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Need new source valve cover grommets & blocked intake manifold gaskets


buick man
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I would like to replace my original 364 valve cover rubber grommets … however all I can find is the hard, too small outer diameter and too thick profile to match the originals.  Also the factory original grommet accommodates a factory thin 1-inch diameter washer and therefore larger then the 3/4 inch diameter head of the new hard rubber replacements …. As seen below the contrast is staggering and incorrect if your mantra is originality ….

 

… Also  looking for a source for the manifold to head gaskets that have the heat passages blocked … there was a guy supposedly making them somewhere in NY state not too long ago … yes there are various methods to block these but the  single purpose single piece gasket is the way to go ….. 

 

 

DSCF1994.JPG

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The photo above showing the factory original washer … yes it is softer and compressed but this original grommet even has a tighter diameter I.D. than the sloppy new replacement I have …. The photo below is showing the too small diameter replacement grommet along with a 1-inch diameter washer to represent the factory washer

 

DSCF1995.thumb.JPG.3992d0653e46bad0ddadf763135467d9.JPG

 

 

 

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49 minutes ago, avgwarhawk said:

If I remember correctly Felpro valve cover gaskets has the rubber grommets.    

thanks Chris … I'll follow that lead up ... I had a NOS grommet hanging around that I can't find but it certainly was not the too small too hard too thick version that it appears every jobber is selling now … they must be getting these from the same source. Here is a photo showing the original proper grommet setup showing proper factory original hose clip, bolt, washer and grommet with factory original paint 

DSCF1997.thumb.JPG.c415f709d96caae625e085f9e89f4c73.JPG

 

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… blocking off the heat passages in a car that operates in 65-95 temps all year round has no need for the heat passages creating a hot plate at the base of your carb that the base plate and gasket cannot overcome as one shuts off the engine and it becomes a greater heat sink area and increased percolation problems ….

 

… the factory NOS grommets regarding valve cover sealing are by definition suppose to be soft pliable compounds not hard  urethane rubber wannabes that belong on the end of your kitchen table legs … not on your engine … and yes the general blah about NOS rubber is true about having decomposed due to shelf product life span …  

 

…  NOS specifications should be followed if one is going to spend the time and effort to recreate an item including the proper compounds used … what many of these suppliers are doing is just tossing in a round shaped objects either found in a bag in the corner or are sourcing them from someone with even less keeness to detail and need … the hard too small O.D. diameter and too large I.D. diameter ones are all I have found .. the Best Gasket kit looks promising and I will check that out … but believe the one I have that is too small - too hard  was sourced from them  ...

 

 

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10 minutes ago, buick man said:

… blocking off the heat passages in a car that operates in 65-95 temps all year round has no need for the heat passages creating a hot plate at the base of your carb that the base plate and gasket cannot overcome as one shuts off the engine and it becomes a greater heat sink area and increased percolation problems ….

 

 

What you want to do is plug the heat track at the carb mounting base. Making your intake cold blooded is still a bad idea due to intake puddling and can lead to rough idle as the gas rolls down the runner in liquid form, giving a rich, incomplete burn. 

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3 hours ago, Beemon said:
3 hours ago, buick man said:

… blocking off the heat passages in a car that operates in 65-95 temps all year round has no need for the heat passages creating a hot plate at the base of your carb that the base plate and gasket cannot overcome as one shuts off the engine and it becomes a greater heat sink area and increased percolation problems ….

 

 

What you want to do is plug the heat track at the carb mounting base. Making your intake cold blooded is still a bad idea due to intake puddling and can lead to rough idle as the gas rolls down the runner in liquid form, giving a rich, incomplete burn. 

Those plugged gaskets were made for racing where you want a cold mixture (some even run a coil of fuel line through an ice canister).  I made some plugged gaskets and ran them for a year with no difference in performance except:  much less percolation and the paint did not burn on the intake manifold.  Apparently my attempt to plug ended in an incomplete seal and later found the intake manifold full of nasty water.  I would consider using again if a complete seal was assured.  The available gas is so volatile that puddling  apparently is not an issue on a nailhead.

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… I hear you guys and thanks for the info … In the late 60's  I was using brass shim stock plates for my first railhead that I would surgically cut and place over the hole coming out of the head and then lay the stock manifold gasket on top of that then placed the manifold on and that seemed to work well regarding minimizing any heat sink related problems and that was when you could get 98 leaded at the pump !  Yes the manifold won't get real ugly fast and the fuel will be cooler as well … any who I would like to find a source for those blocked gaskets ….

 

I suppose if one cannot get their hands on the real deal valve cover grommet … then a uncle bob's hand drill "lathe" setup could be used to turn down a nice soft shock mount rubber and form it and slice it into the correct shape … only the top needs to be the right diameter 1-1/8 " and the profile thickness sitting on the valve cover needs to be 5/32nds thick … of course the I.D. would need be a tight fit …. just thinking out loud - uncle dave  

 

Edit:  Here a comparison photo of the crappy nonsense grommet on the right and the factory original still in the valve cover .. also note the larger I.D. on the wannabe grommet … can you say sloppy ! 

DSCF1993.JPG

Edited by buick man (see edit history)
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9 hours ago, buick man said:

 

 

Edit:  Here a comparison photo of the crappy nonsense grommet on the right and the factory original still in the valve cover .. also note the larger I.D. on the wannabe grommet … can you say sloppy ! 

DSCF1993.JPG

 

 

It looks to me the original is flatten out from the torqued rubber product and years of being under pressure.    

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… Chris refer to the second photo above … this new replacement  grommet diameter is commandingly smaller than the 1-inch washer on top of it.   The first photo and third photos show the original factory grommet and  washer … why would the factory place a 1-inch washer on a barely 3/4 diameter grommet ?   …. To add to this the replacement grommet is  of a very thick non-compressable rock hard urethane material and the i.D. is sloppy large as well and would not shoulder the valve cover bolts leaving a 1/16 circumferential gap … the factory original is of a pliable rubber base compound… firm yet not dried out and is still subtle after 60 years … very little compression and the replacement cannot compress at all and the I.D. would allow leakage even with the washer placed on top which even so ... to even make it close to working would require a smaller I.D. washer … and the only sealing one would get is from the I.D. of the metal washer …  the job of the grommet is to seal and the washer's job is to provide a perch point for the head of the bolt and to allow compression onto the grommet ….

 

Apparently I will have to make a proper grommet … I was hoping to snatch the correct one if available …. 

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8 hours ago, buick man said:

… Chris refer to the second photo above … this new replacement  grommet diameter is commandingly smaller than the 1-inch washer on top of it.   The first photo and third photos show the original factory grommet and  washer … why would the factory place a 1-inch washer on a barely 3/4 diameter grommet ?   …. To add to this the replacement grommet is  of a very thick non-compressable rock hard urethane material and the i.D. is sloppy large as well and would not shoulder the valve cover bolts leaving a 1/16 circumferential gap … the factory original is of a pliable rubber base compound… firm yet not dried out and is still subtle after 60 years … very little compression and the replacement cannot compress at all and the I.D. would allow leakage even with the washer placed on top which even so ... to even make it close to working would require a smaller I.D. washer … and the only sealing one would get is from the I.D. of the metal washer …  the job of the grommet is to seal and the washer's job is to provide a perch point for the head of the bolt and to allow compression onto the grommet ….

 

Apparently I will have to make a proper grommet … I was hoping to snatch the correct one if available …. 

 

Before looking to make one perhaps the local hardware store(Home Depot/Lowes) has a suitable grommet.  Both stores have specialty products in the hardware section.     

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Here is what I consider some good info and advice I got on this forum some 8 years ago from a Guest named Don regarding blocking off the "heat riser" manifold passages with real world results :

 

" …  When we speak of "heat riser" , we are talking of the exhaust passage that is cast into the intake manifold. when your valve on the exhaust manifold closes when the engine is cold the exhaust gasses pass instead of out the exhaust pipe, but up and over and into the exhaust portion of the intake manifold (heat riser) and pass to the other cylinder head and out that side…. David, some of the high performance intake manifold gaskets for Pontiac have a piece of stainless steel in the gasket to block it off, but before they started doing this the factory racers ( myself included) would go to a sheetmetal store or shop and buy a thin sheet and cut it to size and slip it under the gasket. FYI on emisson control vehicles this is a illegal procedure, but for performance minded people and where there is no law prohibiting doing the procedure the gains in engine power from straight flow of exhaust and the cool intake charge (because no heat is applied under the intake runners) increases the engine volumetric efficiency and the cool charge can take more ignition advance without detonation also for more power and MPG. Test have shown that by further insulating the carburetor from heat by using a one inch Micarta Spacer under the carb. is good for a tenth of a second at the end of the quarter mile. You might say a tenth is nothing, but it is equal to one full car length at the finish line! …"   … " Some of my pontiac's I race and some are for show, but on both types of engines I block the heatriser off completely. For racing, the engine makes make about 10-15 HP more, and for show the center part of the manifold never burns off it's paint from exhaust heat. None of my cars have driveability problems even with the heat riser blocked off. On one of my cars the factory intake RA 1V dosen't have a riser crossover attached to the manifold at all. …"  Don

 

A 4-Hole Spacer … As a rule of thumb, this type of spacer ( 4 individual holes one under each barrel of your carburetor ) will increase your throttle response and acceleration.  They can also move the torque and power band down in the RPM range. This is accomplished by keeping the air and fuel flowing in move of a column, which  increases the air velocity.  This can be a perfect addition if your vehicles throttle response is not as good as you'd like, or getting passed when you pick up the throttle coming off of the cornering. A 4-hole spacer can also help make up for something in the intake tract being larger than optimal ( too large of a carburetor, cam, intake etc. )  ...

 

 

Edited by buick man (see edit history)
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If I had a dollar for every prospective customer that had read about blocking heat cross-overs and called me because of drivability issues, I could retire and buy an island somewhere!!!!! :P

 

The rule(s) of thumb:

 

(1) 1 to 1 1/2 PERCENT power increase at WOT (yes, for a trailered racecar, there is a measurable improvement)

(2) 20 to 30 minutes drivability issues around town :rolleyes:

 

And I was one of the idiots that did so to my own car! :angry::rolleyes: I finally ended up installing a manual choke, and I have a manual transmission. I shutter to think of the problems I would have had if the car had an automatic!

 

This modification is really best left ONLY to the racers.

 

Jon.

 

 

Edited by carbking (see edit history)
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I admit it, I really wanted to believe it made a difference, Boy, did it! But not what I wanted!

 

In self-defense, I was about 30 years younger and more gullible (this (*&^%$# mis-information has been around that long).

 

It was easier to install a carburetor with a manual choke (and I like manual chokes anyway) than to undo the heat cross-over modification. Now I have the best of both worlds. I use the choke in town for the first 20 to 30 minutes; and I have the extra 6 1/2 horsepower at WOT :) (Not the 15~25 HP promised).

 

This was absolutely the second worst mistake I ever made in working on vehicles over a 60 year time period. (The worst was thinking I was smart enough to make a Pontiac 301 run decent!). It wasn't really the 301 engine's fault, as it had good torque from 2700 to 2750 RPM. What I really needed was a 28 speed transmission! :P

 

Jon.

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… sorry to hear Jon you had so much trouble with that modification … probably because it can get darn cold out there in the wilderness of Missouri and Texas as well … the first time I did my block off was the late 60's on my first nailhead a 57 century convertible and then in the mid seventies  on my 57 Caballero wagon and experienced no drivability problems whatsoever, of course the temp in my neighborhood only varied about 40 degrees year round … not the bitter cold which most definitely would have a different effect on an experience such as yours … I drive my cars at a temp from 65 degrees to around 90 degrees … if on the other hand I had to endure true cold and I grew up in the midwest so I know what cold means … where a manual choke was my friend as well as a battery charger and an in-line block heater … but that is not my situation now days and blocking off the manifold / carb heat sink allows more benefits in my particular environment and temp ranges in which I operate my cars … - uncle dave 

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Dave - over the last 25 or so years, we have had at least several hundred, and probably thousands that have called us with drivability issues and this modification, from Hawaii to Alaska. Of course, we hear from those that have issues, not those that do not; so do not know the ratio of happy to unhappy; but your experience is certainly not shared by all. My personal Pontiac GTO was drivable only using "heel and toe" technique around town for at least 20 minutes, IN THE SUMMER! Or, I could set the idle at about 1800 RPM (definitely not recommended for a street driven car).

 

There are three solutions of which I am aware: 

 

(1) Remove the modification (best)

(2) Install a manual choke (easiest and least expensive)

(3) Recalibrate the carburetor about 2 sizes rich, which destroys fuel economy, and can also do damage to the engine (not recommended)

 

If one lives near an interstate, starts the engine, immediately gets on the interstate and drives 30 miles at interstate speeds, one would probably not notice issues. But city driving, not a good idea for many.

 

I am happy for you that it works for you.

 

Jon.

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… O,K. so probably will end up like I said making the manifold block outs and the rubber grommets, but whiz all one would think that the replacement grommets at least would her correct and easily available and such a simple copy item … kinda like the now available white air cleaner A/C  and Oil Filter can decals when in reality from the factory were the classic A/C Delco orange/red silk screened color skeme …  Hey … some things like this just matters and if not factory correct they should at least be reliably useable  ...

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I have reproduced the stock carburetor block off plate that goes between the top of the intake manifold and the gasket that goes on the bottom of the carburetor with a 1/16" steel plate.

It works great. I have had it installed now for about 6 years and 10,000 miles on my '56 Century.IMG_0623.thumb.JPG.681de9a35d900308ccba59eeedfa0775.JPGmsg-80448-0-15203000-1447375348_thumb.jpg

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… so you have produced the plate shown above and have effectively blocked the heat passages at the top of the manifold where the carb sits … and have had no drivability problems … Did you also block the passages at the head/manifold … ?  I think some of the problems Jon reported is from blocking off at the head to manifold area and no doubt would render an ever colder upper manifold / carb interface than just a plate blocking off the heat source as the body of the manifold would still be heated … neat info Airy and are you selling block of plates or was this a one off deal … ?  Another version would be to make the plate a little thicker and have it tapped to receive a potential PVC port in the making … :D  - uncle dave

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Airy - if you are making these to sell, they should sell well.

 

Between Carter and Rochester, among various makes of vehicles, there are more than 400 different of these plates used originally. Some vehicles absolutely require them. I think only a dozen or so different have been reproduced.

 

We have made quite a few out of 0.030 stainless (think restaurant going out of business ;) ) steel simply by putting the stainless between two pieces of half inch plywood (support), bolting it together, drawing the pattern on the top piece of plywood, and cutting it out.

 

Many of the vehicles that required these use Carter AFB carbs.

 

Jon.

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