Thought I would ask what some of you that have run the 340s what they run in the 1/4? What could you expect from one with 2 speed,278 rear gears. little hotter cam and home ported heads. Also stock ehx. manifolds. Also what did they run stock. Also was wondering if any one makes long tube headers for them in a 66 skylark. After playing around with one recently I am looking at one for my next project mabey. Thanks
Hey there, I do not know how fast the 340 should run however I know that the 2 speed trans and highway gear are holding it back big time. I would swap to a 2004R trans and a 3.42 or 3.73 gear. It will feel like a whole new car! Google sanderson headers, I think they make a set for you. Personally for a street car I would leave the manifolds in place and just use mandrel bent 2.5" duals with magnaflow mufflers.
Sanderson does indeed make a set of shorty headers for the 340, and you can find a used set of Poston long tube one occasionally. do you have the 2 or 4bbl version of the 340?
here is what a 1967 skylark ran its like a 1966. these are old road tests. 300ci ran 18.3 at 78 mph with 2.78 gears. 340ci ran 17.2 at 81 mph with 2.78 gears. 340ci ran 16.6 at 84 mph with 3.23 gears.
went back on the site these numbers are dynamics simulation software, they seem close to some real tests. Bob, i will get you real numbers on my new 340 build its broken in, has about 200 miles on it.
When stock, my 65 Skylark with Stock 300" motor, stock trans 3.90 gears and dual exhaust would go 16.50s.
heres my 340 numbers. 14.65@100.01. 2 speed sp tranny, 2.78 gears. stock exhaust manifolds and stock intake there is no after market one. dave nelsons roller rocker conversion. smooth, not a big cam idles at 650rpm in drive. little head and intake work by a board member. 323 gears will be in this week. hope to pick up 6 tenths. what do you guys guess, 60ft time now is a very bad 2.43.
Hi Joe, Glad you got your 340 back together. Your engine is what got me looking at the 340s. How much better do 350s run compared to 340s? I know there a whole defferant engine. Also, Joe is this 323 gears going to be a posi?
That is really good MPH. That is enough to run low 13s. That gear change will not give you 6 tenths. However, if you went to a 3 or 4 speed trans and a 3000 converter, that bad boy will run 13s no problem. That 2 speed transmission is just a boat anchor on a heavy car.
your could be right, let you know in week or so. i was sort going by the test times they had 2.78 and 3.23.
Wow thats faster than the GS400's run buy a lot, I hope mine can run times like that but I kind of doubt it. Not with out some more work anyway.
GREAT mph! Lousy 60 ft....I also feel 13's are in your future.:TU: Back around 1984, I ran a mid 14 USING FIRST GEAR ONLY when I ran my blue GS with 2.93 rear, ST 300, and L/60-15's. Was hitting 6000 rpm at the line. After that run, I did use 2nd gear since I had to drive 850 miles back home.:grin: Would you elaborate on the roller rocker setup? And what cam are you using? I'd like to mod my 300. Bob... what kind of flow improvements did you get from those heads? Please post some more pics of that car!
rocker arms are stud ones, there from dave nelson the guy that stroked the 300 in hot rod magazine.theres a thread on the small block site. buy the kit then use chevy roller rockers. i went with the 1.6 ratio. the cam pulls to 6000 nice. i shift at 5400-5500 rpm. its a fast ramp comp cam 216 intake 224 exhaust on a 110 lsa with on a 105 centerline. Walt, thats a good one first gear only. lol ---------- Post added at 10:55 PM ---------- Previous post was at 09:53 PM ---------- .500 lift on the cam xfi intake xe exhaust.
Back when engines were limited by air flow, valve float, coil integerity and the occassional rod exiting the block.
Wow.... looks very familiar! Here's my '66 Special, 300 with '64 alum 4 bbl intake and Richmond 5 speed.
sure does, do you have buckets or bench seat. i still have points in it that came with the car, what are you running for ignition. thanks
