my68barracuda
Well-Known Member
Agree, in the drag racing days the shift point on the slant in my 68 Barracuda was 6500, now that it is a street car, I plan to back that down to 6000 rpm.
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Turbo head build
- Thread starter Slant Six Bumblebee
- Start date
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Slant Six Bumblebee
Well-Known Member
I have decied to not do anything with the cam right now as that would bea. lot more work. Curently my plan is to go with 318 valve springs and stock valves that are back-faced. Where is a good suplyer to get 318 springs and retainers from.
I am also planing to get head studs from ARP.
DODGE ARP 142-4001 ARP Pro Series Cylinder Head Studs | Summit Racing
I would go with the Comp 901 springs if it was me.
pishta
I know I'm right....
9 psi over 2.06 inches is only 18 lbs. Dont think its going to affect your slant springs 62lbs closed sealing potential. Run any more boost than 9 and you'll need some more work elsewhere. If you got the springs already, go for it for peace of mind.
my68barracuda
Well-Known Member
318 springs are basically slant six valve springs, they will fit your stock retainers. RockAuto would be a source to check. You can also watch on eBay.
Are you planning on building your own manifolds?
Gill Welding and Fabrication has some neat stuff for the slant six. Google that. They recently post photos of a slant six turbo piping they are selling, looks nice. Also look over at www.slantsix.org lots of turbo builds over there.
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Slant Six Bumblebee
Well-Known Member
i was going to use a super six with a holley 500cfm and a u pipe on the stock exhaust manifold. i was planing to port match the intake and exhaust manifolds too.
my68barracuda
Well-Known Member
I did not say it was going to be a lot, just said the pressure on the back of the valve should be considered.
Slant Six Bumblebee
Well-Known Member
thats why i plan on getting the 318 springs. i read that with the 340 prings and the stock cam you risk shearing a lobe off. The reason for replacing them is mainly for peace of mine and that my springs are old and might have lost some of there presure.
Horse feathers.
Slant Six Bumblebee
Well-Known Member
where does the comp 901 rate (between the 318 and 340) Is it improbable to breake a cam lobe?
The 901 is about right in line with the 340 springs.
my68barracuda
Well-Known Member
Where did you read that? Lots of slant folks have ran the 340 springs without issue. Me included.
I also ran 318 springs on a cheap slant six build that I drag raced and shifted at 5500 rpm without issues. That was a mild cam a bump above a stock cam.
Slant Six Bumblebee
Well-Known Member
If i use the comp 901 valve springs what other suporting parts/mods do i need.
my68barracuda
Well-Known Member
stronger ( quoting the post ) does not limit lift. Springs with more open - closed pressure can be a contributor to wiping a cam lobe at start up. But those are springs of a much higher capacity than 340 / 901 valve springs.
Even with 318 springs you still want to do things ‘right’ at the initial start up.
1) use a quality moly paste on the cam lobes and at each lifter.
2) lifters turn freely in each bore verified
3) have the motor ready to start, no repeated or lengthy engine cranking prior to start up.
4) run the motor 2000 to 2500 rpm once started. Engine must have the targeted oil pressure.
5) observe that the pushrods are spinning with the engine running,, putting a dot of paint or a paint stripe on each pushrod makes that easy.
with 340 / 901 valve springs you will need the retainers that match up
to those springs. Those springs have a slightly larger OD but still sit in the stock slant head spring pockets.
With your build to conserve money I could go with 318 springs and re use the existing slant retainers and keepers and valves. Do a good visual inspection on the reused parts for wear, those parts are not known to be high mileage failure parts on a slant, but give them a good look over.
TheGrateRonzini
Well-Known Member
I came across this the other day concerning valves as I am building a turbo efi 225 also
pishta
I know I'm right....
The quote was "Stronger springs would not only limit life..." not lift. Bill ran a turbo, he had lots of experience with them.
Again: was that just to buy the valves or did that include the labor to put them in?
When installing larger valves it's almost a "have to", to port these heads to get much benefit from it. Otherwise the rest of the port casting as done by the factory becomes even a bigger bottleneck than stock. Even with stock valves a slant will run noticeably better with clean up of the ports.
my68barracuda
Well-Known Member
And too weak of a spring will also cause problems with valve train instability. The best approach is to consider all factors when selecting valve springs.
Many, many, many, many, many folks have ran the 340 style springs on slant six cams: stock-reground-new with out issue.
although as stated, for this OP, stay with stock sized 318 valve springs, that will save the expense of buying new retainers.
my68barracuda
Well-Known Member
those are the valves that I used in my current slant six build, they are nice pieces, about .096 longer than stock slant six valves.
Slant Six Bumblebee
Well-Known Member
my68barracuda
Well-Known Member
the vs150 also cross over to a 318, so that is your valve spring.
pishta
I know I'm right....
Another thing to consider is the strength of the stamped slant rocker arms. Anyone ever see one fail under a stiff spring?
kesteb
Well-Known Member
I think the OP needs to buy a copy of Dutra's slant six performance book. Then he should go over to the turbo forum and search for anything from Bill Dedman. This will lead to other slant six turbo builds. All of which will explain exactly what he needs to do.
Slant Six Bumblebee
Well-Known Member
I actually have this book and have read it through a few time
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