When replacing a camshaft on a 4.3 vortec do you have to take the heads off or the intake do be able to pull the lifters?

 

I don't think you have to pull the intake to pull the lifters, but I always do that so I can have room. When I rebuilt a 4.3 at my school a few months back, we just took the valve covers off, then we unbolted the rocker arms, and from there the we were able to pull the lifters and push rods.

 

You will need to get the intake out unless you want to drop the lifters down into the block.. There are not retainers that will hold onto the lifters like on some newer engines.

The heads can stay installed when performing a cam swap.

 

I just completed a Cam swap on a 95 4.3L Vortec and removing the intake manifold is a necessity to remove the lifters, lifting the heads is not needed for a cam swap. After the intake manifold is out of the way the valve covers are much easier to remove.

I installed a mild street cam purchaced through Comp Cams with new lifters. I lifted the heads only because I had three weeks to wait for the Cam I ordered to show up, I gave them a good rebuild and found two bad intake seals and pitted exhaust valves after 160K kilometers. The cost of a whole top end seal and gasket set was $30 more then just the intake and plenum gaskets that you will need to do the job anyways.

Here's where I might need some help from a more experienced mined in this area, The truck starts well, sounds great with no lack of power, it idles a little rougher, but is to be expected with a larger cam. My problem is that my check engine light is now on and wont clear, my Blazer is a 95 and dosn't seem to communicate with an OBDII code reader, maybe an OBDI code reader will work but is hard to come by. I've been disconnecting the negative terminal for 5 min to try to clear it but keeps coming back.... I'm looking for ideas here. All the vacume hoses and plugs and wires have been double checked.

Another problem is that when only loading the engine to 5%-10% the engine seems to surge/buck when crusing at any steady speed in town or on the highway, almost like it wants to go fast or not go at all. the spark plugs are new and I've installed a new distributer cap and rotor, ohmed out the coil pack thinking it could be a missfiring cylinder but hasn't changed a thing.

Any help on working out the kinks would be appreciated.

 

You need to find a scan tool capable of reading your vehicle. You have the OBD1.5 setup (not quite full OBD2, but not OBD1 either). It takes a scan tool with the proper programming to read your codes.

I'd bet that the PCM is not liking the cam and freaking out.

 

I have the problem solved now. I got my hands on a scan tool, plugged it in and had the same problem. Checked the fuse box and and found my problem with a blown fuse....After I finished kicking myself, I found a Cam shaft positioning sensor code. The distributer was 23.5 deg off ,(one tooth off). After I popped the distributer and jumped it one tooth forward the engine is running like it has never ran before, with no engine light.

According to the timing procedure, when the engine is at TDC the rotor should point at the "6" marked on the distributer or a degree or two off (EDI distributer), I guess that's not the case. About 20 deg clockwise of the "6", or straight horizontal looking at it from the front of the motor was the answer for this guy.... I hope I'm not the only one that has ever had that simple to fix problem.

 

I spent all that time re-building the top end, making sure everything was perfect, in the end I get burned with a blown fuse and bad ignition timing.... I'll take it as a lesson learned. Total cost for everything to do the job was $900 canadian.... Burning donuts at work and blowing a valve lifter taking out the cam, then having to do a re-build of the top end in the parking lot while it's blowing snow all January is priceless.... Lets just say that it was the most expensive dozen donuts I ever bought.

 

I'm very frustrated with my 2000 Siverado single cab, shoebox, 5 speed with the 4.3. The original engine that I had rebuilt wad done by somebody that probably shouldn't call themselves a mechanic since after buying every performance part for the build he didn't think it was important to have the crank turned.Needless to say I had to boat anchor that motor low km motor installed and after many more visits to various mechanics and huge expense (including the $140/hr GM dealership) it was finally discovered that the plastic part that sits on top of the throttle body (not sure what that is called) was from an S-10.
So over 3 weeks and $1500 price tag from GM to diagnose the problem and supply a used throttle body plastic piece and map sensor I thought for sure the problem would be resolved but to my chagrin it still has no power. Now I realize that we're talking about the V-6 but I had the same motor in a 1998 Safari and it had lots of power (loved that van) and a shortbox single cab PU is probably considerably lighter . Even the original super high km motor that was bagged out seemed to have more power ( if I remember correctly). It's been so long since I've driven the truck without disdained and regret for not giving up on it thousands of dollars ago but the wife and I both really loved that truck (not to mention the sheet metal was almost perfect for a twenty year old truck) Anyways I was intrigued about the blown fuse possibility for the cam sensor and the horizontal position of the rotor in relation to the front of the motor which is twenty degrees clockwise instead of pointing at six. I apologize for my lack of mechanical knowledge and speech (it's all Greek to me) I really miss the days of simple carberated motors instead of computer controlled crank and camshaft engines (and we're talking about technology thats already more than twenty years old. Anyways at this point I just want to solve this riddle and move on so any advice or help .provided would be enormously appreciated.