Thread: SBC mileage

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Don,
I have friends that live on Norfolk Street....let me call them & see if they will pick them up for me. They are nice people that have a local biz. there....I'll let you know in the next day or two...ok?

OK Hambiskit, I will retrieve them from the machine shop as they are not sold there yet. My address and phone number are in the phone book. I have learned a lot about SBC engines and I guess if I were starting over I would take a good look at a 327 where those heads would be a better fit, but for me the C.R. is too high on the 350 block for current gas prices. If it comes to a close call as to who gets them I will respond to the first $150, so don't wait too long.

Don Shillady
Retired Scientist/teen rodder

Thanks, I will call them tomorrow. It's too late there now.

Hambiskit,

I settled accounts with Joe Butler today at his machine shop and he already had a guy put a $50 deposit on the 461 heads two weeks ago, but still owes the other $100. I have not been contacted by your folks so the way it stands is that if they want those heads for you they can just take the money to Joe's Machine Shop at 514 Myrtle Street (in the back of a white building with a church sign in the front) in Ashland and pick them up there. As of now whoever brings the $150 first gets the heads and if your folks are first, Joe will refund the $50 to the other guy.

Don Shillady
Retired Scientis/teen rodder

Maybe this thread is the place to ask this question. Now that I am locked in for a while to a mild 350 with a street torque cam and a 2.79 rear gear, I am wondering whether to trade/sell my rebuilt TH350 transmission for an R700. People and articles tell me that the TH350 is more reliable than the R700, but of course the limit to only three speeds and the fact that I have the early non-lockup TH350 leads to lower mileage for two reasons. Assuming I keep the 2.79 rear gear, what about the change to optional planetary gears on the TH350? The low gear will only change from 2.52 to 2.70 and the gears are expensive so is it worth the change? The good part of that idea is that high gear remains 1.00 so the 2.79 ratio is still available for cruising mileage.
My rough calculations indicate that If I keep the 2.79 rear gear and add the lower ratio planetary gear, the new low gear will be what it would be if I had a 3.00 rear gear, not a great improvement, but still some better performance while retaining the high gear mileage. Any comments from someone who has tried the lower ratio planetary gears in a TH350?

Don Shillady
Retired Scientist/teen rodder

Richard/Tech1,

Back to this issue I have looked at a number of the 700R4 deals and I have several questions. First check out the site for the '94 Corvette getting 18/25 mpg:

http://www.corvettesbyrickdaniel.com...ETTESPECS.html

I note they get 0-60 in less than 5 sec with 350 H.P. and a 700R4 and a 2.73:1 rear. Admittedly the aerodynamics of a '29 Ford roadster cannot compare to the sleek shape of a "Vette, but the '29 is lighter by almost 1000 pounds so the 0-60 time could be comparable with a 300 H.P. SBC and a 700R4 with a 2.79:1 rear. I may be able to swing the finances for a 700R4 in the near future due to a real estate deal but the old question arises about how to handle the electronic lockup. What is a simple way to hook up a 700R4? Also I was interested in your comment about a "manual valve body". After shifting 4-speeds in VWs and a MG midget for many years I would not mind shifting a manual valve body if it is easy, but so far it seems like the idea is to have a ratchet shifter which might be quite stiff. Is it possible to use a Loktar shifter with a manual valve body in an easy manner just as if it were a manual 4-speed without a clutch? Thus can you answer if it is easy to make a 700R4 manually controlled without a computer or use a manual valve body which is easy to use in the usual gear-rowing fashion common with a true manual 4-speed?

Don Shillady
Retired Scientist/teen rodder

Well just to keep the thread going I will mention that yesterday my family attended the Va State Fair in Richmond and I had a chance to look over the stealth Camaro of one of the local counties (Henrico). It is an unmarked maroon 2002 Camaro with a lot of internal gadgets including a PC. The thing of interest is that their sign advertised the car as their 159 mph cruiser with a LS1 engine and a automatic 4 speed. The main feature of interest is that it has only a short stub antenna externally but both forward and backward looking radar with the ability to pick out the fastest vehicle from a pack. Chatting with the officer, he admitted he had only taken the car up to 131 mph and the 159 mph number may be only due to the highest reading on the speedometer dial. But, assuming a 0.7 overdrive gear in my roadster with a 2.79 rear ratio and 735/75/15 rear tires I calculate a theoretical top speed of 197 mph at 4500 rpm! Clearly with 1929 full fenders and a square top I suppose anything over 100 mph would be difficult as well as illegal on the street with a Model-A roadster. I imagine the wind buffeting at high speed in a Model-A would be severe (based on memories) so I am only interested in the 70-80 mph range for "passing" on the Interstates. I looked up the LS1 350 specs and see that the bore is less at only 3.900" but with a longer stroke than my old '76 350. Also as noted above in the 2004 Corvette site the Corvette uses a 2.73 ratio rear with the automatic 4-speed and 0.7 overdrive. The question is when I run the calculation for my tires with a 700R4 0.7 overdrive and my engine, the rpm comes out around 1500 at 70 mph. The question is whether the car will actually run at that low rpm with the non-aerodynamic roadster body and will I have to change the rear to a lower ratio say 3.55? This is just a conversation piece, but I wonder how those 0.7 overdrives can run in the 60-80 mph range with such low rpms and is this only possible with the greater torque of the LS1? On the other hand with lockup in the 4th gear and the automatic making the decision when to shift I guess it works great for a slick body, but will it work easily for a roadster body? Maybe tinkering with the shift point for the OD gear will be necessary?

Don Shillady
Retired Scientist/teen rodder

Don,

My 93 Vette had 2.73'3 (w/ a 700/R4 & 300 HP LT-1)), and I ran all day at about 1850 rpm at 70 mph. I got 29 mpg on my first trip with it. I didn't like the lack of balls on the low end, so I changed out to 3.55's. My mileage on the road is still about 24, and 19 in town. With the lock-up, the trans run very cool.

I'm setting up my '34 with 3.73's and a R4 from Bowtie Overdrives. I spent several hours on the phone with the owner, and he knows more about OD transmissions than anyone I ever met. His transmissions are all run in a mule before he ships them out. He also (for a small price) sends a pressure and temp gauge with the transmission, and guides you through the installation.

After driving a Vette for 8 years, I wouldn't want a manual valve body either. The stock setup works just fine. You can downshift or hold it in gear as you wish.

Richard and Henry, Thanks for excellent answers! It looks like I should be able to purchase a 700R4 soon and maybe later change the rear. For sure the low gear of 3.06 on the 700R4 should be a lot better than the 2.52 gear of the TH350 even with the 2.79 ratio rear and I will have to evaluate the weight factor since the roadster should be lighter than the Vette by 500-800 pounds. It is great to learn from your actual experience!

Don Shillady
Retired Scientist/teen rodder

[QUOTE]Originally posted by Don Shillady
Richard and Henry, Thanks for excellent answers! It looks like I should be able to purchase a 700R4 soon and maybe later change the rear. For sure the low gear of 3.06 on the 700R4 should be a lot better than the 2.52 gear of the TH350 even with the 2.79 ratio rear and I will have to evaluate the weight factor since the roadster should be lighter than the Vette by 500-800 pounds. It is great to learn from your actual experience!

Don Shillady
Retired Scientist/teen rodder [/QUOTE


im running the 700r4 trans in my truck with a 410 gear and other than the overdrive i dont like it. ive changed the trans twice, the valvebody a couple times, used dif. stages of shift kits and its eather to hard with the kit or to soft without the shift kit. cant seam to get it right. don if you will tell joe butler, mike said hi. he used manage one of my shops in richmond a few yrs ago and i hadnt heard from him in awhile. thanks