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By Melly - 5 Years Ago
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Winter is still hang on here but finally got to take my y block out for test drive. During the winter went from a 2 to 4 barrel on a 57, 312. Used a 57 intake, a 57 distributor ( w/points ), and Holley 570 cfm carb. All seemed to go well, fired up great, timed it and figured all was good. Finally got to take it out for test drive today. Started perfect, started down road slow increase speed in 1st at about 3000 rpm stared to run funny tach jumped 6-7k but motor rpm was still running as should motor seemed to be running ruff. Shifted to 2nd and again at about 3000 rpm did same.
Do not know we’re to start looking. I believe points are set correct, and timing ( what should timing and point be ) . Am running the dist vacuum off carburetor ( maybe should run off manifold source ) ?? I do have another dist from a 61 I could try. But really have no clue.
Any help would be great.
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By Florida_Phil - 5 Years Ago
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Start with the easy stuff first. There are lots of Chinese points and condensers out there and they can cause the issue you are describing. Make sure to check the ignition wires, especially the one going from the coil to the distributor. Usually these problems are easy to fix, sometimes hard to find. If your car has been sitting for some time, check the gas.
If the car ran OK before the swap, I suspect the carb or you created the problem during the swap. The carb is the least likely issue. Is the carb new, rebuilt or used? Did you remove the distributor or change the timing? Check to see if the distributor advance is working. The car should run even without the vacuum advance line connected.
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By bergmanj - 5 Years Ago
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Melly,
Possibly "point bounce" at the higher RPM's; that can show as double RPM's on a tach. You might need to check the points spring tension. Most of us don't do that when installing new points; BUT, if not enough tension [see shop manual], they can "bounce" and present as you have described.
Hope this helps, JLB
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By Melly - 5 Years Ago
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Was thinking of doing the PerTronix ll ignitor. Any thought on this? Would you do the l or ll ? Hoping to get around today or tomorrow to start and check thing over. What is the point gap and timing used for this setup? Will check against what I have.
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By oldcarmark - 5 Years Ago
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New Point Gap .014-.016. Timing 10 BTDC is good starting Point. Ignitor 11 is my Preference with the matching Flamethrower Coil and take the Ballast Resistor off. Others will tell U other Suggestions.
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By DryLakesRacer - 5 Years Ago
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My Pertronix ll has been bullet proof for 6 years. I run their coil and kept the factory ballast resistor because it was optional. I did read back when I was wanting to try their system that coils were the problem so I chose to in leave the resistor. I called and they did say it was my choice and the resistor in the system the spark was just not going to be quite as hot..
The Chinese condensers/capacitors (2) were the problem with mine. Someone will chime in here and tell you which micro-farad capacitor you need if you want to stay with points.There will at least no point bounce with the Pertronix...Good Luck
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By Ted - 5 Years Ago
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Melly (5/18/2019)
Was thinking of doing the PerTronix ll ignitor. Any thought on this? Would you do the l or ll ? Hoping to get around today or tomorrow to start and check thing over. What is the point gap and timing used for this setup? Will check against what I have.
As JLB mentions, it sounds like you have point bounce. Back in the day, it was a common practice to cut the spring out from another set of points and wrap that inside the spring of the new set to increase the spring tension. Depending upon the tension created, the rubbing block wear might increase to the point of being unacceptable.
For thoughts about switching to the Pertronix electronic conversion, my personal preference would be the Pertronix II version simply due to the known issues with the version I. The version I does require a 1.5 ohm coil while the version II recommends a 0.6 ohm coil. To date, I’ve installed the version II units with no ballast resistor and run a straight twelve volts to the coil. Zero issues doing that. Ignition timing characteristics are the same for both points and breakerless and that’s dictated by whatever engine modifications have taken place.
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By Melly - 5 Years Ago
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Thanks for all the help. As always y block people are the BEST. Put new point and a condenser. retimed and seem to fixed problem. Now if weather would cooperate will take it for test drive and see how it work on road.
some have mentioned about putting a Pretronix ignitor ll in. Was looking at them on web but different site recommend different numbers.. I have a 57 312 V8 57 4bl intake and dist. which model would be used? I come up with #912810 does this sound right?
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By KULTULZ - 5 Years Ago
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...some have mentioned about putting a Pretronix ignitor ll in. Was looking at them on web but different site recommend different numbers.. I have a 57 312 V8 57 4bl intake and dist. which model would be used? I come up with #912810 does this sound right?
Re-check the cataloging.
Should take 91281 (IGN II) 1957-1974
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By oldcarmark - 5 Years Ago
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91281 is Correct. If You are also going to buy a Coil be sure its Flamethrower 2. I have had a 91281 for Years. No Problems.
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By Melly - 5 Years Ago
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Great thanks again!!! What spark plugs would be used with igniter ll ?
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By charliemccraney - 5 Years Ago
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Standard copper core plugs will be fine, probably exactly what you currently use. Refer to the instructions as some electronic ignitions specify a type of plug but I don't think that applies to a Petronix conversion.
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By oldcarmark - 5 Years Ago
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charliemccraney (5/19/2019)
Standard copper core plugs will be fine, probably exactly what you currently use. Refer to the instructions as some electronic ignitions specify a type of plug but I don't think that applies to a Petronix conversion.
I just stayed with the regular Plugs. For Me the Electronic Conversion does away with variances in Timing and Maintenance for Points. I do keep the old Point Setup in the Trunk just in case of problem with Pertronix.
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By Melly - 5 Years Ago
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Did the test drive today. I put new condenser, points, spark plugs, retimed, vacum runs off port on Holley carb. Starts up perfect and idles 475 rpm. In neutral can run engine up slowly and steady to 4000 rpm, if stab gas pedal shows no issuses. Took it for a drive if you run up speed in each gear seem to be fine. If you put pedal to floor starts to build rpm the tach will go cray ( flashed 6 - 7 k ) without engine going crazy. So as long as you don't floor it seem to run good? My next move it PerTronix ignition.
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By Melly - 5 Years Ago
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Up date. Got looking things over, put a vacuum gage on noticed low vacuum and needle bouncing. Took spray bottle to look for leaks. Found leak around base of carb. Tighten and drove again ran better. But wine it up steady does good. But in the process if put to floor kind of a bog and then seem to kind of float without power, tack go crazy.
I have a Holley street avenger, 570 cfm. It is used so don’t really no about jets. I read somewhere about possible have to place a smaller jet in secondary side. Any thoughts on what’s going on, I am way over my pay grade.
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By kevink1955 - 5 Years Ago
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Tach going crazy could be a grounding issue, is their a ground strap between the engine and firewall, if not under load as the engine torques over it could loose the ground. Also check the braided ground jumper inside the distrubtor, if missing or broken the points loose ground as the vac advance moves the point plate.
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By Florida_Phil - 5 Years Ago
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Holley carbs have an issue that is sometimes hard to detect. On the passenger side of the carb, the vacuum secondary linkage hangs a little lower than the carb base. If you use a wide base gasket, this linkage will hang up causing an inconsistent idle. If it's bad enough, it can cause other issues. If you take the carb off you will see what's going on. You may have to trim your gasket. All the carb linkage should be free moving and the idle speed should be consistent.
Another thing about tachs. I have a modern electric tach in my dash. When I installed a Pertronix module in my distributor, the tach went crazy. I Googled the problem and found that I needed to put a 10 Ohm resistor in line with the tach wire. I did this and it works fine. Check with Pertronix for more information.
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By Melly - 5 Years Ago
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Called Holley today they suggested increasing size on the accelerator pump nozzle???? They seem to after explaining the issue that needs more gas when the throttle is pushed to floor? I am really getting way out side of knowledge base. Any input?
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By KULTULZ - 5 Years Ago
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Here is a basic tutorial - https://www.youtube.com/watch?v=xscWLSpB5Go
What the TECH is describing is LEAN TIP-IN.
I would worry more about the IGN, than the CARB. If the TACH is jumping (depending on quality and hook-up), it sounds more like a GRD problem as mentioned. You could also be experiencing a bad DIST and/or ADVANCE.
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