[steve25]

The problem with a motor of a given CID that is running a Cam with over 78 degrees over overlap and close to not enough compression on the street is that like Cliff posted tuning it to run well below 2200 rpm or so takes experience.

Many street motors that are cam'ed up to being on the edge of not having enough compression will produce more vacuum at just off idle then at idle .

Couple this with the fact that the lower your compression is and the leaner you try to go the more timing you will need.

Even if you have enough compression to work well with your Cam you can not escape the basic fact that at idle with clean burning idle mixture any motor will need more lead timing.

Motors like this need more initial timing and then less mechanical timing that like Cliff points out then needs to come in slower.

The dyno / builder guys who just lob off the vacuum advance and stuff the lightest springs into the Dizzy are doing themselves a time saving deal, but short changing the owner of the motor.

Situations like this are where computer programmable timing set ups are more helpful then having fuel injection.

If you have a motor such as this you need a vacuum gauge and your timing light to work things out.

[Kenth]

Service data for a 1970 1112011 RAIV distributor at 2000 rpm is 8.5°-13° mechanical advance only.
Add to that 15° initial and 20° vacuum advance and you'll have 43.5°-48° cruising at 2000 rpm's.

Service data for a 1967 1111183 428 distributor at 2000 rpm is 21°-25° mechanical advance only.
Add to that 6° initial and 20° vacuum advance and you´ll have 47°-51° cruising at 2000 rpm´s.

Seems like Pontiac's engineers knew what they were doing.

[steve25]

Wasn't there different timing spec between the manual and auto trans of the RA4 engine, and if so which one is this in your post?

Also I must say that the fact that all of these RA4 cars had 3:90 rear gears or better had to have a influence on the total timing that engineering came up with.

[Kenth]

1970 GTO 1112011 RAIV distributor was used for all transmissions.
Same goes for Firebird-T/A 1112013 RAIV distributor.

Timing curves and spec #4719 for both (and 1969 1111941, 1111970 distributors) are 0-4°@1340 rpm, 10°-14°@2100 rpm and max 26°-30°@6200 rpm´s.
Add to that 15° initial and 20° vacuum advance starting at 8-10 in/hg and full @ 15-17 in/hg.

1967 428 distributor 1111183 spec #4615 starts with 0°-4°@1000 rpm, 21°-25°@2000 rpm and max 26°-30°@4400 rpm´s. add to that 6° initial and 20° vacuum advance same 1115365 unit as RAIV.

[TRADERMIKE 2012]

Originally Posted by JSchmitz

You absolutely will feel a difference when you get the timing right. As tom S said, set your initial to 12 and check your total timing. Make sure to disconnect the vacuum advance (as already stated). Then you will need a dial back timing light or a marked balancer to check your total advance. If you have a factory balancer, you can mark 34 degrees, for example, and use that as a total timing reference mark. I had mine marked at 36. Or get a timing tape for your diameter balancer. Easy enough to figure, or measure, the circumference and divide by 360.

Since, I have not rebuilt my dist. with the various parts that I own, in order to change my current Ignition Timing from 6 degrees BTDC to any number higher, more on the Initial and less on the All-in. Example: I was at 10 degrees BTDC after, I pulled the Cam Timing back 4 degrees by going back from the fourth notch to zero on the Crank adjustable gear, that was causing noise, due to over advancement to occur. We went back to 6 degrees BTDC and it runs cooler and well. So, going to 12 degrees BTDC is impossible for us, unless we treat the dist. to a rebuild, correct?

We still have to test on the Highway speeds to make sure that the kickdown is working properly. Other than that, the Trans. is working well.

The reason for us checking the Temp. at various coolers and lines is purely our curiosity in learning how my Engine is cooled, for this novias.

I have approx. , without counting 500 pages of handwritten Notes from both studying automotive 101 and shopping for parts.
I read Manuals that I purchased and found online, plus I read Articles that help too. I also tried new Pontiac mods that I obtained over the PY forum. I will say it again, my motor is cleaner than yours on the inside for sure and that is a good thing. I watch videos online and I converse live on forums. I am learning and I also experiment, "why is it that I am still in this hobby"? I like to believe that I am making progress. With all the different answers that I get from people over the internet, one must extrapolate what is best for me, for no two Engines are the same.

P.S. I have marked the Harmonic Balancer with the tape and we use a Timing light, RPM meter and Vacuum gauge as we time now as well as plugging off the Vacuum hose.

[tom s]

Forget the cam timing.Set your init timing at 12 degrees with the VA disconnected.Then time it and see where your at total at what RPMs that it stops advancing.Tom

[TRADERMIKE 2012]

Originally Posted by Kenth

Have you ever wondered how Pontiac was able to build 100's of millions of cars that functioned decently without all the crazy modifications on your car?

However, it is your car and you do what you want, but it might be a good idea to get a Pontiac Service Manual and learn how to service the engine/car in a sensible way.

JMHO

I started off 10 years ago with this project with only a parts changer degree under my belt. Today by reading and studying the Manuals both purchased and downloaded, I have accumulated a library of information and have plenty of notes to my credit, stop insulting me with that type of message, it makes you look small. However, any type of constructive criticism is welcome. Also, it wouldn't hurt to give positive reinforcement from time to time. JMO

[TRADERMIKE 2012]

Originally Posted by P@blo

I have digital copies of Pontiac Service Manuals if Mike would like to save time and face. He'd have to promise not to attempt to rewrite them though.

My cars also ran hot when in a state of bad tune and remember a chasing the water wetter scam. The stuff should be called "fix your junk it's running too hot".

I have the Manuals on disc, also and I use them, don't belittle me, build me up please. I also have manuals in text, articles on the computer too...What makes you people think that I don't do my research? Anyway, my car is running now and I am the one that discovered the Harmonic Balancer and over advanced Cam Timing being the problem. Again, thanks for the help, just don't ruin the experience by jumping down my throat as a group, like school children.

[TRADERMIKE 2012]

Originally Posted by P@blo

I have digital copies of Pontiac Service Manuals if Mike would like to save time and face. He'd have to promise not to attempt to rewrite them though.

My cars also ran hot when in a state of bad tune and remember a chasing the water wetter scam. The stuff should be called "fix your junk it's running too hot".

This is why we pulled the over advancement out of the Cam, Water Wetter is something I used prior to my current problems, so I thought to use it again. It is not the fix all, but used in conjunction with the Pontiac and 421 mod , I don't see how it can hurt.

[TRADERMIKE 2012]

Originally Posted by Formulajones

Absolutely. To explain further without going into writing a book, Tuning, especially the timing curve, is felt more in the drivability aspect and not so much at the track. At the track, really total timing is all that matters there, so if you're looking for an optimal total timing number, then yes that's one way to find it.

The rest of the timing curve really comes into play with drivability, how well the car behaves in traffic, on the highway, hot starts, gas mileage, engine temps, part throttle drivability, including light throttle tip in and low speed idle conditions will all be affected with how you set up initial timing, the curve, the vacuum advance and how and where it comes in, and how much. Playing with these areas and finding what the engine really likes will give you excellent results in all those categories. Makes the difference between a car that runs okay and gets from A to B to a car that runs absolutely fantastic. Without experimenting with this you'll never really know the difference.

For sure the factory settings are a bit lazy and meant to allow the car to perform well enough to satisfy, while at the same time complying with even a small amount of emissions compliance, but there is absolutely a lot left on the table in the drivability department.
Your engine, since it's not technically stock and has a RAIV camshaft, would most certainly respond well to a custom timing curve, as well as more initial. 6 degrees is really low and not optimal at all for a combination like that. That might work on grandmas 350 2 barrel, (even for that it's low) but not ideal for a camshaft with around 80 degrees of overlap.

Mike wants to know:

When you speak of a new Timing curve, I must install the dist. parts that I have not installed yet into this dist., like the New adjustable Vacuum canister, Weights and springs from a kit and the Black, off round stop device with corrugated edges?

[TRADERMIKE 2012]

Originally Posted by Cliff R

+2

All of these engines have specific timing and fuel requirements and it is worth the effort to spend time in those areas if you want to get the most out of the combination.

Even with that said the parts sold to novice tuners are very poor quality and don't work as advertised. Those "hoaky" HEI kits and "adjustable" vacuum advance units are a perfect example. Complete waste of time/funds and WHY would you use a stepped cam on the BACK side of the VA to control movement when it needs to be on the other side of the arm to stop its total travel......DUH?

In any case, I'll add here that these super-quick timing curves don't cut it. I've removed countless aftermarket spring/weight kits from distributors and set them up with stock parts instead to correct tuning issues with these engines. Dumping ALL the timing on a well-prepared street engine never has worked well dating back nearly 50 years when I got in this hobby and still doesn't work well today. Removing/eliminating VA doesn't work either. Even so countless numbers of these engines are tuned in that manner and folks using those methods are quick to recommend them.

For what you are doing about all that is needed is a little "bump" in the base timing, tightening" up the curve just a tad and get it started right off idle and all-in by 3000rpm's or so. The overlap in that cam is going to favor adding some additional timing at light engine load, probably about 14-15 degrees would be a good place to start. If I were building your distributor here it would have 10 degrees in the mechanical advance (20 at the crank), and another 15 from the VA using a unit that's all-in about 11-12" vacuum. Then I could set the initial timing around 10-12 degrees and move forward from there.

When it comes to these topics, I love real World stories so here goes.

A couple of weeks back, I got a call from a guy who had his engine built and Dino'd by one of the big names in this industry. He claims it sucks WAY too much fuel for his liking and stinky. It says that on the dyno the folks doing the work had to go UP 3 jets sizes because it was "way too lean" during the run-in. I was only getting involved because I sold him the carb. kit and tuning parts, someone else installed them. So, he's basically bellyaching and at the same time telling me I missed the mark on the tuning parts. So, I asked about timing, specifically how much VA timing was being added.

He very quickly and firmly told me that those folks DO NOT use vacuum advance, they just put super light springs in the distributor instead. EURIKA, we have found the problem. You are MISSING about 15 degrees or so timing at light engine load so absolutely and for sure you are going to have to fatten it up some to compensate, problem discovered and solved. However, that wasn't good enough and the customer still bellyached about it and told me that those folks have been doing this for decades and NEVER use vacuum advance.

OK, so they do it that way and have to deal with less efficiency and MORE fuel needs to run through the engine to make it happy.......how is that my fault?

We never worked out a solution and the customer is just going to have to deal with heavier fuel consumption and running richer on the primary side of the carburetor.

As it relates here, vacuum advance is going to be your friend with the 428 engine and camshaft with over 80 degrees overlap. It's going to like, want and respond to a lot of timing at light engine load and be happy with around 44-48 degrees at cruise.......IMHO.

Total timing w/o VA with a higher compression engine on pump gas not so much. The big RAIV cam pushes peak VE up in the RPM range and flattens out the torque curve, which is all GOOD for what you are doing helping to minimize octane requirements at your compression ratio and quench distance. I still wouldn't throw a lot of timing at it and not early in the RPM range. You need to sneak up on thing s like that as it's better to fall a little short than to put rod bearings and pistons into the oil pan, even when they aren't all facing the RIGHT DIRECTION!..........FWIW......

You stated this: " The overlap in that cam is going to favor adding some additional timing at light engine load, probably about 14-15 degrees would be a good place to start. If I were building your distributor here it would have 10 degrees in the mechanical advance (20 at the crank), and another 15 from the VA using a unit that's all-in about 11-12" vacuum. Then I could set the initial timing around 10-12 degrees and move forward from there".

Mikes reply:
I am going by memory so don't Quote me please: I assume you mean after I install the new parts into my dist. or Mill my factory Cam and Weights to a tighter tolerance and using only the factory springs, since you don't favor aftermarket kits.

( MEC. + CENT.) + INITIAL = TOTAL TIMING

10 + 15 + 20 = 45

Note: then set the initial timing to around 10-12 degrees Initial and move forward from there.


You stated:
"As it relates here, vacuum advance is going to be your friend with the 428 engine and camshaft with over 80 degrees overlap. It's going to like, want and respond to a lot of timing at light engine load and be happy with around 44-48 degrees at cruise".......IMHO.

Mikes reply: I have also read this about the 428 ci Pontiac Engine, OfCourse, we don't ever see these numbers while tuning, because we are not at cruising loads to WOT.

I have just found a site on the Internet:

https://www.motortrend.com/

That shows many of the old magazine ads and their books that you can view (for free) along with many more informational resources to add to your collection.

This is what I found interesting: Does this relate to our Pontiacs?

The Chevy 427 ci Engines (ZL-1 and L-88) factory suggestion is that you maintain a finished, everything installed air gap of about 0.035" between the closest points of the Head and Piston top.

[TRADERMIKE 2012]

Originally Posted by tom s

Forget the cam timing. Set your initial timing at 12 degrees with the VA disconnected. Then time it and see where your total is at. What RPMs that it stops advancing. Tom

I would have to rebuild the dist. inside, with the parts I own, in order to try what your saying. I will try this when I rebuild this dist., this will come after the Trans. gets broken in. I would like to have this Engine tuned properly. Currently, we have taken all the Cam timing out and went back to a factory 1.5-degree Cam advance, built into the Stick. We have proven that the Cam is Milled to spec. by the Melling manufacture by using the degree wheel that I purchased recently. Once we pulled the excessive Cam timing out and added Water Wetter to the Pontiac and 421 mods, we have normal Temps. across the coolers and Block and Heads. Further highway speed testing to come.

P.S. For those of you that think I lack the skills you have, better think, it has been 10 years since my novice days started and how many of you have built your own Trans. . I gave myself an "A" for that job. Plus, my motor is still cleaner than most of yours inside by flushing it out with Trans. fluid and if I could I would add an addendum to the Manual depicting so. "This is not directed at Tom.

[tom s]

Don’t rebuild it yet!Do as as I suggested now and see what you actually have!!Tom

[TRADERMIKE 2012]

Originally Posted by Kenth

1970 GTO 1112011 RAIV distributor was used for all transmissions.
Same goes for Firebird-T/A 1112013 RAIV distributor.

Timing curves and spec #4719 for both (and 1969 1111941, 1111970 distributors) are 0-4°@1340 rpm, 10°-14°@2100 rpm and max 26°-30°@6200 rpm´s.
Add to that 15° initial and 20° vacuum advance starting at 8-10 in/hg and full @ 15-17 in/hg.

1967 428 distributor 1111183 spec #4615 starts with 0°-4°@1000 rpm, 21°-25°@2000 rpm and max 26°-30°@4400 rpm´s. add to that 6° initial and 20° vacuum advance same 1115365 unit as RAIV.

This is the number of this 428 ci dist., that came with this project car. 1111255 7B9, Feb. 09 1967. The pages that I am taking a picture of show the detail in which I research an item. For example. So, no one ever says that "I don't do my research again".

[TRADERMIKE 2012]

Originally Posted by steve25

Wasn't there different timing specs. between the manual and auto trans. of the RA4 engine and if so, which one is this in your post?

Also, I must say that the fact that all of these RA4 cars had 3:90 rear gears or better had to have an influence on the total timing that engineering came up with.

Mike notes:
Plus, if I remember correctly," were all Engines the 400 ci motor and not the 428 ci one"? Manual, I believe, standard shift only, with low to lower Rears were the norm. Ram Air induction came in the trunk, except maybe six? Solid lifters, etc... upgrades like round ports eventually. Then they go into an Aluminum and Iron Intakes and 4 bbl from Tri-powers to Dual Quads, too many tunes to be sure.

[TRADERMIKE 2012]

Here is the third temp. reading for the Trans. , measured as the fluid moves out of the Torque converter through the coolers and remote Trans. oil Filter and back into the Sump.

TRANSMISSION COOLERS AND REMOTE FILTER



(1) Out of the Case Temp. 180 degrees F., which is the same as my Thermostat. My Thermostat is a 180* with 3 bypass holes drilled to allow water to allways circulate in an emergency. I use the factory Shroud and Fan. The Thermostatic or temp. actuated Clutch is HD and is like the trucks use. The Radiator is copper, modern and flows well. The Water pump is tightened to even tighter tolerances because the Pontiac Mod shows us how to perform this simple improvement and I stand by it.

(2) In and out of the Radiator, the Trans. cooler is my number one, in line cooler, that has the same temp. both in and out of 180 degrees F. I want to say that the water temp. used to be at a lower temp. flowing out of the bottom of this Radiator and into the lower Block. I would like to speculate, that the different in temp., could be attributed to the Clutch, making the most difference. The Clutch works well with the modified Thermostat, that keeps the water in the Radiator as long as it should, in order to keep the operating system cooling properly at all times. I noticed the difference as soon as I installed the HD Clutch. The tighter clearance in the Water pump made the water flow stronger. The 421 and Pontiac mod. , makes the Block and Heads more even in Temps. all over, also. Water wetter is doing its job along with a good Radiator Cap. Mine has a thermostat built into it, making it easy to compare to the I/P water gauge, which reads 30 * higher than it should. Unfortunately, I can't state exactly what the various upgrades had/made on any of the various improvements. Including the addition of a sidekick Radiator, that I manufactured myself or a Fan that we purchased and installed out in front of the AC condenser. We can use this in traffic or not at all, depending on the Engines' needs at the time. I am hoping that I won't need the additional Sidekick, AC condenser Fan and Rec-90 in the future, if these new mods work as well as people have described them.

(3) The second air cooler 170* F. in and out was 145* F., drop 25* F.

(4) In to the remote Trans. oil Filter is 140* F. and out is 135* F. , drop 5* F.

(5) Nominal temp. loss through lines, as the fluid travels through them called convection.

(6) Back into the case is 130* F. , drop of 5* F.

(7) Transmission Pan Sump measures 165* F. , and is a large Pan from a truck and is air cooled under the Vehicle.

Note: The overall Temp. drop in this system, including the lines. is 50* F.






POWER STEERING

At the power steering cooler IN: 170* F. and OUT of the cooler is 130* F. We use a filter in this system as well. Total cooling is 40 degrees F.






Tonight's test and tune in the drive way, 11/9/23:

Ambient Temp is 68* F.
Temp. @ the Radiator gauge is 140* F.
I/P gauge is 200* F. minus 30 = 180* F.

We used the 110 AC exterior Squirrel Cage Fan in this test to mimic the vehicle in motion.

We did not have to use the Sidekick nor the condenser fan, cool enough tonight.

This is a great sign that we are moving in the right direction with this project. A radiator Cap working correctly could be a major problem in some vehicles.

We found that the upper hose to the Radiator seemed too hard/hot and it had been that way since we finished the Heads. So, we cleaned the rubber and under this Radiator Cap, with the thermostat on it. We think that the fluid was not getting back to the overflow bottle properly. Not good. Further test to come on that new issue, to see what impact it had on the overall system? Every little thing can affect the overall Engine Temps, you must be careful to inspect everything under the hood.

[TRADERMIKE 2012]

Originally Posted by tom s

Don’t rebuild it yet! Do as I suggested now and see what you actually have!!Tom

We are going to do what you say, Tomaro night! It seems that this Radiator cap issue was my last hurdle about the heat issue. However, this Vehicle deserves good timing, after all the time I spent fiddling with the Cam advance, trying to accomplish that very thing.

[TRADERMIKE 2012]

Originally Posted by steve25

The problem with a motor of a given CID that is running a Cam with over 78 degrees over overlap and close to not enough compression on the street is that like Cliff posted tuning it to run well below 2200 rpm or so takes experience.

Many street motors that are cam 'ed up to being on the edge of not having enough compression will produce more vacuum at just off idle than at idle.

Couple this with the fact that the lower your compression is and the leaner you try to go the more timing you will need.

Even if you have enough compression to work well with your Cam you cannot escape the basic fact that at idle with clean burning idle mixture any motor will need more lead timing.

Motors like this need more initial timing and then less mechanical timing that like Cliff points out then needs to come in slower.

The dyno / builder guys who just lob off the vacuum advance and stuff the lightest springs into the Dizzy are doing themselves a time saving deal, but short changing the owner of the motor.

Situations like this are where computer programmable timing set ups are more helpful than having fuel injection.

If you have a motor such as this you need a vacuum gauge and your timing light to work things out.

I have the Equipment to create a better timing curve, it is just a matter of time before I get to it.

I need to try a few tune-ups, before I rebuild this dist., according to some of the forum members.

[Cliff R]

" For those of you that think I lack the skills you have, better think, it has been 10 years since my novice days started and how many of you have built your own Trans. . I gave myself an "A" for that job. Plus, my motor is still cleaner than most of yours inside by flushing it out with Trans. fluid and if I could I would add an addendum to the Manual depicting so."

I stayed at a Holiday Inn Express once......does that count?

[Kenth]

Originally Posted by TRADERMIKE 2012

This is the number of this 428 ci dist., that came with this project car. 1111255 7B9, Feb. 09 1967. The pages that I am taking a picture of show the detail in which I research an item. For example. So, no one ever says that "I don't do my research again".

1111255 is a 1967 400 2BBL transistor ignition distributor.
Starts with 0°-4°@1000 rpm, 10°-14°@2000 rpm and max 18°-22°@4600 rpm´s.
Add to that 6° initial and 20° from vacuum advance starts at 10-12 in/hg and full vacuum advance at 17-19 in/hg.
Makes 36°-40°@2000 rpm cruising and 24°-28°@4600 rpm at WOT, which i think is somewhat low for a "healthy" 428 with a 041 RAIV camshaft.