[Adrock126]

Good morning. I just recently bought my first classic car. It’s a 1969 Catalina 2 barrel 400. So I’ve been reading everything I can get my hands on about timing and tuning. I am confused about total timing. A lot of the forum posts and YouTube videos I’ve watched recommend I set total timing at 32 to 36 degrees with the vacuum unhooked. With my stock configuration that’s not possible unless I set initial very high. I have an absolute max of 13 degrees centrifugal with everything lubed and both springs taken off. If I set initial anywhere near 9 degrees that gives me 22. I get 12 degrees max with my vacuum hooked up. So initial, vacuum, and centrifugal bring me to 34 currently. This setup actually appears to be exactly the way the factory set it. It’s factory points distributor that doesn’t appear to be adjustable at all.
So, with all that said, is my factory centrifugal adjustable at all? Or do I have to go aftermarket? Am I even thinking right to try to get to 34 degrees without vacuum? I appreciate any help for a complete newbie.

[67drake]

I have a ‘69 400 out of a big car in my ‘63 LeMans. That high compression combined with the 2.69 gears in the transaxle make it a detonation machine on 91 octane. My distributor currently puts in 26 degrees mechanical, putting me at 35 total.
Be careful what you shoot for as far as total as your engine might not like it depending on what octane gas, AF ratio, and gearing you have.
A distributor guy can alter your timing curve and max mechanical advance. I plan to send mine in after I work out a couple other issues.

[Adrock126]

Thank you for the reply. Yes there are obviously a lot of factors. The previous owner has the vacuum set up on manifold and it has 2.56 rear gear ratio. Needless to say when it idles 21 degrees advanced you better have a rich idle mixture and high octane. Currently I run 93 octane pump gas with octane booster. I’m not trying to make it a race car. Just wake it up a touch. Even if I could scare 28 degrees of total advance before vacuum I’d like to try. We’ll see.

[Adrock126]

I just got an old school dwell meter so I’m going to set my dwell and maybe try to sneak 12 degrees initial giving me 25 total before vacuum. I’ll set the vacuum to ported and see how that setup runs.

[Adrock126]

I got everything set up at 12 degrees at idle. It runs great. It’s 50 degrees during the day here in Michigan right now so we’ll see when warm weather comes around, but so far so good.

[67drake]

I hope it all works out.

[steve25]

In all likelihood your 2 bbl 400 is only 8.5 compression due to the 90 cc chambers in those heads.

Ping should not be a problem with a total mechanical timing of 34 degrees running on 93 octane.

Here’s what you can try shooting for.

This is the timing from a late 60s high compression 4 bbl 400 motor.

If you scribe or make a mark 2 1/8” around from Zero on the balancer that will be 36 degrees.

Has this motor ever had its timing chain replaced?

What is the 2 letter engine code on the front passenger side of the block?

[PunchT37]

Originally Posted by steve25

In all likelihood your 2 bbl 400 is only 8.5 compression due to the 90 cc chambers in those heads.

Ping should not be a problem with a total mechanical timing of 34 degrees running on 93 octane.

Here’s what you can try shooting for.

This is the timing from a late 60s high compression 4 bbl 400 motor.

If you scribe or make a mark 2 1/8” around from Zero on the balancer that will be 36 degrees.

Has this motor ever had its timing chain replaced?

What is the 2 letter engine code on the front passenger side of the block?

Maybe not. Could be the YD 400. Then, he`ll have to be careful on today`s gas.


I do see you asked about the code.

[67drake]

Originally Posted by PunchT37

Maybe not. Could be the YD 400. Then, he`ll have to be careful on today`s gas.


I do see you asked about the code.

Yeah, and honestly I just assumed he had the YD like I have.

[PunchT37]

Originally Posted by 67drake

Yeah, and honestly I just assumed he had the YD like I have.

Yep. The 10 to 1 400 is more common than the 8.6 to 1 400.




AKA 265hp vs 290 hp.

The 265 hp was an option on the GTO. Not the 290 hp though.

[PunchT37]

I used to have a `70 Executive with the YD 400. It pinged a lot, even with the stock points dist.

[steve25]

Ok, it / they pinged, when at part throttle or full throttle?

At part throttle that was due to some level of vacuum advance being in which would not be the case at full throttle.

The 290 Hp motors stated 10.5 camp was as we all known 10 to one at best.

[Adrock126]

Originally Posted by steve25

In all likelihood your 2 bbl 400 is only 8.5 compression due to the 90 cc chambers in those heads.

Ping should not be a problem with a total mechanical timing of 34 degrees running on 93 octane.

Here’s what you can try shooting for.

This is the timing from a late 60s high compression 4 bbl 400 motor.

If you scribe or make a mark 2 1/8” around from Zero on the balancer that will be 36 degrees.

Has this motor ever had its timing chain replaced?

What is the 2 letter engine code on the front passenger side of the block?

It has code YD which appears to be 290 hp version. The heads are 46.

[Adrock126]

Originally Posted by steve25

Ok, it / they pinged, when at part throttle or full throttle?

At part throttle that was due to some level of vacuum advance being in which would not be the case at full throttle.

The 290 Hp motors stated 10.5 camp was as we all known 10 to one at best.

Pings at moderate part throttle which I understand has vacuum involved. My thing is I read all these guys saying they have 34 degrees mechanical but I’ve read the specs on the lists of 60s distributors and it appears to be they had between 10 and 14 degrees mechanical advance just like mine. That leaves me to assume they have aftermarket distributors. But it doesn’t appear to matter because my car pings at 24 degrees mechanical with my 2.56 rear gears. I do have a 195 degree thermostat. I’ve been thinking about going with a 180 or even 160 but there are so many opinions in every direction. Also, to answer an earlier question I don’t imagine it’s had timing chains replaced. It’s in really good shape for what it is. Seems to have had one round of mediocre body work done on it. Interestingly it was found in an abandoned GM building in Lansing. There was a picture of it sitting directly in the middle of a huge building just waiting for its next life.

[67drake]

Originally Posted by Adrock126

It has code YD which appears to be 290 hp version. The heads are 46.

Same engine/heads as I have.

[Adrock126]

Today was the coldest weather it’s been driven in. It was 28 degrees this morning. The water pump seeped coolant from the weep hole and the diaphragm on the fuel pump leaked until it warmed up. Nice little morning for me and my car. I say all that to say when I replace the water pump it looks like I’ll be a third of the way to replacing timing chain. It seems people ask a lot about the chain I guess that makes me think maybe I should replace it. What do you guys think?

[Cliff R]

High compression engines with stock cams in them will not like a lot of initial timing and likely to "buck" the starter fully heat soaked on a hot re-start.

Heat is your friend with thermal efficiency so do NOT put a lower temp thermostat in it.

Replacing the timing set is a good idea as the factory used Morse type sets back then with a plastic coated top gear. They are known to start flaking off the plastic and plug up the oil pick-up and eventually fail. Replace it with a factory type Cloyes or Melling timing set with a metal top gear. Personally, despite what folks tend to recommend I would NOT put a double roller timing set on it for any reason. Non are nearly as strong as the stock chain nor to they have constant tooth contact. Only the "top shelf" varieties with the IWIS chain and billet steel sprockets are worth two squirts of duck poop right to start with making the stock 3/4" wide link-belt chain a far better bargain and it will last the life of your engine.

Anyhow, I'd remove the distributor and take it apart, clean things up, polish the shaft, lube the mechanical advance mechasism up well and put it back together. The factory used a thin rubber sleeve on the pin and they are usually missing or cracked and brittle. I use a stainless steel sleeve here to replace them. Do NOT put aftermarket parts in the distributor, stock weights and springs are fine for what you are doing. I'd also avoid the temptation to do a points "conversion" but I would obtain a set or two of OEM points off Ebay instead of over the counter. That's what I use here in the shop when I build distributors and wouldn't touch a Pertronix with a 200' pole, have had so many issues with those POS in recent years (I suspect they went to offshore production at some point) I avoid them like the plague.

I'd also stay off of Youtube or at least realize that most of those videos are highly flawed and not done by folks who really understand the requirements of you late 1960's stock 290hp engine with #46 heads on it and factory camshaft. It's making PLENTY of cylinder pressure and doesn't need all the timing in right off idle or much of it. Following a lot of "good" advise on the NET can quickly result in broken ring lands, rod bearings pounded down to the copper if you start throwing a butt-load of timing at that engine early in the RPM range.

Those engines with the factory cams in them make PLENTY of vacuum at idle speed with relatively low initial timing settings so I've never seen the need to add a bunch of timing to one via manifold vacuum at idle speed, which is another topic FULL of miss-information on the Forums and other Internet sources.

I'd also tune for results vs acheiving any specific numbers. In other words start out at or close to the stock settings (once the distributor is rebuilt) and sneak up on the perfect tune using "baby steps" once the engine is back in service. Tightening up the timing set is likely to advance the cam some, so everything changes once you start to tune again. I've NEVER once on any of those early engines found that they like, want, need or respond well to a lot of timing anyplace, especially up against a stock converter, heavy car and numerically "low" axle ratios.......FWIW........

[IMG]https://forums.maxperformanceinc.com/forums/attachment.php?
attachmentid=622664&stc=1&d=1698837219[/IMG]

[Adrock126]

Originally Posted by Cliff R

High compression engines with stock cams in them will not like a lot of initial timing and likely to "buck" the starter fully heat soaked on a hot re-start.

Heat is your friend with thermal efficiency so do NOT put a lower temp thermostat in it.

Replacing the timing set is a good idea as the factory used Morse type sets back then with a plastic coated top gear. They are known to start flaking off the plastic and plug up the oil pick-up and eventually fail. Replace it with a factory type Cloyes or Melling timing set with a metal top gear. Personally, despite what folks tend to recommend I would NOT put a double roller timing set on it for any reason. Non are nearly as strong as the stock chain nor to they have constant tooth contact. Only the "top shelf" varieties with the IWIS chain and billet steel sprockets are worth two squirts of duck poop right to start with making the stock 3/4" wide link-belt chain a far better bargain and it will last the life of your engine.

Anyhow, I'd remove the distributor and take it apart, clean things up, polish the shaft, lube the mechanical advance mechasism up well and put it back together. The factory used a thin rubber sleeve on the pin and they are usually missing or cracked and brittle. I use a stainless steel sleeve here to replace them. Do NOT put aftermarket parts in the distributor, stock weights and springs are fine for what you are doing. I'd also avoid the temptation to do a points "conversion" but I would obtain a set or two of OEM points off Ebay instead of over the counter. That's what I use here in the shop when I build distributors and wouldn't touch a Pertronix with a 200' pole, have had so many issues with those POS in recent years (I suspect they went to offshore production at some point) I avoid them like the plague.

I'd also stay off of Youtube or at least realize that most of those videos are highly flawed and not done by folks who really understand the requirements of you late 1960's stock 290hp engine with #46 heads on it and factory camshaft. It's making PLENTY of cylinder pressure and doesn't need all the timing in right off idle or much of it. Following a lot of "good" advise on the NET can quickly result in broken ring lands, rod bearings pounded down to the copper if you start throwing a butt-load of timing at that engine early in the RPM range.

Those engines with the factory cams in them make PLENTY of vacuum at idle speed with relatively low initial timing settings so I've never seen the need to add a bunch of timing to one via manifold vacuum at idle speed, which is another topic FULL of miss-information on the Forums and other Internet sources.

I'd also tune for results vs acheiving any specific numbers. In other words start out at or close to the stock settings (once the distributor is rebuilt) and sneak up on the perfect tune using "baby steps" once the engine is back in service. Tightening up the timing set is likely to advance the cam some, so everything changes once you start to tune again. I've NEVER once on any of those early engines found that they like, want, need or respond well to a lot of timing anyplace, especially up against a stock converter, heavy car and numerically "low" axle ratios.......FWIW........

[IMG]https://forums.maxperformanceinc.com/forums/attachment.php?
attachmentid=622664&stc=1&d=1698837219[/IMG]

Thank you for that reply. I will take your advice and rebuild the distributor and replace the timing set when I replace the water pump..