'71 LWB Deluxe - 250 engine skipping - The 1947 - Present Chevrolet & GMC Truck Message Board Network

beenydu · 09-22-2005, 11:20 PM

I am having trouble with my 250 skipping. The #3 and #5 pulgs are full of crap. I have just converted it over to HEI and put new NAPA 8mm wires with new AC-Delco 45TS plugs. Of course, the fuel mileage kinds stinks with a loss of power. The other plugs look a little white. Does anyone have an idea why those plugs are building up with crud?

krue · 09-23-2005, 10:57 AM

Check your compression, probably have rings letting the oil blow by.

**Bernie** · 09-23-2005, 11:29 AM

When I had a 250 I could never get rid of vacuum leaks where the intake manifold fitted against the Cylinder head. To see if this is your problem spray carb cleaner around the join and see if you get white smoke from the exhaust, if you do then you have a leak.

chevyfarmer · 09-23-2005, 01:57 PM

I agree with what others have said as well. Did you run this motor before you converted it to HEI? You said that you just converted it, what was it like before, what were the plugs like that you pulled out of it? If it is the new plugs that are full of crap mas you put it, how many miles were they in there? Check to see if you have spark @ these 2 cylenders and check for the possibility of crossed plug wires. Good Luck

shifty · 09-23-2005, 02:57 PM

Two notes that may have nothing to do with your problem:

For points, gap is .035, HEI gap is .045.

Fuel distribution with a 1bbl carb is quite uneven with fuel distribution. It seems like the #3 and #4 cylinder wil always get more than the rear with stock intake and 1bbl carb.

09-22-2005, 11:20 PM	#1
beenydu Got Jesus? Join Date: Apr 2004 Location: Ninety Six, SC Posts: 53	'71 LWB Deluxe - 250 engine skipping I am having trouble with my 250 skipping. The #3 and #5 pulgs are full of crap. I have just converted it over to HEI and put new NAPA 8mm wires with new AC-Delco 45TS plugs. Of course, the fuel mileage kinds stinks with a loss of power. The other plugs look a little white. Does anyone have an idea why those plugs are building up with crud?

09-23-2005, 10:57 AM	#2
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Check your compression, probably have rings letting the oil blow by. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

09-23-2005, 11:29 AM	#3
Bernie Senior Member Join Date: Jan 2001 Location: Northern Illinois Posts: 516	When I had a 250 I could never get rid of vacuum leaks where the intake manifold fitted against the Cylinder head. To see if this is your problem spray carb cleaner around the join and see if you get white smoke from the exhaust, if you do then you have a leak. __________________ Bernie

09-23-2005, 01:57 PM	#4
chevyfarmer Registered User Join Date: Feb 2005 Location: Owosso, Mi Posts: 242	I agree with what others have said as well. Did you run this motor before you converted it to HEI? You said that you just converted it, what was it like before, what were the plugs like that you pulled out of it? If it is the new plugs that are full of crap mas you put it, how many miles were they in there? Check to see if you have spark @ these 2 cylenders and check for the possibility of crossed plug wires. Good Luck __________________ 67 short wide 355ci 3 on tree 69 short wide 250ci 3 on tree 68 long wide 283 3 on tree 72 2wd Blazer project 454 5 speed Last edited by chevyfarmer; 09-23-2005 at 02:02 PM.

09-23-2005, 02:57 PM	#5
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,376	Two notes that may have nothing to do with your problem: For points, gap is .035, HEI gap is .045. Fuel distribution with a 1bbl carb is quite uneven with fuel distribution. It seems like the #3 and #4 cylinder wil always get more than the rear with stock intake and 1bbl carb. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.



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