Engine runs at 35deg BTDC!!
 

Hey all,

Still having trouble with the new 302. I've had a zillion people double check TDC on it, and everytime we're right on, and it WILL idle at about 8deg btdc, but it has a miss, and sounds really weird. Driving it is out of the question. Yet if we advance it, the more we go the better it sounds, and runs. Right now its at about 35deg advance and it runs/drives pretty good!! (Even though I'm only taking it to about 2krpm) Does anyone know what this could be caused by? Could the timing chain be off a tooth? But would it still run pretty good like that?

It almost sounds like its on the wrong firing order, but I've tried both Ford firing orders, and only the 302 one works.

Any help would be great, I'm pretty broke thanks to this motor, and now I don't even have a car to drive...

Thanks

Chris

What kind of car? Carbed or EFI? Type of Distributor? What other ignition components do you have? Timing chain cant be off a tooth but the cam can be. There are index points on the cam sprocket itself. Was supposed to be lined up with the crank key before you put the chain with the sprockets on the motor. Sounds really weird at 8deg BTDC? Like its chugging or knocking or backfiring?


Brad

Hi there!

Its a 1972 302 block with a cam and some headwork. Its got Performer RPM intake and a Holley 600. For the time being it has just a stock distributor with points (I know I know). At 8 BTDC it almost sounds like its not even the same motor. Almost like its on a strange firing order, but its not. It does seem to have a miss for some reason, and its much more evident at that timing.

It stutters really bad when you give it gas from an idle, but once it gets over 1k its as smooth as glass while its accelerating. However if you hold the engine at say 2k RPM, it will start to pop from the exhaust, like a minor to moderate backfire.

Water temperature, and oil pressure are great, however the motor just doesn't run good until it gets the snot advanced out of it. Like I said, right now its at about 35deg BTDC at idle (LOL!!) and that helps the stutter a good amount, and it sounds alot healthier at idle, but that really can't be right. On top of that it acts like it wants to go more.

I've checked the firing order countless times, switched it to both Ford orders, and nothing helps. Any ideas would be a BIG help, this thing is supose to be my daily driver, and I'm starting my new job Monday!!

Chris

Are you sure the timing's right? Just incase, I found these firing orders:

Looking at the motor, the left side (passenger) is 1,2,3,4 front to back. The driver's side is 5,6,7,8 also front to back. The 302 firing order is 1-5-4-2-6-3-7-8 going counterclockwise on the cap. The no 1 spot on the cap is marked. This is the order for all the small blocks except 351W's and the HO302 that uses a Windsor cam. If you have an HO302 or Windsor, the firing order is 1-3-7-2-6-5-4-8.

That sounds pretty weird, when I put my smallblock rogether I accidently put the lugs on the opposite direction on the distributor and it was backfiring/popping/etc.

magnetic pickup?
 

This is a stab, how do you feel about your distro?
Worn points, a bad pick-up, could cause a wealth of probs.
I would swap it, just to eliminate it as a source. Maybe the coil too, unless you feel good about it.

do you have your distruibutor a tooth off?

You've got the vacuam advance pulled right?


-Josh, aka the tireburner

Thanks guys,

As for the distributor, its brand new, pretty much every single thing in the engine compartment is brand new, down to the bolts.

The main question I guess I have is, if this isn't being caused by something stupid that I'm overlooking (I do that alot lol), could something be off in the timing chain department? Would it still run smooth at higher RPM's if it was the timing chain?

Thanks!

Chris

If the dist was off a tooth you could probably still get it running fine, you would just have the dist turned alot more. I would say its either something with the cam maybe being a bit off or the distributor. Just spend the couple dollars and eliminate it as a problem. Just go to a wrecking yard and get a duraspark Distributor. I had a friend who did points in his and it was a pain and he went to duraspark because its 100x easier. Otherwise id make sure your points are gapped properly. And the dwell and everything is good.

Thanks for all the help guys, I fixed it. Ended up being a big vacuum leak, thats why it only ran/drove at like 40deg lol.

Chris

Often times we overlook the simple things and go right for the big stuff.