Indy Cylinder Head 451, oil pan to Demon Carb won't run after about 2 hrs of use.

[oilstrike]

Hello All,

I need help, I can't figure how to fix my ICH 451. When I start it, it won't idle, I have to feather the gas for about 10 minutes, it will idle at about While running at highway speeds all is good for the first hour or so. Coming off the I64 exit onto a local road she idles up to 1500 rpm, and will not idle at 800 rpm. In stop and go city traffic she will overheat, but quickly cools down when able to move. After about two hours of use it wants to die, almost like it's running out of gas. After she rests for 4 to 5 hours it's good for another two hours. Any help is appreciated.

Regards,

Johnnie

 

[jason lewis]

Check float levels,timing,valve lash that is set for the type of cylinder head material.You may need a fan shroud.Or bigger radiator.The fuel may be percolating in the carb because of heat.Is the fuel pressure to low?

 

[ozymaxwedge]

Try another carb or get a carb guy to tune, sounds like it is lean as down low and maybe retarded on the timing.

 

[IQ52]

Which Demon, what jets are in it? What intake manifold and how did you seal it when it was installed? Which Indy heads and were they prepped before installed? Did you check to make sure the the intake was flush all around with the heads before bolting it down? What compression ratio? What cam is in it? How is the cam timed? Like Jason says, lash or preload? What distributor and how is it timed? What size radiator, fan and shroud? What fuel pressure are you running at start up and cruise? How's the engine vacuum?

Could be just low tire pressure and chrome rims.

Or maybe not.....

 

[oilstrike]

Check float levels,timing,valve lash that is set for the type of cylinder head material.You may need a fan shroud.Or bigger radiator.The fuel may be percolating in the carb because of heat.Is the fuel pressure to low?

The fuel levels are good, the complete engine is ICH oil pan to carb (including the distributor). The radiator is a 4 row aluminum cooled with a large electric fan. I'm not sure about the fuel pressure. I'll check.

Regards,

Johnnie

- - - Updated - - -

Which Demon, what jets are in it? What intake manifold and how did you seal it when it was installed? Which Indy heads and were they prepped before installed? Did you check to make sure the the intake was flush all around with the heads before bolting it down? What compression ratio? What cam is in it? How is the cam timed? Like Jason says, lash or preload? What distributor and how is it timed? What size radiator, fan and shroud? What fuel pressure are you running at start up and cruise? How's the engine vacuum?

Could be just low tire pressure and chrome rims.

Or maybe not.....

It is a 750 Mighty Demon, the fuel levels are good. The complete engine is ICH oil pan to carb (including the distributor), Indy performed all of the mechanical work. It has a big cam not sure of the spec's, the vacuum is low to none (like I said a big cam). The radiator is a 4 row aluminum, cooled with a large electric fan mounted flush with the radiator. I'm not sure about the fuel pressure. Spec's follow,

Displacement: 451 ci

Bore and stroke: 4.375-inch bore, 3.750-inch stroke

Pistons: Wiseco forged

Compression: 10.25:1

Con Rods: Eagle H-beam

Crank: Eagle 4340

Cam: Comp hydraulic flat-tappet

Cyl Heads: Indy 440-EZ1, bowl ported, gasket matched

Intake: MP M-1 single-plane, 750-cfm Mighty Demon carb

Power: 525 hp, 500 lb-ft

 

[HEMI-ITIS]

Need to put a vacume gauge on it and see what you have. And because Indy built it,I would also do a compression and leak down test. Really hope it's just a vacume leak,,,,,,,,,,,,,,,,,,

 

[oilstrike]

Need to put a vacume gauge on it and see what you have. And because Indy built it,I would also do a compression and leak down test. Really hope it's just a vacume leak,,,,,,,,,,,,,,,,,,

Will do, as soon as I can.

Thanks,

 

[HT413]

Now I'm no carb guru, but I had a similar issue maybe a year or so ago. I had just swapped intakes and while setting it all up, I had a backfire through the carb. After that it wouldnt stay running for anything. Turns out I blew the cap off the big vacuum port at the back of my Holley 750. Capped it up and it ran great.

 

[lewtot184]

first place i'd trouble shoot is the ignition.

 

[IQ52]

first place i'd trouble shoot is the ignition.

Your are probably more than right lew. Indy uses what they refer to as the 509SW cam in this engine. It requires a 3000rpm stall converter, is 246/246 @ .050, .509/.509 w/1.5 rockers, 108 LSA. My guess is the ignition is way retarded.

Johnnie, What is your initial timing? This cam is going to want in excess of 20 degrees initial at idle, probably 24 degrees. The MSD distributor must be set up for about 12-14 degrees centrifugal advance and that requires a special bushing that MSD doesn't even provide.

It is doubtful that Indy set the distributor up correctly. The smallest advance bushing is 18 degrees giving you a possible 18-20 initial before you have too much total advance. They probably left the stock 21 degree bushing in.

CHECK THE TIMING!

- - - Updated - - -

Need to put a vacume gauge on it and see what you have. And because Indy built it,I would also do a compression and leak down test. Really hope it's just a vacume leak,,,,,,,,,,,,,,,,,,

Polite, very polite. I hope it's no more than timing.

 

[lewtot184]

the timing curve is a very big deal with those big hydraulic cams. i had a similar condition once that was directly related to RFI or DC/AC current feedback. i'm not an electrical guru and usually have friend help me solve electrical issues. anyhow, i didn't have enough resistance in the ignition system and it screwed up the electronics. i could really tell it after driving for awhile. investing in a multi-meter and checking grounds and ohm values is a very big help in trouble shooting. also, fuel pressure checks while driving can be an eye opener.

 

[IQ52]

the timing curve is a very big deal with those big hydraulic cams. i had a similar condition once that was directly related to RFI or DC/AC current feedback. i'm not an electrical guru and usually have friend help me solve electrical issues. anyhow, i didn't have enough resistance in the ignition system and it screwed up the electronics. i could really tell it after driving for awhile. investing in a multi-meter and checking grounds and ohm values is a very big help in trouble shooting. also, fuel pressure checks while driving can be an eye opener.

Yep, and I didn't even ask, What ignition box?

 

[lewtot184]

Yep, and I didn't even ask, What ignition box?

if i remember correctly it was the black FBO box with a 1/4 ohm resister, solid core wires, and non-resistor plugs (j11y's). i didn't work but the engine needed to be heat soaked to really feel it. i worked on the carbs for weeks thinking that was the issue, but it wasn't. thru in a set of high resistance plugs and problem solved. later i re-did the whole ignition making sure there was some resistance in the system. currently using msd 8.5mm wires, plugs with 7000 ohms resistance, and the newer FBO rev-limiter box with a pertronix 14001 coil. very smooth running and driving. best driving 440 i ever had.

 

[oilstrike]

Your are probably more than right lew. Indy uses what they refer to as the 509SW cam in this engine. It requires a 3000rpm stall converter, is 246/246 @ .050, .509/.509 w/1.5 rockers, 108 LSA. My guess is the ignition is way retarded.

Johnnie, What is your initial timing? This cam is going to want in excess of 20 degrees initial at idle, probably 24 degrees. The MSD distributor must be set up for about 12-14 degrees centrifugal advance and that requires a special bushing that MSD doesn't even provide.

It is doubtful that Indy set the distributor up correctly. The smallest advance bushing is 18 degrees giving you a possible 18-20 initial before you have too much total advance. They probably left the stock 21 degree bushing in.

CHECK THE TIMING!

- - - Updated - - -



Polite, very polite. I hope it's no more than timing.

My road runner is equipped with a Passon Hemi 4 speed. The initial timing is set at 18 degrees, if my timing light is working correctly (I have ordered a new one, I don't trust this one). The fuel pressure is 4.5 psi at idle, idle is 850 rpm. I have enriched the idle circuit. I'm not sure what the vacuum should read. I detect an undertone concerning my ICH engine. Is there anything else that I should be checking? All help would be appreciated.

Regards,

Johnnie

- - - Updated - - -

Now I'm no carb guru, but I had a similar issue maybe a year or so ago. I had just swapped intakes and while setting it all up, I had a backfire through the carb. After that it wouldnt stay running for anything. Turns out I blew the cap off the big vacuum port at the back of my Holley 750. Capped it up and it ran great.

first place i'd trouble shoot is the ignition.

the timing curve is a very big deal with those big hydraulic cams. i had a similar condition once that was directly related to RFI or DC/AC current feedback. i'm not an electrical guru and usually have friend help me solve electrical issues. anyhow, i didn't have enough resistance in the ignition system and it screwed up the electronics. i could really tell it after driving for awhile. investing in a multi-meter and checking grounds and ohm values is a very big help in trouble shooting. also, fuel pressure checks while driving can be an eye opener.

Your are probably more than right lew. Indy uses what they refer to as the 509SW cam in this engine. It requires a 3000rpm stall converter, is 246/246 @ .050, .509/.509 w/1.5 rockers, 108 LSA. My guess is the ignition is way retarded.

Johnnie, What is your initial timing? This cam is going to want in excess of 20 degrees initial at idle, probably 24 degrees. The MSD distributor must be set up for about 12-14 degrees centrifugal advance and that requires a special bushing that MSD doesn't even provide.

It is doubtful that Indy set the distributor up correctly. The smallest advance bushing is 18 degrees giving you a possible 18-20 initial before you have too much total advance. They probably left the stock 21 degree bushing in.

CHECK THE TIMING!

- - - Updated - - -



Polite, very polite. I hope it's no more than timing.

if i remember correctly it was the black FBO box with a 1/4 ohm resister, solid core wires, and non-resistor plugs (j11y's). i didn't work but the engine needed to be heat soaked to really feel it. i worked on the carbs for weeks thinking that was the issue, but it wasn't. thru in a set of high resistance plugs and problem solved. later i re-did the whole ignition making sure there was some resistance in the system. currently using msd 8.5mm wires, plugs with 7000 ohms resistance, and the newer FBO rev-limiter box with a pertronix 14001 coil. very smooth running and driving. best driving 440 i ever had.

Yep, and I didn't even ask, What ignition box?

It is a MSD 6AL.

Thank you to everyone. You guys are a great help. I will check everything that you have suggested (provided that I have enough talent). I will report my findings as soon as I get them.

Regards,

Johnnie

 

[oilstrike]

Hello All, I have checked and readjusted the curb idle, timing. The leak down test was acceptable, lost apx 10 psi in 5 minutes. The only issue that I can see is the 4 psi fuel pressure. I am installing an electric fuel pump regulated to 8 psi., hopefully this will correct my problem.

Johnnie

 

[moper]

The last full crate Indy I had to fix had carb issues - crap in the bowls, plus a few "hanging chads" in the metering blocks, plus the timing curve as Brian said was way off. This was a 438" B wedge some years ago. I hope yours is a better assembly & tuning job than that one was.

 

[oilstrike]

The last full crate Indy I had to fix had carb issues - crap in the bowls, plus a few "hanging chads" in the metering blocks, plus the timing curve as Brian said was way off. This was a 438" B wedge some years ago. I hope yours is a better assembly & tuning job than that one was.

Hey Moper,
Thanks for the input. So far everything seems good, no gunk in the fuel bowls. I haven't checked the metering blocks. I'm still not clear as to how to check the timing curve. My engine is a 440 RB.

Johnnie

 

[GearAddict]

The curve is basically the initial timing (which you said was 18 deg) at whatever your idle rpm is and the lowest rpm that achieve max advance timing (without vacuum advance f you have it)

You can theoretically measure timing at every rpm and plot it as a line which is the "curve".. But all we usually care about is initial timing, max timing and what rpm are you "all in" (max timing).

My timing curve is 18 initial, 36 max, all-in at 2600 rpms

You can determine by watching the timing with a light while having someone slowly raising rpm and watch the tach and measure the timing and rpm that the timing stops increasing..

Good luck to ya

 

[oilstrike]

The last full crate Indy I had to fix had carb issues - crap in the bowls, plus a few "hanging chads" in the metering blocks, plus the timing curve as Brian said was way off. This was a 438" B wedge some years ago. I hope yours is a better assembly & tuning job than that one was.

 

[oilstrike]

The curve is basically the initial timing (which you said was 18 deg) at whatever your idle rpm is and the lowest rpm that achieve max advance timing (without vacuum advance f you have it)

You can theoretically measure timing at every rpm and plot it as a line which is the "curve".. But all we usually care about is initial timing, max timing and what rpm are you "all in" (max timing).

My timing curve is 18 initial, 36 max, all-in at 2600 rpms

You can determine by watching the timing with a light while having someone slowly raising rpm and watch the tach and measure the timing and rpm that the timing stops increasing..

Good luck to ya

Hey Scott,
Thanks for the instruction, I will check the timing curve using your methodology. Is your ride automatic or manual? Would that change the all-in rpm? Let me know.

Regards,

Johnnie