Can anyone advise me on HP and torque ratings on these motors? I'm looking at a 1970 Bluebird 31 foot motorhome using the 391 gas engine backed by an allison MT40 model C6TA auto tranny (6 speed).

Are there torque "hop-up increasing" parts avail for the 391, and do you advise upgrading to the 429 or 534 motor for more power/torque? Whats the best bet for gas mileage? I've done many a hop up based on intake, header, exhaust, ignition and cams in the past, but have zero knowledge on this family of motors.

Appreciate any and all advice, tips, or web links.

Dan in USAF in Tx

 

[updated:LAST EDITED ON 07-Jan-02 AT 11:46 PM (EST)]Sorry ,I don't have any idea how to Hop up these motors but,I can help you with some specs.

391/389 :

70-72= 235Hp@ 4400 *Torque= 372@2000
73 = 192Hp @ 3600 *Torque = 333@2400
74-78 = N/A N/A


534 motor:
70-72 =266Hp @3200 *Torque 481 ftlbs @1700
73-78 = 222Hp @3000 *Torque 400 ftlbs @1800

I would suggest an early 429/460 2V for Torque/Hp ratio.
with: Dual Exhaust,non-restricted air cleaner system,
Torque 2V =500Lbs@2800
68-71 Plain 429 2V =320Hp @4400

The 4V can be more fuel efficient while cruising with an egg under the gas pedal though.
Torque 4V = 480lbs@2800
68-71 Plain 429 4V = 360HP @4600

Dennis
Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"







78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles

 

Dan, your 391 is an FT, a heavy truck version of a 390. Your block is a beefier casting and the crank is forged instead of cast. thats good. The 391 also has its own heads which don't breath as well as the car/pickup truck heads, thats bad. there is hope however. The bolt patterns are the same for the FT and the FE. You might consider swapping out the intake manifold, cylinder heads, and exhaust manifolds, replacing what you have with light truck parts. Save your original distributer, you will reuse it. D2TE-AA castings would be good cylinder heads for you, they will breath better than what you have and are easily found on any 72 or later 390 or 360. The manifolds you need will be there too. But you have to do the whole deal. Just swapping manifolds or just the heads won't work well because the heat riser patterns are very differant. DF

 

Dan,the 391 should be a good engine for your application as long as it is in good working order.You could increase torque output through a change of camshaft,I would also want to degree the new cam in.Also a good carburetor and ignition system upgrade as well as exhaust system upgrade.To my knowledge there is no aftermarket intake or headers for that engine. I would not recomend a change of cylinder heads to the light truck version,those heads will not take the heat generated by the load of the motorhome.You will have exhaust valve problems as well as exhaust seat recession problems. As far as a swap to the 429 or 534 i would think it to be prohibitive because of the need to change mounts,trans. bellhousing.Also the 534 would require a large increase in cooling system capacity and maybe even suspension system,the 534 is very heavy. I hope this helps answer some of your questions.

 

 

DWBon, what is this about exhaust trouble ? Your going to scare the poor guy. The FE and FT heads are made of the same iron aren't they ? Why would one be any more likely to have valve seat erosion than the other ? Some FTs (389s?) come with hard seat inserts but a medium duty 391 probably won't have them. The D2TE-AA light truck heads have 3/8s valve stems that are plenty tough, and the ones from a 75 or 76 truck will have induction hardened seats. Really Dan should do a valve job on the new heads before putting them on, and could easily have hard seat inserts added if he was worried about it. Better yet, stainless 1.65" 428CJ sized exhaust valves, with hard seats installed, and some bowl work would make them indestructable and add plenty of power at the same time. I like the ignition idea however. Pertonics is way better than points. DF

 

[updated:LAST EDITED ON 08-Jan-02 AT 09:48 PM (EST)]I appreciate all the great posts. I know a lot more about this motor now from the info here.

On other web sites, I have learned this motorhome (bus) is approx 23,000 pounds loaded for the road. From 1964-1976 - Ford industrial gas engines were factory installed as standard engine. 391 and 534s were used, and I have heard but not verified that 429s were used. I'm not sure if the Allison MT40 6 speed auto was used on all - I believe a spicer 5 speed manual was used on some. I also learned 55 to 65 is about the speed it'll "cruise" on the flats, returning between a high of 8 and a norm of 5 MPG. Less on the mountains.

If I buy this bus I'll likely keep the 391 and try and increase torque. I'll start with easy to do's like full tuneup and fluids, a large K&N air filter to replace oil bath, check exhaust size and likely replace with high flow, pick a carb and ignition upgrade. At that point I'd drive it a while. "Modern" motorhomes used the Ford 460 until the V10 came on the scene, so I'm still wondering if the 460 is a viable swap that may yield more HP/torque? I also wonder about the feasibility of a 3208 Cat swap in - but have no clue how to go from gas to diesel, and whether the current tranny would work.

All in all, it seems if I buy this 1970 rig, I should work with the 391. This one has 53,000 miles on it, and another seller is asking me to look at a 1972 identical bus, same motor/trans, but with a 2 speed rear end, and a rebuilt 391 and tranny 3,000 miles ago.

What carb/ignition would you advise, and is there a torque "RV" cam available. I'll also start researching the usual suspects like edlebrock, holley, etc.

Thanks again - great advice and comments ,,,, and I'd sure appreciate more input as well.

 

do not confuse the ft 429 with the 385 family 429 they are completely diffrent animals. an are not interchangeable.

 

Did you happen to notice that you are responding to an ancient thread? The post you responded to was typed January 8, 2002.

There is no such thing as an FT 429.

FT engines (330 2V M/D, 330 2V H/D, 361 2V, 391 4V) introduced 1964, used thru 1978 in 500 series and larger trucks, with one exception.

1973/78 F350's made exclusively for U-Haul used the 330 2V M/D (aka X/D).

The first year the 370 and 429 were offered for 500 and larger series trucks was in 1979.

 

hey the heavy truck 429 ft is real an i found out because the machine shope ordered pistons for that when i built my 429 for my pick up thanks. an i dont care how old the thread is. why be a dick about it. the deck hight on the heave truck 429 is substantially taller. thanks for the info douchbag!!!!!¡!!!

 

You can call me whatever you like, kiddo...but there still no such thing as a 429 FT engine.

As I said, there is a 429 heavy truck engine but, it's not an FT engine.

 

"douchbag!!!!!¡!!!" WOW, someone has had a bad day. Real mature. ;o(

 

yes i am sorry just got ****ed over at work an ****ed out if a 428 cj 40.000 mile original motor bit tiffed lol sorry man

 

Bought 1974 f-100 everyone says has 391 in it ,on right side block casting numbers say 391 ,NGOs can make sure looking at it. Are 10! Head bolts under Val covers ,can't find tag any where vin number said came with 302

 

Most people haven't a single clue what engines came in these trucks, so take with a grain of salt the term everyone.

There is no block casting number that contains the numbers 391.

Block casting numbers contain a prefix (D1VE for example), basic casting number of 6015, and a two letter (AB) or two letter and one number (A1B) suffix.

391's were only installed in 500 and larger series trucks.

1974 F100/350's were available with 360 and 390 FE engines which look very similar to FT (330 2V/361 2V/391 4V) engines.