[Hacksaw]

Originally Posted by cdminter59

That could be a possibility. They do take a long time to warm up. You don't have a spare Performer RPM you could try do you? Maybe a buddy might have one on the shelf? Have you checked your coil lately? Here is how to check it with an ohm meter. How to Test an Ignition Coil

I don't have a buddy with a spare Vortec RPM intake. And yes, I swapped out two different MSD Blaster 2 and Blaster 3 coils. Same effect. It's not in the ignition.

[Hacksaw]

I'm sorry. I didn't mean to sound like a turd. Your only trying to help! I swapped put every component of the ignition system twice. That's why is said "it's not in the ignition".

[abritton77]

Sounds just like the gremlin that I had last year. I thought it was ignition related and I upgraded everything with no luck. I would think at times it was fixed but then it would prove me wrong. I switched to an electric fuel pump and the problem was gone for good.

[steeny]

This might sound out of line but I had a tach some years ago do what you are describing. It was intermittent miss fire at times then other times a miss that was consistent around 3k then disappear. I unhooked that tach and the problem went away for good. Just a thought.

[Hacksaw]

Originally Posted by steeny

This might sound out of line but I had a tach some years ago do what you are describing. It was intermittent miss fire at times then other times a miss that was consistent around 3k then disappear. I unhooked that tach and the problem went away for good. Just a thought.

Hahahaha. Yeah, already tried unhooking the tach. No change.

[Hacksaw]

Originally Posted by abritton77

Sounds just like the gremlin that I had last year. I thought it was ignition related and I upgraded everything with no luck. I would think at times it was fixed but then it would prove me wrong. I switched to an electric fuel pump and the problem was gone for good.

Now the fuel pump has not been changed at all. It is a new Holley Big End 110 gph mechanical pump. I Have always used an electric pump until now. And I've been thinking of switching back to electric!

[cobalt327]

Originally Posted by Hacksaw

Then started playing with pump arm gap. Adjusted to have a slight gap in the pump arm and pump lever.

Just to be sure- the gap is only at WOT, not at rest (idle), right?

Still a bit concerned with having 24 degrees initial, but there is zero pinging.

I'm guessing the cam is fairly 'healthy'. If that's the case, absolutely nothing wrong or unusual about the amount of initial timing.

BTW, good job on the carb tuning as well as the timing. A LOT of guys stumble (npi) on this.

[cdminter59]

I read in one of your post about the trash you found in the 4150 carb. What type fuel filters are you using? Most manufacturers recommend a 100 micron filter at the tank. Also a 40 micron filter in the line up front. Another interesting thing I read the other day is not to use teflon tape on any gas or oil fittings. It said to use a paste type sealer with teflon in it. I used Permatex 59235 when rebuilding my engine last year. You have replaced everything in the ignition system and it hasn't fixed the problem yet. How about your fuel. Gas with 10% ethanol has a shelf life of about 3 months. The ethanol absorbs water from the atmosphere. I have heard of using a timing light to watch the gas as the carb squirts the gas. IDK but it is said you can see water in the gas. Here is the article (advertisement) i was reading. USA Fuel

[abritton77]

I was using a summit racing summit racing 110 gph mechanical pump. I had installed it over the winter along with some other changes is why it took me so long to figure it out. I would swear that our description sounds just like my nightmare. It cost me a small fortune to figure it out.

[Hacksaw]

Originally Posted by abritton77

I was using a summit racing summit racing 110 gph mechanical pump. I had installed it over the winter along with some other changes is why it took me so long to figure it out. I would swear that our description sounds just like my nightmare. It cost me a small fortune to figure it out.

This Holley Big End pump was purchased off eBay. I'm sure its a knock off just like the summet pumps are

[cdminter59]

Yeah, I think that pump might be suspect too. Probably losing volume as rpms increase. Try your electric pump maybe it will be the fix. Hope it works for you.

[Hacksaw]

Drove the car again today to work. 32 degrees this morning. Ran decent but the slight hesitation was back at part throttle. Now it's 60 degrees and the car is running awesome. Seriously thinking the RPM Air Gap isn't for cold weather! I hate to buy a RPM Vortec intake just to try. But I don't know of any to borrow. My heads are the Edelbrock E-Tech 170 so...

[steeny]

Beginning to sound like poor fuel atomization in the intake and ports leading to a lean misfire. Does this engine ever get to operating temp when it is cool outside?

[Hacksaw]

When it's cold, it runs between 170-180 degrees. When it's warmer it's running around 190. There is a 180 thermo installed. It does seem like it runs much better around the 190 range

[Hacksaw]

I don't know if it mattered or not, but it is a late model roller Vortec block with one piece pan and rear main. Those engines use a 195 degree thermo I believe. But due to the carb intake I figured thermostat shouldn't matter? Would the combo of thermostat and spark plug heat have any affect?