Engine Backfire Diagnosis Led to Wiped cam Lobes

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Skweegle89

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85swb "Fancy"

Holy crap comp cams has a lot to choose from.


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Skweegle89

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85swb "Fancy"

Is that 260h my best bet with this sm465 4x4 and these 3.73s?


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DoubleDingo

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I looked it up and it says it has good mid range and is good for 4x4 and towing, so pair it with a good dual plane spreadbore intake, get everything dialed in, and you'll be rocking.:headbang:
 

Skweegle89

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Lol I will have been able to buy a new crate motor by the time it is all said and done.


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350runner

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With a standard trans you will like the torque a smaller cam provides on the bottom rpm range.

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Skweegle89

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85swb "Fancy"

It's bonus time again next week so I have to wait until then to order all this stuff. In the mean time, I'm going to paint the water pump and all the brackets, as well as the push bar and roll bar I got.


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Skweegle89

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Alright I'm going to need a list of everything I'm going to do this cam swap.

Cam
Lifters
Timing chain set
Valve springs?
Push rods?
Will I need a new oil pan gasket?
What kind of break in oil for cam?

Does the radiator have to come out to get the cam all the way out?

Who is going to come babysit me if this doesn't fix my problem to keep me from going postal on the whole town?


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350runner

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Who is going to come babysit me if this doesn't fix my problem to keep me from going postal on the whole town?


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If your just burying it all y not make sure you find the real issue first? Honestly that's the way to go. Better to get acquainted with valve lash and feel comfortable B4 putting a new cam in :).



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Skweegle89

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85swb "Fancy"

If your just burying it all y not make sure you find the real issue first? Honestly that's the way to go. Better to get acquainted with valve lash and feel comfortable B4 putting a new cam in :).



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Because the whole front of the motor is already off the truck. I haven't ordered a cam yet, I'm waiting until I pull the timing cover being as how I'm almost there anyway. I would just hate to put it all back together and then it end up being the cam. Idk what to do. I'm at a loss here. Don't want to spend all that unnecessary money,
But also don't want to adjust all the valves and put it all back together, then it wind up being the cam and having to take it apart all over again. I just want to drive the damn thing lol


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350runner

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No find the problem. The 5th and last post give you an idea of how to check your cam for worn lobes.

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firebane

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Alright I'm going to need a list of everything I'm going to do this cam swap.

Cam
Lifters
Timing chain set
Valve springs?
Push rods?
Will I need a new oil pan gasket?
What kind of break in oil for cam?

Does the radiator have to come out to get the cam all the way out?

Who is going to come babysit me if this doesn't fix my problem to keep me from going postal on the whole town?


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I have the comp cams 12-300-4 and it uses stock heads. Don't buy into the cam kits as they end up usually costing more money than what you need.

I bought my pushrods and lifters through Rock Auto and bought my cam seperately and I came out cheaper than buying a cam kit.

Timing chain is always a good investment if your switching cams as they are dirt cheap such as the Cloyes double roller.

I just put a bunch of stuff into the top end of my truck including the cam with refreshed heads. I put a new double roller timing chain into it as well as a 1 piece new oil pan gasket and depending on the year of your block if your rear main seal is 2 piece you might as well do that for some extra insurance.

I'm going to be using studs for my valve covers and have felpro blue gaskets for those already and I picked up a cheap Edelbrock performer intake for my truck as well.

I am hoping that once all is done the truck runs good and I won't have to worry about it for awhile or until the bottom end needs a rebuild.
 

firebane

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No find the problem. The 5th and last post give you an idea of how to check your cam for worn lobes.

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Easiest way to check for worn lobes is pull your valve covers and then put a mark on the pushrods. Turn the crank over by hand and the pushrods should be spinning and your marks should change position.

If they do not spin or some move slower than others you have worn lobes.
 

Skweegle89

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85swb "Fancy"

No find the problem. The 5th and last post give you an idea of how to check your cam for worn lobes.

Sent from the dust in front of you!

It's not backfiring through the carb anymore at idle. It's popping through the exhaust at idle. The only backfire through the intake comes in about 3rd gear under a load. I have already cranked it with the valve covers off and everything seemed to move the same. I'm not opposed to doing a valve adjustment and trying that, but how often does a valve just randomly go out of adjustment? I'm asking because I don't know. Trying to diagnose this was fun for awhile, but now I'm just getting pissed off. I have dumped every spare dime I had into it and I'm not any closer to fixing the problem. I would love to find out what it is and fix it, but when the only knowledgeable help I have is via Internet and you guys aren't here to actually hear to see and hear the problem,
It's kind of a pain in the ass.


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