Stockish 340 upgrades, cam needed

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oldkimmer

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Ok, since this build changed a lot I’ve decided to start a new thread. 1970 340. Stock crank, rods with beams ground down and shot blasted. 2332 forged 10.5 pistons. The pistons are .015 a ove deck. The will be mills down for zero deck. My buddy has decided to go with TTI headers 1.5 to 1.75 step headers. Full TTI X pipe exhaust. Speedmaster CNC heads. LD340 intake, 650 dp Holley. This is a street cat that won’t be raced. The wife will be driving this also. He would like us to pick a cam that will take advantage of these CNC heads and TTI system. This is a 4 gear car with 3.23 rear gearing. 1973 Cuda. Thanks. Kim
 
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Hell Kim, I don't see anything wrong with as "close as you can get" to the 68 340 OEM "stick" cam. I have no idea, tho, where you would get or duplicate that, maybe Oregon Cam?
 
Flow of CNC'd SpeedMaster heads from the head flow section
SM CNC - Flowed by @PRH

Lift—- in/ex
.100— 64/49
.200—126/95
.300—166/132
.400—206/163
.500—242/179
.600—271/187
.700—284/190
You didn't specify if you were using hydraulic flat tappet, hydraulic roller, or solid flat tappet. Also, what gears and converter, rear tire, vehicle weight?
 
Lift—- in/ex

.200—130/100
.300—179/135
.400—224/160
.500—261/172
.600—277/185
.700—279/188

These are the numbers from my CNC SM heads.
 
Extremely similar build in the wife’s car. Her ‘67 Cuda is a 11-1 - 360 / 904 / 3.55 gear on 26X10X15 Weiand Stealth 750 AFB, tti stem to stern.
Use 1.6 rockers with this HR cam below for .573/.569 lifts. Lunati also has a similar cam. I was going with them until they couldn’t seem to send me the right cam or correct it. It took weeks to get my money back.
(Fuckin scumbags!)
If a HR cam is out, look at the similar solid FT cam.
24DA1C42-FACE-44DB-B62A-3D06413991BC.jpeg
 
oldkimmer said:
Ok, since this build changed a lot I’ve decided to start a new thread. 1970 340. Stock crank, rods with beams ground down and shot blasted. 2332 forged 10.5 pistons. The pistons are .015 a ove deck. The will be mills down for zero deck. My buddy has decided to go with TTI headers 1.5 to 1.75 step headers. Full TTI X pipe exhaust. Speedmaster CNC heads. LD340 intake, 650 dp Holley. This is a street cat that won’t be raced. The wife will be driving this also. He would like us to pick a cam that will take advantage of these CNC heads and TTI system. This is a 4 gear car with 3.23 rear gearing. 1973 Cuda. Thanks. Kim
Click to expand...


Do you really need to 0 deck the pistons?
I would buy a custom head gaskets to get the quench to .040 and let that piston pop up .015 out of the hole.

Are you going to have the deck squared? (so all the piston pop up the same amount)
 
Tires are 275/60/R15. 1973 Cuda, 4 gear car, 3.23 gears. He wants to stay hydraulic flat tappet. More than likely Hughes 1.6 roller tip rockers. Kim
 
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Deck is square decked. I was gonna use the Fel Pro 8553 that r .053 compressed for .038 clearance but then that really isn’t quench. It was recommended to 0 deck the pistons and use the 1008 gaskets that are .039 compressed as they are a better gasket. Kim
 
Ether way would work and yes that would be a reasonable quench distance. The gaskets are made the same way. Nether is better than the other.
 
oldkimmer said:
Deck is square decked. I was gonna use the Fel Pro 8553 that r .053 compressed for .038 clearance but then that really isn’t quench. It was recommended to 0 deck the pistons and use the 1008 gaskets that are .039 compressed as they are a better gasket. Kim
Click to expand...

Quench is the distance between the flat part of the piston and the flat part of the head.
so yes .038 is thirty eight thousandths Quench as well as 0 decking and piston and different head gasket is.039
 
LMAO! A 242@050 cam with 3.32 gears?

Balance my friends!

Kim, your going to be hard pressed to get a Hyd. cam that will work nice, nevermind really well with 3.23 gears and take advantage of the heads ported ports. Even with 1.6 rockers.

Custom grind time
 
Agree wholeheartedly, and I bet the wife would hate driving it! This is really custom hydraulic roller territory when you get into heads that are worked for this much flow at these lifts.
 
He wants good street manners as his wifey will also be driving it. I tried to sway him to the non CNC Speedmasters But there is no way. Kim
 
Try the Comp extreme hi lift 20-227-4 and have them out it on a 108 for the manual trans. Add the 1.6 rockers.
I’m not sure 231@050 is OK with the set up.

image.jpg


image.jpg
 
Have you sat down and figured what compression ratio you are going to have.
just a fyi, them 10.5 piston on a stock X head 340 =9.4:1.......Maybe a fraction more because you squared the block.
How many cc is the combustion chamber on the SM heads
 
These heads are a done deal. They are going on. I tried for a BP408. His car is a 340 Cuda and that’s what it’s getting. Kim
 
Even if he gets to a 11-1 ratio, that’s pump premium gas all day long.
 
rumble
your HR same @ .050 as the 268 comp (right? without looking it up)
why 274 @.006 with the HR?
 
And a 1.6 rocker. The head flows, OK down low and picks up nicely later where most Hyd. cams do not lift that high.
 
Rumble. I like that cam but I don’t want to be pulling it out if he doesn’t like it. No I haven’t cc’d them yet. Heads are Supposed to be 65 cc. I was told the 1008 gasket is a much better gasket for aluminum heads than the 8553. Kim m
 
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