engine bogs

[slammed70gmc]

yea I know this is a common question. Ok my 350 has been bored 30 over, 488 cam, intake headers, double humps, edelbrock fuel pump, and edelbrock 650 carb. My only problem is that it bogs and sounds like its got a rev limiter when it hits 5200. The motor should be able to turn more and it sounds like it wants to. My timing is set at 8 degrees. Should I try a smaller carb. Any ideas would be great.
THANKS!

[crazy longhorn]

I doubt the carb is too big, if you are running a stock type HEI, you might try bumping the timing to 12 degrees, & see how it acts. A little more info on cam specs, dist, & fuel pump pressure would help sort it out....crazyL

[caminokid]

Originally Posted by crazy longhorn

I doubt the carb is too big, if you are running a stock type HEI, you might try bumping the timing to 12 degrees, & see how it acts. A little more info on cam specs, dist, & fuel pump pressure would help sort it out....crazyL

I agree with this too. If you are using the 1405 or 1406 carb...it good enough for a small block.

[Billla]

I suspect an ignition problem - it's definitely not the carb unless you've got a sticking choke.

First, ensure the throttle linkage is opening the carbs all the way - have someone floor the pedal and then look down the carb and see that the primaries are all the way open.

Next wires - you aren't running wires that have the carbon strings in them, right?

Finally, ignition and advance; many good references but basically you're looking for 32-36 degrees total mechanical advance by 3000 RPM.

If you're still not getting those R's after all this, post back.

[slammed70gmc]

Ok Its hei with accel cap, rotor, super coil, and spiral 3000 wires. I can't really check total timing because i don't have a wrap around tape.
cam specs Operating Range 1500-6500 RPM
Duration Advertised 308° Intake/318° Exhaust
Duration @ .050'' 234° Intake/244° Exhaust
Lift @ Valve .488'' Intake/.510'' Exhaust
Lift @ Cam .325'' Intake/.340'' Exhaust
Lobe Separation Angle 112°
Intake Centerline 107°
Intake Timing @ .050" Open 10° BTDC
Close 44° ABDC
Exhaust Timing @ .050" Open 59° BBDC
Close 5° ATDC
THANKS!

[Troy-Built]

That looks about the same specs as the Performer RPM cam. That cam never quits pulling.
I am sure you know better but don't hold wide open while it's running to check the throttle linkage.
How are the valves adjusted and what kind of lifters are you using?

[crazy longhorn]

HEI dist, if you go 14 up on the timing @ idle, you will be right @ 34 total. You need a timing tape on the balancer to check the "all in" spot(2800-3000 rpms).....then a little added to the vacumn timing(10-12 degrees, hooked to a full vac source @ the carb). crazyL

[joedoozer]

I know this might sound like I am stating the obvious but.......what about the float bowl level? You could possibly be running the bowl empty because of improper level, or a float with a hole in it. Being that it doesn't happen until higher RPMs. Just my 2 cents.

[Blackbird66]

I agree with crazy, I think the timing is too low. I would go for 12-14 at idle. My timing light was not that expensive from autozone, and you can set advance with it. No need for extra timing marks. After my last new high performance damper came apart with less than 500 miles, I switched to a GMPP, with only a single timing mark.

[Troy-Built]

As far as timing goes, make sure the vacuum advance is working. Also look at your weights under the rotor to make sure that they move freely.

[slammed70gmc]

It is the edelbrock cam and lifters. The vavles were set by the machine shop. I'm gonna try to set the timing tommorow after work.
THANKS!

[heavy70]

do you have aftermarket valve springs? If they are stock you could be floating the valves, or a number of possibilities.

[slammed70gmc]

Well this is alittle weird. I set the timing to 12 and it made it worse and it felf like it had a miss at all rpms.
THANKS!

[crazy longhorn]

That is odd, usually bigger cams like more initial timing. It could be that your balancer & pointer marks dont match, or the ring slipped on the balancer. How does it act if you go the other direction(say 6 degrees up)?

[crazy longhorn]

Had another thought.....pop the dist cap off, & give the rotor a twist & let go. Does it snap back into position, or feel stuck in 1 spot?

[slammed70gmc]

The rotor is not stuck and I'm pretty sure the vacum advance is working because I can put vacumm to it and it will work. I haven't tried going back to other way yet.
Thanks!