The Circuit Rider ... Has an Engine Miss and Water Leak???

[70cst]

Ok...
I am now going to try and do some of my own work on my truck as long as it's not to technical because I was born mechanically challenged.

Issue #1
My truck started to miss about 20 miles after a fill up at the Flying J...so 70stjr and I thought I got bad gas. I went and bought some gas additive and have since filled the tank with Shell 92/93 Octane. But...it still misses. It seems it misses when I put the pedal to the metal or I noticed it last night going up our hill it started to miss/misfire/sputtered three different times. So under torque is when I notice this.
I have Pertronix Flame Thrower HEI installed and its about 6-8 years old but less than 2000 miles since it was installed.
Ok...possible issues?

Issue #2
My truck is leaking down under the dash...I suppose this has to do with a seal around the dash? I don't think it’s a window issue.

I will take your suggestions and when I get free time I will roll up my sleeves and dig in.
Thanks in advance.

[Zoomin]

I would check the vacuum lines first. Sounds like one has worked it's way loose.

Where is the leak, and what is it - water or antifreeze?
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[Classic Heartbeat]

Are you talking about rain as a water leak or anti-freeze? As for the miss, it could be lots of stuff. I would check to see that all of your sparkplug wires are fully snapped in place. Also, was your engine rebuilt? WES

[dadsworktruck]

If you havent drained and replaced fuel with fresh clean fuel i would do that, also replace your fuel filter and add a lil seafoam to the fresh gas. might even have to clean the screen filter at inlet of carb if stock..

[vectorit]

Electronic ignition?

If so, check all the connections. Loose ground, or hot lead?

[70cst]

Water...rain water down by the feet.

Engine fully rebuilt. It ran like a top for about 750 miles. And like said...I filled up with Flying J gas and then after about 20 miles the miss started.

I will check:
All connections and vacume hoses.

I did put in Fuel cleaner plus Octane Booster...since then filled with Shell High Octane gas. As mentioned it only seems to miss for the most part when I accelerate hard or go up a hill. When acclerating slow to moderate is seems to do ok.

I appreciate all the ideas..

[bigguy69]

I got some bad spark plugs and it done what you said. Changed them out and was good to go.
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[MagmaJct]

I find it hard to believe it's the gasoline. Also, Octane has nothing to do with the problems your are experiencing. Octane is just a measurement of a gasoline's anti-knock properties.

Fire stands on 3 legs. Air, fuel, and heat (spark). When laying into the throttle you are missing one of these things. It's not likely that you are missing air, that leaves spark or fuel.

I'm not sure how lack of spark would only occur when laying into the throttle. So I'll focus on fuel.

I missed what carb you have, but if it's a 4 BBL I'm wondering if there's a problem with the fuel circuits in the secondaries. Or there may be a problem with the metering rods that are preventing them from enriching the mixture during load.

These are just starting points.

[ChevyLvr4Life]

I would check spark plugs and wires like mentioned. I have had plugs go bad before and cause a miss. Also on my truck I've had 2 plug wires get burned on exhaust manifolds and create a miss like your mentioning, especially going up hills. I have a similar water leak on my truck coming from under the dash on pass. side. I figure it might have something to do with the heater box seal, water seems to be coming in from around that area. Will be curious to see what others say on this too.

[71 super]

Change the fuel filter. Mine will do the same thing when filter is crappy, change it and all is good again.

[KMACD71]

Mine sputtered like you described going up hill, and after the fuel filter and air filter were changed it was fine.

[70cst]

My only concern with the gas is if I got some bad gas which can happen. The carb is the stock QJet (the one that came with the truck) which has been rebuilt by a quality company.

Originally Posted by MagmaJct

I find it hard to believe it's the gasoline. Also, Octane has nothing to do with the problems your are experiencing. Octane is just a measurement of a gasoline's anti-knock properties.

Fire stands on 3 legs. Air, fuel, and heat (spark). When laying into the throttle you are missing one of these things. It's not likely that you are missing air, that leaves spark or fuel.

I'm not sure how lack of spark would only occur when laying into the throttle. So I'll focus on fuel.

I missed what carb you have, but if it's a 4 BBL I'm wondering if there's a problem with the fuel circuits in the secondaries. Or there may be a problem with the metering rods that are preventing them from enriching the mixture during load.

These are just starting points.

[70cst]

Originally Posted by 71 super

Change the fuel filter. Mine will do the same thing when filter is crappy, change it and all is good again.

This I will do...

[mrein3]

I had that happen to me twice with my old 350. Both times I was replacing a cam shaft with a worn out lobe within 100 miles of when I first noticed it. I'm talking about the "miss" not the water leak of course.

How is your oil pressure at idle?
Is it barking or popping up through the carb? (Tough to tell if it only happens under load and full throttle)
Do you let it sit at idle all the time with low oil pressure? This is a good way to wipe out a lobe on your camshaft.

Let's say it is your camshaft. You need to look at that situation with your glass half full. This would be the perfect opportunity to replace that little 402 with a 454 or bigger.

[70cst]

Originally Posted by mrein3

I had that happen to me twice with my old 350. Both times I was replacing a cam shaft with a worn out lobe within 100 miles of when I first noticed it. I'm talking about the "miss" not the water leak of course.

How is your oil pressure at idle?
Is it barking or popping up through the carb? (Tough to tell if it only happens under load and full throttle)
Do you let it sit at idle all the time with low oil pressure? This is a good way to wipe out a lobe on your camshaft.

Let's say it is your camshaft. You need to look at that situation with your glass half full. This would be the perfect opportunity to replace that little 402 with a 454 or bigger.

I am thinking that with over 750 miles w/o any issues I am hopeful this isnt the issue. It had an Isky RV cam installed when it was fully rebuilt and it was broken in properly. Curt has rebuilt engines for over 35 years but one never knows...

I am hoping its hoses or spark plug/wires related and its an easy fix. Again with this happening within 20 miles after a fill up I am leaning towards dirty gas and dirt in the lines or dirty fuel filter.
Thanks for you response.

[lolife99]

What kind of oil are you running in it?
The new oil doesn't have the zinc levels it use to.

I have a buddy with a '70 Chevelle SS 396 with a flat camshaft for this very reason.
Quality rebuild, and normal break-in on the cam at start-up.
But the cam has now got a bad lobe.

[Gobbles]

Check your carb for any small fuel leaks, on my Holley I had a small set screw back off and it leaked a very small amount but caused a similar problem. I am also with KMACD71 and would go for a fuel filter.

[special-K]

Does the water leak on one side or both at your feet? It could be the seal for the wiper motor.

Wouldn't a flat cam lobe (or bum lifter) show at all rpms at any amount of throttle? I'd do the filters (air is probably still clean). The fuel filter may have just done it's job by collecting crud from your tank. Honestly,I'm leaning towards a spark advance issue. Does it miss revving to a higher rpm not under load?

[mrein3]

Originally Posted by special-K

snip
Wouldn't a flat cam lobe (or bum lifter) show at all rpms at any amount of throttle?
snip

Yes but only after it is totally flat.
In my first flat cam experience I was driving up north for deer season. On a long straight away I got into it to pass a 1952 camper that only sees the road the first weekend of November (you MN folk who drive the highways and byways of MN the Friday before deer opener have seen these campers). About the time I got next to the vehicle I was passing I noticed a little miss which was actually one of the cylinders barking back up through the carb.

I made it all the way up and back (500+ mile round trip) before things really went south.

The next time I was out duck hunting at the in-laws a couple of years later. Once again I thought I had a miss. I remember really getting on the throttle to make it snap back through the carb when I first noticed it. Once again shortly after I got home it was new cam time.

After that one I put in another cam and started collecting parts for my 383.

Now I'm not saying the Circuit Rider has a flat cam lobe but on every cam replacement I follow the break-in spec to the letter.

And if I knew then what I knew now about flat tappet cams I'd have started with a roller block for my 383.

[70cst]

Originally Posted by special-K

Does the water leak on one side or both at your feet? It could be the seal for the wiper motor.

Wouldn't a flat cam lobe (or bum lifter) show at all rpms at any amount of throttle? I'd do the filters (air is probably still clean). The fuel filter may have just done it's job by collecting crud from your tank. Honestly,I'm leaning towards a spark advance issue. Does it miss revving to a higher rpm not under load?

The water is coming in at the feet at both sides.

Oil...
Lubriplate Super GOP SAE 15w40 (See LINK)
http://www.lubriplate.com/products/a...otor-oils.html

As mentioned...
I am going to change the fuel filter, check all vacume hoses, and spark plug and spark plug wires.

[1968SWBBigBlock]

Duane - check your cap and rotor - my pertronix cap was toast after 1 year
It will be going back to pertronix for an evaluation.
Check to see if your distrbutor will move as it sits -(just grab it and see if it will move eaither direction) it is possible that if the distrbutor is not tightned correctly your timing will move under load once and you are out of specs. from that point on under load you could expereince these same issues
If you need a timing gun just let me know
FWIW - Jegs stocks the Pertronix caps and rotors as well

[70cst]

Originally Posted by 1968SWBBigBlock

Duane - check your cap and rotor - my pertronix cap was toast after 1 year
It will be going back to pertronix for an evaluation.
Check to see if your distrbutor will move as it sits -(just grab it and see if it will move eaither direction) it is possible that if the distrbutor is not tightned correctly your timing will move under load once and you are out of specs. from that point on under load you could expereince these same issues
If you need a timing gun just let me know
FWIW - Jegs stocks the Pertronix caps and rotors as well

Thanks for the info...I am thinking its nothing major. I figure its time I roll my sleeves up and starting learning what makes my truck tick. Good point on the Pertronix...it's at least 6-8 years old.
Thanks again.

[into69z]

Had the same type of water leak on my truck-turned out the windshield gasket was leaking so a new "precision" brand from GMC Paul's and new glass solved the problem. Good Luck-nice truck

[special-K]

The windshields need to be sealed once installed. The factory used the black butyl type on the outside of the flange and white lithium type on the inside,then sealed to the glass once installed.

[OhioDan]

I think Wes sent ya some bad Ju-Ju in that hot dog?LOL Ya never did tell the story behind it last weekend. Do ya just notice the water on the floor, or can ya look up under your dash and see some? Might be leak in windshield washer hose? Just throwing that out there for something to check. Have ya had a vaccumn line to the dist crack or come loose. Are the weights in top of dist. rusty and hanging up? Condensation in dist cap?
Send me yer email, and I'll send ya that pic of that tag I was showing you.
Hope yer problem isn't to hard to fix. Some can be so obvious you overlook them. Dan