In a couple of weeks I will be putting my 69 442 on a dyno.
What limits should I use when doing this:
Timing advance
Max RPM
Engine is a basically stock(stock heads, intake and carb) 400 CID with HEI distributor. Rear gear is 3:23 posi
Thanks
Jerry

 

What should I allow the RPM to go to on my 69 BB 400 stock engine on a dyno?
Also what max HEI timing advance on the same
This will all be on a chassis dyno
Thanks
Jerry

 

Are you dyno-tuning or just making some runs?

 

This will be for a Dyno Tune.
Eng is basically stock with HEI ignition, 3:23 rear gear.
I'm just looking for input from some of you guys with way more experience with these Big Block Olds engines.
I don't want to over rev the 48 Year old engine. (59,000 documented miles)
Thanks
Jerry

 

I'd keep it under 5k and I would assume they will adjust the timing and jetting for peak performance. What you have it set at right now will be a good start.

 

Thanks Eric, I appreciate your advice.
I'm convinced in my own mind that I have forgotten more than I ever knew.
This getting old stuff is beginning to suck, but I guess it beats the alternative.
Jerry

 

When the HP numbers stop climbing I'd say that's a high enough RPM.

 

I owned two bone stock 1969 442s with the auto trans & 325 hp 400. One with 3.07 gears (Canadian built with 12 bolt) & one with 3.23s that I later switched to aftermarket 3.42s.


There was no power above 5200 rpm in either one. I revved them higher as an experiment but they just stopped pulling. Afterward I usually just short shifted them at about 4700 since the cars were slow anyways & higher revs were pointless.

 

From what I understand there was power to 5400 with a fresh engine, but I would not go there with an original 59k mile engine.

 

Consider a timing chain and gears, @ 59K miles the chain isn't of concern; but, the nylon on a forty plus year old original cam sprocket is probably brittle. It would improve reliability and make the valve timing more accurate.

Good luck and please post the dyno results.

 

I wouldn't even do this chassis dyno pull with those old parts. You are just asking for problems. If not when you do the pulls soon after.JMO

 

Agreed. There's not much, if anything, to gain by dyno tuning a stock engine, especially that old. Set to factory specs and run it. There's lots of guides an guesses about timing. I'd say set it for ~34 degrees all-in mechanical advance, then modify to get good idle and cruise. None of that requires a dyno. It seems like max power on an olds tends to fall between 33 degrees and 36 degrees, but for a stock engine, the differences are very minor.

Now, a dyno pull just for giggles - go for it! But keep it brief. As noted, the cam sprocket is certainly going to be in bad shape, so it can get exciting inside the engine over 5k rpm.

 

I ran my 69 cutlass on a dyno last fall. First time on a rack and it was awesome.
My limits were 32 degrees all in and I let off at 5800 rpm. It was still making power
but I wanted to know the numbers in the range I plan to run it on the street.

 

After reading all the above post, I'll ask the Dyno operator to limit max rpm pulls to 4900-5000 RPM or where power starts to fall off.
As to timing advance, I think maybe I should shoot for 32-35* mechanical and 48* with vac advance.
As mentioned in different post that I was reading in this forum concerning Tach's reliability, I have recently had my Tach out for work at Redline for repair and then I adjusted readings of the Tach to my Innova digital timing light and Tach is now within 25-40 RPM at low, mid and 5000 RPM range. I also expect that the Dyno operator will be using a calibrated Tach for his Dyno.
Do these sound reasonable?
Thanks to all for your inputs
Jerry

 

I merged your 2 threads.

 

Thanks Eric, Next time I'll try to be specific where I post

 

The dyno would have a built in tach coupled to the output shaft. Something like a magnetic wheel and transducer setup. He's not going to rely on a pickup off the distributor or a store bought tach to do his job. Let the man do his work. After all you're paying him for that.

 

Yes Trip, I'll allow the Dyno operator to do his thing, and I never had any thoughts otherwise, however I think that it is prudent on my part to tell him what max limits I want to maintain.
As stated above and with input to from all above, including you, I was looking for suggested limit inputs from you folks as to what RPM and timing limits I should set. So far 5000 RPM seems to be acceptable and I'm still a little unsure what Max timing we should use. Is 48* max good, or should I go to 50* or less than 48*? Carb metering jets will be checked as to what works best. At this moment I have 47 primary's and have a pair of 49s that were removed when carb was rebuilt at the suggestion of Cliff Ruggles.
Dyno operator has several pairs other than what I have.
I appreciate every ones input, especially you engine experts.
Thanks
Jerry

 

Again, the tuner should determine the most optimum timing and jetting that your engine likes best. What you have in there now is a good starting point.

 

Brain fart guys, I posted some incorrect info as to what metering rods are installed. Correct info is 44 metering rods with 69 jets. Both recommended by Cliff Ruggles. Complete overhaul kit supplied by Cliff including new float and accelerator pump
Sorry for the incorrect info.
Eric, the dyno operator will be allowed his best judgement(within reason)
Jerry

 

As mentioned let the dyno operator change timing as warranted.
But for the record, I've never seen the best cruise vacuum at 50* or even 48*. Not sure why people think that's the optimum setting but I hear it all the time.
Remember the vacuum advance shouldn't be adding any timing at WOT so all you're WOT timing should only be mechanical.
And I'll be interested to see what you end up with for hangers, jets and metering rods vs what Cliff Ruggles recommended.

 

What have you seen as the best cruise vacuum advance settings?

 

Normally around 45 is the best. How do I know? Simple, doing EFI teaches you a lot. It's great to be able to change timing at any load and rpm and watch the results.
You can add more than 45 or so at cruise but it typically doesn't add any vacuum signal so why go there. Just like at idle that's what you're shooting for, the best vacuum at every engine speed. That's the benefit of EFI with full timing control. You can't duplicate that with a conventional distributor.