Brokedown in Blythe

[Mike Phillips]

Typing on an iPhone in a hotel, excuse my choppy typing.

On my way to Florida, 200 miles down the road i started to hear a ticking sound?  A few more miles and the engine starts to backfire through the carb, sounds like a loud popcorn popper.

I pulled over at the next rest stop and later call Tripple A

called a couple mechanic friends and they agree that it's intake valve related.  Anyone want to take guess at  what the problem might be?

It will be very expensive to have the truck towed home.

Feel free to call on my cell phone in the morning if you have asugestion as to what to look for as that's a faster than than me trying to post with my cell phone.

760-515-0444

there's a auto repair shop next door and it will cost less to have it fixed than to tow it home.

Mike

[Irish_Alley]

it does sound like a valve problem idk may distributor is lose letting it advance it self, could be timing chain slipping??? i don't know what that would do if it would retard it or advance. spring problem
the ticking was the timing being to far advance then the popping was from the timing being way to far advance try turning the distributor it probably will turn by hand

[VileZambonie]

Agreed, Definitely check the distributor and the timing.

[Captkaos]

Pull the valve cover off an see if you dropped a lobe?

[Mike Phillips]

Had timing checked and it was okay.  Will do a compression check when I get her home.

[Mike Phillips]

Pull the valve cover off an see if you dropped a lobe?

I'm sitting in an air conditioned room waiting for my buddy toget here with my car trailer.  Will probably have a buddy of mine that's a transporter haul the truck to Florida for me and then I'll tear into it.

[Blue 82]

Sounds like you lost an intake lobe on the cam
Mine sounded exactly as you describe
40,000 miles on the cam......

[joesgarage71]

Sounds like you lost an intake lobe on the cam
Mine sounded exactly as you describe
40,000 miles on the cam......

 40k and the cam went, I'd be paying better attention to the oil you use. Todays oil is made for todays roller cammed engines flat tappet engines need better oil.
 Mike sounds like you wipped a few lobes off.

[eventhorizon66]

I thought, this being a late model marine engine, it would have a roller cam.  So wiped lobes wouldn't be an issue.  What about the rocker adjustment?  Maybe a bent pushrod?

And while I agree on the oil comment, I think a major contributor to the high number of wiped lobes on aftermarket performance flat tappet cams is spring pressure.  As lobe profiles have become more aggresive, cam companies have increasingly spec'd higher spring pressures.  For example, Comp Cams specs a #981 spring for their SBC XE268 cam.  That comes to 281.5 lbs over the nose if installed at 1.7".  And 280+ lbs over the nose is just too much if you care about cam longevity.  The solution, though not a cheap one, is beehive springs which offer improved valve control with lower spring pressure.  That same cam with #26986 springs installed at 1.75" will only have to contend with 256.5 lbs over the nose...much better.  If I had a flat tappet cam in a BBC (which are notorious for wiping cams), I would definitely be running beehive springs with less pressure than would be the norm for traditional springs.

There, another short essay complete.

[SUX2BU99]

^ True, and although I could be wrong, I don't think 1.7 rockers on SBC's are entirely too popular. I know on Dodge small blocks like the Magnum series they are as a performance upgrade since the factory rockers are 1.6. SBC's are usually 1.5, so 1.6 is generally the upgrade. I don't know but do you know how much pressure those same #981 springs put on the nose at say 1.6 and 1.5 rocker ratio's? Kinda curious about that.

[VileZambonie]

bbc rocker ratio is 1.7:1

[eventhorizon66]

^ True, and although I could be wrong, I don't think 1.7 rockers on SBC's are entirely too popular. I know on Dodge small blocks like the Magnum series they are as a performance upgrade since the factory rockers are 1.6. SBC's are usually 1.5, so 1.6 is generally the upgrade. I don't know but do you know how much pressure those same #981 springs put on the nose at say 1.6 and 1.5 rocker ratio's? Kinda curious about that.

I wasn't refering to a 1.7:1 rocker.  I was talking about the installed height of the spring.  All of those figures were with a 1.5:1 rocker.

Matters are worse for flat tappet cams in BBC's as lifts are higher and valvetrains are heavier (mandating stiffer springs).  So beehive springs can offer even more advantage here.

[SUX2BU99]

Ah my mistake, I saw 1.7 and thought rocker ratio, not installed height.

[joesgarage71]

 UpDate, whats going on Mike?