New performance cam going into old engine... good or bad???

[Benzo]

I was thinking about changing my cam and putting in one I like much better. The only thing is I don't know if it is a good idea to swap in a new cam with a well used engine. I actually do not know how many miles are on this engine, but it runs sweet and it sure loves gas. I know the main bearings are pretty worn because I have 15lbs. oil pressure with the engine idling at 180 degrees. When the engine is at a cold idle, I have 60 lbs. of oil pressure. I am still thinking about what kind of engine to build and I want to play in the mean time. I just do not like the stock cam and I was planning on changing the timing chain. To tell you the truth, I was just going to change the timing chain and then I started thinking.... Hmm the front of the engine will be opened up. You know, just staring at you and I want a differnet cam anyway. After that it's time, gaskets, and adjustments. Yes I am hooked. What do you think about the swap?

 

[SteveL]

depending on the cam size the extra lift can kill the old worn parts. I did it in a worn 350 and it lasted about a month.

 

[tyedupgood]

pointless to change the cam without a rebuild, top and bottom, on a spent engine!! The increased displacement of a performance cam will eventually spit your stock pressed in rocker arm assembly studs out. I tricked out the 289 in my 67, cam -crank-performance head rebuid, for about 1,000.

 

[74bronc]

Actually, there is nothing wrong with replacing the cam in a well broken in motor. I have done it many times without problems. You definitely don't want to get to radical with the cam profile, but a nice RV cam would make a big difference in your 302. When you start getting into big cam profiles, clearances such as piston-to-valve clearance must be checked. I put a Crane Energizer 266 in my 302 when it had a gazillion miles on it and it ran for about 4K miles until I built a new 351W. You can get a performace cam/lifter set for about $100.00 and go to town.

 

[Broncobowsher]

You are the one who knows what shape the engine is in. If it is about dead, a big cam can quickly finish it off. But if it is a good engine, a mild cam shouldn't hurt anything. <br><br>Make sure that you follow the cam breaking procedure. Change the oil as soon as you have done the 20 minutes at 2000 RPM. Use the cam lube that should come with the cam, new lifters and a new timing chain.<br><br>While you have the intake off, you may want to take advantage of the new cam with a 4 barrel and an aluminum intake if you don't already have it.

 

[Rustytruck]

Before you do anything wire the carb wide open pull the plugs and do a compression test on all cylindars If the compression levels are all the same within 10 % go for an RV cam and LIFTERS and a new chain and if your truck is a street / trail runner and no high rpm running put the cam in 4 degrees advanced and go play. If it runs extended freeway use run the cam straight up. If the compression sucks and is all over the place save your money.

 

[Benzo]

This is for my 351C. Which is already high RPM engine. I was thinking about putting in a competion cam. <br><br>255 Dual Energy™ is great for low RPM, high torque applications. It will also give good fuel economy. The 255 will have a smooth idle and will work well in an RV or towing application.<br><br>I will check compression first, but none the less since I am changing the timing chain to a double roller, I will at the very least add the 4 degree advance on the cam. I have heard very good things about doing this on cleveland engines. I don't want to force a rebuild and I don't have the space to build out an engine in the mean time. The other thing is, I do not think it is a good idea to add the four degrees advance to the cam if it is an after market one.

 

[wildbill]

8) 8) 8) Putting in a RV cam whould not hurt to much but dont go to a winder or you mite blow the bottom and if you have it open and dont want to rebuild go with new berg rod & main's also new HV oil pump and timming chane and you should be good to go. ;D ;D ;D Bill :

 

[Rustytruck]

In the case of an off road or towing machine where you will rarely go above 3500 rpm adding cam advance makes sence and with a 351C you would be hard pressed to even use the rpm capability unless running Dunes at full speed. Bringing the cam in early will move the rpm band down some and make power where you need it most. On a true hp machine with aftermarket modifications I wouldn't advance the cam since the performance should have been planned for the application. But for the early for stock smog machine it really helps a bunch.

 

[Yellow75]

How much of a pain is it to change the cam without pulling the engine??

 

[75MIKE]

To Yellow75, It's a giant pain to change the cam with the motor in.You still have to pull the intake, valve covers, radiator and the whole front of the motor off. Plus , the biggest pain, you have to unbolt the front grille to get the clearance to slide the cam in straight.After looking at pulling the grille and being hunkered over the fenders working on the motor, I figured 12 more bolts and I can just pull the motor.Trust me , it's easier to pull the motor.Your back will thank you.

 

[74bronc]

[quote author=75MIKE link=board=5;threadid=8727;start=0#63161 date=1031417539]<br>To Yellow75, It's a giant pain to change the cam with the motor in.You still have to pull the intake, valve covers, radiator and the whole front of the motor off. Plus , the biggest pain, you have to unbolt the front grille to get the clearance to slide the cam in straight.After looking at pulling the grille and being hunkered over the fenders working on the motor, I figured 12 more bolts and I can just pull the motor.Trust me , it's easier to pull the motor.Your back will thank you.<br>[/quote]<br><br>I agree with this. I have tried it and he is right. Got mine all torn apart and needed about 1 more friekin inch of clearance at the grill. I ended up cutting one of the grill slats to get it out (the grill was already a POS). I would definitely recommend pulling the motor if you have access to an engine hoist.