I have a 76 sr5 20r l put a delta 260 cam and new rockers, weber carb, header,k&n filter, pertronix ignitor and coil on it. It idles fine but when i excelerate under a load its misfires badly. My friend who is the mechanic and I can't figure it out! Any ideas!?

 

What weber are you running?

 

If you have a 32/36 and you haven't changed the jets there's your (or one) problem, if you have a 38 it should be performing good to great on the jets it came with.

 

Im pretty sure its a 32/36 I had it on my 18rc for a couple thousand miles then it sat four a few years but was bought brand new.

 

yeah when you get a bigger cam that jet setup probably won't be able to keep up. I hear this is a common problem where people over cam but don't adjust the rest of the system to make up for the cam.
If I remember correctly my buddy had what he called a RV cam and went too a 36/38 on his.

 

You can tune the hell out of a 32/36 also to run a larger cam (delta 260 is not so big) and supporting mods, it's just that at one point it becomes a restriction.

Your problem could be from the fact the carb sat 4 years, depends on how it was stored, and/or incorrect jetting, amongst maybe other things we don't know. Spending thousands on engine work and parts and not spending a couple hours and 50$ on a jet kit to make it run good is a waste! There are many good threads on how to tune your 32/36 and specific rules to follow with them i.e fuel press, throttle screw setting can't be open too much, etc. Good books too.

 

And I don't think they had sr5 in 76? I thought it started in 81, maybe 80.

 

That's it! A delta camshaft rv 260, it is supposed to be a mild upgrade. So you think I mite need bigger jets in carb?

 

There is an easy way to find out by how many turns out your mix screws are out, here read this thread, after that you'll be a pro at carb tuning and your truck should run pretty strong.
https://www.yotatech.com/forums/f114...tuning-261129/