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10-28-2019, 06:50 PM | #1 |
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Carbon build up inside intake bores?
I took the 4 barrel intake off my 8BA to change to Tri-Power intake. Motor has less than 3000 Miles. Inspected intake valves & springs which looked fine. I was surprised to see carbon build up in the intake bores that line up with the intake manifold between where they mate & the valve stems? No combustion S/B happening to create carbon in those bores? Maybe valves leaking igniting gas vapor in passage ways? Assuming needs disassembly to clean carbon to keep carbon pieces out of cylinders? What’s going on?
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10-29-2019, 10:28 AM | #2 |
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Re: Carbon build up inside intake bores?
Could running rich cause that?
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10-29-2019, 01:04 PM | #3 |
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Re: Carbon build up inside intake bores?
Depending on how hard you drive it...valves floating give you issues like that...
Burnt valves or a hole between heatriser and intake would make the car run bad... Does it run as it should ? |
10-29-2019, 01:44 PM | #4 |
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Re: Carbon build up inside intake bores?
Always ran well, smelled a little rich but thought that was the nature of the beast. Never pushed it real hard. 3500rpm-4000rpm shifts occasionally. Engine has fewer than 2500mi’s
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10-29-2019, 02:33 PM | #5 |
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Re: Carbon build up inside intake bores?
From experience,its sucking oil up or around the guides
Lawrie |
10-29-2019, 03:33 PM | #6 |
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Re: Carbon build up inside intake bores?
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10-29-2019, 03:34 PM | #7 |
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Re: Carbon build up inside intake bores?
One of the big culprits causing the problem Lawrie mentioned is using the engine "coast down" as a method of braking. The crankcase pressure can push oil up the guides/valves and into the port. Most of my experience has shown the accumulation of carbon on the valves, rather than the ports.
There is also something to be said for valve timing, but that is a big subject and might not be associated to your problem.. |
10-29-2019, 03:40 PM | #8 |
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Re: Carbon build up inside intake bores?
I agree with the other guys. Worn guides and way to rich.
It should have stunk when it was running too. |
10-29-2019, 03:54 PM | #9 |
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Re: Carbon build up inside intake bores?
In hindsight yes it smelled rich, but the older cars all smell rich compared to the modern computer controlled fuel injection. I have a ‘67 442 runs perfect but smells a lot more than my ‘07 BMW. Guess I thought it relative as old to new engine science. Beside a few typical issues the 8BA always ran, idled & accelerated great! I do admit to what JWL mentions & do use the engine & Tranny compression braking to slow down especially w mechanical brakes.
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10-29-2019, 04:22 PM | #10 |
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Re: Carbon build up inside intake bores?
Question is: Do I just surface clean the intake ports lightly removing loose carbon w wd40 or spin a wire wheel on drill to clean all? If I do are precautions like shop vac running on each at same time enough? Or is it break engine down clean polish ports then clean block & reassemble engine time?
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10-29-2019, 04:43 PM | #11 |
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Re: Carbon build up inside intake bores?
Did you change camshafts recently ? If it has a cam with a lot of overlap (intake and exhaust valves opened at the same time), then it's possible to have reversion in the intake which is backwards pulses from the exhaust. I had the inside of an intake manifold turn black because of this.
Sal |
10-29-2019, 05:37 PM | #12 |
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Re: Carbon build up inside intake bores?
For personal interests, would MMO or Sea Foam help keep such deposits from forming?
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10-29-2019, 05:52 PM | #13 |
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Re: Carbon build up inside intake bores?
I haven’t. U could b right on the valve timing? I’ve heard same w modern perfed engines. I have several classics & work on them but never had One w adjustable solids so no experience there. I stumbled into the Flatty thing when my 90 yr old Mom’s 80 yr old widowed girl friend had a car she wanted me to look at & let her know what I thought she’d get for it. Thought I’d be checking out a Pontiac Parisian or something. Turns out to b a 60k mile ‘35 Tudor in her heated garage for 30 yrs perfect condition since her husband died. Missing engine ( another story for another time). I could of got it for $2k but as was Mom’s friend gave $6500. So found a Flatty builder ( Jerry Livingston owner of United Engine Specialists) & had an 8BA perf’d up a bit built 5 yrs ago. He put a 3/4 isky cam & adjustable lifters. Got under 2500 miles on it. So, probly should put 4 barrel intake on it get rid of it & put a Sb Chevy (more my territory) in it. Probly gut reaction cause not a happy camper right now!
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10-29-2019, 06:21 PM | #14 |
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Re: Carbon build up inside intake bores?
I'm not real smart but if the exhaust stinks, I would think the engine is running to cool if the plugs look good.
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10-29-2019, 06:46 PM | #15 |
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Re: Carbon build up inside intake bores?
Kind of weird. When I saw carbon buildup in the ports I pulled a head to see if carbon extended to valves. Saw some but minimal so thinking Lawrie had it right. But also pulled plugs on same side & 2 were a nice light toast color & two were black? I have a temp gauge on each bank and one coming off radiator push side in the dash. Runs at 180-200 pretty consistent.
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10-29-2019, 07:00 PM | #16 |
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Re: Carbon build up inside intake bores?
if you want to get rid of the carbon get a coffe cup fill with water. bring eng rpm up to about 1500 rpm pour the water down the carb slowe you don,t want to stall the eng do that when ever you think the eng needs it
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10-30-2019, 01:54 AM | #17 |
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Re: Carbon build up inside intake bores?
Better than a cup would be a restricted flow, ketchup squirter or any squeeze bottle. This to control volume of flow. Higher RPM would also be better.
Never want to add too much, at a time. I once killed a good motor. Boo Hoo. I did however perform many 'miracles' In the day.
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10-30-2019, 02:30 AM | #18 |
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Re: Carbon build up inside intake bores?
Over a few years in my 33 babbit engine, I had this problem.
My fault first up, using old guides and valves. next try better valves . still same problem, 3 rd try (slow learner) good valves and guides,better.but still would oil up and on a LONG down hill blow smoke at bottom. Fitted new straight valves and guides with bronze liners in the guides and seals on the inlet valves, No problem from then on. The current engine in the 33 (99a),first I still tried the old mushroom valves and split guides for a while but it would oil a plug or two on trips, did the same as the old engine with new straight valves and guides with the seals on the inlets and bronze liners, that engine has done about 70000 klms ,uses no oil runs great. Lawrie |
10-30-2019, 04:39 AM | #19 |
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Re: Carbon build up inside intake bores?
And Lawrie said :
straight valves and guides with the seals on the inlets and bronze liners, that engine has done about 70000 klms ,uses no oil runs great. The answer i believe ...... |
10-30-2019, 05:55 AM | #20 |
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Re: Carbon build up inside intake bores?
We began addressing this very issue with my own F-1 back in the late '70's, got totally fed up with "hanging" valves in the 239" during long periods of storage. Needed to come up with a sure fire fix!
Took all 16 guides out and lined them with the K-line bronze liners! Machined all 16 guides for some "Perfect-Circle" rubber/teflon valve stem seals, today we do the 8 intakes only unless customer wants all 16 done. We've learned over time the exhaust's weren't necessary. Since we began this procedure we've probably used/sold a couple thousand or so! The bronze liners in conjunction with some stainless valves was one of the best moves we ever made on the Flatheads! A very close friend of mine back here on Long Island built nothing but Flatheads, we worked closely with him on all the machining, he would bring us about 10/15 a year back then? Every single one of his builds got the S/S valve/bronze liner pkge! Thanks, Gary in N.Y. P.S. Here's a couple shots (again) on the package, valves, lined guides, and today's Viton stem seals! We stopped using the rubber/teflon a few years back now! The Vitons are easier to install, no "sleeves" involved!
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