6.0-928S

Hi folks, It's been a while since I've been on, I had another major eye surgery & I'm still not done yet. But anyway, I'm having trouble getting my stroker to start. It seems like the spark timing is too advanced. I hired a local Porsche factory tech & race team crew chief check my assembly. All the mechanical timing marks line up perfectly, we have spark & fuel. But when we try to start it it backfires flame out the intake. Since the spark timing isn't adjustable we're confused. Has anyone had this happen or does anyone have a suggestion?

TIA, Hammer

fbarnhill

Sorry Hammer, I can't help but I can't believe you have a 65 Hemi Belvedere. In 1972 I had a 66 Hemi Coronet in NC. I got a funny ticket one day by finally catching up with the only other Hemi of the period that I knew about which was a 65 or 66 Belvedere. We were on a 4 lane road (45mph) and I finally caught up with him without too much traffic. So, I am reving my engine to get his attention, He just laughs and points behind me. There were blue lights everywhere. They got me for 55 in a 45 while trying to catch this guy. Lucky for me the cop didn't wait a few more minutes...LOL... I will never forget it. Hard to believe but that coronet was one of the best handling cars I have ever driven. Not to mention the TORQUE ... Mine had the 426 with 2 4s, Dana rear end and 4 speed. For a while I raced it every weekend at the drag strip and it was my daily driver. God, I miss cheap gas!

Good luck with your 6L. I hope you will post a sound byte when you get it running. Do you have the stock mufflers on the Hemi? Mine had them when I first got it. The only clue you had were the emblems on the side and the muffled rumble at the rear...

dcrasta

PICS of the Hemi.


Whats your static timing set for? what happens when you retard it slightly ?

dr bob

Basic: Fuel pump fuse pulled so no fuel available. Put a timing light on the #1 plug lead and see what te timing is like while cranking.

Basic: Verify that the timing marks on your damper coincide with TDC on cylinder 1. Remove the spark plug, and move the engine by wrench to just before TDC on the damper. Long pencil or wood dowel in the plug hole. Watch the pencil/Dowel as you slowly roll the crank through and past the TDC mark. Did the motion of the dowel crest at thr TDC mark on the damper?

Then verify cam & valve timing against that TDC mark. PorKen's 32VR tool is handy for getting cam timing just right. If cam timing is off, you risk the backfiring symptoms you describe. If you replaced the cam chains in the haeds, there's another opportunity to get one of the cams in each head timed wrong.

A simple compression test is a gross detector of cam timing problems. Low on one bank is a telltale.

6.0-928S

The timing isn't adjustable. It's set by the ECU.

Rob Edwards

What's the engine management hardware on this beastie? I poked around in your old posts but couldn't find anything.

Mike Simard

I'd take the valve covers off and verify valve timing on #1 and #6

6.0-928S

Dr Bob, We spent a few hours doing that last night. I used the Porken tool when I degreed the cams. Compression was 195 on all cyl's on one bank & all were 205 on the other.

Thanks, Hammer

6.0-928S

Rob, At the moment it's the factory ECU's. I have a shark tuner but when I install the STII PEMs I don't have spark so we were trying to get it to start first & then check with John to see why I have no spark with the PEMs installed.

Hammer

OBehave

+928! This is mandatory if you are running aftermarket or reground cams. I have Devek B2 cams in my stroker and when timed with the porken tool the car had BIG issues. The Porken tool is a great help but it MUST be calibrated and checked against the old fashioned way of valve cover of and dial indicator installed.
What cams are you running? And did you triple check the parkplug wire routing?
Ed

Cosmo Kramer

+1 This one bit me in the *** one time.

6.0-928S

Yes. we triple checked the wires. It has reground cams. But I did set them with the dial indicator. And checked 4 times & got the correct readings. Checked it, rotated the engine 9-10 revolutions, checked it again.....etc.

Hammer

Mike Simard

Well it's either valve timing or spark timing out. Maybe it would help to look at it as though you haven't checked anything yet.

First verify your damper degree marks are good

Check cylinders 1 and 6 both intake and exhaust opening at 1mm or whatever it's supposed to be checked at.

Blow some air into each cylinder when valves are closed to verify that valves are indeed closing.

That leaves the spark. What does a timing light say while cranking? It's wasted spark so you don't have to worry about being one revolution out. It's theoretically possible but unlikely for the crank to have been miss drilled or a flywheel that had a timing ring added to be off.
Have those parts run in another engine?

John Speake

Good to see you back working on your 928 project !!

You haven't worked on the Flywheel /timing ring, have you ?

6.0-928S

Mike, the damper is the ATI Super Damper we got together on remember? The flywheel was used & I didn't modify it.
I guess I'll have to pull the cam covers & do the dial indicator again.
John, I get no spark with the ST II PEMs installed. I had to put the OE chips back in.

Thanks, Hammer