Driveshaft clearance is easy.
CK5
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2nd vote for Thrush welded. Had a used pair off of Larry's K10 on my old '75 with a bazillion mile 350. Previously it had glass packs on 2.25" duals that the tailpipes rotted off of. The sound with the wiped out glass packs was horrible. I ghetto fabbed the Thrush mufflers on with a couple of reducers and a handful of clamps and no turndowns on the outlets of the mufflers. The Thrush mufflers transformed the sound of that truck. They had that cool muscular sound at idle, very Flowmaster like for sure. Driving in anger rewarded a sound that you didn't think a wheezy worn out 350 could generate, but still calmed down at part throttle cruise.
I liked the sound and the price so much I made sure I bought another pair for the '91's exhaust system with the 5.3. The main difference was the addition of tailpipes vs the '75's lack of them. The tailpipes took the harder edge off, but still sound great at full boil and have that sweet distinctive idle quality.
I'd go with duals. 2.25 or 2.5" size. Depending on the skill of the exhaust guy bending 2.5" pipe tucked up and out of the way might be a challenge. The 2.25" stuff will be easier to route and package and not lose anything for flow over a single 3" system. I would add an H-pipe after the t-case though. That will help mellow the tone slightly.
I liked the sound and the price so much I made sure I bought another pair for the '91's exhaust system with the 5.3. The main difference was the addition of tailpipes vs the '75's lack of them. The tailpipes took the harder edge off, but still sound great at full boil and have that sweet distinctive idle quality.
I'd go with duals. 2.25 or 2.5" size. Depending on the skill of the exhaust guy bending 2.5" pipe tucked up and out of the way might be a challenge. The 2.25" stuff will be easier to route and package and not lose anything for flow over a single 3" system. I would add an H-pipe after the t-case though. That will help mellow the tone slightly.
The 73 has Thrush welded in a single 3" that dumps at the rear axle; I like it.
I have the LARGEST Flowmaster I think they make on the crewcab, and it's a little quiet for my taste. I'm thinking I'm going to put a thrush in it too. It's single exhaust also but 3.5" because I couldn't have a 454 with the same size exhaust as my 350 truck.
The 66 has dual 2.25" with Flowmaster 50 series delta flow. I also think they are too quiet even tho they dump out in front of the rear tires. Sometimes I stop at lights and I think the motor has died because it's so quiet. Want to put Thrushed welded on it too.
bp71k5
3/4 ton status
For reference, I’m using a single 3” and a magnaflow. The tire noise drowns out any exhaust noise on the freeway unless I romp on it. I also like the single dumping exhaust out of the opposite corner of where the driver sits. Don’t get any fumes that way, even without a CAT.
So finally got around to doing a compression test on the motor.
1991 Chevy 350 TBI @ Colorado altitude
Compression test: cold, cranking only.
Cylinder
#1 120
#2 115
#3 100
#4 95
#5 95
#6 100
#7 100
#8 100
Thoughts???
1991 Chevy 350 TBI @ Colorado altitude
Compression test: cold, cranking only.
Cylinder
#1 120
#2 115
#3 100
#4 95
#5 95
#6 100
#7 100
#8 100
Thoughts???
You had the throttle plates open, and engine somewhat warm? Even for your altitude should still be higher I'd think. Something like 3% per 1k ft elevation..? You also have about a 20% variation between cylinders which seems a bit high also.
All plugs out and cold. Just cranking.
Those seem like numbers I've gotten before, good or bad I don't know.
Ring end gap will close up a bit w/ warm numbers, so you lost a couple percent there. Not sure what that engine had from the factory. But I'd have guessed closer to 150ish even cold and at altitude.. But I'm not an engineer either.
Cam can have some effect on the static cranking pressure - lots of overlap will bleed off. I had a higher compression pontiac 400 was about 12.5:1 , w/ a pretty lumpy cam and it was still pushing 195ish.
Cam can have some effect on the static cranking pressure - lots of overlap will bleed off. I had a higher compression pontiac 400 was about 12.5:1 , w/ a pretty lumpy cam and it was still pushing 195ish.
Compression test should be done with the throttle wide open, first dry,, and then with a bit of oil. How the numbers change and by how much will tell you a lot.
In the cylinder being tested the cylinder is drawing against a closed throttle, AKA a vacuum. With the throttle open it can draw in as much as it can, and then compress it giving you a true reading. You'll see numbers as much as 20% higher with the throttle wide open.
Oh yeah, if compression goes up with oil in the cylinder that is generally worn rings. If compression doesn't change with oil that is usually valve related.
So basically a cold, crank only test will result with the lowest numbers, meaning it can go only up from there. I can live with not knowing the true higher numbers then as I don't plan on doing anything internal with this motor anyway, plus I really don't have any motivation to remove brand new spark plugs over a hot motor. lol
I've had a few engines with a couple of worn cam lobes on intake valves make the compression read lower in those cylinders..
Even with the throttle wide open,the valves weren't opening fully and the less air that gets in to compress,the lower the reading is..
I did 2 cam swaps on small blocks that had only 90 psi (cold) in two cylinders,and didn't feel like taking the heads off for a valve job,or doing a full rebuild with new rings,I just put a new cam in them and hoped for the best..
It turned out the intake valve lobes on those two cylinders were almost wiped out,they were barely opening..(which I knew due to the "gargling" thru the carb at higher rpms,I can tell when a cam lobe is dead by the sound now! ),and the engines ran great after the swap--tested the compression a few weeks later and those cylinders that had only 90 psi cold,had close to 130 warmed up,like the other six did..
Even with the throttle wide open,the valves weren't opening fully and the less air that gets in to compress,the lower the reading is..
I did 2 cam swaps on small blocks that had only 90 psi (cold) in two cylinders,and didn't feel like taking the heads off for a valve job,or doing a full rebuild with new rings,I just put a new cam in them and hoped for the best..
It turned out the intake valve lobes on those two cylinders were almost wiped out,they were barely opening..(which I knew due to the "gargling" thru the carb at higher rpms,I can tell when a cam lobe is dead by the sound now! ),and the engines ran great after the swap--tested the compression a few weeks later and those cylinders that had only 90 psi cold,had close to 130 warmed up,like the other six did..
Slap some correctly gapped plugs in and run it.
