Finally got a running 65 C10

[1low4x4]

I wonder if my low idle/surging idle could be due to over tightening valves?

 

[DoubleDingo]

Cranked the truck up and drive it out of the neighborhood. Let it sit running for while. So effing loud. But it just doesn’t seem to run right. Almost like a vacuum leak but I can’t find one. Like it’ll run low low rpms and then all of a sudden spike and run high for awhile. It never really gets that nice cam sound, either way too low rpm or like you’re holding your foot on the gas a little

Might be too much cam for the little 283

 

[DoubleDingo]

I wonder if my low idle/surging idle could be due to over tightening valves?

If the valves were over tightened it would run erratic, like really bad, and a vacuum gauge would bounce just as bad. Been there done that on Crusty Biscuit. Went with 1/2 turn instead of 1 turn and it smoothed out. I later changed the cam because the one it was a sh!tty cam. Sounded cool, but ran like cr@p, was gutless no matter how I timed it or tuned the carb. Went with the 300hp/327 cam, but the engine in Crusty is not a 283.

 

[Ricko1966]

The thumper cam doesn't have much vacuum at Idle and lots of overlap.Thats how they get the race car style idle. The smaller the engine you put a cam in the bigger the cam is proportionally. That's why those old 302s would wind out so far they had the biggest baddest 350 Cam that Chevrolet made. The thumper is pita to tune on a 350 a 283 moreso. I'd add a bunch of timing at idle,see if I could cleanup the idle and low end,make sure the idle stop screw isn't turned in to far,and get vacuum readings you may have to change springs in the carb if vacuum is low enough that you are getting into enrichment circuit at idle. Bump the tim8ng a bunch,see if that helps,then we will have to limit advance on the other end to keep you down in best total timing.

 

[1low4x4]

Man, the more I read about the thumper cam I got, the more I think it was a terrible choice. 279/297 .479/.465 Apparently it wants higher compression than what I have, and a higher converter. I can attest to that by the way I have to rev it to take off….and it definitely hurt the drivability on the top end. 60 is at much as I wanna go.

I brought my trailer home so I can load the truck up and take it to a remote area to see if I can give it some more timing and play with it. But I’m really starting to think I should go back to the stock cam or at least something better suited for the little 283

 

[Ricko1966]

Man, the more I read about the thumper cam I got, the more I think it was a terrible choice. 279/297 .479/.465 Apparently it wants higher compression than what I have, and a higher converter. I can attest to that by the way I have to rev it to take off….and it definitely hurt the drivability on the top end. 60 is at much as I wanna go.

I brought my trailer home so I can load the truck up and take it to a remote area to see if I can give it some more timing and play with it. But I’m really starting to think I should go back to the stock cam or at least something better suited for the little 283

Remember if you bump the initial timing you have to limit the amount of centrifugal in the distributor. What advance springs are on it now? Do you know?

 

[1low4x4]

Remember if you bump the initial timing you have to limit the amount of centrifugal in the distributor. What advance springs are on it now? Do you know?

I have no idea. It’s just a unit from oreillys like a street fire or something

 

[Ricko1966]

I have no idea. It’s just a unit from oreillys like a street fire or something

Is it a Streetfire? Do you have the tuning sheet?

 

[1low4x4]

Is it a Streetfire? Do you have the tuning sheet?

I do not sorry

 

[1low4x4]

Headed to my mom‘s house in the boondocks so I can fire this thing up and give it some timing and idle.

 

[Ricko1966]

Headed to my mom‘s house in the boondocks so I can fire this thing up and give it some timing and idle.

Found some info on the web for you. Have you installed the limiter on the vacuum advance? It should have come with one. And they sell a seperate advance kit which if bumping the timing helps out from idle to 2500 rpm or so, I'd suggest you get it. It comes with limit bushings to bring the advance in the distributor down to 18* which would allow you to run 18 degrees more or less initial. Also the softer springs would bring the centrifugal in sooner.Remember while testing at your mom's if you go 18 degrees + the 22 in the distributor will be 40* which is probably too much total.

 

[1low4x4]

Thanks for the info. I was kind of reading on that myself yesterday. Being completely honest, I think the timing is close to 40° total already. I’m going to check that. Should I be checking it with the engine revved up a little bit? Because that’s not how I checked it last time. I just checked it with the vacuum van hooked up at idle.

Honestly, this morning, after I let it semi warm up and took the choke off, the RPMs dropped down to sub 500. Maybe I just need to crank it up to around 1000 idle? I’m going to do some alterations and see.

 

[Ricko1966]

You don't check timing with the advance hooked up. I would usually check it with the engine revved past point of maximum advance. Shoot for 36*. But since I know there's 22 centrifugal in that distributor,check it now at a low idle,vac disconnected. Bump it up to 18,see if it's better bump it to 20 see if it's better. As for idle are you setting it with the mixture screws? If you run the idle stop screw in too far you create a new set of problems.

 

[1low4x4]

You don't check timing with the advance hooked up. I would usually check it with the engine revved past point of maximum advance. Shoot for 36*. But since I know there's 22 centrifugal in that distributor,check it now at a low idle,vac disconnected. Bump it up to 18,see if it's better bump it to 20 see if it's better. As for idle are you setting it with the mixture screws? If you run the idle stop screw in too far you create a new set of problems.

I haven’t touched the mixture screws. Honestly, I’m just adjusting the what you would call idle stop screw I guess. What is the proper position for how far that thing is screwed in? Is there one?

 

[Ricko1966]

I haven’t touched the mixture screws. Honestly, I’m just adjusting the what you would call idle stop screw I guess. What is the proper position for how far that thing is screwed in? Is there one?

You need to set your mixture screws,then adjust the throttle stop screw. Usually while the carb is off you look at the transition circuit and with the throttle closed the slot should appear to be square not rectangle. @legopnuematic has a good pic. Then you set your timing,then you set set your mixture screws. Then you fine tune idle speed with the stop screw. If you have to turn it in a bunch we have to figure out why.because open too far steals fuel from the transition circuit. Rumor has it,but I've never checked, as long as you aren't pulling vacuum at the ported vacuum source you aren't in too far.