I have a "71" 351c 2bbl with 0.30 over flat top forged pistons, longer duration cam (can't remember the exact number), APR bolts all around in the lower end, new dist, Petronix II ignition w/flame thrower II coil, and a few other things, all stuffed in to a "70 F100. It seems to run fairly well off idle ( from 1500-4000 rpm). But when I put the truck in gear it tries to die unless I feather the throttle. After driving it for a few mins it will idle when I come to a stop (with a little help) but if I shift gears (say from forward to reverse or vis versa) it will try to die. I have adjusted the timing, replaced all the plugs, wires, and dist, adjusted the petronix ignition again and I went through the carb. All this seems to have started shortly after changing the ignition out. I had a petronix I ignition in it before but the module went out and I switched to points while waiting for the new one. It ran fine with the Petronix I ignition and the points but now this problem has shown up. I cannot seem to find a vacum leak anywhere which is what I thought was the problem due to the way it acts. I tried a trick learned on this site (with engine running , cup hand over carb to see if it will idle up (vacum leak) or die immediatly with out an increase in rpm's)Any ideas as to what I might try? Could the petronix ignition be the cuase of my problem?
Thanks

 

Carb adjustments! Keep working.

Make sure your vacuum and mech advance is working properly, not sticking with a timing light.

 

Could the power valve in the bottom of the bowl be cuasing this?

 

A defective power valve will usually show as a lot of black smoke out the exhaust.

 

Hmm, it doesn't smoke at all. I have been fighting this problem since Sat and have not made any progress. I am going to try going back to some blue streak points to eliminate that part of the puzzle. Yesterday I clamped off each vac line one at a time and could not get any improvement out of it at all. And I also tried adjusting the Petronix module ( the specs say to set it at .030") from 0.032 down to 0.028 with no effect either. Any thing else you guys can think of let me know and if the switch back to points works I'll let you know.
Thanks again

Edit: according to the compression calculator that I found in the forums I am running around 10.5-10.9 to 1 comp, which would explain the need for high octain fuel.

 

Update: I changed the Petronix II ingnition out and went back to blue streak points and now it runs fine with out changing anything else on the engine. Has anyone else had this sort of problem with Petronix ignition systems?

 

Kenny,

I have a 74 ford and installed a 351c in it as well with a pertronix II with similar issues. I was thinking that maybe I had installed the timing gear wrong but now that I saw your posting I will change out the pertronix II and give it a try. I had ment to do this since 2 weeks ago but the rain has kept me from doing it. Thanks for your postings. Hopefully they will help me out. If it turns out to be the pertronix I wonder what I can do to get refunded since it is brand new but I've had it for a long time though?

 

I hope you guys know that the points and rubbing block wear and will have to be adjusted regularly for the proper gap and replaced periodically. The timing will have to be adjusted regularly also.

 

On a magnetic trigger ignition it is important to observe polarity on the pickup wires...........

 

Yea, I checked the polarity 3 times just to make sure. As for the rubbing block wearing down, the Petronix ignitor I and II have a magnetic ring that slips over the dist cam and a module that takes the place of the points with an air gap of around 0.030" so there is nothing that touches to waer down. I called Petronix and tried everything they suggested and a few other trick I've picked up over the years and nothing helped. I don't know why the petronix did that, I called the place I bought it from ( a site that does not support FTE so I wiil not mention them here) and they are sending me a new one. I will try that to see what happens and report back. ladiabla74, I see you had the same issue that I had. I am now wondering about the viability of the new and improved Petronix Ignitor II, I had a Ignitor I in my truck for about 2 to 3 years and never had a problem out of it until the module gave up the ghost, thats why I was so stoked when I seen the new and improved ignitor. I should have the replacement by this weekend.

I'll keep everyone posted

 

Kenny,

I replaced the pertronix II yesterday and guess what? No timing issues or anything like that. It was all in the pertronix II. Installed an MSD system that was in my 78 and it is working like a charm. IT FEELS GREAT TO CRUISE IN THAT OL FORD..... DAAMMMM..... How I missed those old trucks. Now I just have to get the suspension straight and take it to get inspected. AND ENJOY IT SOME MORE.......

By the way, my brother landed a job at autozone and he told me he heard of two other incidents with the pertronix II systems just like ours.

Kenny, once again, thanks for your post. I almost tore my engine apart had it not been for your post.

Now I just have to get a dizzy for the clevo and return the MSD to its original engine.

 

Your welcome, I don't understand it either, the Petronix I that I had before ran great. I should get the replacement in soon and I'll post the results of that one. I am a little disturbed at what your brother said so I am not sure how it will work. I had to replace my dizzy a few years ago and got it at Autozone for around 35$ if I remember correctly. Good luck with your clev, they are great little engines after you get them to breath better. I put a longer duration cam in mine from crain cams which made a big difference.
I'll keep everyone posted om the petronix.

 

Your welcome, I don't understand it either, the Petronix I that I had before ran great. I should get the replacement in soon and I'll post the results of that one. I am a little disturbed at what your brother said so I am not sure how it will work. I had to replace my dizzy a few years ago and got it at Autozone for around 35$ if I remember correctly. Good luck with your clev, they are great little engines after you get them to breath better. I put a longer duration cam in mine from crain cams which made a big difference.
I'll keep everyone posted on the petronix.

 

Your welcome, I don't understand it either, the Petronix I that I had before ran great. I should get the replacement in soon and I'll post the results of that one. I am a little disturbed at what your brother said so I am not sure how it will work. I had to replace my dizzy a few years ago and got it at Autozone for around 35$ if I remember correctly. Good luck with your clev, they are great little engines after you get them to breath better. I put a longer duration cam in mine from crain cams which made a big difference.
I'll keep everyone posted on the petronix.

 

Well, I see that the post I made on 04-04-07 popped up 3 times, I don't understand why, could one of the moderators delete the last 2 posts so it doesn't look so strange?
Plus I have and update to the petronix issue. I got the new one in and after some debate with myself as to wether to install it or not, I tried it out. Same *#$! problem, the truck will not idle in gear. All I did was put the petronix II on without changing a single thing, I even went as far as to check the air gap 3 times. I even tried to adjust it 0.01-0.02" both ways (plus and minus) with no real affect. I put the points back in and bam, runs great so I will be calling the place I got it from and request an exchange for some new holagen headlights and relays to install them on my truck. I may not have the electronic ignition but my truck will run fine and I will be able to see better at night.lol