andrewdains

Hey all, Im working on a 96 Firebird Formula, I pulled a motor from a 96 Roadmaster, and have cleaned it up but not rebuild it. I put a Comp Cams Hydraulic Roller Tappet, Duration 260/270, Lift .560/.555, Grind 260XFIHR13. 1.6 rockers and new rods/lifters. I have the 4L60e trans out of the firebird and I have a TCI shift kit and boost valve to install. Long tube headers are on the list. Im still planning on using the stock rear end, 3.42 gears. My question is what torque converter should I run? Any help would be appreciated.

Thanks
Andrew

96capricemgr

iTrader: (1)

Why get this far in before asking questions?
You know the iron heads won't accommodate .550 lift without machining right?

On stall since mild and cheap seems to be the criteria I would it use an Edge Racing converter in the 28-3200 stall range 9.5", not a 12"

andrewdains

Im working on this as a hobby and I only know enough to be dangerous. This is the biggest project Ive taken on. Everything I've read about the cam never said anything about machining the heads for .550 lift, I did install new bee hive springs from comp as well. What is the difference between all the sizes of torque converter, ie why is a 9.5 better than a 12?

96capricemgr

iTrader: (1)

The iron heads are different than the aluminum, only accept something like .535ish lift reliably without checking retainer to seal clearance.

On stall once you get over 2500 or so a 9.5" converter is more efficient. And they are a lot lighter.
Stock cam engines benefit from 32-3400 stall.

revolutions

iTrader: (1)

Iron LT1 heads have pressed in studs and they can pull out when subjected to higher lifts.
A 9.5 is lighter, less likely to balloon/distort under high pressure, typically will be more efficient and have a higher torque multiplication factor.
Generally speaking you want to run the smallest diameter converter that will handle the power level you are at and achieve the desired stall speed.

96capricemgr

iTrader: (1)

With beehives there is unlikely enough to be enough pressure to pull a stud, but the lift is a real problem, maybe use 1.5s?

andrewdains

I do still have the original motor from the firebird, would I be able to swap my valve train parts over to the aluminum heads and still be ok or am I up a creek with this cam/head combo? I have a machine shop close by, but i'm trying to get by without a huge bill.

KW Baraka

iTrader: (7)

If you can cite a case where a iron-head LT1 pulled out its studs, I'd like to see it.

In the B-Body community, we've talked about studs being pulled out for years....but no one have ever cited a single case.

KW

BALLSS

OP

that XFI cam published specs on lift is with 1:6 RR (most cams are spec at 1.5 lift RR). Your Comp 465 cam with 1:6 RR has lift of .560/.555. With 1:5 RR it would have .525/.520

if you went with 1:5 RR your intake lift would be .525...which is under the .535 Caprice notes that "may" be a problem if higher than .535 on iron heads

with the iron heads you need to be careful with to much lift either causing retainer to valve stem seal clearance issues or on spring pressure. Since the iron heads have pressed in studs vs screw in studs some feel to much lift or spring pressure may cause the rocker stud to pull out or raise slightly which will puke your spring pressure. I have not personally seen this happen, only "read" it did on a iron head motor .

Back when these LT1 motors were new many did the Crane 227 cam with iron heads but used 1:5 RR on the exhaust side to keep the lift down. They used 1:6 on intake side. I remember people selling 1/2 sets of 1:6/1:5 RR when they did that cam on iron heads

on the bee hive springs...I know the XFI cam specs them. Mine lasted 20k mi before failure so you need to pull them and check spring pressure and for signs of cracking. Even then, as I did, you don't know if they will fail say for example checking them at 10-15k mi where they check out fine visually and on a spring pressure check...then at 20k mi you find you have a 2 piece spring. The XFI has fairly aggressive lobes vs other cam grinds. The 465 you have is the mildest (in terms of lift) of the XFI grinds offered. I suspect keeping revs under 6200 (that cam will be way done making power before that) you would really not have a problem. Rotate motor by hand and watch retainer to valve stem seal clearance. Your iron heads take a 1.75 installed spring. The bee hive spec at 1.800" installed height. You will have slightly more seat and open spring pressure with them installed at 1.7x" height than what their published specs are. Not really a big deal until your cam lift gets close to what the spring lift can accommodate.

revolutions

iTrader: (1)

I can't say I have ever heard of it happening on an LT specifically but it has happened on many occasions with gen 1 heads.
I wouldn't think there is any difference since I have seen reports of it happening on vortec heads which are from the same time frame
and should be of equal quality.

MonmouthCtyLS7

iTrader: (6)

Give the guys at Circle D a call. Top notch customer service.

andrewdains

Thank you all for the information! Im going to have the aluminum heads cleaned up and swap everything over to them. I found a set of 1.52 Comp Cams RR that I think I'll use instead of the 1.6 RR for now.

96capricemgr

iTrader: (1)

1.6s are fine with aluminum heads.

andrewdains

Even with the .550 lift that I have?

BIGsmokey10

iTrader: (3)

Yank or circle D

Puck

iTrader: (17)

Keep the 1.6RRs, swap everything to the aluminum heads, then run a ~2800-3200 stall from a reputable manufacturer like FTI, Yank, Edge, Circle D, etc.

That cam on 1.6s is no problem for the aluminum heads, no need to get new rockers.

KW Baraka

iTrader: (7)

I've only heard of it happening on old (1970's and 1980's) iron heads.....never on LT1 heads.


I have a low-miles Yank SS3600 stall TC.....PM me if interested......

KW

BALLSS

AL heads 1:6 RR are fine and I would use them. The studs are screw in vs pressed on iron heads.

the .550 lift will be no problem but get better/new springs over the stock LT1 AL head spring.

I use Lunati #73925K5 kit. Got it from LE