Engine upgrades-Opinions needed

[sav300]

I am currently running a 355SB in my 70 chevy and on the chassis dyno I put down 252HP and 320TQ. I am impressed considering what all is done to the engine. Now I am looking to get the most out of it and for the recorded I'm trying to get the most TQ out of it.

Here are the current specs:
Stock crank
Forged Scat 6" rods
KB claimer pistons (rated at 10.4:1 w/ 64cc heads)
Port and ploished stock 305 heads (CNC'd at 68cc)
Edelbrock Performer Air gap intake
Edelbrock Performer cam
Full roller rockers 1.6:1
Stage 2 Quadrajet
MSD Billet distributor
Headman headers (1 5/8 primaries)
True dual 2 1/2" exhaust

I'm going to put on a set of aluminum heads with the following specs: 64cc chambers, 190cc intake (not sure if I should go with the 210cc?), dual valve springs good to .650 lift, and stainless 2.02 1.60 one piece valves. On top of that I will put in a Comp Cams XE268 or 270, Weiand Team G aluminum water pump, a new set of headers, and some hotter ignition.

My question is, should I put in a new crank and harmonic damper? I was looking at an Eagle Forged crank and Summit Street/Strip Competition damper. Looking at what I have now I'm hoping to gain about 100 plus FTLBS of torque. Let me know what you think as far as my list goes, what I might gain in numbers, and if there is anything else you would look at or do.

Thomas

[Camaro_nut2001]

Originally Posted by sav300

I am currently running a 355SB in my 70 chevy and on the chassis dyno I put down 252HP and 320TQ. I am impressed considering what all is done to the engine. Now I am looking to get the most out of it and for the recorded I'm trying to get the most TQ out of it.

Here are the current specs:
Stock crank
Forged Scat 6" rods
KB claimer pistons (rated at 10.4:1 w/ 64cc heads)
Port and ploished stock 305 heads (CNC'd at 68cc)
Edelbrock Performer Air gap intake
Edelbrock Performer cam
Full roller rockers 1.6:1
Stage 2 Quadrajet
MSD Billet distributor
Headman headers (1 5/8 primaries)
True dual 2 1/2" exhaust

I'm going to put on a set of aluminum heads with the following specs: 64cc chambers, 190cc intake (not sure if I should go with the 210cc?), dual valve springs good to .650 lift, and stainless 2.02 1.60 one piece valves. On top of that I will put in a Comp Cams XE268 or 270, Weiand Team G aluminum water pump, a new set of headers, and some hotter ignition.

My question is, should I put in a new crank and harmonic damper? I was looking at an Eagle Forged crank and Summit Street/Strip Competition damper. Looking at what I have now I'm hoping to gain about 100 plus FTLBS of torque. Let me know what you think as far as my list goes, what I might gain in numbers, and if there is anything else you would look at or do.

Thomas

Motor upgrades sound good. For what you are upgrading I would leave the bottem end. If you decide to start throwing some juice or boost etc... to it I would then upgrade my bottem end. With the heads & cam upgrade I might go with a better carb, a little lighter spring & a dual plane intake. JM2C

[Captainfab]

If it's torque you're after, IMO those 190cc intake ports on a 355 aren't going to help in that area. I'm not an expert, but I would suggest heads with a 170-180cc intake port. As for the cam you chose, the XE268 wouldn't be bad, but I think a cam like the XE2624X or the next smaller, would produce more torque in the low to mid range.

[69GMC910]

[QUOTE=Captainfab;4243021]If it's torque you're after, IMO those 190cc intake ports on a 355 aren't going to help in that area. I'm not an expert, but I would suggest heads with a 170-180cc intake port.

I totally agree. I would go with the Edelbrock Performer RPM heads.

[Marv D]

Heads are where the power is made. Cams, cranks, and all the trick pieces (other than forced induction) won't do much if you don't have heads that are up to the task. Spend your money wisely there. Brute flow numbers is not what you need to look at ewhen trying to build a high torque motor. Pay attention to the guys that talk about port volocity, not big flow numbers. Two companies come to mind,, Edelbrock and AFR. Not that Dart, Brodix, and others arent a good head. But they are more geared to making big power in a higher rpm range (racing type motors). For a street bound 355 in a heavy truck I'd like to see something like the 170cc Edelbrock E-tec (if you were willing to make the jump to a vortec intake and rocker covers), or the old AFR 180cc street head. Both deliver decent flow with excellent port volocity for low lift / low rpm driving

but just my 2¢

[sav300]

Im not so focused on keeping the RPMs low because I have the gearing on my side. I'll take all the torque I can get but I wont throw away the high RPM HP in order to get it down low. With the cams I'm looking at and the heads the peak TQ should rise about 1000RPMs (just a rough estimate). Right now my peak TQ comes in at 2200rpms.

I currently shift at 5000 and the engine is still pulling but I run into two issues with my current heads; air flow and floating the valves. This all happens around 5700. With the higher RPMs I will definately run better ET's due to the fact that I can go faster than 106 and not have to milk it.

Now that I have thrown that out it might help you see a little more of what I have going on. I drive it on the street on occasion and run it down the track quite often. Now that the weather is getting colder its time to do some upgrades.

Thomas