It’s ALIVE! 1968 Rocket 350
February 28th, 2021, 04:52 PM
#1
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Join Date: Apr 2010
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It’s ALIVE! 1968 Rocket 350
We managed to get the old Rocket 350 cranked up! Car has not been started for over 10 years! We put a freshly rebuilt Quadrajet on her and hap hazardly attached what was left of the exhaust... HEI gave us fits with no spark so installed a new AC Delco ignition module and that did the trick! Here are a couple of videos of the first startups... After we ran it a couple times for about 2 minutes at a time, we redid the compression test and although we got consistent pressures across the cylinders, they seem kind of low at 105 psi on every cylinder except cylinder 7 with a 95 psi... what gets me is for a car that has sat for over 10 years, it idles fine and has very decent throttle response... what are y’all’s thoughts?
February 28th, 2021, 05:09 PM
#3
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Join Date: Dec 2006
Location: Melville, Saskatchewan
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You may have sticking rings or partially sealing valves or a combination of both. Is it a stock 4bbl motor? If so, it should be much higher. Even a 2 bbl motor would be 150+ in good health.
March 1st, 2021, 06:02 AM
#4
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Get it hot, change the oil and filter. Add a quart of Marvel Mystery Oil additive and 4 qts. of engine oil with zinc. Add a bottle of top engine lube to the fuel tank and take it for a couple of long drives after you are sure the rest of the car is road worthy.
March 5th, 2021, 03:55 PM
#6
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Yeah, the oil was clean, but we went ahead and changed it. We Marvel Mystery Oiled all the cylinders and rotated by hand a few times a day while adding more Marvel in the cylinders. Then we changed the oil and put on a newly rebuilt Quadrajet and a small fuel tank just to crank it. Cranked up pretty quick once we did what we needed. I know the compression is low, but at least they are all the same psi. I think we are gonna just pull it out, give it a paint job and go with what we got.
I already have new motor mounts, new pair of Hooker Headers, Summit Racing 2" exhaust kit with mufflers, and a new Carter AFB mechanical fuel pump... I think that will give us a good start.
Still debating on pulling the water pump and timing cover off to inspect the timing chain. But I think i'll check it through the fuel pump port before making the final decision.
I already have new motor mounts, new pair of Hooker Headers, Summit Racing 2" exhaust kit with mufflers, and a new Carter AFB mechanical fuel pump... I think that will give us a good start.
Still debating on pulling the water pump and timing cover off to inspect the timing chain. But I think i'll check it through the fuel pump port before making the final decision.
March 5th, 2021, 08:36 PM
#8
Out of Line, Everytime😉
Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 9,004
Kleenflo Combustion Chamber Cleaner is the only thing I have seen that actually gains compression if it is stuck rings. I gained as much as 35 psi, just be careful filling cylinders and running it, I hydro locked and bent a rod. ATF in the oil may help as well.
March 6th, 2021, 05:37 AM
#10
Out of Line, Everytime😉
Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 9,004
Unless you can see it enough to tell if it is the original nylon coated timing chain, it won't do a ton of good. You might be able to check slack. The shedding of the nylon coated cam gear is hit or miss. All my 307's and 350's looked surprisingly good but your motor is older and the nylon may be in your oil pump pickup.
March 6th, 2021, 12:45 PM
#11
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Man, I guess since we are gonna pull the motor to paint it, might as well remove timing chain cover and oil pan so we can put new gaskets on and replacing water pump anyway. I'll update soon! Thanks a bunch guys, we are getting more and more excited about it.
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