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Thread: DARK brown--BLACK plugs SBC Reply to Thread

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Topic Review (Newest First)

02-03-2008 10:12 AM

Joshua Lee

I will check out all that.... I appreciate the help man, I totally forgot this post was about the carb being ritch, lol...

02-02-2008 08:09 PM

Joshua Lee

Ok.....

If the heads show up good, Im gona clay the pistons and if that shows up good Im swaping timing chains and claying the pistons again and putting it back togather...

02-02-2008 03:05 PM

nitro_baller4692

has anyone thought that the cam may have twisted.
sorry but 9 pages and we haven't found the problem

02-02-2008 12:16 PM

Joshua Lee

Well, I just cleaned off #6 and the Exhasut valve deffinatly hit, it dented the piston..

01-25-2008 02:20 PM

Joshua Lee

If the bearings were thin the cap would be loose... It wasnt, the bearings look fine so assuming the heads check out ok... Im at another stoping point

01-17-2008 05:45 PM

RexRat

Sbc

Dude take that thing apart and inspect all aspects. There is a lot of literature on the subject.
I think Bogie was getting at that your main or journal bearings may be thin. Based on the fact that the engine has a lot of heavy use on it many things can be wrong.
Many of the possible operations such as checking for piston to valve are on this thread. But the first thing you should do is freshen up the bottom end. I will look over your input on this thread and sum up if you want but you should use your powers of deduction and get wrenching!

01-17-2008 05:42 PM

BogiesAnnex1

Quote:

Originally Posted by Joshua Lee

ttt

bogie? anybody?

I'm here, Chain stretch and 4 degrees retarded could cause these collisons. But I'm troubled by the combination of opposites. I don't have an answer, but it bothers me, I need to mock up an engine and cogitate on the possibilities.

Bogie

01-17-2008 04:43 PM

Joshua Lee

ttt

bogie? anybody?

01-15-2008 01:15 PM

Joshua Lee

Bogie... Somehow or another I have been saying my cam was retarded 4* well it's ADVANCED 4* not retarded... I just looked at the crank gear and it's in the triangle hole = 4* Advanced...

Does this change anything?

01-07-2008 04:05 PM

Joshua Lee

hmmmmm..... chain stretch still isnt a option?

01-07-2008 10:55 AM

BogiesAnnex1

Quote:

Originally Posted by Joshua Lee

#5 Intake bends (twice now)
#6 Exhaust touches but no damage (both times)

Number 5's intake lobe and number 6's exhaust lobe are located next to each other on the cam with their lifters opposite each other and only a small space apart. I'm wondering if the cam can move enough to where the incorrect lobe is clipping the lifters, or if something else related to this area is happening. I think it bears some careful inspection and testing.

Bogie

01-04-2008 02:23 PM

Joshua Lee

#5 Intake bends (twice now)
#6 Exhaust touches but no damage (both times)

01-04-2008 11:58 AM

BogiesAnnex1

Quote:

Originally Posted by Joshua Lee

What throws up a red flag when them two valves are the only ones hitting??

Nothing in particular, but 5 and 6 share a common crank throw between the 3rd and 4th main bearings, the lobes for both are located between 3rd and 4th cam bearings.

Maybe it's just coincidence or maybe something else is going on. I'm not pin pointing anything, just pondering.

Which valves are doing the impacting and which one was the worst, too lazy to go thru 8 pages to find the answer.

Bogie

01-03-2008 04:42 PM

Joshua Lee

What throws up a red flag when them two valves are the only ones hitting??

01-03-2008 10:28 AM

BogiesAnnex1

Quote:

Originally Posted by Joshua Lee

Bogie...

I finally took the passenger head off and the #6 exhaust valve tapped the piston just enough to see the carbon was gone.... Does that help us in any way? lol....

I'm also taking the heads in tomorrow hopefully to get a second opinion....

I noticed that the lifter on #5 where the valve bent seems a little sticky, can I hone the lifter bores??

Thanks x 10000000000000000000000000

Yes you can hone the lifter bores. Check the clearances, they should be about .001 to .0015. If your shop is capable of this, checking the lifter bores for being truly at 90 degrees to the cam centerline is a good thing to look at. The same can be said for lifter alignment with the valve and rocker centerlines; what I'm hunting for here is that miss-alignments can result in parts inclusive of the tappet, rocker, or valve binding because of introduced side loads. I'm also trying to rule out that miss-alignments between the tappet and rocker could lead to a bending of the push rod. Also while we're here, you want to look for any potential binding of the push rod in its guide or contact where it passes thru the head. High cam lifts in general or high lift ratio rockers i.e. 1.6:1 or greater can change the geometry to where the push rod gets to rubbing or binding somewhere along its length.

I'm intrigued by the fact that your problem seems to be at opposing cylinders 6 left and 5 right and they follow each other in the firing order 1-8-4-3-6-5-7-2.

Bogie

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