[Burningbird]

Finally getting my 389/400ci back from the machine shop next week, but second guessing my cam choise now. I have a the Voodoo 703 (227/233@050, 110LSA) but after reading the post by another member here who made 400hp/450lb-ft with the smaller 702 cam (219/227@050, 112LSA) in almost identical engine I regret not going with the smaller cam. The car is a 60 Bonneville with 4-speed hydramatic and 3.08gears. The engine is the original 389 bored 058 over, Icon pistons with 11cc dish, Eagle rods, stock crank, balanced, ported #76 heads from a 65 389, 1.5 roller rockers, Crower 68404 valve springs, Edelbrock RPM intake and a Holley 750. SCR is 10:1. The stock log mainfolds are port matched, cleaned up inside and the outlets opened to 2.2" with Pypes 2.5" downpipes to 2.5" Cherry Bombs Vortex mufflers. Should I bite the bullet and order the 702 cam instead?

[steve25]

If your not going to run Rhoads veri lifters with that 703 Cam then with your cid, the cars weight and rear gears then I would for sure step down to the smaller Cam .

[Cliff R]

I think you'll be fine with 10 to 1 compression and a 4 speed application. Should be pretty "rowdy" and work well with the manual transmission as idle quality is less important and you aren't up against a converter that might be a bit too tight.

We've used the Crower 60243 cam which is 228/235/112 LSA in similar engines with great success. It requires 10 to 1 compression for best results, but idles well and good street manners in 400 engine builds.......Cliff

[PunchT37]

He’s got an auto trans. I would step down. Maybe you can swap em out so you don’t have to buy another cam?

[Burningbird]

Originally Posted by Cliff R

I think you'll be fine with 10 to 1 compression and a 4 speed application. Should be pretty "rowdy" and work well with the manual transmission as idle quality is less important and you aren't up against a converter that might be a bit too tight.

We've used the Crower 60243 cam which is 228/235/112 LSA in similar engines with great success. It requires 10 to 1 compression for best results, but idles well and good street manners in 400 engine builds.......Cliff

My first choice was the Crower 60243 with Rhodes lifters but later decided to go with the 703 Voodoo. The car has the old Hydramatic transmission with 3.97 first, 2.55 second, 1.55 third and 1:1 fourth. With 3.08 gears in the back it calculates to 12.2 first, 7.6 second, 4.8 third and 3.08 fourth. For comparison a car with TH350 trans and 3.73 rear gears have 9.4 first, 5.7 second and 3.73 third. The #76 heads are 68cc so even with 11cc dish pistons the comp will be at 10:1. A smaller cam is more likely to cause detonation but on the other hand I don't want the engine to be "lazy" below 3000rpm.

[Burningbird]

Originally Posted by PunchT37

He’s got an auto trans. I would step down. Maybe you can swap em out so you don’t have to buy another cam?

I live in Sweden so that can be a problem sending the cam back, but I can probably sell the cam/lifters here to make up for some of the loss. If I order the Voodoo 702LK kit from Summit it will cost me around 380$ with shipping, tax and toll. But if that cam is better suited for the car/engine combo I will order one today.

[Cliff R]

I personally wouldn't be afraid of it, and the larger cam will be less prone to detonation all else being equal......Cliff

[Half-Inch Stud]

Stay your course; that larger cam promotes ping-free pull-away.


my 455+ 060 runs the Street ping-free on 87 Octane, per cam below.

[Steve C.]

Evaulate what the pressure will be with the Crower 68404 valve springs at your VERIFIED installed height. With that in mind take notice that based upon his dyno testing and extensive use of Voodoo cams Paul Carter recommends 130-135 lbs seat pressure with 30 degree seats and 330-340 lbs open pressure with the Voodoo hyd flat tappet lobes. Also he suggests to keep the distance from coil bind around 0.100". That and if you look at a Lunati catalog I believe you will find their recommended 73949 spring rated 120 at 1.650". Also keep in mind valvesprings will lose pressure after run in.



.

[Jay S]

FWIW, if you a trying to run higher compression and your running a 702, but having problems driving it around on pump gas the 703 will not be much better. The 703 only has a slightly higher power band with a more power. Not really great ingredients for running extra compression.


The 703 was a great choice but it does not to need or want 10 scr compression, 9.5 would have been a lot better with either the 262/268 or the 268/276. I were in your shoes I would be unstrouding the valves and trying to drop the compression down to run the cam you have.

[shaker455]

Originally Posted by Burningbird

Finally getting my 389/400ci back from the machine shop next week, but second guessing my cam choise now. I have a the Voodoo 703 (227/233@050, 110LSA) but after reading the post by another member here who made 400hp/450lb-ft with the smaller 702 cam (219/227@050, 112LSA) in almost identical engine I regret not going with the smaller cam. The car is a 60 Bonneville with 4-speed hydramatic and 3.08gears. The engine is the original 389 bored 058 over, Icon pistons with 11cc dish, Eagle rods, stock crank, balanced, ported #76 heads from a 65 389, 1.5 roller rockers, Crower 68404 valve springs, Edelbrock RPM intake and a Holley 750. SCR is 10:1. The stock log mainfolds are port matched, cleaned up inside and the outlets opened to 2.2" with Pypes 2.5" downpipes to 2.5" Cherry Bombs Vortex mufflers. Should I bite the bullet and order the 702 cam instead?

Stick to your gun's and do the 703.
I used it in a 69' T/A RAIII build & idled great and made 380 hp .
Nice cam choice!

[straycat]

What's the quality of gas in Sweden? Would there be a seat of the pants difference in the cams with that heavy car? Wouldn't a Performer intake be a better choice? Is this car pretty much a cruiser?

[Burningbird]

Originally Posted by Steve C.

Evaulate what the pressure will be with the Crower 68404 valve springs at your VERIFIED installed height. With that in mind take notice that based upon his dyno testing and extensive use of Voodoo cams Paul Carter recommends 130-135 lbs seat pressure with 30 degree seats and 330-340 lbs open pressure with the Voodoo hyd flat tappet lobes. Also he suggests to keep the distance from coil bind around 0.100". That and if you look at a Lunati catalog I believe you will find their recommended 73949 spring rated 120 at 1.650". Also keep in mind valvesprings will lose pressure after run in.



.

I will use +.050" locks to get some clearance against the guides. If I install the 60404 springs @ 1.550" the seat pressure will be 129lbs, open pressure @ 0.500lift will be 302lbs and coil bind @ 0.950". Maybe a little soft spring pressure but I will not likely rev the engine much past 5000 were the Hydramatic shifts at WOT.

[Burningbird]

Originally Posted by Jay S

FWIW, if you a trying to run higher compression and your running a 702, but having problems driving it around on pump gas the 703 will not be much better. The 703 only has a slightly higher power band with a more power. Not really great ingredients for running extra compression.


The 703 was a great choice but it does not to need or want 10 scr compression, 9.5 would have been a lot better with either the 262/268 or the 268/276. I were in your shoes I would be unstrouding the valves and trying to drop the compression down to run the cam you have.

I plan on unshrouding the valves when I get the heads back to gain a few cc. But I just spoke with the machine shop and they have to mill the heads a little more, maybe the chambers will drop to around 65cc now? If so the SCR will be 10.35:1. I already have to much time and money in this engine to change pistons or heads now... I have a RA4 cam in the garage, maybe I should use that instead - LOL!

[Burningbird]

Originally Posted by shaker455

Stick to your gun's and do the 703.
I used it in a 69' T/A RAIII build & idled great and made 380 hp .
Nice cam choice!

Sounds good! If the SCR was 9.5:1 SCR or lower I'm sure the 702 would be the better choice but with 10:1 the DCR might be to high.

[Burningbird]

Originally Posted by straycat

What's the quality of gas in Sweden? Would there be a seat of the pants difference in the cams with that heavy car? Wouldn't a Performer intake be a better choice? Is this car pretty much a cruiser?

We have gas equivalent to US 93-94 octane here. I don't know which of the cams that makes the most power between 1500-5000 but i'm guessing the 702. The high 10:1 SCR made me choose the 703 instead. I already had the RPM intake for free so that was a easy choice. It's mostly a cruiser but I like to drive my cars quite hard.

[Burningbird]

I just looked at the cam card for the 703 cam and the adv. duration is 275/281, not 268/276?

[400 Lemans]

https://www.lunatipower.com/voodoo-h...8-276-284.html You may have the 704.

[Steve C.]

+.050 locks will increase installed height.


.

[Burningbird]

Originally Posted by 400 Lemans

https://www.lunatipower.com/voodoo-h...8-276-284.html You may have the 704.

Duration @050 is spec. at 227/233 and lift .489"/.505".