Post cam install blues

[fallguy]

New cam springs & lifters are in. After 45 mike drive started a horrible shudder in lower rpm range.....missing. Replaced all plugs. Pass side good. Driver side 1-3 gas on em and some carbon, 5 fine, 7 very wet and lots of carbon. Ran perfectly for 125 miles. Started to stumble when moving from stop and coughed then slight shudder. Advanced timing. Ran more smoothly at idle and from stop but bad shudder back again. Pulled plugs. Pass side good. Driver side all good but 7 very wet and carboned up. Replaced plugs. Found carb balance screws off as driver side one full turn richer than pass (4 to 3) so balanced out to 3.

What am I missing or am I good now?

 

[350runner]

Valves adjusted to tight?

 

[texnet]

Since you did not state what engine, cam and lifters I can only assume you installed a flat tappet (not roller) cam and lifters... if so did you properly break in the camshaft and did you add a zinc additive to the oil prior to starting the engine?

The reason I ask is because this is a step often missed by someone not following breakin proceedures for a flat tappet camshaft. If not broken in properly, with a zinc additive to the oil, the camshaft and lifters will not harden properly and you will end up with one or more flat lobes on the camshaft, and lots of small metal particles (part of the cam and bottom of the lifters) in your oil pan.

To check for this, pull off the valve covers, disconnect the coil wire and turn the engine over slowly and check for any rockers that are not moving full cycle. Those lifters will be cupped on the bottom and the lobes on the cam will be flatter than they were when you installed the cam. If this is the case, pull the cam, lifters, oil pan and oil pump. Wash out the metal particles, install a new cam, lifters, oil pump and the pan... break in the cam and hope no more damage has been done!

FYI, most cam manufactures recommed the engine be run at 2000 RPM for 20-30 minutes when you FIRST start the engine after a flat tappet cam and lifters are replaced.

Another note... flat tappet cams and lifters require zinc to harden them initially on a new install and over the course of the engine's life. On any flat tappet cam engine I build I use VR1 Racing oil and a bottle of Lucas Oil Engine Break-in Oil for the first 1000-1500 miles. After the initial break-in mileage I use VR1 Racing oil only. VR1 Racing oil contains enough zinc to keep the cam and lifters hardened.

I pray this is not the issue with your engine.

 

[fallguy]

Break in procedure followed as stated. Oil changed after that and zinc additive added.

290hp 350 flat tappet cam

 

[fallguy]

120 mile drive today...blew out #7 again. Could hear loud lifter clicking in lower rpm range at 55mph. Shifted out of OD and ran smooth to home...let rpm drop in OD and the miss is unbearable

 

[350runner]

I'm really leaning toward.Valve adjustment....

 

[fallguy]

Ran 3 120 mile trips. All drivers side plugs fouled out each time. 1-3 wet and black wit a small chunk or two of carbon. 5 black and gray. 7 caked with carbon, wet and very black. This happens every time! wTH!?!

 

[rich weyand]

What plugs are you running? Is it a dual-plane manifold? Which carb is it? Are both sides of the carb set the same (idle mixture, jets), and acting the same (all the widgets move the same on both sides)? Could you be running dead ass rich on the drivers side? Maybe a vacuum leak on the passenger side, then you adjust for that to be working right and you made the right way rich?

You could also have a step-up piston stuck in the up position, which would make it way rich on the cruise circuit on that side. Cleaned them up lately?

 

[Thunder]

Could this be a spark issue?
If the cam is a Comp Cam ditch the lifters. Go with Rhoads or Howards. The last two sets of Comps lifters I have installed have had issues.

 

[rich weyand]

Given that it's bank-related, I think it has to be something like one side of the carburetion is off (like a stuck step-up piston), or one side of the dual exhaust is blocked up, or something like that. Odds that a batch of lifters would have all the bad ones on the same side are pretty low.

 

[DoubleDingo]

If like 350 runner said, possible valve adjustment being off, couldn't that cause it.

Which method was used to adjust the valves? The 2-roll method or the engine running method? Were the dots both at 12 0'clock before starting the adjustment if it was the 2 roll method? If the cam gear was at 6 o'clock and the crank gear was at 12 o'clock then the engine was 180* out on 6tdc. The books don't tell you this when you install the cam and timing set. They just tell you to line up the dots on the cam gear and crank gear. They don't tell you to roll the engine on revolution to get it to 1tdc and 0 on the timing tab after everything is installed and torqued up.

I found out this little tid bit when I started adjusting my valves after replacing my cam. I left the dots lined up thinking it was on 1 tdc. Before I pulled the cam I set it to 1tdc and then took off the timing cover to see the dots both at 12 o'clock. I was confused, and luckily I had Pop to walk me through over the phone by watching the lifters as I turned the engine.

 

[fallguy]

What plugs are you running? Is it a dual-plane manifold? Which carb is it? Are both sides of the carb set the same (idle mixture, jets), and acting the same (all the widgets move the same on both sides)? Could you be running dead ass rich on the drivers side? Maybe a vacuum leak on the passenger side, then you adjust for that to be working right and you made the right way rich?

You could also have a step-up piston stuck in the up position, which would make it way rich on the cruise circuit on that side. Cleaned them up lately?

Bosch Platinum plugs 3 sets worth

Dual plane manifold yes. Edelbrock Performer

Yes on the carb setup the same on both sides.

Not rich on one side.

No vacuum leaks from what can tell....

Carb was torn down cleaned all new gaskets and such installed.

The current carb setup has existed for a year now with no issues like what I am describing. Only 2 things have changed, cam/springs/lifters and a frayed throttle cable kept the secondaries from opening and made the pedal a hard push due to it's binding up...new cable fixed that.

 

[rich weyand]

Which carb? If it's the Edelbrock, pull the step-up pistons out and wipe them off, then clean the piston bores with Q-tips, then re-assemble. This is a periodic maintenance procedure: they gum up, get sticky, and then you will run either rich in cruise or lean in the power circuit, but only on one side.

Autolite 24 are probably your best plugs to use. Much more resistant to fouling than the ACDelco R45TS. And lots of talk on the net that the Bosch plugs and Gen 1 SBCs don't play well together. Given how cheap plugs are, I would swap them out and see what you get.

 

[350runner]

I run ngk ur4 plugs and my engine feels like it did 100k ago way better than AC Delco

 

[fallguy]

Which carb? If it's the Edelbrock, pull the step-up pistons out and wipe them off, then clean the piston bores with Q-tips, then re-assemble. This is a periodic maintenance procedure: they gum up, get sticky, and then you will run either rich in cruise or lean in the power circuit, but only on one side.

Autolite 24 are probably your best plugs to use. Much more resistant to fouling than the ACDelco R45TS. And lots of talk on the net that the Bosch plugs and Gen 1 SBCs don't play well together. Given how cheap plugs are, I would swap them out and see what you get.

Did that process already with the step up pistons. No change. I'll try changing plugs.....again but really I feel something has to be causing this to happen to the plugs,