Can too little compression for a camshaft cause engine heating

[topradman]

How are you getting the RPM signal input, through the 14 wire analog input bundle on the RPM + (Black/White) RPM – (Blue) or using the inductive clamp and the 2 wire connector?

Black wire to coil negative.

[user-23911]

How about photos of the plugs?

That usually works.

Still waiting for pics.



They're going to be black with soot........aren't they?
Pre ignition, then overheating.

[topradman]

How about photos of the plugs?

That usually works.

Still waiting for pics.



They're going to be black with soot........aren't they?
Pre ignition, then overheating.

Did some reading up on plugs w/today's gas ( running 91 pump ). They really don't show much like a lot of forums suggested they wouldn't with todays gas. Little dark on the bottom thread, little dark on the electrode, insulators pretty darn white, no highly obvious "salt n pepper" low on the insulators. After reviewing the info I can find on the 5 gases, all point towards rich, nothing yet points towards detonation ( highest NOx was 400 ) but don't totally trust that info either until I get the AFR's tamed down, then will see. Car is hard enough to work on, especially with engine warmed up (hot under hood) that not practical to run to 3000 ( or any other rpm ) and kill the engine to pull plugs on the side of the road ( unless you think plug readings would be accurate running to 3000 rpm in Park and shutting off? ) so all I can go by is color when I pull it back into the shop, shut off and let cool down, then plugs look as described. I assume that with out any engine load plug colors would be skewed as well?

[Tuner]

How are you getting the RPM signal input, through the 14 wire analog input bundle on the RPM + (Black/White) RPM – (Blue) or using the inductive clamp and the 2 wire connector?

Black wire to coil negative.

I guess you mean Black/White? Did you try that with the Blue connected to ground? You might try a length of resistance plug wire in the + Black/White.

[topradman]

How are you getting the RPM signal input, through the 14 wire analog input bundle on the RPM + (Black/White) RPM – (Blue) or using the inductive clamp and the 2 wire connector?

Black wire to coil negative.

I guess you mean Black/White? Did you try that with the Blue connected to ground? You might try a length of resistance plug wire in the + Black/White.

Had one of my techs hook that up and you are correct, black/white ( wire was extended to reach coil negative ). I did not try with blue connected to ground as Innovate didn't tell me to try that. Should I?
Length of resistance plug wire meaning in line on the end of the black/white?

[Tuner]

Yes, ground the Blue wire and add some resistance to the Black/White with a resistance plug wire. It isn't the same as the Innovate instructions about using a variable resistor pot with the center terminal grounded (as shown in Innovate LM2 instructions page 41, Section 6.8, Attenuating a Tach Signal), so I don't know if this will help, but it can't hurt. Maybe you can approximate the VR with two high resistance wires, 10,000 + Ohm each, and ground the connection between them, What the RPM Input wants to see is a simple high/low voltage pulse without being overloaded with coil primary flyback ringing.

From the Innovate LM2 instructions (you did read them, didn't you..???), page 31.

5.1 RPM Input
The LM-2 has a direct tach signal input signal. This input can be used to feed a signal
from the negative lead of a coil, ECU, negative lead of an injector, or ignition box (i.e.
MSD 6AL). This tach signal can be feed to the RPM + (Black/White) wire. The negative
wire (Blue) can be connected to ground if a tach signal is not being registered.

[CharlieB53]

I keep coming back to the fuel boiling issue. With an air gap manifold boiling the fuel before the engine reaches temps of 240 I seriously suspect there is a problem with sufficient air flow through the upper area of the engine compartment. This is why I made the suggestion of raising the hood somehow and re-testing. Allowing air flow should make a huge improvement in fuel temps in the carb. If this proves out only then would I suggest punching Louvers in the hood.

A second contributor may be the strange exhaust header system radiating heat into the compartment.

Would having those headers coated reduce radiant heat? Thus reducing some of the compartment heating that may be contributing to the fuel boiling problem.

I cannot believe too much cam can be the root cause of these problems.

[MadBill]

X2
Header coating would certainly help, but I don't see it as a silver bullet. Removing the hood to verify exit air flow (however tricky the process) is just about the last substantial possibility...

[GARY C]

Ok, yeah it's me and still fighting a heating problem. 461 BBC, GM iron open chamber oval port casting #14092359. I cannot find any info on chamber cc's for this head anywhere and engine is assembled. Has flat tops w/only 2 intake valve reliefs per piston, gaskets 0.027 thick x 4.320 hole size. If chambers are around 113cc @ zero deck height I guesstimate CR around 8.9:1 but if chambers are around 118cc, maybe 8.4:1 CR. Nearest I can tell from trying to degree the cam w/engine assembled in the car ( using pushrods for measuring and has hydraulic lifters so don't totally trust readings to be on the dime ) specs are about 109 lobe separation, about 229 @ 0.050 intake/exhaust duration , 0.544 valve lift intake/exhaust which specs out pretty close to a Lunati 10110424 camshaft.

These small open chambered oval heads #14092359 still have 2.06 intake/1.72 exhaust valves. Question being, with this potentially low CR ( chamber cc ??? ), could this camshaft cause this engine to struggle getting exhaust out of the cylinder head or have possible valve intake events that could encourage an overheating problem at sustained cruise rpms of around 2600 or so?

I can jack up the ignition timing to around 44 btcd base (!!!) and get her to cool down wonderfully at 2600 rpm sitting in the shop but do not want to drive her this way. I advanced the CAM timing up 4 degrees and backed the ignition timing back to 16, then 14, then 12 btdc but it didn't help much so I have the cam timing back to straight up now and after going through the in the car degree process, the afore mentioned cam specs are what I came up with for straight up cam timing.

Thoughts on this cam for this engine with potential low CR causing heat??
Anyone know for sure what cc this head chamber is?? ( looked everywhere for hours )

So you found the problem but you refuse to use the solution?

[In-Tech]

I would do mechanical advance of 28 initial, 38 total and then another 10 degrees vacuum advance. Problem over. Still fix the carb tune so it's nice to drive and that extra fuel in the pipes aren't helping your EGT's along with retarded timing.

[rp930]

I would do mechanical advance of 28 initial, 38 total and then another 10 degrees vacuum advance. Problem over. Still fix the carb tune so it's nice to drive and that extra fuel in the pipes aren't helping your EGT's along with retarded timing.

Sounds reasonable to me.

[GARY C]

I would do mechanical advance of 28 initial, 38 total and then another 10 degrees vacuum advance. Problem over. Still fix the carb tune so it's nice to drive and that extra fuel in the pipes aren't helping your EGT's along with retarded timing.

Yes, you could always add a low dollar timing retard box if the engine likes more down low then you can adjust out with dizzy alone.
Normally running an adj vac advance on full vac so it becomes a vac retard will suffice.

[Abbottracingheads]

When the fuel is burning in the exhaust port instead of the cylinder it will run hot. Had a race engine that got winged to past 900 from a dyno malfunction. It cranked and ran and still sounded fine. Put it in the car and it would get way too hot too fast. After checking found that all the exhaust valves were bent. Fixed the heads and the cooling issue went away. With too low compression for the camshaft your dynamic compression ratio is too low. When it is rich running down the highway it is burning the fuel in the exhaust ports. Either change the cam, or better yet angle mill the heads and get the compression up. With the compression it will run much stouter and more efficient. The excess ignition timing is crutching your condition and is trying to tell you something.I would mill the heads.