Okay i have a quick question about lifters, I have a 78 F100 300, its all stock, Will changing lifters make any difference in the way it performs? i know if the lifters are too much longer than stock it will cause valve to piston connection and will cause major problems. I would like to know if different lifters will change anything. I was on FTE once and someone said you can use chevy 350 lifters on a 300. I dont know if thats true or not please correct me if anything i said was wrong.

 

I think what you're thinking about is the rocker arms. You can use Chevy 250 (the inline 6) rockers on a 300 for a little extra valve lift (which is comparable to a mild performance cam).

Longer lifters, however, could technically give you more lift (although I think your valves may even be stuck open), but would throw off your valve train geometry and could damage, bind up, or at minimum, prematurely wear out your valve train. Longer lifters is basically like putting in push rods that are too long.

 

thats what is was 250 rockers, how easy are those to install? and do i have to change anything with that?

 

and what ratio do i need

 

Standard 250 rocker arms are 1.75s. If you have the original '78 300, should be a bolt-on. Remove the valve cover, replace the rockers one at a time, reset gaps, replace the valve cover and retune. Make sure you are not getting any undue interference on the pushrods etc. when you reassemble. Think that covers the normal process... do a search for better detail (always a good idea before asking any question. 95% of the questions on these forums have been repeated multiple times.)

 

I guessed 1.75 because they are common, any suggestion on brand? i see some for $120 a set and some are $450 on summit. Also when you say re-tune do you mean carburetor? And when you say set gaps what should gaps be set at with new rocker arms.

 

Do a search for 1978 300 valve setting and you will get a ton of info. Me, I suggest checking everything - you are essentially changing the cam so checking advance, spark, and carb settings should all come as part of the job. Try Rock Auto, I think they have them for about $50 or so.

 

Look in tips and tricks. It is the second thing discussed. Good luck and have fun.

 

I believe they are 1.73 ratio. What happens is with the higher ratio you are moving the p.rod closer to the fulcrum/pivot point/rocker stud. I used 1.7 rockers for a while and could easily see that my p.rod was uncomfortably close to the side where it passes through the head. And I have the desireable
slot type hole thru head.

I can't help but wonder how wise it is to add more stress to the springs, r.arms, studs, of an engine with many miles on it. Putting on the chebby rockers reminds me of the 'Instant Engine Overhaul' cans they sell in the A.parts stores.