Hydraulic flat tappet vs Hydraulic roller

[HAMBURGLAR]

One for the engine guru's. Have just grabbed a 347 from a friend that knows nothing about the engine except it wasn't friendly. It is a 5.0 ltr roller block with Trick Flow heads #69951-2 and air gap manifold. I removed the rear welsh plug to see the details of the cam. It is a Crane cam #H-296-2 Hydraulic flat tappet.   Being a roller block with provision for a spider , I would like to change to maybe a comp cam XE-274-HR . Is there any better suggestions for cam and lifters ( do I need linked lifters ). Don't know compression but it has a eagle steel crank and forged rods with SRP pistons #S40FS.  Is there any good reason they would go with a hydraulic flat tappet cam in a roller block ?

[GLENN 70]

I have no idea why they went a flat tappet hyd cam and not a hyd roller other than cost .  If you go roller it's not just the cam and lifers etc it's changing the valve springs too .  It's a complete running engine and unless you want to go with a roller cam ,yes I know they are better ,I would just stick with what it has . Question , is yours  a manual or auto that makes a difference with running that cam .  . Shaun and Barnett will talk you into the roller cam ,but most likely not that baby one  .  Let the fun begin 

[GLENN 70]

Barnett are you asleep . Waiting waiting .

[HAMBURGLAR]

Barnett are you asleep . Waiting waiting .

My brain's hurting just thinking about trying to answer his questions. 

[HAMBURGLAR]

I have no idea why they went a flat tappet hyd cam and not a hyd roller other than cost .  If you go roller it's not just the cam and lifers etc it's changing the valve springs too .  It's a complete running engine and unless you want to go with a roller cam ,yes I know they are better ,I would just stick with what it has . Question , is yours  a manual or auto that makes a difference with running that cam .  . Shaun and Barnett will talk you into the roller cam ,but most likely not that baby one  .  Let the fun begin 

I have no idea either so I thought it must be to some advantage why they did it. Its going to run a AOD trans , 3.7 gears and 28inch tall rubber.

[GLENN 70]

The auto will need a good size hi stall converter . 3,000 rpm

[shaunp]

They did it to save a few $. Lunati voodoo 272 is a nice torquey cam in a 347, very mild idle

[HAMBURGLAR]

They did it to save a few $. Lunati voodoo 272 is a nice torquey cam in a 347, very mild idle

Is that a flat tappet or roller cam shaun ? Looking for something strong down low only.

[shaunp]

They put a flat tappet in it to save $200 odd, The 272 Voodoo cam is a Hydraulic roller, 282 is hotter and has lumpy idle. I've used the 272 in a couple of 351s and 347s, its just noticeable at idle, will rev past 6k and pulls the whole way. Last car i put one in was a 68 FB basic 347 with as cast 170cc Edelbrock RPMs airgap and 650 double pumper, 10.5 comp. Car didn't have an LSD rear, if you nailed it would just light up the rear till you backed off. 2500 stall convertor is the go  I dont think you will regret a 272 Voodoo roller its a great street cam
 

[HAMBURGLAR]

They put a flat tappet in it to save $200 odd, The 272 Voodoo cam is a Hydraulic roller, 282 is hotter and has lumpy idle. I've used the 272 in a couple of 351s and 347s, its just noticeable at idle, will rev past 6k and pulls the whole way. Last car i put one in was a 68 FB basic 347 with as cast 170cc Edelbrock RPMs airgap and 650 double pumper, 10.5 comp. Car didn't have an LSD rear, if you nailed it would just light up the rear till you backed off. 2500 stall convertor is the go  I dont think you will regret a 272 Voodoo roller its a great street cam

   Sounds like the one.    To go back to roller I guess I will need a cam , spider and dog bones , linked roller lifters and new valve springs. Would that be a good start ?

[GLENN 70]

And the valve springs set to the correct Spring pressures for the roller cam . And a high stall converter , 2500-2800 rpm .

[HAMBURGLAR]

And the valve springs set to the correct Spring pressures for the roller cam . And a high stall converter , 2500-2800 rpm .

    Sweet. Any preferred brand for all the components ?    Also had someone today say that I should just put another flat tappet cam similar to the Lunati cam shaun recommended  and new lifters in and save a heap of money.    What kind of cost roughly am I looking at with the roller conversion ? Cheers.

[GLENN 70]

Why don't you want the cam that's in the engine now ? , if it's a bit lumpy who cares , put a 3,000 rpm hi stall converter in it and it will drive like a std car but sound and go good . My 66 has a big flat tappet hyd cam and with the 3,000 stall drives like it's near stock . No matter which way you go it will need a hi stall converter any way . 

[HAMBURGLAR]

Why don't you want the cam that's in the engine now ? , if it's a bit lumpy who cares , put a 3,000 rpm hi stall converter in it and it will drive like a std car but sound and go good . My 66 has a big flat tappet hyd cam and with the 3,000 stall drives like it's near stock . No matter which way you go it will need a hi stall converter any way .

I love a big cam as much as the next bloke and the 3000 stall is find. He said it wasnt friendly and one of the reasons was the lack of vacuum for the boosted brakes , which then calls for a vacuum pump. He also said he was running a 4000 stall.   Im happy to keep it if it will work with the AOD and 3.7 rear gears and 28inch tyres. Thanks glenn i appreciate all the advice especially on the hi stall as i dont really understand how they operate.

[GLENN 70]

Go find someone with a hi stall converter around 3,000 rpm and a biggish cam and go for a ride ,not a drag race drive but a street drive and see what you think . As for vacuum for your brakes yes it can be a problem but depends on the tune ,intake manifold and the size of the brake booster . My 65 has no problems what so ever ,big hyd cam ,3,000 stall and 3.5 diff ratio behind a C4 ,  you could down size the cam in it if you wanted ,new cam and lifters most likely , as long as your valve springs are at the same rating .  If it were me and mine I would leave it and go the 3,000 converter and worry about the brakes later .  A high stall is a bit like a slipping clutch a bit but then locks up at its lock up rpm , drive easy or normal and you can hardly notice any difference to a stock auto .  No mater what you do in cams you will need a high stall . The converter will cost around $900 for a name brand built here in Australia .   

[HAMBURGLAR]

Go find someone with a hi stall converter around 3,000 rpm and a biggish cam and go for a ride ,not a drag race drive but a street drive and see what you think . As for vacuum for your brakes yes it can be a problem but depends on the tune ,intake manifold and the size of the brake booster . My 65 has no problems what so ever ,big hyd cam ,3,000 stall and 3.5 diff ratio behind a C4 ,  you could down size the cam in it if you wanted ,new cam and lifters most likely , as long as your valve springs are at the same rating .  If it were me and mine I would leave it and go the 3,000 converter and worry about the brakes later .  A high stall is a bit like a slipping clutch a bit but then locks up at its lock up rpm , drive easy or normal and you can hardly notice any difference to a stock auto .  No mater what you do in cams you will need a high stall . The converter will cost around $900 for a name brand built here in Australia .   

  Cheers Glenn.  What would be a good brand in OZ ?

[GLENN 70]

Dominator converters in VIC . They will need some information like what cam , carby ,intake manifold , gear box ,diff ratio and weight of car .  If you import one you have no come back if it has a problem .  People think a big hi stall the engine will rev high to get the car going and it's not like that with a converter under 4200 rpm . I'm still thinking 3,000 is what you want .  Talk to them about it .

[shaunp]

   Sounds like the one.    To go back to roller I guess I will need a cam , spider and dog bones , linked roller lifters and new valve springs. Would that be a good start ?

Check what springs  on the heads now they maybe OK if not I'll give you a trickflow part number for their upgrade roller springs which are actually a PAC racing spring, you can either use the lifters with spider if its a roller block or use some howards link bars, these are better lifter but you cant remove/fit without taking the heads off.  You want springs with min 140 pound on the seat and 240 or so open.  the 272 voodoo works great with mid 2000 stall, the last one i did the car had 2600 stall, and 3.5 rear it was excellent & quite quick. The owner had no trouble dusting his mates 2017.

[HAMBURGLAR]

Dominator converters in VIC . They will need some information like what cam , carby ,intake manifold , gear box ,diff ratio and weight of car .  If you import one you have no come back if it has a problem .  People think a big hi stall the engine will rev high to get the car going and it's not like that with a converter under 4200 rpm . I'm still thinking 3,000 is what you want .  Talk to them about it .

Yeah im one of those guys that thought a large stall would never lock up while doing 2000rpm on the highway and would overheat because of excessive slipping. I'll contact Dominator with my specs. Did find this in the Crane catalogue .

[HAMBURGLAR]

Check what springs  on the heads now they maybe OK if not I'll give you a trickflow part number for their upgrade roller springs which are actually a PAC racing spring, you can either use the lifters with spider if its a roller block or use some howards link bars, these are better lifter but you cant remove/fit without taking the heads off.  You want springs with min 140 pound on the seat and 240 or so open.  the 272 voodoo works great with mid 2000 stall, the last one i did the car had 2600 stall, and 3.5 rear it was excellent & quite quick. The owner had no trouble dusting his mates 2017.

Thanks Shaun , taking cost into consideration at this time as I have a heap still to spend on this project and I already have the running gear and just need the hi stall , I will most likely run with this combo till later and then switch back to a roller using your suggestion when the funds free up and the boss is looking the other way. I might even try doing this myself. Cheers mate.

[Dingo80]

Hopefully not hijacking your thread Hamburgular as question is relevant hopefully. Your cam card shows max rpm 6800 and valve float at 7200rpm. Does that mean this cam could be rev'd to 7000rpm for example? I have the next cam down in my 351W and H-286-2 and my cam card (thanks hamburgular, crane sent it to me) says max rpm 6600rpm and valve float at 7200rpm. So theoretically could I up my rev limiter on occasion?

I think I understand there is more to it related to the head package, intake manifold etc, but theoretically is this true? Or does it mean past the max rev limit, there is too much overlap, more to exhaust and torque/HP will drop off dramatically?

[HAMBURGLAR]

Hopefully not hijacking your thread Hamburgular as question is relevant hopefully. Your cam card shows max rpm 6800 and valve float at 7200rpm. Does that mean this cam could be rev'd to 7000rpm for example? I have the next cam down in my 351W and H-286-2 and my cam card (thanks hamburgular, crane sent it to me) says max rpm 6600rpm and valve float at 7200rpm. So theoretically could I up my rev limiter on occasion?

I think I understand there is more to it related to the head package, intake manifold etc, but theoretically is this true? Or does it mean past the max rev limit, there is too much overlap, more to exhaust and torque/HP will drop off dramatically?

No problem mate. Hopefully one of the boys will jump in and clear this up for you as I don't know enough to comment. Good luck.

[GLENN 70]

With all the goodies to go with the cam ,carb,heads, etc etc that cam makes power to 6,800 rpm ,it may rev higher but the power will drop off from the cam side of things . With the valve springs set up for that package they will float at 7,200 rpm . If you had the mother of all valve springs the engine will rev higher without valve float but make no power up that high . The cam with all the right gear might make a bit more power over 6,800 rpm .  6,800 rpm is over the top for most 347 strokers unless they have an after market block ,6,200 rpm is about max for a street driven engine . My old 347 I had I took it to about 6,000 rpm and never had a problem in 10 years .  Still ran 11.9 at 115 mph on the strip and was a mild low comp engine .

[HAMBURGLAR]

With all the goodies to go with the cam ,carb,heads, etc etc that cam makes power to 6,800 rpm ,it may rev higher but the power will drop off from the cam side of things . With the valve springs set up for that package they will float at 7,200 rpm . If you had the mother of all valve springs the engine will rev higher without valve float but make no power up that high . The cam with all the right gear might make a bit more power over 6,800 rpm .  6,800 rpm is over the top for most 347 strokers unless they have an after market block ,6,200 rpm is about max for a street driven engine . My old 347 I had I took it to about 6,000 rpm and never had a problem in 10 years .  Still ran 11.9 at 115 mph on the strip and was a mild low comp engine .

  115mph in a 66 . Wow , I wouldn't plan on going anywhere near 6800 rpm. How would that cam that I posted do down low and mid range with a 3000 stall and 3.7 rear with 28 " tires ?

[barnett468]

Barnett are you asleep . Waiting waiting .

Sorry, I have been in a coma.