Thanks Larry, that might work. I also found these. http://www.summitracing.com/search/...ole/Gasket-Thickness-in/0-250-in/?Ns=Rank|Asc Its a shame they dont put any of the measurements, so i'd be buying it blind, but its cheap enough to where it probably doesn't matter. By "lifting" the carb further away from the manifold, will that cause any issues? Being that the fuel will have to travel father in a sense to get to the cylinders.
As long as you get a square bore gasket, it will fit. Holley and Carter use the same square bore pattern. No issues on lifting the carburetor.
Awesome thanks for the help! Today i will try using the previous gasket in between the carb and the heat plate, see if that does anything. Then wait for the 1/4in plate to come in.
I believe the whole thing with the heat shield was brought up in a post awhile back.....I found that it's fairly common on the 340's that the heat passge has corroded through the heat shield and thus into the carb base. That would explain the vacuum leak....I didn't look at your carb base but that's where I was going with the heat shield thing.
The bottom of the carb is pretty straight. No corrosion like ive seen in other carbs. But there are hi and low spots and some wear from age. I'll try and snap a pic of it. I do have new intake gaskets now as well as valve cover gaskets that i could replace in the event that the carb isnt the main issue.
Im going to replace the manifold gaskets this week. Is it necessary to drain the ENTIRE cooling system? or can i just unhook the upper radiator hose and pull off the intake manifold? thanks
I wouldn't mess around...any engine coolant which spills out will ruin your cam and lifters. Just drain the radiator, and disconnect both upper & lower radiator hoses to drain the block as much as possible. The heads and intake will be drained, at least. Then you can remove the intake and clean it up with the new gaskets & seals.
When ever I do an intake at work, I also wash down the lifter valley with some fresh oil (generously) poured over the lifters to wash away any spilt coolant. And then a oil change, leaving the drain open for awhile to get anything that went from the valley into the pan to drain free.
My first thread on this board was my journey into my lifter galley to retrieve a wayward PCV grommet: http://www.v8buick.com/showthread.p...Engine-PCV-Grommet-HELL&p=1725347#post1725347 There's some photos and tips on what to do and not do in getting it all bolted back up. If you have air tools, use some 3M roloc pads (red or brown) with a grinder to clean the gasket surfaces. Also, make sure your intake bolt holes are completely clean and free of any debris, or you can break bolts off.
Thanks for the post, i'll be referring back to it soon. One thing i noticed after i installed the carb spacer from summit is that the mounting bolts seem to loosen as i tighten one side of the carburetor. How can i fix this? How tight should they be? It did make an improvement on the idle, but im afraid with the vibration of the engine, the bolts will keep coming loose. This is what i bought, it's made of foam it seems like http://www.summitracing.com/parts/MRG-4278G/ thoughts?
I like to use a little bit of lock tight on most bolts so they do not back out. The trick is in evenly torquing the bolts down. First put them all in to about 5 foot pounds, then 10 and I am pretty sure that the spec for the carb bolts is about 15.
I re-timed my engine and brought the initial timing between 6-8* to see how the engine would idle and perform. it sounds good. I may bring it down closer to the specs in the book of 2.5* and see how it works there. One thing i did notice is when my vacuum advance is disconnected / plugged and the carb outlet it plugged. the engine runs extremely smooth. Very nice idle and when in drive it idles nicely as well. When i re-connect the advance the idle comes way up (which is expected) but it is not as smooth as it was without the advance. why is this?
For my carb, the vacuum advance is connected to the ported source on the carb. This vacuum source only kicks in when slightly on-throttle, and it goes away as throttle is opened to WOT. The other way to hook it up is to a manifold source, which is always on at idle and goes away as the throttle is opened to WOT. It sounds like you are hooked to a manifold source. If you are connected to this source, another 10-14 degrees of advance automatically get added in at idle. I'd reduce initial timing and see if the idle improves. Once it is going steady, hold your hand over the primaries to cut off some of the airflow, and see if the idle smooths out & RPM goes up. If it does, your idle is too lean and needs a bit more fuel/air flow through the idle circuit.
Haven t heard this one yet. Some good info. Im thinking of bringing the timing down closer to 2-5*. It is on manifold vacuum right at the front of my Carter. When i currently put my hand over the primary it does raise the idle and smooth it out. Right now my screws are at 1 1/2 turns out from the seat. Im thinking though that the closer to 0 i get, the less fuel mileage / power i will have. I suppose its a give an take. Right now the 6-8* sounds good, just a little high for my Buick Boat Cruiser
The consensus on the board is that manifold vacuum is best, and about 32-34 degrees total timing once the RPMs are up enough to totally engage the mechanical advance weights in the distributor. I run ported vacuum and have my total timing in at about 3200...comes out to around 35 degrees total. I checked my timing with the vacuum advance plugged, and only got about 20 degrees total at about 2800 RPM. With the vacuum advance connected, I got another 14 degrees on top of it. I may try switching to manifold some day and see how it likes that source.
When I went from the tvs to straight manifold vac I had to adjust the timing a bit and also adjust the curb idle. The increased timing at idle was throwing things off a bit so the other little adjustments made it all work out nicely. My base timing now is about 6 and that lets me run the cheap gas (87 octane) with no detonation anywhere in the rpm range. Since my motor is a '73 it has slightly less compression which allows slightly more timing before detonation kicks in.
I would try to adjust the idle mixture screws to get max vacuum readings on a gauge. You must be lean at idle if the idle raises with less air when you cover the carb. Or you just have a massive vacuum leak which we have been thinking...
