I started my '81 frame off a long time ago. Started the engine rebuild a little over 6 years ago. So far it's had the machine shop work done:

Cleaned
Bored .030 over
Align Bore Checked
Crankshaft ground (I don't think it needed it; they just do it)
Check/Polish rods
Fit pistons to rods

So now I've got a 355 that's been partially assembled, well greased, and been sitting bagged for about 6 years. It's in great shape still, no rust that can be found and ready to go. It was coated liberally with WD-40 before being bagged and never painted so I am probably going to disassemble it, clean it up, and paint it before moving forward.

Here's the list of parts that I currently have that I'm planning to use:

Trick Flow 23 Degree 64cc Aluminum Heads - TFS-30400001
TRW Speed Pro Power Flat Top Forged Pistons - TRW-L2256F30
Sealed Power Performance Piston Rings - SLP-E-251K030
Summit True Roller Timing Set - SUM-G6600
Fel-Pro Gasket Set - FEL-KS2600
Summit High Volume Oil Pump and Pickup - SES-3-60-08-001

So, to my point. After reading this article: http://www.superchevy.com/technical/...bolt_on_tests/ I decided I wanted to build a similar engine as what they did with the XE268H. The biggest difference will be my TF heads instead of the Holley Heads they used. I've also read a few other magazine articles that use my heads and this cam and I liked the results.

I'm planning to get this cam and lifter kit:
Comp Cams XE268H Cam - CCA-CL12-242-2

and their valve springs:
Comp Cams 417 lbs/in - CCA-981-16

I'm leaning toward 1.6:1 rockers (based on this article: http://www.compcams.com/Community/Ar...?ID=2132654598 which happens to use my heads as an example). How do I ensure they will not cause a clearance problem before I buy them?
Is there a significant difference between the Comp Magnum Roller Tip Rockers and the Comp Pro Magnum Full Roller Rockers?

I'm leaning toward the Edelbrock Performer RPM air gap Intake - EDL-7501 and the Speed Demon 750 CFM carb. Is that too much carb?

I plan to run Hooker Headers sidepipes with spiral turbo baffles.

I have no clue as to what is the best ignition/distributor setup to go with this.

I've also purchased the Keisler TKO-500 manual transmission kit that I will be putting in so basically I won't want/need any of the computer controlled stuff that was originally in the car. I've dropped all the A.I.R stuff as well.

I appreciate any time/thought you guys can put into these questions. Any additional ideas are appreciated.

The vette will be a street machine mainly and I'm happy with this cam choice; I just need to fit the other pieces together.

Thanks!!

 

Quite a list. I'll offer my opinions here, so don't take anything to the bank.

I'd go with the cam maker's spring recommendations. They designed a spring to work with a specific cam, allowing for lift, open/closed pressures and that type stuff. As far as rockers go, the stamped steel are very durable, but the roller types has less friction. Flip a coin. You'll need to monitor the condition of the rollers a little more than the steel. As far as cam choice goes, look at what you're going to do with the car. Weekend warrior? daily driver? Or just want a little thump in the exhaust. Talk to Comp about that. Rear gears, compression, and trans all make a difference. Your pushrod choice will be dictated by your other combinations..

I feel you're right about the 600 carb being a little small. I had a 650 on a 350 that I built years ago. It was great, super low end response right up to the point it couldn't flow enough to feed the 350. I ended up with a 750. But I was also turning it to 7000 RPM too. If you're not planning on turning that high, the 650 may be plenty.

There is nothing wrong with a HEI ignition either. If you're going to change, I'd look at the MSD or Crane- something like that. I've already got the factory TI ignition, but I'm looking really hard at the Crane HI6 for both a hotter spark and rev limiter. MSD is good, but I'm not sure I like the rev limit operation of the MSD compared to the Crane. And there may be a better one out there.

 

Thanks for the reply. In hindsight my post was way too wordy . I've taken it down a notch and gotten a little more specific. Hopefully others will have a chance to chime in.

 

Have you checked your compression ratio with that setup? That cam may not be able to bleed off enough compression with 62cc heads and flat top pistons.

 

You are probably close to 11 to 1. Pretty small cam for that much compression. Hey! I got a set of Brand new AFR 190 74 CC heads for sale that would probably work perfect with your setup with that cam!

 

Looks like Summit's website had the heads listed wrong. I just looked at my paperwork that came with the heads and they are 64cc heads. I'm not sure how much difference that makes for compression ratio.

I've looked online and found several compression ratio calculators but I'm just not coming up with the answers to the questions to be able to calculate it properly. I'll keep trying.

 

There is a good calculator listed in this thread along with the story of the reason my AFR heads are up for sale!http://forums.corvetteforum.com/show....php?t=1621965

 

I would have to guess I can buy new pistons cheaper than new heads right?

 

Yes! And sell your flat tops, but they are fitted to the rods and probably balanced to the crank and rods you now have. Or buy my heads and sell yours!

 

I am just going to throw my .02 in the pot here but keep in mind what rear end gear you have. If you are building an engine that makes power higher in the band you will need lower gears. (Higher ratio) If you have a 3.08 gear and a sb that is making peak power at 5500 RPM you wont like the end result of your build.

 

With the TKO 500 kit you have and the 268 cam you will be fine even with a 308 gear. But you have to knock your compression down to use that cam or go bigger on the cam.

 

I've got 3.70:1 gears in the rear with the TKO-500. I don't think I'm going to like a bigger cam so I it looks like I either need to find a buyer for the pistons, or the heads. That's not cool.

The machine shop didn't balance anything but the pistons are attached to the rods. Of course if I'm going to get the rotating assembly balanced I could get the new pistons put on at the same time. Hmm... Just depends on which I think I can sell first; heads or pistons I guess.

 

You Have a good combo of things. rethink the poor choice of cam.

good everything....... 373................ 5 speed. Do I want a chance at a flat cam or some junk that sounds bad or is bad?

 

Make sure you verify those springs are within spec.

I purchased the same set and found them to be out of spec.

I called them and they pulled another set off the shelf and tested them while I waited on the phone..... that set was also out of spec.

I don't know where they get their valve springs, but don't assume they are good right out of the box.

I have a RIMAC spring tester...

http://www.gearheadtools.com/16365.htm

and Comp Cams #5316 calibrated spring to double-check my RIMAC.


Buyer Beware

 

Before the shop actually balances assembly, they have to know the weights of both big & small end of rod. Assuming (again assuming) the rods themselves are weight matched to one-another ... shop will have to remove at least one piston from one rod and weigh rod ends separately & weigh a separate piston. If they don't, they're guessing. At $150-$250 for a balance job, suggest don't waste your $ on a guess.

-also- the budget gasket sets usually have a thicker ~0.040"~0.050" head gasket. If block has NOT been decked ... that combo w/64cc TF will be close to ~9.5~9.7:1 SCR. If block has NOT been decked ... A thinner victor 5746 gasket will make about ~10:1 and much better quench.

 

I would not use the high volume pump no need for it. do you have
a bigger pan for the pump ?? non decked block flat top pistons
64cc aluminum heads should be under 10.1 comp. you will be ok
with that cam.

 

My bad! I figured 62 CC heads, flat tops. a 4.030 bore and good quench he would be pushing 11 to 1.

 

With an engine like this, guessing about 400 HP, is there a real need/benefit to getting it balanced? When I had the machine work done, I told them that I would be building it around 300 HP and they said it didn't need it for that small of a build up. I didn't have a better shop to go to back then but would definitely choose a different shop today.

 

I read in one of my engine books that a 9.5:1 CR is about right for a street engine. I'd like to understand why 10:1 is more desireable. Is it just going to make a little more HP with 10:1? I'll have to read up on quench as well; not familiar with the term.

Thanks for all the replies so far!!

 

personally I like wider LSA like 112 - 114. It gives you a higher average power band spread over more rpm. Your 5 speed has you covered much better than an auto tranny. wider LSA will make a motor more emission freindly and getter higher MPG

If you have to have comp cams - Look at the marine or computer controlled cams like the 12-268 -4 for 114 lsa 224/230 or the XM270H 112 lsa 226/236

I prefer crane cams like the 278 powermax.

With any one of these cams I would use up to 10.5 compression with aluminum heads.