Max RPM
#1
442 dyno limits
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 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
#2
Max RPM
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
Also what max HEI timing advance on the same
This will all be on a chassis dyno
Thanks
Jerry
#4
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
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
#6
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
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
#8
my experience
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.
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.
Last edited by oldsmobiledave; January 5th, 2017 at 09:16 AM.
#10
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.
Good luck and please post the dyno results.
#12
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.
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.
#13
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.
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.
#14
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
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
#17
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.
#18
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
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
#20
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
Sorry for the incorrect info.
Eric, the dyno operator will be allowed his best judgement(within reason)
Jerry
#21
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.
Last edited by cutlassefi; January 5th, 2017 at 03:23 PM.
#23
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.
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.
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