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Heat riser modifictions


RivNut
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I read in the archives that some of you have removed the flapper, shaft, and weight from the heat riser so that it just acts as a spacer in the exhaust system.  Can someone explain the steps to take to dismantle it?  Or do you just take a hammer and chisel to it then weld the shaft holes shut. Thanks in advance.

Ed

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The shaft on my '63 heat riser valve was rusted frozen shut for a long time. Someone had gone in there and bent the ears of the flapper open as best they could, but it still provided some restriction. I went in with a hacksaw blade and cut the shaft inside the manifold as close the the sides as I could and took the flapper out (plus the center part of the shaft).

 

In Texas it was no big deal having no heat riser, except in the coldest of winter days. Now up here in the Smokey Mountains, I notice the engine is slow to warm up a lot more and performance is not too good until it does. Once warmed up, it runs great.

 

The '63 heat riser is an integral part of the exhaust manifold.  Later years had it as a separate little unit bolted to the manifold, that the exhaust pipe then bolted to.

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Starting in temperatures of the mid to high 30's and lower 40's is where you would notice the lack of the intake manifold heating. I calculated it once based on air density and the fuel charge came out around 20% lean unheated, enough for a slight stumble.

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Good ideas. My 64 has the separate heat riser.  I’ll figure out a way to remove the innards. Or, if someone has one that is frozen, I’ll work about a deal for mine which works freely.  No cold enough to check that it closes properly but a heat gun opens it.  

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  • 2 weeks later...
On 11/10/2021 at 4:37 PM, 60FlatTop said:

Starting in temperatures of the mid to high 30's and lower 40's is where you would notice the lack of the intake manifold heating. I calculated it once based on air density and the fuel charge came out around 20% lean unheated, enough for a slight stumble.

Here in Northern Canada, I'm keeping my heat riser intact on my '63. It operates freely but remains closed even during a heat wave. It will open momentarily when revving the engine but will close even when keeping the revs up.

The small visegrip I clamped on the weighted side of the wheel will remain in-place until I can continue troubleshooting my rough idle when engine temp is up. Will have wait until spring now.

This is probably unrelated to my idling issue.

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I am with Jim. A rough idle and a stumble would be different things to chase. First on the list is a compression test. An overlooked problem is worn valve guides. Once they wear the valve doesn't sear properly and the seat surface will lose its edge. It can be hard to track down and I have seen only one valve out of 16 wear. really hard to find. The job is for a real nit picker but you can catch it with an oscilloscope or in some instances by comparing secondary voltages to the plugs. When those untenable problems show up on a Nailhead I will remove the rocker arm assembly and wiggle the valve stems with my finger. That's the quick test.

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10 hours ago, 60FlatTop said:

I am with Jim. A rough idle and a stumble would be different things to chase. First on the list is a compression test. An overlooked problem is worn valve guides. Once they wear the valve doesn't sear properly and the seat surface will lose its edge. It can be hard to track down and I have seen only one valve out of 16 wear. really hard to find. The job is for a real nit picker but you can catch it with an oscilloscope or in some instances by comparing secondary voltages to the plugs. When those untenable problems show up on a Nailhead I will remove the rocker arm assembly and wiggle the valve stems with my finger. That's the quick test.

The retiree that rebuilt my original AFB this summer does throttle shaft bushings. I brought him a switch-pitch throttle shaft to swap during the rebuild. No re-bush required, all good.

 

All ignition replaced with new, including new obsolete Bosch sparkplugs @ .050"

Compression test OK.

Sealed Power RP3173 Pushrods spin freely, A Sealed Power HT-896 lifter or two clatters on startup for a while after having not run for a while.

Cold idle OK off the fast idle cam with choke fully open. Alternator light comes on is how slow the idle is until warm. However, once warmed-up, it has a slight lump with me feeling it over under the hood. It's when I have it in Drive waiting at a red light that its most noticeable, annoying. I have it improved but, still unacceptable to my standards.

 

I'll check the sparkplugs next. They were sooty black at the start of my trouble-shooting.

No silver bullet, Thanks all.

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According to Dennis Manner, the original 63 cam was pretty aggressive.  You might not have any issues other than just not liking the aggressiveness of that original grind.  In an issue of the Riview (if I had an idea which one,mid post it) Dennis Manner wrote an article about the cams that Buick used in the 63 - 66 nailhead.  Very interesting.

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13 hours ago, XframeFX said:

unacceptable to my standards.

My standards are based on what a 1960's professional person would lay out around $5,000 for. Sometimes I just shake my head and think a car never would have made it off the showroom floor running like this. But there are so many poorly running ones they get based on a different standard. I have been at more than a couple of cruise night and heard someone say "Wow! Sounds like it has a cam in it!" when a crappy running car is started.

 

A few years ago I threw out a bag of sooty AC44 plugs. I have been using 45's in my GM cars for years. Recently I have turned to NGK plugs. I set the AC plug on the parts counter and ask to match it up. I figure if they run well in a V12 Jaguar they will do well in anything, has worked for me.

Don't overlook wiggling the valve stems. It is easy to do.

 

My cardiologist and I had a lot of fun when he first bought his office Ultrasound machine. It works an awful lot like an oscilloscope. Your diagnostics would be greatly enhanced with one of the newer, quite inexpensive ones. The learning curve is steep with those. I had a big Allen unit but generally use a simple inductive secondary side voltmeter on each wire these days. That can narrow issues down to the cylinder level. Then you can expand to the valves, intake runner, carb section, and so on. It's fun but you have to stay with the very basic functions. Making things too complicated can cause one to overlook a problem.

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I'm with Bernie on valve guides being a possible cause for rough idling.  In my case it was a 327 in a Chevy that ran excellent overall but had a rough idle.  After chasing possible vacuum leaks, ignition, and carb, it turned out to be oil getting into the cylinders because several valve seals had dried out.  Replacing the seals fixed the idle problem, along with blue puff on startup.

 

 

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15 hours ago, RivNut said:

According to Dennis Manner, the original 63 cam was pretty aggressive.  You might not have any issues other than just not liking the aggressiveness of that original grind.  In an issue of the Riview (if I had an idea which one,mid post it) Dennis Manner wrote an article about the cams that Buick used in the 63 - 66 nailhead.  Very interesting.

Hi Ed,

 

I don't recall the article from Dennis Manner on nailhead cams.  Will have to look in my trove of Riview back issues. 

 

If you come across the article, please post it.

 

Thanks!

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On 11/22/2021 at 6:33 PM, XframeFX said:

I'll check the sparkplugs next. They were sooty black at the start of my trouble-shooting.

Sparkplugs. They didn't tell any story as they were all black. I pulled the 4 on the driver's side just now and all are except #6 are tan. Will see if the other side cleaned up with my summer mileage tonight. Small steps.

 

I noticed the Shop manual reminded me that the heat riser for '63 is integral to the manifold. I replaced a cracked one in the '80s. It also indicated to load the spring 1/2 turn to the anchor pin. I will check mine as it appears too strong, won't fall open. Also, missing the anti rattle spring.

17 hours ago, RivNut said:

Some digging and I came up with it.  Volume 5, Number 1, Page 16.

Thanks Ed. wonder if 2 and 4 BBL called for different camshafts. Mine is early '63. Also, all full size '63 Buicks had the 401? Even the base LeSabre?

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The shop manual shows a diagram of the fuel passages through the intake manifold. Match the darkened plugs up with their runners and it may lead you to one side of the carb that is feeding a little rich due to some malfunction in the barrel feeding the runner.

 

I like the digital manuals because you can print the pages for your job and scribble notes and readings on them. Print that manifold picture and label the runners black, white, or tan.

 

One more level of insight.

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On 11/24/2021 at 11:35 AM, 60FlatTop said:

The shop manual shows a diagram of the fuel passages through the intake manifold. Match the darkened plugs up with their runners

We can all trouble-shoot be it process of elimination which I've been using or, tapping resources "been-there-done-that"!

 

So, the sparkplugs are saying something this time. Plugs #2, 3, 5 & 8 have tan electrodes which are fed from the driver's side plenum.

The Passenger side plenum has plugs that vary from sooty black (two) to a dark tan  and a fourth with a tan spot on a black electrode.

Plug #7 had oil on the outside and upon re-installation, oil in the recessed cavity, nowhere else. I can't imagine where it came from. I'm sure I did not remove the valve cover from the last time I checked the plugs.

 

Still with my lousy idle at temperature and now this, I'm about ready to ditch my recently rebuilt original AFB and splurge for a new E-Clone 1407 performer carb and swap the top to use the original air filter, period.

 

image.png.1e8f707b6a999f4510c69ad721b7db02.png

 

Back to the Heat-Riser valve, the shop manual states to not tamper with it, LOL.

 

Thanks Bernie.

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The next step would be looking into the carb while at idle to compare to see if any fuel is dripping from the venturi nozzles or near them. There should be none. If there is it could be your float level or a bleed port.

The idle jets should be close at around 1 1/2 turns each. Screw them both back in to see where they are. I like to count by 1/2 turns, seems easier. 3 half turns should seat them both. All the fuel should be coming from the idle port below the throttle plate. If you see any droplets above while running it is a problem.

 

The one oily cylinder is one that I would pop the rocker arm assembly off and wiggle the valve stem with my finger. Being at the rear some valve train oil could be seeping down.

 

Don't rule out anything. A old squashed transmission mount could divert oil to the valve area and away from the head drain holes. Or affecting the float level.

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9 hours ago, 60FlatTop said:

A old squashed transmission mount could divert oil to the valve area and away from the head drain holes

Or maybe the drain hole on that end of the head is blocked (or partially obstructed) by something (e.g., piece of old valve cover gasket)?

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On 11/26/2021 at 9:38 AM, 60FlatTop said:

The one oily cylinder is one that I would pop the rocker arm assembly off and wiggle the valve stem with my finger.

Thanks All. Will do that too but going to focus on the AFB, specifically the passenger side primary barrel. It might fix that rough idle at temperature as well.

 

Float bowl over-flow (dripping) was occurring before the rebuild. I think my local rebuilder basically did an ultra-sonic cleaning and threw in a kit. I will take it back to him as I paid for the service to be 100% He may have charged me extra to swap out that primary shaft which is nothing while apart.

 

I tinker with DIY but at this point want turn-key results. I'm considering a new Edelbrock #1411. At 750 CFM, too big for a 401? Appears to be calibrated for a BBC 454 but nailheads prefer big carbs?

image.png.11a2eb77af195a53997c586120cc5bc9.png

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There was a guy on the V8buick.com forum who was making a copy of the heat riser for the 400/430/455 engines. Don't know IF he has any left or planning on making any more. Turn out it was EXACTLY the same as the "Nail" except the studs were 7/16ths. as opposed to 1/2". All that was required was to drill the holes in the cast replacement piece to 1/2".

 

Tom T.

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  • 1 month later...

Thought i would follow on with this  Heat Riser , that Ed asked a few weeks ago, in the last few days i suspected

my current  riser  was not correct or partly  blocked , so like with other Buicks i have previously owned,  checked this one ,

and removed it ,.

Living in Australia did not really require it because of temps warm temps here.

A very easy job to do, when you remove the 2 bolt  nuts and lower the  holding bracket, the housing holding the flap

and spring  just drops down as a complete unit, you then just cut the flap axle with a hacksaw blade on the inside, place a blade threw

the housing and cut at axle ends, then the whole axle and flap fall out ,then all that is required is to have the  2 holes, welded,--then remount 

and slide back on, and  bolt up.-.--Note my flap was jambed at about  60-70 degress angle not good.---a few photos./ 

 

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Edited by Wayne R (see edit history)
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I guess that Christmas got in the way and I did not respond to show you what I did to a heat riser to convert it into a spacer.  Here's what I did with a sawzall and a stone and my drill.  I've yet to smooth it up with a grinder.  IMG_20220104_193751570.jpg.7ea3c41926cb7ce5c46e299654d415b9.jpgIMG_20220104_193905921.jpg.174cbb9a36ff127302f06ca07dcb971e.jpgIMG_20220104_193922585.jpg.05233ca623896d969bbfc2e88732ee78.jpg

 

That's the gasket that Tom M. gave me the part number for. 

 

Ed

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Thats  great  Ed,, strange though  this car never had a gasket  at the manifold  top end, and my other Rivieras never did

years   back, so i left  mine left metal to metal,   terrific job with yours  though.- Ed,--Thank you.

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Originally from the factory it was a metal-metal fit. Over the years the metal mating surfaces on the manifold & heat riser get corroded from the heat & years of heating/cooling cycles. The correct way to perform this task is to take the manifold & heat riser & have them resurfaced to make a like new flat area to seal against exhaust gases. 

The quick cheap way is a gasket. They both serve the same purpose to prevent an exhaust leak.

 

Tom T.

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Thanks for that  TomT,  i actually used a flat file on the flat areas , and  finished with   120 wet  dry paper.

no leaks now  good.

regards.

 

 

 

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