Vacuum

Doug,

Thanks for the input. That was a very informative website.

What type of upgrade did you do to notice the boost you saw? I currently have a points housing with a Crane XRI electronic module and a MSD Blaster II coil. I am desiring a stock appearance for show reasons. This was reccommended by John Osborne, which did my carb as well as recurved the distributor and put the module in. I am thinking the plugs may be a slight problem, and I need to get the correct combination. I also have a new set of Accel 8mm spiral core wires. I metered the wires the other day for resistance values and found a wide range from 760 to 1600 ohms for the wires, definately length dependant on the values. I am not sure as the importance of them being more closely matching though.

Thanks for the ideas, Mike

:beer

 

I did a complete rewiring of my car this summer because the old wiring was so hacked up. Went with an EZwire set. As part of the process I put in a newer style GM alternator. Got the alternator from a friend of mine that was a stock Delco (it is important to get a stock Delco because the internal voltage regulator is so much better.) I also rebuilt my stock distributor with a Crane optical trigger and Crane Hi-6 box with Crane coil. This was a switch from a GM HEI. The HEI was a good reliable unit that I never had a problem with. I also had the GM HEI set up with the Crane external coil.

I picked up 500 rpm after making these changes and the engine was just pulling harder. I do not think the new distributor was the key to the performance gains. I think it was the new harness and alternator. Instead of 11.5 to 12 volts I am now 12.5 to 13.75 volts. It does not seem like much but if you subscribe to the theory that the coil is the heart of the ignition system it makes sense. The coil needs the correct feed to work properly. Any drop in voltage to the coil will be mutliplied there. No matter what you have down the line you do not make up for lack of power from the coil.

There is some opinion that the MSD coil is not as good as it used to be or that epoxy coils are not as good as oil filled (I think the Blaster is an oil filled.) I really don't know if that is true. I use an epoxy coil and it is working good. I think the ignition system is working well to keep my Buick running better than it should with the carb it has on it. The carb is off my old motor and needs modifications for the new motor. Worked great on my old motor with just a light brown plug reading. Now they are bone white.

Question? Did Osborne drill any holes in the primary butterflies on your carb?

 

A couple of thoughts:

Is the coil getting a full 12 volts?

Do you have a good engine ground?

The best way to solve this is to get a wide band A/F sensor.

My bet is the car is really lean. That will effect idle and vacuum.

 

I will check coil voltage tomorrow, but I believe it is a good 12V or so. I believe I have a good engine ground, but I will check that as well.

I do know that I have a power problem of some amount. My front interior lights vary quite a bit in intensity all the time. I believe it is the voltage regulator, but not for sure. I do not want to remove it, but how easy is it to install an internal regulated altinator? Is it possible to install one and keep the external regulator on the firewall with the harness all in tact? I was thinking that it is easy to do, but could use some advice.

With regards to the carb primaries, John did not drill holes in the butterflies. I am not for sure if I am in the idle circuit, as I have not removed the carb since getting it back and installing. I know that I have the idle screws turned out about 4 turns. I did talk to John about the ignition problem, as I did not know where I should have set the gap and was in thought that was some of my problem with the miss, which was correct. He also mentioned that I should be 2 1/2 to 3 turns out on the idle screws as well. I did a compression check, and I was well withing the 10% between all cylinders averaging 160 PSI.

The motor runs somewhat strong to me, but I have not been behind HP's for a while and am not for sure. And I still have the pegleg 2.56 gear rear for the moment. But it does act differently at times idling when it warms up. Yesterday it was idling kind of high compared to last week and even today.

Needless to say, I know I have a lot yet to do to get this motor running optimally. It has been challenging to get to where I am now, but worthwhile. I appreciate this board quite a bit. Thanks all for the advice and tips. I hope that I will be able to help other as well.

Thanks, Mike

 

Mike,
Keep at it. Takes a long time to get a combination right. I had my old combination working great and then blew the tranny. Took me two years to get it dialed in. Now I have a lot more motor and am finding the new week spots. I know the whole fuel system needs upgrade so that will have to be done to make any progress.

As far as feeling the HP you are way off on your gearing. The 413 cam will not come on untill 2500 to 3000 rpm. I run a 3:73 but I think you can get away with 3:42 and a mild converter.

Cannot tell you how much I like my new wiring harness. All the lights are strong, have good circuits to tie into, and I do not have to worry about the harness catching on fire! I am sure mine was in worse shape than yours, but over 30+ years there can be a lot of hacking on a system. I will try to find my diagram for doing a bypass on the voltage regulator with an internal regulated alternator. I removed mine but I am sure there is a way to at least make it look like you still have one.

Almost done driving up here. We have had a great fall so getting some miles in. Fall color drives are great and I now have a working heater.

Keep pluging away. What kind of plug color are you getting and are you getting any soot out of the exhaust?

 

How much was the wiring harness? Just curious... And difficulty to install? I believe mine is in very good condition. I was very fortunate with this car, it was in really untouched condition. Everything was origonal except the radio. Even had the origonal PCV valve in her. And the two plates that covered the points inside the distributor. Pretty wild, as I never saw them before on any of the cars I have had.

As far as gearing goes, I have been trying to find a 3.42 setup with posi for my rear. But I am even closer to using the other rear that I have sitting in my garage. It has 3.90 gears and posi. It was in a parts car that I bought. I recently discovered exactly what it is, being a 8.5 chevy with c-clips type rear. I was thrown off with the cover not having the clam shells cut out and thought it was an 8.2, but it did not have the U-bolts and nuts. At least I know what it is now. They are GM gears also. I know it hooks up solid, as it was behind a big block in my parts car and it would get sideways at 20 MPH rolling romps in the car. I was just not wanting that tall of a gear. But I am thinking that it would be a lot of fun, and that the 2 tracks medium close to me are 1/8th mile. I am a believer that a true track to race is 1/4 mile, that gears can help any motor, if you understand what I am saying. What is your thought on the 3.90's? I have 255/60R15's all the way around... And a 2400 RPM stall to go between.

I appreciate the pep talking. It helps quite a bit. I know it will take time, but can be fustrating at times. At least I have some good people to turn to here.

Thanks, Mike

 

The harness from EZwire was about $170. The hard part for me was the dash. There are 2 different dash sets and getting the diagram for the Rally guages was a problem. It does take a lot of time to do. If your GM harness is in good shape consider yourself lucky. The stock harness is very good qualitly. Mine was in very bad shape. I had no heater, burned wires, and hacks everywhere. I pulled the whole harness out of the car and laid it on the floor. Then set up new harness next to it. Did all of the splices that I could out of the car then reinstalled. Took alt least 40 hours but it works great. I am a real fan of new (10si and 12 si) GM alternators. They really put out the juice.

The 3:73 gears that I have with the TH400 trans was not a good combination for highway work. I think 3000 rpm was needed for 65 to 70 mph (speedo was so far off this is a guess.) I now have a 200r4 and can do 80 at 2500 rpm. Not sure how it will hold up for the long run but like it so far. I would consider a 70 series tire on the back. Will act like a little taller gear and give you good hook up and a good ride.

 

Sailbrd,

You mentioned in another post inquiring about the 413 cam that it does not like a stock cam.

I have a 1970, 750 CFM cam that John Osborne re-worked. He said it would be enough for the motor. It sounds from those posts, that it would like more carb than I have. I am curious on your thoughts, and anyone else that may have an input.

Mike

 

Mike,
Buicks like big carbs. I know that Phil Sedlin is running a 113 cam (that is what I was told was in my old motor) and he uses a Bigs/Holly 950 HP. Phil is running in the 11's with a convertable. With the heads I have it just seems to need more than a fairly stock 800 and you are running a 750. The other question is why did Buick go to 800's in 71 if the motor does not need it? A stock 71 does not have as much compression or cam as what we are running. So for me the plan is to do a complete rebuid of the fuel systeim. I think that I will probably go with an 850 Edelbrock Qjet and see if I can afford to go to Earick racing and do a dyno tune. I still think you are looking a something in the ignition and not the carb at this time. What do your plugs look like?

 

I replaced the plugs with NGK UR5's this afternoon. When it fired up, I could tell a difference right away. It idled much smoother with no roughness. I took her for a ride and it felt pretty good. I only had the AC R44TS's in for a total of 40 miles or so. So I do not think that a reading would do much with the exception of I did start the motor earlier in the day. And some of the plugs were actually slightly wet like. Not like I dipped them in gas, but a wet look to them and a gas odor. That sort of tells me that they were not firing well at all. I definately feel that the problem lies in the ignition system. But I am wondering if it is led by voltage to the coil as well, that when the motor is running above idle, the charging system is putting out more voltage and assisting the needs of the coil. I checked coil voltage earlier and there was 12.6 volts at the coil with the motor not running. Will it do any good to check when running? I am not sure if I will see a voltage when the coil is charging and discharging. I am at a loss now with regaurds of carbs now after spending some good money on this rebuild by John. I wished he would have told me to get an 800 CFM to work over, although he said this would be OK for me still. I am also at a bit of a loss, as I really want to keep a stock appearance also.

Two things I noticed this evening... first, it seems that the motor is loading up some, as I will cruise in first around 1500 RPM, and then throttle it some and it feels sluggish, and I will do it again and it feels good and responsive. Secondly, I thought this happened before and did happen tonight, but I slowly took off and then floored it. Shortly after chirping into second, I let off the gas some and it started to die out on power, kind of like it was running out of gas. I need to investigate more to see if it still does it if I keep on it or not. I have a stage1 fuel pump and a new fuel filter.

Any ideas? Thanks, Mike

 

Mike,
Check the voltage at the coil with the motor running. The measurement you are getting is battery voltage and that is good. With the motor running increase the rpms to between 2000 and 3000 and see if you get a jump to 13.6 to 14.2 volts. This show that the alternater is acuated. Then let the motor go back to idle and put max load on the electrical (turn on everything) see if the system will maintain 12+ volts (mine will stay around 12.8 to 13.3) If it keeps dropping into the 11 volt range you will have problems loading up at idle and the motor acting rich.

I went through this with my sisters Mustang and the %^$#%^$# Ford alternator would not keep the voltage up so I had to switch back to a points system. A Delco si alternator with a 3 wire hookup will easily hold good voltage.

 

Doug,

I did some more checking yesterday, but will do exactly what you are talking about here in a little bit. When the motor was idling, I had 13.? volts on the battery, but only 11.87 at the coil. This is funny, as when the motor was not running, I had the same voltage at the coil but much less at the battery as there was no charging going on. I did use a new 12V wire from the fuse panel (Ignition switched) to the ballast resister that came with the coil. I did that becouse a couple of weeks ago I was pulling out of the garage and the car shut off and would not start. I immediately checked for voltage at the coil and it was gone. I wiggled the harness some and it came back. So, I know I have a problem there. With that in mind, I figured it would be best to use a seperate feed and use the resister for the coil.

What confuses me is that the voltage to the coil is dropped quite a bit across the resister when the altinator is charging. I only know the resistor as a resistor, not a voltage dropping circuit. I will take a reading of the resistor later also.

Does this all sound right to you?

Should I actually have a higher voltage at the coil when the motor is running?

Thanks for the help, ideas and inputs ...

Mike

 

Mike,
I think that would be correct for your system. I forgot that you had to have a resistor. The resistor is supposed to be .8 ohm. I have forgotten the formula for how much that cuts down the voltage but it seems about right.

Also that was a good idea to run a new wire to the resistor. On many cars the pink ignition wire was the resistor. If the wire had a steel core and is kind of stiff it was a resistor wire. Check your voltage at both sides of the resistor.

I would not be too concerned about carb size. The only place that really limits you is on top end horsepower. Could you use more carb? More than likely but a well tuned smaller carb will outperform a badly tuned bigger carb. You should be able to get good performance out of the carb you have.

I still think it is ignition. You should not pull out a wet spark plug. Is there an old timer mechanic around with a Sun Engine Analyzer? That would show you what is going on.