..Its either he's got a huge huge cam and/or big carb with healthy jets..lol

Daz

 

In My opinion you don't want to have initial timing any graeter than 12 degrees and optimum total advance (without vacume) should be 34 to 38 depending on the cam/heads etc.

As has been already said you have to do this by altering the mechanical advance ability of the distributor. to increase it you generally need to modify the weights and the center cam that the weights ride up against.

As I said I believe that 12 degrees is about the highest base timing you would want to run. Anything higher will generally cause engine to ping and hard starting.

All of this assumes we are talking about a street set up with vaccum advance connected. If you want to go to the track and do some runs with the vaccum advance disconnected thats another story.

In this cas we don't care too much about initial timing what we are looking for is 34 to 38 degrees of total timing.

To accomplish this just plug vaccum advance and rev engine to about 3000 rpm and set timing to 34 to 36.

By the way having the distributor professionally recurved only costs 75$ at Jims Speed in London.

Ric

 

Thanks guys.

I need to clear something up.
I recently found out the actual compression ratio. No more guessing or hypothesis. It's 10.673:1. So I will be changing my sig.

Oh, and my base timing is currently as of yesterday sitting at 20 degrees. The downside is that it I only have about 27-28 degrees total timing, so I need to do some work there.

 

you just lost 30 horspower there..and timing still depends on the cam..The more duration (especially a stroker)the more timing you can put on(not necessarily what you need)..Cause theres less cylinder pressure which in turn has less chances to detonate..

Daz

 

How did you get that comp ratio? I've done mine on paper numerous times... but I would like to have an actual factual number. My paper calculations didn't consider the valve reliefs... and a few other things.

 

Well, i got my e-test done at the shop that sold the engine. He remembers what kit it was he sold me and brought out the paper work. The pistons with a 64cc head were 10.673:1. The block was not decked, the heads were not shaved, and we used a basic .040 head gasket.

Yes, Daz, I lose hp. On the DD it drops me down to 420hp/432ft-lbs.

But I would rather less compression. My saftey zone is now larger.
I would love to sticker a supercharger on this thing. I figure a thicker head gasket, and bigger combustion chamber heads, and I'll be good.

 

LOL that would make it 375 in real world horspower and 330 rear wheels..minus traction I would say 13.2 at best

Daz

 

Even so, that still puts me a half second quicker than you.

 

lol
You and paul got some decent winter plans (is the supercharger/head talk winter?). You guys should be in the 12s with some luck... And with any luck I will be in the 13s . Im hoping the slps and catback put me in the low 14s. If I can snag LTRs for 200-300usd used I think that would easily put me in the 13s with a fully ported base and port matched plenum. Crossing my fingers...
greg

 

ya think?

Daz

 

Well, get that Superrammed 383 all fixed over the winter, I'll get my problems fixed, and we'll find out next season, how about it?