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#1
05-07-2021, 05:06 PM
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Bent valves/pushrods questions (1960 389)
I had the timing chain jump out of time on my 60 389. So far got the timing chain & gears replaced and the car timed. Seems to run fairly ok, but suspect I likely have some bent valves. Per the manual the compression spec @ cranking speed is supposed to be 200-210. Back in 2008 I did a compression test and got the following...
190 185 194 193 205 188 186 191 The range today varied from a low of 155 to 175 for a high. The car sat for a couple of years so I dont know if that could be a contributor to the lower numbers or not. Question...what is the likelihood of having bent pushrods wo also having bent valves? Doesn't seem likely to me. I think pulling the valve covers is next on the agenda. Opinions/comments? Thx. |
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#2
05-07-2021, 05:15 PM
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Please don’t tell me that chain and gears where still stock!
Anyway the stock 4 bbl 472 cam used in 1960 still had .400” lift at the valve and with a high compression 4 bbl head I bet it’s a interference fit motor as I don’t recall those early motors having much of a valve notch in the pistons, In short I think you indeed might have some bent valves! A leak down test will tell you in 30 minutes what’s going on or not.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 05-07-2021 at 05:21 PM. |
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#3
05-07-2021, 05:38 PM
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Ok, I won't tell you ( cause I don't know the complete history of the car) . Btw, the engine is the high compression 2Brl, 283 horse. Same as the 4Brl motor]. Thx for the repl.
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#4
05-07-2021, 05:38 PM
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Ok, I won't tell you ( cause I don't know the complete history of the car) . Btw, the engine is the high compression 2Brl, 283 horse. Same as the 4Brl motor]. Thx for the reply.
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#5
05-07-2021, 07:07 PM
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I had the nylon timing gear round the teeth off on a 67 Le Mans with a 326. It tweaked a valve, I drove it like that for probably 2 years with that slight miss at idle. Once you got the RPM up the miss went away. It ran perfectly before the timing gear broke so I'm sure it bent one of the valve heads, but very slightly so it only missed at idle in gear.
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Brad Yost 1973 T/A (SOLD) 2005 GTO 1984 Grand Prix 100% Pontiacs in my driveway!!! What's in your driveway? If you don't take some of the RACETRACK home with you, Ya got cheated    
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