Old tricks to determine if Cam has been upgraded

[Tim Chavez]

Hey Gents,
I’ve been struggling with getting this car tuned enough to idle for some time now. I’ve feel like I’m getting somewhere finally and got it sitting at around 800 rpm with no choke but it sounds strange. My buddy said it might have a cam upgrade but I don’t know enough to tell that by the sound without it being some ridiculously large “shoes in a clothes dryer” cam. I’ve got a video from my YouTube channel embedded. Maybe you guys can help? The timing also seems EXTREMELY finicky leading me. Let me know what you guys think.
Upgrades*
HEI distributor
100,000 coil
Plugs,
Wires
Edelbrock carb rebuilt
Long tube headers
Freshly rewired engine harness
Timing claims it’s at 18 initial around 30 at rpm

 

[69 GTX]

Just listening I would say yes!

 

[wyrmrider]

you can easily check the lift on the In and ex retainers, when you are looking what heads?
check the compression
what motor?
some pay extra for that sound

 

[Tim Chavez]

you can easily check the lift on the In and ex retainers, when you are looking what heads?
check the compression
what motor?
some pay extra for that sound

It’s a 1970 340 with J heads

 

[oldbee]

Just listening I would say yes!

+1.....

 

[Tim Chavez]

This is what I mean by finicky timing. I twisted the distributor to advance the timing just a hair and that’s what it does

 

[khryslerkid]

I'd double check your firing order. Make sure you don't have a plug wire burnt through or shorted.

 

[Tim Chavez]

I'd double check your firing order. Make sure you don't have a plug wire burnt through or shorted.

Firing order is good. Plugs and wires are new. If I retard the timing back it will wrap the tach but doesn’t want to start

 

[Paul_G]

Is the idle mixture adjusted properly? Make sure there are no vacuum leaks.

I would take a good look inside the distributor. Check the advance springs, cams, and make sure nothing is broken and it all moves freely.

 

[burntorng70]

Take off the valve covers and check rocker movement. It may have a wiped cam lobe.

 

[Tim Chavez]

Is the idle mixture adjusted properly? Make sure there are no vacuum leaks.

I would take a good look inside the distributor. Check the advance springs, cams, and make sure nothing is broken and it all moves freely.

Idle mixture should be good, about 1.5 turns out give or take. The distributor is new and seemed to function properly when installed.

Take off the valve covers and check rocker movement. It may have a wiped cam lobe.

I was ruled out mechanical damage because it will rev smoothly with the timing retarded but it will not start quickly

 

[Paul_G]

Take off the valve covers and check rocker movement. It may have a wiped cam lobe.

That is a good idea. You can also determine if there is an individual cylinder problem like a mis fire or a valve problem with a laser infrared thermometer if you or a friend has one. Scan each header tube. They should all be close to the same temp, if you find a cold one look at that cylinder first.

 

[Tim Chavez]

That is a good idea. You can also determine if there is an individual cylinder problem like a mis fire or a valve problem with a laser infrared thermometer if you or a friend has one. Scan each header tube. They should all be close to the same temp, if you find a cold one look at that cylinder first.

Haven’t done anything scientific but all tubes feel like they have the same heat. One minor thing with this engine also is the amount of crank pressure. I initially did not have a PCV hook up on the valve cover just a vent and I kept shooting the dipstick out and spraying oil on the pass side of the engine. Swapped the vent for a PCV valve and that seems to have fixed that. Didn’t know if that meant anything special.

 

[Johnpat]

If you know someone with a Sun machine
Have them scope it
I was a Sun diagnostic tech,should be able to
see the problem with cyl kill feature & scope.
Also check coil output,may be weak??

 

[Tim Chavez]

If you know someone with a Sun machine
Have them scope it
I was a Sun diagnostic tech,should be able to
see the problem with cyl kill feature & scope.
Also check coil output,may be weak??

Hmm hadn’t thought about coil output. I did just re wire the ignition/charging harness could have left those connections too loose I’ll go there bext

 

[oldbee]

That is a good idea. You can also determine if there is an individual cylinder problem like a mis fire or a valve problem with a laser infrared thermometer if you or a friend has one. Scan each header tube. They should all be close to the same temp, if you find a cold one look at that cylinder first.

Maybe you have an exh.valve not opening?

 

[Jackpot50]

Does it have electronic ignition?
Did it do this before wiring?

 

[Tim Chavez]

Does it have electronic ignition?
Did it do this before wiring?

It’s HEI now. It wouldn’t run whatsoever before I replaced the distributor and ignition system. After I replaced it I’ve had it driving but never easily (lots of keeping slight throttle and fiddling to keep it running). I rebuilt the carb and have been fplaying with timing ever since. and that’s where I’m at now. It seems like if I have the timing set one way it starts without issu but pops and backfires with any throttle. Set it the other way and it takes 30 seconds to a minute of cranking to start But will wrap the tach well over 5500. Both posted videos are at the same timing setting.

 

[Johnpat]

Sure you don't have distributor tooth off or so??

 

[Tim Chavez]

Sure you don't have distributor tooth off or so??

Pretty sure.(I kept reference points and kept the motor at TDC on cylinder1 when I did it) Also It’s a blade not a gear wouldn’t that mean it can only be in 1 of three positions? In, out and, and 180. right?