Engine Dies After Driving

[RPM 1,190]

rebuilt 351W stroked to 393, AFR 185 heads 10.2 cr, Weiand Stealth intake, Speed Demon 750 vac secondaries, stock distributor w/vac advance, electric fuel pump listed for carb, FMX, pwr brakes, 15lb rad cap and car is red :)

 

Engine was broken in but no real miles on it. It will idle for days w/o any issues. When I drive it around the neighborhood it's fine accelerating and stopping for a few minutes. But after a bit, it will die when slowing and braking to a stop. I've never had a hot rod with an auto trans, power brakes or Demon carb. No other issues with the mechanical functions. In park I can rev the engine and the rpms drop w/o the engine dying. No vacuum leaks.

 

Fuel starvation or too much fuel? Any clues

 

 

[LiLMike 42]

After it dies, does it start right up or do you have to pump the accelerator a few times to get it started again? I had a similar problem and it was the fuel pump.

[stangnet33 88]

Might wanna check for vapor lock ? Going to Grabber Orange may also help 

On 4/7/2017 at 0:53 PM, LiLMike said:

After it dies, does it start right up or do you have to pump the accelerator a few times to get it started again? I had a similar problem and it was the fuel pump.

+1

[LoneWolf2U 136]

First recheck your floats for proper setting. Too high will cause this problem, When slowing down the nose drops and fuel will slosh to the overflow and dump in the intake.

Too low and the fuel flows away from the idle holes and starves the carb.

Siting still and it is fine but stalls when moving is the problem.

[1969Fstback 58]

Does the fuel tank have a baffle for the pump?

[Caseyrhe 650]

I agree with Mach 1 Rider, might also check the muffler bearing

[RPM 1,190]

Well, it's a whole lot better now. The rear float level was perfect, and the front was just a tad high. I lowered the front and centered it. It will still drop the rpms a bit down below the idle rpm of 700 occasionally when coming to a stop, but it never died. I feel comfortable enough to drive it. I took it up to 90, it pulled pretty good, straight as an arrow, no vibrations and the brakes work. Life is good.

I have a carb with the pump outside the tank.

The red is Porsche India red which has enough orange in it for me :)

Last year I changed out the muffler bearings and installed bushings.

Thanks guys.

[barnett468 418]

what carb do you have?

[RPM 1,190]

8 hours ago, RPM said:

 Speed Demon 750 vac secondaries,

5 minutes ago, barnett468 said:

what carb do you have?

 

 

[LoneWolf2U 136]

Do you have windows or plugs for fuel level?

both should be set at the bottom of the hole, Just visible in window or slightly coming out the open hole.

I have found this to be the best all around float point even for curvy spirited driving.

[Bob & Sue 110]

You might want to put a vacuum gauge on it to set the low idle jets, don't do it by rpm's it's not accurate enough, be sure your on a high vacuum port it will take several try's to get the highest vacuum reading. 

Might want to check your butterflies to see if there closing all the way and the air slot is lined up.

I need to go through mine again just put a new thick aluminum gasket on, if your running the thin paper gasket that can also cause trouble they tend to leak. 

[Ridge Runner 1,113]

On 4/7/2017 at 4:53 PM, RPM said:

Well, it's a whole lot better now. The rear float level was perfect, and the front was just a tad high. I lowered the front and centered it. It will still drop the rpms a bit down below the idle rpm of 700 occasionally when coming to a stop, but it never died. I feel comfortable enough to drive it. I took it up to 90, it pulled pretty good, straight as an arrow, no vibrations and the brakes work. Life is good.

I have a carb with the pump outside the tank.

The red is Porsche India red which has enough orange in it for me :)

Last year I changed out the muffler bearings and installed bushings.

Thanks guys.

And drive it he did ,about 120 mile round trip  ?Wind whistling in his hair and bees bouncing off the windshield, haha                Um...you did make it home ?

[Ridge Runner 1,113]

Depending on your cam 700 may be to low for the idle ,  my old 69 had to idle around 800-900 or it would try to die at stops 

[RPM 1,190]

Yes I did make it home, and found a free loader bee! I did that 120 mile round trip to Ridge Runner's to get my rear glass installed, what a great guy, so generous! It ran well and never stalled.

Mach 1, the BG Speed Demon has glass windows and fuel half way in the window is what the instructions call for. I'll try lowering the level.

I do have a vacuum gauge Bob and I know I need to set the jets with it. Thanks for the nudge and reminder. The butterflies are adjusted so the air slots are square, per the instructions.

I'll play with the idle after I do the jets with the vacuum gauge.

Thanks guys.

[barnett468 418]

forget the instructions . they are wrong . set them near the bottom of the window as was suggested.

[RPM 1,190]

19 minutes ago, barnett468 said:

forget the instructions . they are wrong . set them near the bottom of the window as was suggested.

I be getting right on it mr boss man.

Tanks!

[barnett468 418]

1 hour ago, RPM said:

I be getting right on it mr boss man.

Tanks!

xlnt saib! and wile you're at it . check your timing curve!

[RPM 1,190]

Like I know what timing curve is.

Hey Jim, check out this pic. Removed my shaker and saw the remnants of a few bees, then looked at the radiator. Not too bad I suppose.

[RPM 1,190]

On 4/7/2017 at 11:53 AM, LiLMike said:

After it dies, does it start right up or do you have to pump the accelerator a few times to get it started again? I had a similar problem and it was the fuel pump.

Since I didn't answer this question... it starts right up w/o pumping it.

[barnett468 418]

2 hours ago, RPM said:

Like I know what timing curve is.

 

[RPM 1,190]

After googling it, I knew what the timing curve was but not that they called it that. I'll check it tomorrow.

[barnett468 418]

2 hours ago, RPM said:

After googling it, I knew what the timing curve was but not that they called it that. I'll check it tomorrow.

i will post tomorrow how you can check to see if the idle timing and the timing curve are set close to their optimum level.

[Bob & Sue 110]

7 hours ago, RPM said:

After googling it, I knew what the timing curve was but not that they called it that. I'll check it tomorrow.

From what I've found my initial timing is set at 10* at 2500 rpm it's at 35* with no vacuum advance, My springs are to weak I'm going to change to a stiffer set of springs Pertronix recommends 12* at 1000 & 24* at 3000. I'm also using the 1/2 vacuum port off the carb, 

As far as setting the floats mine runs the best at mid point in the windows per Holley spec.

I'd check the accelerator pump adjustment also if it's not making contact at the touch of the throttle it can give ya a hesitation. Make sure there's .015 clearance at wide open throttle ask me why I have a new diaphragm. 

Be glad you weren't on a Harley I drove through a small swarm on my old chopper 30 years ago doing 70 mph on I-5.  Dug about 10 half bodies out of my neck & face with a couple getting inside my right sleeve dam near lost control of the bike. 

[barnett468 418]

1 hour ago, Bob & Sue said:

Pertronix recommends 12* at 1000 & 24* at 3000. I'm also using the 1/2 vacuum port off the carb, 

 

The can't accurately determine what the best setting is . It needs to be set for each individual engine.

Never heard of a 1/2 vacuum port.

[RPM 1,190]

Thanks guys.

Bob, back in '84 I was a motor cop and too hit a swarm of bees. I saw it ahead but had no idea what it was till after contact. The five minute ride home dried those bees to my boots, helmet, wingshield so hard that I was removing the remnants for weeks.