| 1970 Tiara with Toronado FWD Question about power train [message #344706] |
Mon, 01 July 2019 00:15  |
Rick Daley
Messages: 4
Registered: June 2019
Karma: 0
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I have a 1970 Ultravan Tiara. It uses the same Toronado drive train that the GMC motorhomes use. My mechanic tells me the engine is in good shape. The low cylinder shows 145 and the high cylinder shows 154 in a recent compression check. My rig weighs 8,000 lbs which is heavy for a Tiara. They were delivered at 6,500 lbs.
I understand the 23 foot GMC motor home weighs 10,000 lbs and the 26 footer 12,000 lbs give or take a few lbs.
I recently crawled over the Cascades on Washington Hwy 20 east and was routinely down to 20 mph with the vacuum gauge in the deep red. If my rig weighed 12,000 lbs I am pretty sure I would still be on the other side of the Cascades.
Can anyone give me some recommendations or some threads to pull on improving my rigs climbing performance? (I don't have a problem doing 70 on the flat but usually keep it at 65 or below).
Regards,
Rick Daley
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| Re: 1970 Tiara with Toronado FWD Question about power train [message #344712 is a reply to message #344706] |
Mon, 01 July 2019 11:10  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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The secondaries on your carburetor may not be opening . Rebending the throttle linkage may cure this problem if it exists. With the choke full open look in the carburetor with the gas pedal to the floor are the secondaries open you will need to open the rear throttle plate to see the rear butterflies. Engine off of course. Also your distributor advance may need to be recurved or cleaned and the weights lubed also it should be set at about 10 dog initial . If you are interested in a lower final drive gearing call Jim k at applied he supplies various gear ratios for your rig.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: 1970 Tiara with Toronado FWD Question about power train [message #344718 is a reply to message #344715] |
Mon, 01 July 2019 13:08 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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Compression alone doesn't dictate the health of the motor. Ignition makes a huge difference in how it runs as well as fuel (carb) or lack of same as in restricted fuel supply which could be any number of things. You also could have a gear ratio that's not RV friendly such as a 2.73. You'll just have to do a bit of research to figure it out. Good luck, Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: 1970 Tiara with Toronado FWD Question about power train [message #344720 is a reply to message #344706] |
Mon, 01 July 2019 13:09 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Rick Daley wrote on Mon, 01 July 2019 01:15I have a 1970 Ultravan Tiara. It uses the same Toronado drive train that the GMC motorhomes use. My mechanic tells me the engine is in good shape. The low cylinder shows 145 and the high cylinder shows 154 in a recent compression check. My rig weighs 8,000 lbs which is heavy for a Tiara. They were delivered at 6,500 lbs.
I understand the 23 foot GMC motor home weighs 10,000 lbs and the 26 footer 12,000 lbs give or take a few lbs.
I recently crawled over the Cascades on Washington Hwy 20 east and was routinely down to 20 mph with the vacuum gauge in the deep red. If my rig weighed 12,000 lbs I am pretty sure I would still be on the other side of the Cascades.
Can anyone give me some recommendations or some threads to pull on improving my rigs climbing performance? (I don't have a problem doing 70 on the flat but usually keep it at 65 or below).
Regards,
Rick Daley
Rick,
The Ultravans that I have seen that were 455 were all fit with power directly removed from a Toronado. Most of the standard package had a 2.73 final drive, but the 3.07 (what was shipped in TZE) was from the trailer tow package, and it was wrong for the TZE that day. There are better available now.
We have a 9460# 23' coach, and we crossed the Big Horn (the GPS reported 9200msl) on the way to Yellowstone with out any real issues. I expect any naturally aspirated engine to have not put out full power over 8000MSL.
I fully agree that you may not be getting the secondaries open. When we open ours, the racket is unmistakable. If the carburetor is still the stock Rochester, then the secondaries are mechanical link. You can have someone step on the throttle and see if they do open fully. (The actual throttle, not the air valve.) If not, fix that before you do anything else.
If you ever have to do engine work, we have people that can provide some important guidance.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: 1970 Tiara with Toronado FWD Question about power train [message #344721 is a reply to message #344706] |
Mon, 01 July 2019 13:11 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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downshifting and keeping a little more rpm's.
I would believe you have some performance issue with your engine. making sure carb is working properly is one thing, the next is to make sure the distributor is working properly. 20MPH is pretty slow.
the motorhomes have a ratio of 3.07 for stock coaches. Many drop to a lower gear ratio for the best in mountain climbing, and towing. But there are plenty of 3.07 GMC motorhome gears that people climb mountians doing 40MPH in 2nd gear.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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