Nope dont have a heat shield. Are those typically replaceable items or are they something you re-use? Does sealant need to go under them? I'll have to try and track one down for a 340. thanks!
read this....might be an issue.. http://www.v8buick.com/showthread.p...ainless-baffel&highlight=340+carb+heat+shield
Would this work? I have a Carter AFB and it's listed under the application... although $30 is kind of pricey. http://www.summitracing.com/parts/MRG-3710/?rtype=10 ---------- Post added at 09:57 AM ---------- Previous post was at 09:49 AM ---------- http://www.ebay.com/itm/Buick-300-3...Parts_Accessories&vxp=mtr&hash=item53ea39da1c Just came across this, looks like what i need :TU: Thanks for tracking down the article. Should i still use some sealant on any of the gaskets? There is this one also http://prestoliteperformance.com/carburetor-heat-shield.html The ebay listing seems to be what most guys were using in the article MGHS provided.
I just ordered the stainless steel heat shield for the carburetor. It should be here either Monday or Tuesday. Hopefully that will fix the idle problem. MHGS, Since that one cylinder came up to 125, do you think I might have a bad valve at that cylinder? Or maybe a leak in the gasket could be causing the weird idle?
no....we took +/- 5-6 cylinder strokes so who's to say that we were not 132 133....within range they were good. I still haven't heard anyone chime in on the pcv location for a stock 340.... I know that the 350 is in the intake but yours is in the valve cover, somebody must know ? I remember feeling that there was a TON of vacuum from the carb base to the pcv which is why I am thinking the heat shield thing...just maybe the bottom has access to the plenum ...just a thought. Who knows...we will narrow it down and find the culprit....hang in.
Ha, alright. I'll wait for the heat shield. From the best of my memory the pcv has always been in that location. I have ran the car with all of the vacuum ports, manifold and carb plugged off and it still has a rough idle, if that makes any difference. Thanks again for all the help. ---------- Post added at 05:50 PM ---------- Previous post was at 05:20 PM ---------- PCV info scroll to page 29 www.teambuick.com/reference/library/67_chassis/files/60-b.pdf
alright..thanks Larry.... Your input, Think about this....As I mentioned, when I pull the vac source to the pcv it almost feels like there is more source than to the carb itself.... almost like there is a leak to the carb base if that makes any sense ? At idle there is definately an erratic rythim but once off idle cicuit it seems to be happy...I lean towards the carb but although there is consistent spark to all plugs it could be a weak coil....I need this car for a few days...
I appreciate all the help and patience with my problem fellas. I know its frustrating, hopefully one of these suggestions will work out. One step at a time. Thanks again!
If the engine is stock, it should pull very close to if not 20" of vacuum. I'd start there. If the vacuum is erratic, I'd look at the valves. Could be the valves are too tight. Too long of a push rod will do that. What is the history of this engine?
no...the vac is fairly steady and was as I remember +/-16,17...When I stand there and listen to it my gut says ignition...
That is low for a stock engine. Has it ever been rebuilt? Camshaft change? What do the plugs look like?
The engine was rebuilt in 2009. One of the heads were cracked so it was replaced along with the rocker assembly. It says on the receipt that the lifters we're replaced and the valves were ground down. If I replace the gaskets on the manifold, i suppose i'd have access to the push rods and the lash could be adjusted accordingly at that time. The plugs have always looked great. MHGS can attest to that. ---------- Post added at 10:56 AM ---------- Previous post was at 10:56 AM ---------- I'll go pick up a coil right now and put it in. Maybe my pointless ignition is going out, but i'd think that would just shut off completely. Thanks
I'd look at lifter pre load on the side that got the new head. Buick valve trains are not adjustable. When you take the intake off, I would check lifter pre load on both sides. If it was me, I'd get a set of adjustable push rods and get that set right. If the valves are too tight on one side of the engine, it could make it idle rough and have low vacuum.
any recommendations on adjustable rod (brands) that will work with a 340 buick? How would the rods all of a sudden begin to act up and cause a rough idle? Being that the car ran perfect prior to the overheat.
It wouldn't. This thread is so long that I can't keep track of everything. If it started after an over heat, you may have warped something causing a compression or vacuum leak somewhere. Doesn't look like it from the compression tests, but something is wrong, and it started after an overheat. If the engine is stock, it should make 20" of vacuum. Yours doesn't, and that isn't normal.
OK, well hopefully like MHGS has been saying it might be ignition related. I remember coils going bad from being so close to the block, maybe it got affected by the overheat as well. Well, i went to my local O'reillys and bought a stock coil, before i could even install it, one of the terminals snapped off :af: POS!!!! So I upgraded to an MSD coil, but i cant find a ballast resistor at any of the local shops, so i'm going to order one. So it's not installed. My question now is, with my points eliminator by accel and a new msd coil, can i wire it as before? I think i might be causing more issues here with this new coil so im beginning to second guess myself...
