c3_dk

Hi Tom,

Yes 1.6 is correct, you will only get the valve lift that Comp Cams specifies if you use 1.6 rocker arms.

Thx,
John

c3_dk

Ok I understand, I would do the same.
But just so you know, a single intake would be best. But there must also be something to change in the future :- )

Metalhead140

The dual plane shouldn't hurt you, I'm running my Fitech on a Performer RPM for the same reason - because I had it. Runs great!

Domobomb

Guys, I'm back with another question.

I'm ordering a bare set of the ProMaxx heads. When I order them bare they are special order and I can request 60, 62, or 64cc combustion chambers.

The 60cc chambers would put my compression ratio at 9.95:1 with 0.040" quench.

Is the 10:1 SCR OK to step up to the 280XFI you think?

Domobomb

Hey guys, resurrecting this old thread but I have results on this combo:


Result:
60' 2.007
30 5.615
1/8 8.544 @ 84.29mph
1000 11.059
1/4 13.169 @ 108.85 mph

Combo:
Block: GM 350 Roller Block
Heads: ProMaxx MAXX 183cc int 64cc chamber 2.02" valves
Compression: 9.4:1
Roller Cam: Comp 268XFI - Lift .570"/.565" - Duration @ 0.050" 218/224
Rockers: Lunati 1.6 Full Roller Rockers
Intake: Edelbrock Performer RPM
EFI: FiTech GoEFI 600HP
Torque Converter: Stock
Trans: TH350
Diff Gears: 3.55:1

I have a th350 with stock converter and side pipes. This is easily a 12 second car with a decent converter, but I didnt want to go with one because I intend to autocross a lot more.

71chimera

OP
good job; thanks for the update

-add-
seems you were a college student during the cam/head swap. Did that work out as well ?

gkull

I went with flat top pistons, 200 cc heads, and a cam of 232/238 in a 30 over 350. Kinda like your other choice. It's really sad that people continue to repeat old wifes tales about head cc size and cam durations when they personally never even tried bigger heads or even a roller cam and they are the expert giving advice. Roller cams make so much more vacuum and smoother idle that you can run 10 degrees more than their flat tappet counter parts and make more power across all rpms. Only I had real long tube headers not side pipes with 3.55 rear a hopped up th350 with original l-82 TC.

It was about a second quicker in the 1/4 and preformed very well on the Auto-X in BSP class. On Auto=X weekends I used to Stop way back from the start line and flagger. your time starts when you break the starting line beam. I put the ol vette in first and power braked it. When the flag waved go I did a big smoky burn out across the starting line. Got heat in the tires and hit the beam with some MPH. Other people saw me do it and then every one did that until they made it illegal. :lol Maybe you can try that in Canada!

You really threw away lots of power.

Domobomb

Yeah, I have an engineering degree

Domobomb

This is interesting - I have a bone stock GM bottom end anyway, and it's probably at the limit with this combo - when this goes I'll prob do a forged 383 shortblock, up the compression and go with the bigger cam then. Happy with what I have now.

gkull

I used my original L-82 and it came with an OKay crank, rods, windage tray on kinda studs from the main cap bolts. Just forged two valve relief flat tops. I think that they we called -7 cc. It's hard to get compression in 350's even with 64 cc heads unless you go to domed pistons.

I was going to say that i ran that motor to 7200 rpm for years before pulling it and moving up

71chimera

congrats on that !

c3_dk

Thanks for the update
Enjoy your ride.....

Domobomb

7200 wow! What were your 60' times?

I've got a 90s 2-bolt truck block (got it for free) so I set my rev limit around 6K rpm. You can hear in the vid I bounced off the limiter on the 2-3 shift, and the log shows kind of a rounded peak. I think I'll take it to 6500 next time.

I brake torqued to ~1450 rpm and the stock L82 torque converter seemed to flash to ~2200 rpm.

Here is the FiTech log:

gkull

Bracket racing doesn't allow for electronics. No stutter box rev limiter for staging so you can launch at the same rpm every time. Power braking is tricky because a little too much gas pedal and you overcome the rear brakes and it will push the front tires and cause a red light. So I figured out to turn up the idle speed screws to say 1600 rpm in "N" Then when you roll up to the line really slow riding the brakes and just trip the stage lights on for a shallow stage. Then just hold the brake on and and watch the lights. That way you don't have to be thinking about the gas pedal and power brake rpm. I actually prefer the protree, But you can get very good at either.

It's so long ago that I threw away the log books and 100's upon hundreds of time slips of each year. I do remember driving my Alki injected dragster and thinking the only things faster in the 60 foot times is the Pro classes with 1.064 doing 7.60's in the mid 170's.