Chestermo
MS
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Joined: 08/06/2009
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I put a set of Bridgestone R250 225s on my 93 four years ago. Handling is much better. The duals have never touched each other. I run about 85 lbs all around. It did slow me down for any given RPM, but I'm not in too much of a hurry. The improvement in handling was worth it.
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high5
Michigan
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Joined: 06/09/2010
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Tire update
I went with the 225R70 19.5 Goodyear G670 tires on both axles. Handling has improved. The first thing I noticed was less body sway in high winds. Turning and braking are better also. The speedo reads 3 to 4 mph higher at 60. The lowered height of this old Cruise Master actually makes the RV look better IMHO. It was expensive but I'm happy. Now onto the next task on my list - the generator.
This is off topic but might be helpful. The garage where I bought the tires also did some other work while the wheels were off. They found the timing was set at 10 BTDC - way too early. They set it to the specified 4 BTDC and now the starter has no problem turning the 454. I haven't noticed any power loss although I expect to lose a mpg.
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Jim83Itasca
La Quinta Calif
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Joined: 09/16/2003
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high5 wrote:Tire update
I went with the 225R70 19.5 Goodyear G670 tires on both axles. Handling has improved. The first thing I noticed was less body sway in high winds. Turning and braking are better also. The speedo reads 3 to 4 mph higher at 60. The lowered height of this old Cruise Master actually makes the RV look better IMHO. It was expensive but I'm happy. Now onto the next task on my list - the generator.
This is off topic but might be helpful. The garage where I bought the tires also did some other work while the wheels were off. They found the timing was set at 10 BTDC - way too early. They set it to the specified 4 BTDC and now the starter has no problem turning the 454. I haven't noticed any power loss although I expect to lose a mpg.
Depends on what the "Overall" timing turns out to be at your cruise speed, I forsee hotter engine temps, Poor mileage and lack of hill climbing power....
On my sold 87 Chiefton 22' the timing (stock) was 4º BUT the "HEI" only advanced (Mechanical) 16º for a grand total of 20º BUT don't forget the vacuum advance is setup at 25º which becomes totally useless under 6 inches of vacuum.....
My now 83 Itasca was setup the same way and at 4.5 MPG it was a complete dawg and the 87 only handed out 5 MPG.....
The big blocks "Chebbys" at the track love 36º-40º max ignition to run hard and I see NO reason to advance ours beyond 32º cruising up the hills and 42º down the flat slab at and around 3000 RPM.
With the summer fuel now in play I have advanced the ignition to 11º base and 22º mechanical plus 10º more with the vacuum advance...
Take a good long hard look at what is happening once your on the road cuz your in for a surprise....
Jim
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Brian in Michigan
S.E. Mi.
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Joined: 03/13/2003
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High5 Where did you take it to?
1990 GEORGIE BOY 28' 454 4BBL, TURBO 400 TRANS, Thorley Headers B&M trans cooler. Auto meter hooked to output of trans. Flowmaster mufflers
((((Was 7.5mpg Now 8.75mpg ))))
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high5
Michigan
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Brian in Michigan wrote:High5 Where did you take it to?
Hey Brian. I use Superior Services in Belleville. When I first went to them about 5 years ago most of their business was commercial heavy trucks. Last week their yard was 95% motorhomes. They have fair prices and do very good work.
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high5
Michigan
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Jim. I do expect to lose gas mileage but it's worth the peace of mind knowing the 454 will start when I want it to. It hasn't lost any power from a standing start and the temperature is good so far. I've only run it about 30 minutes at 60 mph on flat roads. Finding a hill to climb in my neighbor is not easy. I can always bump it up a few degrees if necessary. I don't know what my total advance is but so far the effects have only been positive. I guess time will tell...
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sum1
So-Cal
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Joined: 11/07/2005
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I love the big rain grooves in the Goodyear 647 225's and putting them up front greatly improved responsiveness. I went with Load Range G. Rear dual clearance on my Accuride wheels is well in compliance with specs but I haven't done the rears yet due to an odometer problem - it hasn't advanced much in the last year or so. 
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sum1
So-Cal
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High5, Jim knows of what he speaks. With a good tuneup and hi-test gas, your cooling, performance, and mileage should improve and starting should be trouble-free with your base set earlier than 4°BTDC. So maybe with stock springs, vacuum gear, etc. 10° was too much, but following Jim's guidance on the rest of the timing curve is likely to multiply your gains. This engine is capable of much more than your getting now.
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Brian in Michigan
S.E. Mi.
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High5
You always have the long hill at Barton Hills. Thats as good as it gets around here.
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high5
Michigan
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Jim. I'm new here any I haven't done any research as yet so this maybe redundant on the forum. Have you re-curved the distributor? Do you have spring and vacuum sets you recommend? I'm assuming carburetor induction and electronic ignition. Do you have experience with a Q-jet?
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