could cam be wiped but are lifters ok?

[crm318]

i just put together a 350 and i got it up and running. the engine idles fine but only bogs when i drive it over 35 or try to get on it. the carb is also new and its vortec heads are new. everything is new and the timing is set good as well. i took all of the lifters out and the all look good. is it possible that the lifters be alright by the cam be slightly worn?

[manimal]

Did you mark what hole the lifters came from? If you think the cam is flat, then replace them both. DONT REUSE USED LIFTERS ON NEW CAM!!!!
-Lance

[jhow66]

Need more info:
1--time set at what?
2--new carb-used-rebuilt?
3--bogs above 35-how? (when you step on it or just cruising?)

[jsbgump]

Never re use lifters on anything.

[chipflyer]

You can reuse them if you want to go through the same problem again in a couple months.
No, do not reuse them!

Jeff

[Overkill67]

Also check that the vacum advance is working properly. Points or HEI? What is the cfm of the carb?

[crm318]

i realize that this post may make me seem like i dont know about the do and donts about cams. i know that you cant reuse lifters. i have all of the valvetrain on a tray to fit back into the assigned lifter bores. it just seemed that the cam might be wiped by the way it was acting. the engine is a vortec headed 350 with a newly rebuilt quadrajet, new accel HEI distributor, timing set at 10 degrees (have experimented with diffrent settings). it accelorates up to 35-40 nicely under cruising conditions. after that it starts to run rough. full throttle is out of the question. the lifters look great so i assume that the cam is ok. when i get it buttoned back up, i plan to take the quadrajet off of my running truck and put it on to see if its a carb problem. could it be unadjusted valvetrain? i tried to do the hose in ear adjustment but it seemed that there was a slight ticking on all the rockers no matter how much i tightend them.

[albertarose]

ttt move to top so next viewer sees first ?

[albertarose]

you need new lifters for your new cam...anyone else ?

[bryanw1968]

The problem doesn't sound mechanical. Are you running roller tip rockers?
If so, they're just going to be noisey no matter what you do. Also, certain cams that are very aggresive slam the exhaust valve down hard and it will make the same "loose rocker" noise.

What cam are you running? 10 degrees may not be enough timing. Also, there is a good chance that your vacuum advance may not be right. Which port on the carb do you have it hooked to? It should be connected to the port that has NO vacuum at idle. Otherwise if you have it connected to constant vacuum it will be pulling timing into your initial timing.

Got any pics?

Good luck,
B

Originally Posted by crm318

i realize that this post may make me seem like i
dont know about the do and donts about cams. i know that you cant reuse lifters. i have all of the valvetrain on a tray to fit back into the assigned lifter bores. it just seemed that the cam might be wiped by the way it was acting. the engine is a vortec headed 350 with a newly rebuilt quadrajet, new accel HEI distributor, timing set at 10 degrees (have experimented with diffrent settings). it accelorates up to 35-40 nicely under cruising conditions. after that it starts to run rough. full throttle is out of the question. the lifters look great so i assume that the cam is ok. when i get it buttoned back up, i plan to take the quadrajet off of my running truck and put it on to see if its a carb problem. could it be unadjusted valvetrain? i tried to do the hose in ear adjustment but it seemed that there was a slight ticking on all the rockers no matter how much i tightend them.

[crm318]

the cam is .440/.440 212/212. i meant to say that ive run it with as high as 14 degrees and as low as 10 degrees.

[crm318]

i dont have any pics right now because the top half of the engine is off. i will take a few pics when i get it all back together.

[bryanw1968]

Originally Posted by crm318

i dont have any pics right now because the top half of the engine is off. i will take a few pics when i get it all back together.

Do you remember how you had the vacuum advance hooked up to the carb?
What kind of vacuum are you reading at idle? With a cam like that you should have over 15 inches at idle.

[seanu]

Sounds like a carb problem to me...had something similar when I put to much carb on a SB 350 I had...

It seems to me that if it was a cam or lifter problem..since they are completely mechanical..that it would be present at any RPM and at any speed...that fact that it is only under certain curcumstances...makes me think carb..or possibly spark.

just my .2¢

[riche]

I would lean towards the carb, fuel pump or filter. If a cam lobe was wiped I would have expected you to complain about backfires or running on after the engine was turned off. The only other thing that bothers me is this comment

"could it be unadjusted valvetrain? i tried to do the hose in ear adjustment but it seemed that there was a slight ticking on all the rockers no matter how much i tightend them"

If you suspect the valvetrain adjustment I would seek a good valve adjustment procedure to eliminate that variable. I have never used a hose in my ear to set valves. There is always ticking, but there is a distinct difference between clacking and ticking.

[Billla]

Originally Posted by crm318

i just put together a 350 and i got it up and running. the engine idles fine but only bogs when i drive it over 35 or try to get on it. the carb is also new and its vortec heads are new. everything is new and the timing is set good as well. i took all of the lifters out and the all look good. is it possible that the lifters be alright by the cam be slightly worn?

When you say "put together" you mean overhauled?

If the idle is fine, I wouldn't suspect a worn cam lobe right away. It happens during break-in, but not all that commonly. I would double-check the valve adjustment, then look at the ignition and timing and finally the carb.

[bryanw1968]

Originally Posted by Billla

When you say "put together" you mean overhauled?

If the idle is fine, I wouldn't suspect a worn cam lobe right away. It happens during break-in, but not all that commonly. I would double-check the valve adjustment, then look at the ignition and timing and finally the carb.

Right, timing first, then adjust carb.

What do your plugs look like by chance and what plug are you running?

[crm318]

plugs and wires are new. the plugs are autolite 25s. i have heard that vortec heads take a specific plug, but i use the same autolites on all my small blocks.

Just to clear a few things up:
1. The carb is a 750cfm Q-Jet rebuilt recently, and run successfully on another motor for three months.
2. The fuel pump is electrical due to the year of the short block. The short block is out of an 89 silverado, and is rebuilt. I usually have shortblocks that take mechanical fuel pumps, but this is a first. My fuel pump is new and pumps at 4.5 psi.
3. There is an inline fuel filter placed before the fuel pump, and mounted at the tank as directed.
4. The HEI, plugs, wires, coil, etc are all new.
5. Now that the cam and lifters look ok, I'm going to readjust them properly, and... I'm not sure what the next step is.

To retract my prior statement, the vehicle bogs and sputters any time it is driven. When gas is given, it bogs and sputters. More when more fuel is delivered, but it's constant unless left at an idle.

[rage'nrat638]

yes vortec heads require a longer threaded plug or the plug is firing in the threaded hole and
not in the chamber where it's supposed to be

check the vortec's what to know in the FAQ section for the correct plug from AC DELCO that may be your problem

http://67-72chevytrucks.com/vboard/s...ghlight=VORTEC

Special Spark Plugs For The Vortec Heads
R44LTSM, set of 8
MR43LTS, set of 8
P526S Accel U-Groove “SHORTY” Double Platinum Header Plugs approximately 3/16" shorter then R44LTSM plugs, set of 8

[crm318]

Which plug is suggested. I see three listed. Let's rule out the accell plugs because spacing is not an issue. So...
R44LTS?...or...
MR43LTS?

[rage'nrat638]

this is what i am running R44LTSM

m stands for metric

went outside and took a picture

[rage'nrat638]

picture

[gator2511]

When I set my timing at 10 BTDC the truck runs ok but when I hook it to the full vacuum port on the carb and let it sit at 20 BTDC at idle it has much better throttle response and runs great. Right now I'm at 8 BTDC initial and full vacuum port and I have a total of 38 Degrees of advance at 3000 rpms. As you accelerate the vacuum goes down and the vacuum advance drops off as the mechanical starts cutting in. I'm not saying that is your problem but its easy to switch the vac can to the other port and see what it does.

[crm318]

This may be a dumb question, but I have to ask. I picked up a set of R44LTSM plugs today, and they're all pre-gapped to 40. What is the appropriate gap for these plugs? I just want to get it right the first time.