Engine tick under load

[Zwap]

New build 383, 030 over, 915 heads, correct preload on lifters, new ignition parts, 12 degree initial and 32 degree total @ 2.200 rpm, 95 octane gas.
I thought it was a exhaust manifold gasket leak but I replaced the gasket and looked at the gaskets i replaced and they are okay and no sign of leaking. I can not find any leaks anywhere in the exhaust system.
It's total quiet at idle or just revving. It has to be under load. Cold or warm doesn't matter, it's ticking under load.
The ticking frequency sounds like one of the eight cylinder cycle.

Any sugesstion?

 

[69monaco]

Flexplate crack.......?

 

[68 4spd Fury]

Bad lifter?

 

[dieseldazzle]

Be careful most rod knocks ive ever heard start only under load then get progressively louder

 

[Davea Lux]

New build 383, 030 over, 915 heads, correct preload on lifters, new ignition parts, 12 degree initial and 32 degree total @ 2.200 rpm, 95 octane gas.
I thought it was a exhaust manifold gasket leak but I replaced the gasket and looked at the gaskets i replaced and they are okay and no sign of leaking. I can not find any leaks anywhere in the exhaust system.
It's total quiet at idle or just revving. It has to be under load. Cold or warm doesn't matter, it's ticking under load.
The ticking frequency sounds like one of the eight cylinder cycle.

Any sugesstion?

Might want to check to see if the heat riser passage under the carb has a good seal to the heads. Also be sure all plugs are in tight.

Dave

 

[Zwap]

Flexplate crack checked, and no crack.
Failed lifter should sound at idle, no more under load.
Heat riser is solid and the plugs are tight, 035 gap NGK V-Power XR5.

Rod knock, maybe but this is more like a tick than a knock, new bearings everywhere.
It has forged piston but they should be more silent when warmed up, there's no difference when warm vs cold.

Next step is to set the timing lower, lets say 5-8 degree and see what i does.

I have only run it about 60 miles to break in the engine this far and it's runs pretty well but has this annoying tick at load...

Any more suggestions?

 

[rexus31]

I had an issue similar to this. It turned out to be the trans dust cover hitting the flex plate. It's worth a look.

 

[Yatzee]

New build 383, 030 over, 915 heads, correct preload on lifters, new ignition parts, 12 degree initial and 32 degree total @ 2.200 rpm, 95 octane gas.
I thought it was a exhaust manifold gasket leak but I replaced the gasket and looked at the gaskets i replaced and they are okay and no sign of leaking. I can not find any leaks anywhere in the exhaust system.
It's total quiet at idle or just revving. It has to be under load. Cold or warm doesn't matter, it's ticking under load.
The ticking frequency sounds like one of the eight cylinder cycle.

Any sugesstion?

I had a '69 442 many years back that had a quiet tapping on heavy acceleration, a bit like solid lifters make, and because it was under warranty I went back to the dealer all concerned. It turned out that what I was hearing was really the valves seating under increased cylinder pressure. They loaned me a Cutlass while they checked out the 442. Damned if it didn't do the same thing as it had a high performance engine as well. Not saying this is your issue but if the tick is consistent in occurrence it may well be. I know from experience that rod knock is low in frequency as the sound travels through thick heavy metal. If the sound is consistent ( occurs on all cylinders and not spuratic ) I would think it's coming from the valve train and my first suspect would be the valve springs.

 

[65sporty]

If the ign timing changes it then it's spark knock and look at your total timing not just your initial timing.

 

[sgtdave]

I had an issue similar to this. It turned out to be the trans dust cover hitting the flex plate. It's worth a look.

Had the same thing as Rexus31.

 

[PontiacJim]

I don't pretend to be an expert on Mopar engines, but if it were a Pontiac, I would suggest to stretch your total timing up to 2500-2800 RPM's with iron heads and see if the later curve might help. It sounds like possible detonation. Also, 95 octane might not be enough depending on your compression. I can say that a factory 10.5 compression Pontiac engine with iron heads needs racing gas or a high octane additive. 95 octane would not work - you would get "pinging" - detonation.

Again, knowing nothing about your build, or the 383 to be frank, I did find this on the web: "If we throw those 915s on a low-compression 400 B-engine, with the stock-type low-compression pistons in the bore, 0.100-inch at TDC, we pick the compression up, but the quench and squish effects are lost. That 0.100-inch (plus head gasket thickness) minimum clearance between the piston and head is prime detonation territory. The same result applies to the 906, 346, 902, 975, and 452 heads, all of which come through with a 0.100-inch recess open chamber. Filling the quench area (welding or metal spraying), or using special quench-dome pistons, has been the solution for engine builders who seek the quench and squish advantages with these open-chamber heads."

 

[max1196]

Is all the ignition components new! Cross arcing dist cap or plug wires, or are they wet?

 

[CBODY67]

The "quench dome" pistons effectively make an open chamber chamber into a closed chamber situation, with more "squish" and related combustion chamber turbulence. David Vizzard states that the optimum piston/head clearance on closed chamber heads is about .020", as if that dimension has some resonant frequency issues with the spark knock/detonation dimension. That might explain why some higher-compression builds aren't noted for spark knock/clatter but 8.2CR engines will clatter with a little more-than-spec timing. In theory, shouldn't be any way a 8.2CR engine would clatter on 98Research Octane fuel (about 93 posted pump octane), but they will.

CBODY67

 

[Zwap]

Thanks for all replies and tips!

PontiacJim, I'm little into that too, the CR is measured to only 9.3:1 but I know that the total come in a little bit early and I've now ordered springs that will fix that. The distributor is a FireCore from Mancini Racing

All ignition components is new and dry plug wires.

 

[livininharrow]

its your clock.

 

[PontiacJim]

Thanks for all replies and tips!

PontiacJim, I'm little into that too, the CR is measured to only 9.3:1 but I know that the total come in a little bit early and I've now ordered springs that will fix that. The distributor is a FireCore from Mancini Racing

All ignition components is new and dry plug wires.

OK, 9.3 should work with the 95 octane gas. Ok on the springs too - you can see how they work once you get them installed.

A few other suggestions which we throw out on Pontiac builds. If you go with a bigger lift cam, sometimes your rocker arms can hit the baffle in the top of the valve cover, or even the valve cover - this is more likely to happen with aftermarket aluminum roller rockers. The solution for some who want to keep the factory chrome valve covers is to install a thicker valve cover gasket (which they make) or an aluminum spacer under the valve cover (again, which they make for this purpose). The other alternative is to go with a taller aftermarket valve cover for the really high lift roller cams & aluminum roller rockers.

Another member had a strange tick coming from his engine and he posted a video of it. It turned out to be a faulty PVC valve rattling (check ball) about .

So just a couple more of the less obvious. The exhaust leak at the manifold to head when the gasket goes bad or the junction at the head pipe and manifold outlet, has shown up a couple times to be the culprit for a ticking noise, but you said yours was ok.

The next thing I would look at is the valve train. I would pull the valve cover and check for the obvious looking for anything loose or out of place. I would get my rocker arms on each cylinder in the fully closed position (no lift/cam on the base circle) and spin each pushrod. You should be able to spin it with some effort/drag with your fingers. You may find one too loose or even too tight - especially if any head/block milling has been done. This will change rocker arm geometry and sometimes a different length/set of pushrods are needed to compensate. I know the rocker arm/shaft assembly can be shimmed if needed, but others will know far better than me. I would also watch the valve train while it was running to make sure all your pushrods are rotating (might get a little messy, so have rags on hand and run it as short as possible, one side at a time with the valve cover off). Lifters (non-roller) will rotate on the cam as part of their design and the pushrods will typically rotate with them as well. If a pushrod is too tight, they generally do not spin.

Just a few more suggstions.

 

[1970cat]

are your engine and trans mounts good. fan hitting shroud?

 

[Zwap]

Thanks again for all inputs and tips!

New engine and trans mounts.
The cam is a mild Lunati 256/262 and the lift is only .454/.475

All suggestions make sense (except the clock )but what bothered me is that it ticks only under load.

I've done and checked a couple of these suggestions but haven't been manage to testdrive yet because of the weather (snowstorm where I live in Sweden right now...)

 

[rexus31]

Thanks again for all inputs and tips!

New engine and trans mounts.
The cam is a mild Lunati 256/262 and the lift is only .454/.475

All suggestions make sense (except the clock )but what bothered me is that it ticks only under load.

I've done and checked a couple of these suggestions but haven't been manage to testdrive yet because of the weather (snowstorm where I live in Sweden right now...)

Did you check the dust cover on the trans? This is exactly what I experienced. All you need to do is pull the cover and inspect for rubbing.

 

[Zwap]

Thanks!
Didn't check that yet, it will be one of the thing I check this weekend.