What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Edelbrock Cam Please Help???

P

pseudomike

1/2 ton status
Joined
May 11, 2007
Posts
726
Reaction score
0
Location
MA
Hi guys:

Having somewhat of a headache here with an Edelbrock camshaft. I have a buddy that I'm trying to help out and I'm about ready to pull my hair out.

Here is the story...the guy has a 91' Blazer with a 350 TBI. It was a little tired so he picked up a used core motor and went to town rebuilding it. While he was in there he bought an Edelbrock performer cam kit and intake (he had a guy burn him a chip for the setup). Otherwise the motor was stock. I gave him a hand last weekend swapping the motor in, plumbing it up etc. We went to start the beast Sunday night and....pretty much nothing except a bunch of popping, farting, and flooding. It was late so we quit and sat on it for a day. I went over a couple times this week and played around with it. First thing I tried was rotating the distributor 180 degrees thinking he had it on #6 instead of TDC when he dropped it in...no dice. Next, I figured maybe he set the valve lash wrong if he was on #6 instead of TDC...so I set it a couple times, swapped the distributor..back and forth....again no dice. At that point I started looking at how the valves were moving..especially cylinder #1. After #1 comes up for compression stroke the exhaust valve opens..I could feel a suction in the plug hole...seemed wrong. I'm not an engine expert...but...we had fireballs coming out of the TBI about a foot in the air so I have a hunch something ain't right. At that point I decided that he must have set the timing marks on the cam incorrectly. He was pretty certain he lined them up....and it shouldn't matter if he was on TDC or #6...i think? Just the same we tore it apart, and sure as #*&@ they were lined up. I played with them a little bit, inspecting the TDC location on the balancer, valve location, and distributor location. According to everything I have ever seen, and according to all the manuals this baby is set up correctly.......but we have foot tall fireballs out the TBI.

So I went checking on the internet and found on the Edelbrock website that they reccomend their own #7800 timing chain kit for this particular camshaft. He used an clevitte OEM replacement or something of the like. I then went and found the intructions for the timing set they called for and it specifically states that it is not for an OEM camshaft setup. I am guessing this is the problem? PLEASE!!!, if anyone has run across this let me know. I ordered the kit from Advance for tommorow morning and am praying it fixes the problem. It makes sense I just can't understand why anyone would make a cam that required a proprietary timing chain set?? Seems funky but I hope it works.. If anyone has insight please let me know....I just hope he didn't bend any valves up now if the chain is the culprit.
 
What part # is the chain you ordered?
 
There are several other things which can cause this, major vac leak, crossed plug wires...check these closely first. The fire order should be in your manual, but is 18436572
 
Cam part # is 2102.

I've checked the firing order about 10 times. 18436572...got it memorized.

Pretty sure there is no vac leaks...but seriously we aren't getting anywhere near the RPM range to notice them. This thing barely fires...and when it does fireballs about a foot high. It has yet to continue turning over without starter assist if you know what I mean.
 
Did you set the valves according to the cam card? All the wires plugged in the correct place and fully seated? All ground wires attached to the motor, no missing plugs in the intake or the brake booster hose not attached?

Mine is using a non-Edel chain. Have also used non-edel chains on their cams before, non-issue.
 
I didn't have a cam card to work with. I set the valves like any other 350 hydraulic lifter setup i have ever messed with. Second time around I set the lash loose figuring I could dial them in once it was running...also thinking the intake valve would have to be open for fireballs to shoot out the intake?

Wires are plugged in. New plugs, new wires. We aren't talking about skipping or running on 6 cylinders....this thing is a ways off from that. I'm fairly sure all the ports not used are plugged up. I can check once there is daylight..but fairly sure. This truck has a hydroboost setup so no brake booster issues.

Ground straps are in tact. I had to jump it with my truck after a but and did so with the ground right to the block.

I'm not really sure whats going on/ I fthe chain doesn't help I'm going to try swapping the distributor for a spare I have kicking around. Not sure what else to check. I think we have checked all the obvious things?
 
I hope you find a missing plug on the back of the intake. Doesn't sound like the timing chain should be the problem.

When I have had these issues, it was almost always a vac leak. I have even experienced the much dreaded internal leak, where a guy can't use the carb cleaner trick to find it.

Did you set the timing at dead zero first?

Intake sealing properly on the heads? Spit a gasket out when the intake went on?

(sorry, ment which chain are you using now, you gave me the edel #. Still shouldn't matter)
 
I'm not sure which chain he is using now other than it was a NAPA bought OEM replacement. He's been building it up for a while and most of the original boxes are gone.

I' left it with the timing cover and valve covers off for tommorow. I have a factory chain set out of another LO5 block that I am going to match the EDL up to to see if there really is a difference. I'll post pics if there are. The cam installation instructions have a big warning that if a stock timing gear set is used you will have to dial the cam in. I wouldn't imagine it being more than a few degrees in which case the thing should still start. It's not even close...it's so ar off that it will even nearly stop the starter after it fires. Something is definitely wrong.

I will tripple check for vaccum leaks tommorow. The intake looks like it is seated good. Hard to tell now that it's in there with a rats nest of TBI sensor and wires. It ws a brand new intake, fresh block, and Felpro gaskets. This guy has built a bunch of motors too which leads me to believe it's on there right. You never know.......

I've never seen a vaccum leak do what this is doing. I've played with this type of stuff pretty much my whole life and never seen anything quite like this. Far from an expert...but I simply don't think it's reaching an RPM where vaccum has any effect. It really isn't even fring.


Also don't understand why the exhaust valve is opening right after TDC? Understand it needs to open to let the spent air/fuel out but it's doing so in the suction/downstroke. I don't the finite details of it's rotation but it seem to me that exhaust should be on an up/compression stroke.... meaning the cam is either advanced or retarded like 45 degree (would have to think about that for a bit and it's late). My thoughts.... exhuast valve opens on a compression stroke on #1, closes, then intake opens on downtrokes (air & fuel enters), then compression stoke TDC, then downstroke (power/combustion), then compression stroke with exhaust valve open and so on. Thats 4 stroke/cylce right? If the exhaust valve is opening after TDC then there is a problem right? I might be way off. Not really sure?
 
The timing set will not matter in this case (but i'll bet the set they recommend has an advance built into the gear).

When you lined up the DOTS were they DOT to DOT? If so then you need to rotate the engine one revolution to get it on #1 cylinder TDC. When the DOTS are lined up that is #6 cylinder TDC but it makes it easier to line up the marks.

Next are you sure that the wires are in a clockwise rotation on the distributor cap?

Have you pulled the distributor cap and verified the rotor location while the engine is on #1 cylinder TDC?

The cam he got didn't happen to be a 4-7 swap cam was it?

Last thing, i'm sure you know which cylinder is #1 but just in case there is any questions it is driver side front cylinder.
 
dumb question. could you have a 305 damper on a 350.
 
Like Scott said about the timing gears is critical, I always used a soap stone and ruler to double check the alignment.

Make sure that #1 piston TDC is matching the TDC reading on the damper
 
Ok, well we got it going.

The marks on the new EDL timing gears looked identical to the OEM set (other then the advance/retard options). Buttoned it together and it fired right up. I'm not convinced the gears were the culprit and it's probably more along the lines of we corrected something with more sleep and a watchfull eye. None the less, the truck is running and idling good. I still need to re-adjust the valves as there is one noisy lifter, but I will probably do so once it cools down.

Thanks for all the help.
 
You must log in or register to reply here.

Latest Posts

Top Bottom