cam change

[bobtail]

still trying to dial in on a cam change. i switched a stock cam for an rv cam. i thought it would be a three day job. so far its been a month long event. i have learned a lot in the last two months. i started out knowing little about cams lifters 'springs and now i know little about cams lifters springs. so here is where i'm at. after leaning about some cams changing the firing order, mine is now the same as a 351 the tappets are quiet. it idles smoothly. when i drive it performance is poor. when i step on the gas slowly it does alright. when i step on the gas quickly it bogs down and wants to die shooting flames out of the carb. any hints about what i'm doing wrong. its a 302 w/ original motorcraft carb.

 

[garberz]

Check your ignition timing, it seems like you’re a tooth off on the dizzy. Too retarted.

Mark

 

[ledslinger29]

Move the distributor a tooth first, after that check your timing if it is way off and you can't pull it in Then you may start to wonder if the cam isn't indexed properly. Degree your cam, if you can't come up with anything else. If you degree the cam you will know without a doubt that it is right.


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[DJs74]

still trying to dial in on a cam change. i switched a stock cam for an rv cam. i thought it would be a three day job. so far its been a month long event. i have learned a lot in the last two months. i started out knowing little about cams lifters 'springs and now i know little about cams lifters springs. so here is where i'm at. after leaning about some cams changing the firing order, mine is now the same as a 351 the tappets are quiet. it idles smoothly. when i drive it performance is poor. when i step on the gas slowly it does alright. when i step on the gas quickly it bogs down and wants to die shooting flames out of the carb. any hints about what i'm doing wrong. its a 302 w/ original motorcraft carb.

What camshaft did you install? P/N? How did you set your timing between the crankshaft and camshaft - zero, advanced or retard?
What else new was installed in addition to the new camshaft and lifters - timing gear set, valve springs, rocker arms, pushrods?
How did you go about installing the distributor, meaning... @ TDC or something else?

DJs74

 

[B RON CO]

Hi, X2. Go for the distributor check first. I like to make a sharpie mark on the distributor body directly under the #1 terminal. Now bring the balancer around (clockwise) so the pointer marks line up and see if the rotor is right over the sharpie mark (if the rotor is 180 degrees off, turn the balancer 1 full turn. Good luck

 

[hucklburry rev2]

Did you change the 4 plug wires to match the new firing order? You didn't say so I have to ask. I could tell a story about how I got a Bronco that sat for 2 years, took me a week to figure it out, swapped the plug wires and BAM she ran awesome.

Like you are saying, it would start and idle, but no power and backfire. I swapped those plug wires to get the correct firing order and she rocks.

 

[DirtDonk]

Hopefully this turns out to be something simple, but if you did not get the chance to do a cam break-in, it could all end very badly.
Were you able to run the cam in at 2000 to 2500 rpm for 20-30 minutes before you started doing any checking, fiddling, twiddling or (more importantly) any idling?
If not, then part of the lack of power could be lack of cam left over after at least some of the lobes are being worn down.

Now that all the dire news is done, don't worry about that just yet. Plenty of other things it could be. So check those all first.
But if you did not successfully break in the cam, or are not using zinc-rich oil, then the bad news could just be getting worse as the engine runs.

Crossing fingers that all got done.

Paul

 

[Broncobowsher]

Take off all your plug wires and put them on again.

I once had the same symptoms. Fought it forever. Finally found I had 2 plug wires swapped. Only found by accident. Refused to check them because I know I put them on right. There was no way I could have put them on wrong. A month because I was too stubborn to believe the plug wires were on wrong. There was a carb rebuild involved before I proved myself an idiot, and that was a brand new carb.

 

[blubuckaroo]

Take off all your plug wires and put them on again.

I once had the same symptoms. Fought it forever. Finally found I had 2 plug wires swapped. Only found by accident. Refused to check them because I know I put them on right. There was no way I could have put them on wrong. A month because I was too stubborn to believe the plug wires were on wrong. There was a carb rebuild involved before I proved myself an idiot, and that was a brand new carb.

Ha!
This happens a lot when a Chevy guy tries to work on a Ford.