I built my 355 last summer only to have a high volume oil pump break the teeth off my distributor. So I pulled the motor out, tore it down again and went with a bigger cam and set of heads. Below is a list of the parts I have going together. Its getting built at the machine shop... should have it back really soon.

30 over 350, L98
Scat crank, rods
Speed Pro flat top pistons
Comp XR276HR cam, 224-230 503/510 on a 112LSA
AFR 195 heads, hardened pushrods, comp roller lifters
SLP Runners, fully ported base and plenum
Hedman headers, 3" Magnaflow exhaust
Yella Terra Roller Rockers
Brand new 24lb fuel injectors
And a tune from Hawks...

And I'm running a T-5 trans with Ram Powergrip HD clutch. My hope is to break 350 RWHP.... is that a realistic goal with this setup? I'm upgrading to a Holley Stealth Ram intake later on, but for now my ported and siamesed TPI will have to do. Thanks

 

Sounds good.

Not sure on the RWHP goals, others may chime in.

Have you done anything to the T-5? As you probably know, thats the weaklink.

 

Possible if base and runners are ported enough. Hsr will definately get there with 1.6 rockers. Get the lift up. Tune also needs to be good

 

I'd say that's an overall well balanced combination. I hope that you and your machinist have worked out installed deck height clearance of the pistons for final compression ratio. The block may need to be decked to get 10.2:1 or so CR, which is what you will want with aluminum heads and that cam. Are the pistons you're running two brow or four brow? With .010 deck clearance and 64cc chambers, you want two brow(+4cc) pistons for 10.2:1 CR.

As Orr said, sufficient porting of the base and runners, especially the SLP runners, will be the key to getting the HP up where you want it. I had a set of SLP runners and chose not to run them because I couldn't see a way of porting them fully with what I had to work with. I have seen others cut them open to port the entire runner. Without this level of porting, they are restrictive. The HSR will definitely get you where you want to be.

 

Awesome, my pistons are four brow flat tops. So with 64cc chambers I'll need to deck the block more? I'll talk to my machinist about that and see what he can do. I'd like to be around that compression ratio or 10.5:1. I have spent numerous hours porting the base plate, which was a major PITA. But it's opened up and smooth. I gasket matched the ports to a 1205 intake gasket and siamesed the ports about an inch. On the SLP runners I just siamesed the bottom half an inch to match the base and massaged the upper opening to match the plenum. I'm running the stock throttle body for now, may port it a little. I'll post pics when I get a chance.

As for the T-5. I installed new bearings and seals... other than that its stock. Shifts great and synchros feel fine. If something comes apart in it then I'll upgrade to a T-56. Its basically the only thing left to upgrade on the car... but I can only do one thing at a time. Maybe it'll stay together for the summer... the car won't see a drag strip so maybe it will.

 

Seeing how you were able to work on the T5 I would suggest a cluster support plate.

Make sure you get a steel plate not aluminum.

 

Stock TB is fine.

I ported my base and runners to match 146 tpi gaskets which are 1 3/4". I did not siemese the base or lower part of runners.

You may have to mill your heads to get compression up. Most of the 4 brow flat tops I have seen for 350 advertise 9.35:1 with 64 cc heads.

 

The 4 brow pistons, according to the CR calculator I ran yesterday, will put CR at 9.83:1 with 64cc chambers, .039 gasket, and .010 deck. The two brows raise CR to 10.3:1 with the same gasket and deck. You can deck the block but be careful going too far with that as you will need the clearance for valve overlap when running a big cam. You also want to end up at about .040 quench.

To get right down too it, you want to use assembled piston height, block decking and head gasket thickness to set quench and then use combustion chamber volume and piston dome to set compression ratio. The AFR heads have a good chamber that will work well with 10:3 to 10:5 CR. A good engine machinist, one who builds alot of high performance and race engines, will know these things and should help you get where you want to be. Now is the time to get things right. Once it's done and in use, it's a little more difficult to go back and fix it.

 

According to speed pro, it's 9.35:1

of course that's probably due to a shorter compression height in the pistons which is common in replacement units.

Probably would take a good bit off the deck to get them close.

 

I just used the CR calculator at Summit Racing. Who knows how accurate it is. Used to use the basic geometry formula to figure the total swept volume / total compressed area, but it's too much math for me today. Lol. Summit's CR calculator does figure in deck height, which is vital in determining CR. The speed pro pistons may have larger valve reliefs. I used the standard of +8cc for four reliefs and +4cc for 2 reliefs.

Either way, if the OP wants 10.5:1 which wouldn't be bad with his combo, he needs to go with different pistons. Even with 0 deck, he still only gets 10.06:1. .005 over deck would put CR at 10.2:1 and that's .034 quench which is getting pretty tight.

Milling the heads down to 60cc would put CR at 10.5:1 with a zero deck but 4cc is alot of material off the heads. You would end up with intake manifold alignment issues.

 

I was just looking at Probe pistons web site and I noticed that their basic 4 brow flat tops are actually -2.5cc. If this is representative of the 4 brows you're using, this changes things. CR with -2.5cc, .010 deck and .039 gasket is 10.35:1. A little closer to what you were wanting. My main point in all of this is to discuss these things with your machinist before the motor goes together. You can ask the manufacturer of the pistons you're using for actual dome specs.

 

Perhaps the OP should post the part numbers for the Speed Pro Pistons he is using.


Probably these,

http://www.jegs.com/i/Sealed-Power/8...ductId=1434022


Piston Head Volume (cc): +5.00cc


Which are the ones I am using. it would be great if they were closer to 10.35:1.

When I plug it in with 0 deck it shows 10.41:1 which is great. Curious why Speed Pro says 9.35:1 with 64 cc.

 

That is weird. I come up with 9.93 even with a .020 deck. Summit's CR calculator agrees with 10.41 at zero deck. I looked at a few different 4 brow flat tops this morning and they range from 5cc to 6cc. I don't see how Probe's could be 2.5cc. But even on their own website they state this spec. I plan to use their 2 brow flat tops to replace my 4 brows when I do rings maybe next year.