[mudbone64]

Back to live action. I had to remove a valve cover to adjust a valve. I also removed all of my spark plugs to do a compression test and verify that my timing mark on my balancer was correct. At any rate, things are beginning to come back togethor and I'll be re-checking my total timing as I have installed new mechanical advance springs (as per Lars Grimsrud). After I set my timing at the suggested value of 36 degrees at about 2,900 r.p.m. I'll need to measure my manifold vacuum.

My questions are: should I install a vacuum "Tee" between my vacuum can and my manifold vacuum source and record the vacuum value or should I just connect my vacuum gauge to my manifold vacuum source and omit any connection to the vacuum can or does it make a difference? Should I measure the vacuum with the car idling in gear or just leave it in park? Any instructions concerning this process are appreciated. Also any instructions pertaining to the selection of the proper vacuum can would be appreciated. Should I just purchase an adjustable vacuum can?

Gene

 

[mudbone64]

Well after about 3 months of trying I know what was causing my 454 to ping and clatter, I had my heat riser valve installed upside-down. I know, I know, this is completely embarrassing so please be gentle. I have my excuses about how I did this but I won't take up your time.

The good news is I have returned the initial timing, vacuum can and the advance weight springs back to their stock configuration and the engine doesn't ping at all. It is very sluggish but it doesn't ping. Now the trick will be to see how much initial and mechanical timing I can put into this engine in order to get it to run better.

Atleast now I'm back to ground-zero as opposed to being below ground in terms of how the engine performs.

 

[69SSRat]

Reading this might help alot

http://corvetteforum.com/techtips/viewsubtopic.php?SubTopicID=109&TopicID=3

 

[mudbone64]

The timing article references the exact road I was going down with respect to my engine timing. However, nothing I did was working. Still ping, ping and more ping. It wasn't until recently I discovered I had my heat-riser valve installed upside-down which was effectively plugging my exhaust and shooting my cylinder pressure sky-high not to mention what it was doing to engine temperatures. After I discovered the valve was installed incorrectly I returned the ignition system to a stock configuration just to see if it would still ping. Now that I don't have any pining issues I can embark on getting the engine to perform in an acceptable manner.

 

[SWHEATON]

GENE,even though the heat riser was the nosie issue you had at the time it still doesnt take away from the fact your initial timing and stock mech ign curve is dead wrong for the mild aftermarket perf cam your running.

Thats exactly why the motor is runng sluggish like you stated when you set all timing setting etc back to stock because your running the initial timing too retartded and the mech adv curve is worng for an aftermarket perf cam like your running not to mention the vac adv isnt right either.

Go back to the earlier suggestions i made and setup everything back to thoses setting and the power/perf will return to you motor,its as simple as that.

18 initial/18 deg mech in dist all in by 2800-3k rpm = 36 total along with whatever vac adv i suggested hooked up to full vac on all the time for vac adv operation when at idle to assist idle with perf cam.

Scott

 

[69SSRat]

Here is also a link to help your vac advance questions.
http://corvetteforum.com/techtips/viewsubtopic.php?SubTopicID=115&TopicID=3

The timming article was just to help with any questions you might have had.

The heat riser in backwards was a good find but a hard one I'm sure.

The cam specs you posted are quiet mild compared to mine and no offence to Scott
but 18 initial is way out there if this is a street car I had close to that when mine was first built.

After reading the Lars articals and a few Emails back and forth from him
I changed out my HEI and went with a ready to run MSD and love it.
I have about 12 initial 36 total all in at 24to2600 rpm
I only run mabe 6 in of vac so I had to also change power valve to 3.5

This cam I run is
Duration @.050 IN/EX: 244/244;Lift IN/EX: .572"/.572";LSA / ICL: 110/108;RPM Range: 2800-6300

I hope my rambling on has helped and like I said no disrepect to Scott but following the articls I think will show you not all engines will
need 16 or 18 there all a little different in some way.

 

[mudbone64]

Scott,
After I wired the heat riser valve open the engine still pinged just a little. I changed the vacuum can back to the stock can and all of the pinging went away. Now that I have the engine where it will run without any audible issues I am going to begin the process of advancing my initial and mechanical timing until the engine starts to ping again. Then I'll just back the system up til the noises go away. I also realize I will have to get another vacuum can.

My stock vacuum can requires about 15 inches of vacuum to fully deploy and my engine is currently making 12 to 13 inches of vacuum. The vacuum can I installed fully deployed at only 8 inches of vacuum which I think was too low considering the engine still pinged somewhat at part throttle acceleration. This may have been discussed before but what are your feelings concerning adjustable vacuum cans?

As always your help is appreciated.
Gene

 

[mudbone64]

Here is also a link to help your vac advance questions.
http://corvetteforum.com/techtips/viewsubtopic.php?SubTopicID=115&TopicID=3

The timming article was just to help with any questions you might have had.

The heat riser in backwards was a good find but a hard one I'm sure.

The cam specs you posted are quiet mild compared to mine and no offence to Scott
but 18 initial is way out there if this is a street car I had close to that when mine was first built.

After reading the Lars articals and a few Emails back and forth from him
I changed out my HEI and went with a ready to run MSD and love it.
I have about 12 initial 36 total all in at 24to2600 rpm
I only run mabe 6 in of vac so I had to also change power valve to 3.5

This cam I run is
Duration @.050 IN/EX: 244/244;Lift IN/EX: .572"/.572";LSA / ICL: 110/108;RPM Range: 2800-6300

I hope my rambling on has helped and like I said no disrepect to Scott but following the articls I think will show you not all engines will
need 16 or 18 there all a little different in some way.

69SSRAT,
Your post came up while I was responding to Scotts. I do appreciate any and all of the input I can gather to help me get this thing sorted out. I think it's kinda going to be a trial and error process for me. The good news is I've learned a ton during this ordeal. I've actually learned way more than I ever wanted to. I suppose it's all good though, the more info a person is armed with the better.

Thanks again,
Gene

 

[69SSRat]

Gene
Glad it is helping I think the timming article
if you read taking the springs off the fly weights in the distributor and using an inductive timming light will help setting up the 36 deg
I not real good at writing some times but I used it on a 64 corvette with a factory dist. and it made a big difference. this guy Lars worked for GM when these cars were built.

Being the sorry writer I am if you have any problems I will be glad to call you and help.
But this will work.

 

[mudbone64]

Gene
Glad it is helping I think the timming article
if you read taking the springs off the fly weights in the distributor and using an inductive timming light will help setting up the 36 deg
I not real good at writing some times but I used it on a 64 corvette with a factory dist. and it made a big difference. this guy Lars worked for GM when these cars were built.

Being the sorry writer I am if you have any problems I will be glad to call you and help.
But this will work.

I've read Lars' timing article many times and I was wondering why does he suggest a person remove one of the advance springs? If you do remove the spring should you tie the advance weight down so that it doesn't move?

As always, any help is appreciated.
Gene

 

[mr 4 speed]

Gene,bottom line...what is your total timing w/o the vacuum advance?
I have never,ever had any n/a V8 engine with the total set between 36-38* ping..ever.
Again,this is w/o vacuum advance.
I have a stock 1973 454 in a 1980 Malibu with a similar cam and it runs 38* total with no vacuum advance.And of course,it doesn't ping.
And btw,a 1972 454 is about 8 to 1 compression at best (flat top pistons/119 cc chamber heads)
I stress,set it up w/o vacuum. After you confirm the total,drive it and confirm it doesn't ping,hook the vacuum advance up. Note how much more timing the vacuum adds.If it ping,you need to reduce the amount of vacuum advance. Usually,I set them up so the can only adds 10*
Lars article is pretty cool,but I don't understand the thing about removing the weights either.

 

[mudbone64]

mr 4 speed,
Right now my total is like a woeful 21 degrees and the car wouldn't jerk a well cooked and lubricated noodle out of a cat's anus. At one time I had the total timing set at 36 degrees but it pinged like crazy. However, the pinging was due to the fact I had my passenger side exhaust effectively plugged. During the time before I discovered the heat riser valve was my problem, I was trying anything and everything to get the engine to run properly and thats why I re-installed the heavier stock advance weight springs. Now that I'm back to ground zero, as opposed to being six feet under, I can start the tuning process all over again and the first order of business will be to return the total timing to the recomended value of 36 degrees.

I was hoping to really get on this thing this weekend and do a big smokey burn-out but the weather in the Blue Grass is going to suck. Wet roads mean no tune and drive. Hopefully some time next week I can report some good news and we can all enjoy a cold one. Well, we can enjoy a cold one regardless. Let's not let a little timing issue get in the way of a good time.

I'm going to pick up a new curve kit today. I used the good springs from my last curve kit on my buddy's '68 427. Now he's grinnin' like a mule eatin' saw briars but I have no springs.

One more thing. If you don't have a "dial-back" timing light I highly recommend picking one up. My life become so much more fulfilled when I purchased mine.

 

[mr 4 speed]

Gene, if your total is 21* what is your base timing?

 

[mudbone64]

Right now it's at 6 degrees. Again, I was trying anything before I disocvered what the real problem was. Since I discovered the problem I haven't persued any performance improvement steps (yet).

 

[mr 4 speed]

Gene,so if you have 6* base and 21* total that means you have have 15* of mechanical
I would set the base timing for 21* for now and do NOT hook up the vacuum advance.
You will now have 36* total.
if that doesn't make you grin when you hit the throttle I don't know what will

 

[SWHEATON]

Gene,with the perf cam your running 6 deg base timing is extreemely retarted by approx 12 deg becasue it needs a min of 18 deg base,no wonder you say its running sluggish.

BTW,try running 93 fuel when you try adv the timing to get your ign timing dialed in correctly.

Again,18 base/18 mech in dist (all in by 2800-3krpm)for 36 total is a good place to start.

After you adv the base to 18 deg then take the idle vac reading (autoin gear) and get a vac adv that fully activated at tidle for even better idle and low speed perf & fuel economy.

As Chris stated in may cases you do have to end up limiting the amt of total vacn adc for when at partial thtorrle cruise to stop ping if it happens.

But as you mentioned your ilde vacuum was lower then the full activation vac setting for the stock vac adv you have and that can lead to all sorts of unstable idle orlow speed operation which is why its importatnt to match the vac adv cut in & fully activated vac spec for the cams idle & low speed vacuum esp with auto trans if thats what yourr running.

But for now your motors timing curve with 6 deg base/21 deg total and incorrect vac adv for ilde/low speed vacuum is a completely wrong for a street perf motor with a mild perf cam.

When you adv the base to 18 the motor will really wake up alot but watch for the total going over 38 deg over 3k rpms with 18 initial/base timing.

If that happens you will have to re-curve the mech adv in the dist for approx 18 deg in by 2800-3k fto run with 18 base for a 36 total along with the proper vac adv.

If your motor still pings with 93 fuel when get the base & total setup correctly with vac adv unhooked then try retartdeing the timing 2 deg max to 16 deg base/34 total to see if that stops the ping.

If ping is gone great and proceed down to the info on the vac adv,but if ping is still there after retartding the timing to 16 deg bump it back up to 18 deg base/36 total and here is why i say to do that.

If its a wk end use only car run some kemco oct booster and be done with it,the ping will be gone and the motor will likely put out more power too. Yes you could retartd the crap out of the timing to stop the ping at that point but then the motor/perf really suffers and it also kills fuel mileage with overly retartded timing @ 6 deg base where your currently at when that cam needs approx 18 deg base. Running the kemco in a wk end only cruiser may only cost you approx $75-$100 more a yr for a motor thats dialed correctly with full power/perf felling crisp and tourqy which is a small price to pay (IMHO) for a properly tuned/running motor.

Then with the kemco also you can run the correct vac adv dialed in for approx 12-14 deg additional timing for approx 48-50 at cruise which is pretty avg for a street perf motor and that will increase your fuel economy and also get you better throttle resp of idle and when at low load/low speed part thorrle cruise. Remember,the vacuum adv goes away when the throttle is opned like above 3/4 thorttle due to int vac dropping to la ow lvl below activation point of most vac adv units so the vac adv doesn'thave anythng to do with WOT or very close to WOT timing & perf in that case.

Your patience when dialing in your timing correctly will really reward you with a nice crisp/powerfull feeling motor but retartding the heck out of the timing to stop the ping if its still there with the proper timing curve & vac adv will just leave you with a miserable running/feeling motor IMHO. In that case the additonal $100 a yr for the kemco is well worth it if your motors comp ratio & head/cam combo needs it.

Of course i am assuming you dont have any issues like vacuum leak/s or incorrect way lean fuel calibration going on that could also cause ping due to leaning fuel mix out when motor is at a low load/low speed part throttle cruise.

In some cases too hot of a spark plug can also add to a ping issue too.

Scott

 

[kettbo]

Gene,
I see you've been at it since SEPT.....
Look in my signature for the short list of toys and link to the pics.....

1. Run a Pertronix or Crane electronic ign conversion. I've run the Pertronix unit 5 years now, no issues.

2. Scott has some great starting/starter/battery tips....you'll need to be on top of this when you crank on some additional initial timing

3. The factory rating for 1972 454 appears to be 8.5:1 (though likely less actually) with OC heads so your pinging you found with the reversed heat riser should be the end of the story...

4. I have somewhere around 10.5:1 CR in my 68's 427. I run it 16 initial and 18 mechanical on the street, 34 deg total. With good fuel, booster, etc, I raise the initial to 18, 36 total.....this last 2 deg feels like 20 horses are added. (L2268 domed pop-up pistons, 781 OC heads fitted with 2.19/1.88" valves, 235/235* @ .05 .542/.542" lift, 111 LSA Erson cam, 4-spd M-20 3.36 gear). Several years ago before I got smart, I was running 10 degs initial plus all kinds of mech adv in the stock tach drive distributor. When I'd adv the timing to make the car run, she'd ping...small wonder with around 27* from the factory. It appears there was a factory nylon bushing on there that expired.... I installed a brass limiter bushing on the distrib's advance limiter rod and some careful peening of the limiting end of the slot had me in business. Much easier to have a quality shop set your distributor up for you vs numerous distributor removals and installs.... I suspect I can gain more by yet more initial adv with less adv in the distributor but my Vette does not like to start well (see item #2 above) with 'more on the crank'

5. Just MHO here but I'd start with one light and one med dist adv spring.
Ensure the weights are clean and I throw a bit of WD-40 to help them slide.
My adv is 'all-in' at 2850-2900 with this combo, your results may vary.

6. I assure you, when you adv the distributor to even 19* initial with your current mech adv in the distributor 19+ 15= 34 and do your first run with vacuum system unplugged/stopped....you'll be like this: :thumbsup::hurray::beers: and you'll leave two long black marks on the road if ya stay on it... Naturally when you adv the base timing, you'll have to reduce the idle speed as you go; some more adv, turn the idle down then more adv and less idle speed until complete. You'll have a pretty wicked and solid idle when done. I figure you could also adj the idle mixture screws for best idle vacuum.

 

[GolfisSerious]

just another idear....
if you don't want to really mess with anything, unhook your vacuum hose from dizzy and plug it.
rev motor up to 5500rpms and adjust timing to 36*

let the initial fall where it lay... take it for a drive leaving vacuum hose plugged.

I saw another poster say pretty much the same thing earlier... this is what we do with all our old cars that are still factory "equiped"

most likely this will solve your pinging problems...it will only take a few minutes and requires no real modifications to your car... unless you will go crazy knowing you have a vacuum hose laying in your engine compartment with a screw or bolt stuck in it.

most likely though your springs in your dizzy are worn, and your getting a ton of advance that you shouldn't under load and @ rpm.

hope this helps and good luck... btw... this isn't fixing any problem... its just allowing your car to work properly with what you have... I call it afro engineering and for you politically correct fellas out there I have seen many a white guy with an afro... so there

 

[mudbone64]

I can't thank you guys enough for all of the info. Though I am primarily a Corvette man with most of my posting done on the Corvette forum, if I need some info on how to make an engine perform this forum is my number one source. I'll start my tuning process when the roads are dry again and at some time in the future I should have access to my friends LM1 in order to get my air-fuel ratio maximized. Again, thanks for all of the tips.

kettbo,
My friends yellow '68 400h.p. Vette is the sin-twister to yours. And oh yea, my first car was a '67 Elky so I have an appreciation for those too.

One more thing. Yesterday on my way home I saw a red convertible Chevelle with SS logos at a dealer's lot. I haven't checked it out up close yet, but if any of you are interested let me know. Hopefully next week I'll have an update.

Thanks so much!
Gene

 

[kettbo]

A lotta Chevelles out there in KY. Do let us know what you find.

The yellow 68 is my 3rd Vette, I've had it 16 years now. I bought it non-running and very ugly....lots of problems getting it sorted out after I rebuilt it.....distributor with worn breaker cam, yikes, what an ass ache. Ign, carb, starters....I've been around the block on all this...a few times each! Thing is, a Vette is just another Chevy when ya get right down to it. Just a few more systems to screw with and less room to do it in! The Vette needs the frt susp overhauled in the spring and I've assured the local T-C guys she'll make at least one outing this year. I have maybe 5000 miles on the car since I've had it. Hangar Queen? Pampered Princess?

Send some more pics of your car to me. I'll PM my email. Get some pics of your intelligent friend's Yaller 68 too.