'70CutlassHoliday

Hello all, it's been awhile since I've posted here. So here is my problem, I get a horrible popping through the carb at around 2500 RPM, and complete loss of power (seems like its throwing spark too soon). Tried adjusting timing with no results. I have an MSD 6A ignition box, and MSD Pro Billet distributor, and MSD blaster coil. The Car has become my daily driver, and I need to get it running properly again. I don't want to go blindly replacing parts. So I would greatly appreciate it if someone could point me in the right direction, and yes I have tried to research the issue on MSD's site and found people with very similar issues, but no posts on how to resolve it.

silverriff

Do you have the pluggs gapped properly for all that spark your getting. I used to have an old Monte Carlo that would do what your describing after I replaced the sparkplugs for the first time. Turned out I didn't realize the previous owner had put in an HEI that required the plugs to be gapped almost twice the stock gap. I increased the gap, never had the problem ever again.

'70CutlassHoliday

Could it be that my mechanical advance is fully advancing too soon?

* posted before I read your post


I don't remember what I set the Gap to. I will check.

silverriff

What is the timing you are getting at 2,000 RPM? do you have an adjustable timing light? If not I just picked one up at Harbor Frieght last weekend for about $30 bucks, works great. It could be the timing but it would have to be waaay off to get it to pop like that. It wouldn't be a question of how soon the advance is coming in, bu how much total advance you are getting.

'70CutlassHoliday

I just went out and pulled some plugs, I set them to .035.
I don't have a timing light.
She ran okay for about 400 miles.

silverriff

Yeah my old M.C. did the same thing, ran ok most of the city driving I did, but it wasen't until I took it onto the highway, weeks after I replaced the pluggs, that it started popping to the point I had to pull over cause I thought the car was going to explode. I guess it was the long sustained crusing at over 2,500 rpm. In any case, what engine is it? And is that the stock gap you have it set to? I know that my 1972 455's stock gap is .040, but the research I have done one upgrading my points distributor says that if I was to put in an HEI, I should gap it quite a bit higher. How do the plugs look? Are they grimy or smell like gas?

'70CutlassHoliday

Sounds exactly like what happened to me. When it first started they weren't fouled, when I just pulled a few they seemed to be. The engine is a 350, I went with .035 based on the manual I had for Chevy 350's.

'70CutlassHoliday

So I replaced the cap and rotor, new set of plugs, different gap. Same problem but less harsh. She doesn't do it until I drive it down the road, then the misfire starts, and will occur when in park afterward.

'70CutlassHoliday

So I replaced the cap and rotor, new set of plugs, different gap. Same problem but less harsh. She doesn't do it until I drive it down the road, then the misfire starts, and will occur when in park afterward.

D Appeldorn

trie to disconect the vaciuum advance.
and drive it again, close propperly the vaciuum lines.

older cars did'nt have the advance unit on the distributor.

D Appeldorn

When i runing a hei than i need to adjust my plug gap?
That's something new for me, do you know how much?
i have a 350 4bll (used to be a 2)
Runs at higher rpm nicely but can't adjust stationary.
That's a litle ruff and need the choke till it's heat up.

it's stock 350 with i put on a 600 edelbrock 4bll with manual choke and olds 4bll intake.
Thought about it to run bigger rods and primary's.

'70CutlassHoliday

I'm running a Mechanical advance