Timing set up

[Chuck]

Make

Chevrolet

Model

Impala

Year

1968

Miles

75537

Engine

5.3L 327 cid

Hello everyone. It's been a few years since I last posted, but I have a question. I have a '68 Impala four door post car with the original 327. I'm getting ready to do a tune up and I was wondering if I can set the timing to get a bit more power. It's an all original car. No aftermarket upgrades in any way. Any help would be much appreciated. Thanks

 

[billr]

It's possible you can change spark timing from OEM stock and gain some benefit, but it is equally possible you will end up with negative results, and not even realize it. The only way to tweak things like that in for best over-all results is with a steady-state dyno. Also, a stock '68 is likely to run into knock problems unless you are willing to use high-octane/price fuel.

 

[Chuck]

I have to use the lead additive if I run regular gas. Thanks for the answer. I just wanted to now if there was anything I could do without having to use aftermarket parts. I don't really wanna change anything unless absolutely necessary.

 

[billr]

I feel like I gave you a rather vague/useless answer, but it was the best I could do. With a SBC there is a vast range of what can be done, limited only by your budget. However, if you are sticking with the stock heads/valves, cam, intake, exhaust, etc, it will be difficult to improve over-all driving performance from what the OEM designers built into it.

 

[Mobile Dan]

Pretty basic engine. If you have a timing light, you can verify that the vac advance and mechanical advance are working. You could try to bump up the timing a little extra to compensate for timing chain wear. Idle quality and a test drive may tell you if there is any improvement.

 

[Chuck]

Thanks again. If I did do a real changes it would be to an HEI ignition, but that would by way down the line since the old points distributor still works well.

 

[nickb2]

One of the throw backs from this era.

Increasing timing is ok for high revving engines, so in this case would be detrimental.

Best mod I did to my 1979 pontiac lemans was to throw a 350 in it in stead of the in line six it came with. Bonus of the in line six, it came with a power glide 2 speed. Very sought after in the drag race clientelle.

If you decrease timing, in frenche we say retardé

You will have low end but no high end snap and will pinck pr again as we say in french, sounds like a empty 24 case of beer in the hood on 1/4 mile


But I found this article on line that probably explains this better than me. Take a gander, its free.

Understanding Ignition Timing: Making Maximum Power Means Knowing the Science

In a spark ignition internal combustion engine, the purpose of advancing the timing of the engine spark is to get past ignition delay. Ignition delay occurs during the time that it takes to fully ignite the mixture with a spark plug.

www.enginebuildermag.com

 

[nickb2]

If you over advance, you get heat and stock wont hold up. If you decrease, well you get low end but no giddy up in high. And this is a 327, mucho cheap mods out there,


I f ed with a long time ago when running a few cars on 1/4. One of which was a 1984 gt t top mustang. I added honda parts to it.

But this is a whole other story. How to keep it stock and add power is the question, if your f ing with timing and not willing to throw a cam at it, I think you will get same response from old timers like billr and mobile dan and me for that fact.

 

[nickb2]

Billr here had a corvette with a 327 if my memory serves right, with a megasquirt system.

So HE is the resident expert on these 327 engine of this era.

Did I say HAD. Yeah he gave it away. Wish I had a step dad like that.

Anyway. This looks like a project, keep us abreast of any thing you do, these cars are starting to get real rare. SO keeping it stock is a good thing.

But you cant have fun with it in 2021 as per rules, but there are options. such as adding a megasquirt.

Bur when you get there, the OEM is just not gonna take the constant abuse of a 1/4 run to get to final.

If your goal is to keep it as stock as possible, go for a carb cam fixed timing kit. Work on my 250 swap in the lemans.

When you go back to sell it as stock, easy stuff to remove, internals left behind are the same

 

[nickb2]

Btw, if you do sell this car, can you plz ship it to me up here in northern canada, have not seen on of these in a while, I know a few guys who will pay premium for calif and such cars.

 

[nickb2]

As usual, I am bored, my gf works nights now. So in essence, if your not willing to put slash throaw some stuff at it, keep it stock timing, nothing to gain, and if you do, that case of beer you hear in engine bay will come back to haunt you.

 

[nickb2]

 

[billr]

The Corvette is a 427, but I have spent plenty of time with SBC engines, too. Yeah, the easiest and most practical performance upgrade is to put in a 350, even if you stick to the original heads, intake, etc.

 

[Chuck]

Like I said about the only "mod" I might do is put in an HEI ignition down the road. Probably when the old points system gives up the ghost. I like it as it is right now. Runs and drives well. Currently getting all the small things fixed or replaced as they wear out or working again. It's really a nothing special sedan. So if anyone sees it at a drag strip or circle track, it'll be in the parking lot. I just wanted to see if I could get a little more oomph without changing anything. I'm currently looking for new seat covers and door panels with the lower carpet. The seats are the textured ones with the little buttons in them. It's a blue on blue car so if anyone has those send them.my way please. Thanks for the info everyone.

 

[Chuck]

The Corvette is a 427, but I have spent plenty of time with SBC engines, too. Yeah, the easiest and most practical performance upgrade is to put in a 350, even if you stick to the original heads, intake, etc.

I currently have no want to replace the 327 with a 350. It stills gets around well, and it's still fun to say my stock '68 327 out powers your stock '86 Camaro 350.