Tranny and diff recommendations.

[HAMBURGLAR]

Looking for an option on an  auto and diff ratio to go behind a 347 (450+hp).  AOD or C4 , C6. Don't really want a huge stally and won't be drag racing so can I use a stock converter or something like a 2000 to 2400rpm converter. Mostly highway driving but also cutting laps around town , so maybe 3.25 or 3.5 ? This motor came out of the 66 and is going in a 56 f100. Seriously thinking of swapping out the solid cam to a suggested cam by a few of you genius's including the late Boofhead to calm it down. I can hear Barnett calling me a pussy already.

[Dwayne]

I'm going with a beefed up AOD with 3.8 gears.

Quick acceleration and low freeway ram's for the best of both worlds 

[GLENN 70]

If it's 450 HP plus or even near that it will have a big cam and it will need a large size hi stall converter . If changing the cam well that's a different story . Nothing wrong with just a C4 with a small hi stall depending on the cam you refit . Valve spring with have to be changed also . Other wise stick with what it has and go a good hi stall . Diff ratio depends on the wheel height so we need to know that ,and then we can work it all out . Need the weight of the truck also .

[HAMBURGLAR]

I'm going with a beefed up AOD with 3.8 gears.

Quick acceleration and low freeway ram's for the best of both worlds 

                                                                                   



That's sort of what i'm after Dwayne.

[HAMBURGLAR]

If it's 450 HP plus or even near that it will have a big cam and it will need a large size hi stall converter . If changing the cam well that's a different story . Nothing wrong with just a C4 with a small hi stall depending on the cam you refit . Valve spring with have to be changed also . Other wise stick with what it has and go a good hi stall . Diff ratio depends on the wheel height so we need to know that ,and then we can work it all out . Need the weight of the truck also .

Glenn the tyres are 28inch tall and the truck weigh's 1500kg wet. I do have a XE274HR cam somewhere around the joint  that I was going to swap out with the solid. Main reason is I can't see my wife driving the truck with a 4000+ hi stall. You say I need to change the springs as well ? I assume the lifters will be changed as well. 

[derwin66]

I put an AOD in my 60 truck, bit it only has a 289 with a Fitch system.  It sits real nice on the highway and in suburban streets

[GLENN 70]

As its only going to be a cruiser it's just the wrong combo . At 450 plus HP from a 347 it must be quite an engine . What carb ? What intake ? Is it a flat  tappet solid lifter cam ? . If it's a big solid lifter cam and you change to a medium hyd lifter cam you Will have to change the valve springs or pressures .  You could leave the cam and run a 2500 -2800 rpm converter that will drive fine . Change the carb and intake for a more street friendly set up .  Box ,yes a 4 speed auto if you want to go down that track or just a C 4 .  Either 3.5 or 3.25 will do the job with a C4 and that will give you at 100 kph 2,600 rpm with 3.5s and 2,400 rpm with 3.25 gears . I would think the F - truck will weigh more than 1500 kg as that what a 69 mustang  351 would be .  If it's got a bit of compression and go change the cam to a small one the compression will go up .

[Dwayne]

I'm happy to swap you a stock 302 for your angry 347 if it helps keep your wife happy.

Willing to make this sacrifice for a fellow forum member 

[GLENN 70]

What a nice guy 

[Dwayne]

The sacrifices we make for others 

[lukep6470]

So I have a 460HP 347 and my main issue is when slowing down the AOD really likes to hang on to 3rd until about 800rpm so I have had to fuel cut on overrun to stop the lugging and thrashing of the diff that causes.  It's pretty frustrating.

[HAMBURGLAR]

As its only going to be a cruiser it's just the wrong combo . At 450 plus HP from a 347 it must be quite an engine . What carb ? What intake ? Is it a flat  tappet solid lifter cam ? . If it's a big solid lifter cam and you change to a medium hyd lifter cam you Will have to change the valve springs or pressures .  You could leave the cam and run a 2500 -2800 rpm converter that will drive fine . Change the carb and intake for a more street friendly set up .  Box ,yes a 4 speed auto if you want to go down that track or just a C 4 .  Either 3.5 or 3.25 will do the job with a C4 and that will give you at 100 kph 2,600 rpm with 3.5s and 2,400 rpm with 3.25 gears . I would think the F - truck will weigh more than 1500 kg as that what a 69 mustang  351 would be .  If it's got a bit of compression and go change the cam to a small one the compression will go up .

Yes Glenn , its just going to be a cruiser with the occasional squirt. The weight of the truck from factory specs is approx. 3200lb which I worked out about 1500kg's which surprised me as well. Think i'll take the engine to a builder and get it changed to a hyd roller cam around the 350 to 400 hp mark and tune it on their dyno. I like the idea of a AOD 4 speed and 3.5 gears. Cheers.

[HAMBURGLAR]

I'm happy to swap you a stock 302 for your angry 347 if it helps keep your wife happy.

Willing to make this sacrifice for a fellow forum member 

What a great bloke. 

[HAMBURGLAR]

So I have a 460HP 347 and my main issue is when slowing down the AOD really likes to hang on to 3rd until about 800rpm so I have had to fuel cut on overrun to stop the lugging and thrashing of the diff that causes.  It's pretty frustrating.

I couldn't cop that mate. 

[shaunp]

I think to make an AOD nice its takes some work, Silver fox valve body I think is the go. with respect to the stall it all depends on who makes it,. I did a 347 late year and guy had one made in Brisbane  I can find out where,  for a C4 its 2600 and you can not tell it even has a stall unless you actually stall it up or give it it full throttle. I understand deleting the the lock up function in the AOD converter also transforms them. They do like to hang onto gears

[HAMBURGLAR]

I think to make an AOD nice its takes some work, Silver fox valve body I think is the go. with respect to the stall it all depends on who makes it,. I did a 347 late year and guy had one made in Brisbane  I can find out where,  for a C4 its 2600 and you can not tell it even has a stall unless you actually stall it up or give it it full throttle. I understand deleting the the lock up function in the AOD converter also transforms them. They do like to hang onto gears

WOW , the more I read about these AOD's the more I'm getting put off. Maybe I should just go for a C4 or C6 with a 2400 to 2600 stall which would be a lot cheaper than buying a AOD and beefing it up.

[GLENN 70]

Gee I think someone said that ,gee it was me . C4 or a small block C6 auto is fine .  Around a 2500 rpm converter and a shift kit in the auto ,trans go brand . Dominator brand converter also . As I said you could try leaving the cam for now and just fit an edelbrock RPM intake and something like a 750vac sec Holley carb . Either 3.5 or 3.25 gears and your done . The cam you have now is over kill but by changing the intake and carb will make a huge difference for better low down torque . Keep the exhaust size down to a twin 2 1/4  or a single 3 inch will help also .

[HAMBURGLAR]

Gee I think someone said that ,gee it was me . C4 or a small block C6 auto is fine .  Around a 2500 rpm converter and a shift kit in the auto ,trans go brand . Dominator brand converter also . As I said you could try leaving the cam for now and just fit an edelbrock RPM intake and something like a 750vac sec Holley carb . Either 3.5 or 3.25 gears and your done . The cam you have now is over kill but by changing the intake and carb will make a huge difference for better low down torque . Keep the exhaust size down to a twin 2 1/4  or a single 3 inch will help also .

YEAH YEAH YEAH.  I know you did but I was really keen on a 4spd because of all the highway use but I can compensate that with the rear gears. Which is better C4 or C6 ?   I have already changed the manifold to a RPM Air Gap and it has a Barry Grant Silver Claw 750 carb.  Has anyone had any dealings with Matt Kay from Transmatt in SA ?

[GLENN 70]

C4 or C6 either one really . The C4 might be easier to get and parts are easier to get also . You will have plenty of room for either box and either a pan or case fill C 4 will be ok . Aussie s call them C10 s for the later C4 v8 box .  Finding extractors to go past the big C6 can be a problem and they drain HP those C6 boxes .

[barnett468]

Seriously thinking of swapping out the solid cam to a suggested cam by a few of you genius's including the late Boofhead to calm it down. I can hear Barnett calling me a pussy already.

 

[barnett468]

you absolutely need at least 3.43 gears if you have a real 450 hp 347, otherwise, it will be a pig off the line. if you don't have an overdrive, I would not go higher than 3.50.

a 2000 rpm stall is useless with 450 hp, it meds to be at least around 2400.

so 2400 and 3.43 gears would be a nice non racing combo.

[shaunp]

what cam does it have now?

[HAMBURGLAR]

you absolutely need at least 3.43 gears if you have a real 450 hp 347, otherwise, it will be a pig off the line. if you don't have an overdrive, I would not go higher than 3.50.

a 2000 rpm stall is useless with 450 hp, it meds to be at least around 2400.

so 2400 and 3.43 gears would be a nice non racing combo.

OK. I am getting a quote for a performance built C4 with a 2600 stall. I have a 9 inch with 31 spline Strange axles but no centre yet.

[HAMBURGLAR]

what cam does it have now?

Don't know the specs Shaun. All I know is that it is a pretty nasty Crane solid. Think I will swap it out for a XE274HR if its no good with the rest of the package I get.

[shaunp]

Don't know the specs Shaun. All I know is that it is a pretty nasty Crane solid. Think I will swap it out for a XE274HR if its no good with the rest of the package I get.

274 XE HR is a good street cam and it will still make good power. I've seen a 347 with AFR heads 750 DP go over 400 hp no trouble, and its very driveable I like this cam ground on 110 centers rather than 112, I actually have this in my temp 347 with 195 AFR comp heads I run it 1.7 rocker to get the lift to 600 thou. Its a bit more aggressive than the similar Voodoo cam.  I think you will prefer that cam.