help! I screwed up, and need suggestions.....

66fastback · 07-20-1999, 05:42 AM

and I don't mean about where to stick the camshaft. I tried to start up the new engine and all it did is puff-puff-backfire-puff-puff-backfire--etc.

I'm not new at this, and I'm lost as to what I might have missed or done wrong. The engine is a 5.0 (351W firing order) and I've tried rephasing the plug wires 180 degrees, advancing/retarding the timing, and even the 289 firing order on the slim chance they ground the cam to the wrong firing order--which I would have caught when I set the lifter preload.

So far all I can think of is

1. I might have crossed the wires on the duraspark unit. I think that could cause this problem....

2. Maybe I set the lifter preload too tight, and the valves aren't seating. This doesn't seem very likely, I've done this MANY, MANY times.

That's all I can come up with....if anyone has any ideas, I'm willing to listen. This is embarrassing for me, I've never had one that didn't fire off in the first 10 seconds before....Thanks for any ideas, good, bad, or just plain crazy.

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66 GT Fastback 5.0, 5-speed, 3.40 gears, Fuel Injection soon

Clark Rodgers · 07-20-1999, 09:28 AM

I don't have a miracle cure but you know if it is back-firing it has to be a timing issue.Go through it again and don't leave anything to "that can't be it" thinking. Bring #1 piston up on it's compression stroke look at the valves and make sure the dist. rotor is pointing at #1. This alone will verify that the cam and all the timing are there. If your getting a backfire that means your getting the spark just not at the right time.Good luck and be patient you'll figure it out.

66fastback · 07-20-1999, 08:22 PM

Problem solved....turned out to be the wiring on the duraspark. I got the wires crossed.

The good news is it was a 30 second fix....after spending an hour and a half last night going over firing order and rotor phasing....

Ok, I feel a little stupid, but I'm so glad to have the 5.0 running with the windsor jr. heads on it, that I really don't care. These heads sure work good with the roller cam.

Can't wait for this weekend and the chance to really tune it out. At least the drive to work will be more fun now.

------------------
66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?

red · 07-21-1999, 09:08 AM

It is always good to hear it was an easy fix. Have fun with the new motor.
-JON

Clark Rodgers · 07-21-1999, 09:09 AM

Don't feel stupid, you just couldn't wait to get that baby back on the road and when you get close, it's even worse! I'm envious because my 69 is sitting waiting for more funds.Sorry about the archeologist jab but sometimes you can't resist.

07-20-1999, 05:42 AM	#1
66fastback Registered Member Join Date: Mar 1999 Location: Dallas, TX Posts: 208	help! I screwed up, and need suggestions..... and I don't mean about where to stick the camshaft. I tried to start up the new engine and all it did is puff-puff-backfire-puff-puff-backfire--etc. I'm not new at this, and I'm lost as to what I might have missed or done wrong. The engine is a 5.0 (351W firing order) and I've tried rephasing the plug wires 180 degrees, advancing/retarding the timing, and even the 289 firing order on the slim chance they ground the cam to the wrong firing order--which I would have caught when I set the lifter preload. So far all I can think of is 1. I might have crossed the wires on the duraspark unit. I think that could cause this problem.... 2. Maybe I set the lifter preload too tight, and the valves aren't seating. This doesn't seem very likely, I've done this MANY, MANY times. That's all I can come up with....if anyone has any ideas, I'm willing to listen. This is embarrassing for me, I've never had one that didn't fire off in the first 10 seconds before....Thanks for any ideas, good, bad, or just plain crazy. ------------------ 66 GT Fastback 5.0, 5-speed, 3.40 gears, Fuel Injection soon

07-20-1999, 09:28 AM	#2
Clark Rodgers Registered Member Join Date: May 1999 Location: Rowlett,Texas Posts: 306	I don't have a miracle cure but you know if it is back-firing it has to be a timing issue.Go through it again and don't leave anything to "that can't be it" thinking. Bring #1 piston up on it's compression stroke look at the valves and make sure the dist. rotor is pointing at #1. This alone will verify that the cam and all the timing are there. If your getting a backfire that means your getting the spark just not at the right time.Good luck and be patient you'll figure it out.

07-20-1999, 08:22 PM	#3
66fastback Registered Member Join Date: Mar 1999 Location: Dallas, TX Posts: 208	Problem solved....turned out to be the wiring on the duraspark. I got the wires crossed. The good news is it was a 30 second fix....after spending an hour and a half last night going over firing order and rotor phasing.... Ok, I feel a little stupid, but I'm so glad to have the 5.0 running with the windsor jr. heads on it, that I really don't care. These heads sure work good with the roller cam. Can't wait for this weekend and the chance to really tune it out. At least the drive to work will be more fun now. ------------------ 66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?

07-21-1999, 09:08 AM	#4
red Registered Member Join Date: Sep 1998 Location: Millburn, NJ Posts: 310	It is always good to hear it was an easy fix. Have fun with the new motor. -JON

07-21-1999, 09:09 AM	#5
Clark Rodgers Registered Member Join Date: May 1999 Location: Rowlett,Texas Posts: 306	Don't feel stupid, you just couldn't wait to get that baby back on the road and when you get close, it's even worse! I'm envious because my 69 is sitting waiting for more funds.Sorry about the archeologist jab but sometimes you can't resist.