Weak springs?
 

Hi,

I have a Crane TR-272/4167-2S-10 cam in my 509.

The cam card says:

1967-UP CHEVROLET V-8 396 THRU 454 CU.IN.
MODERATE COMP. ONLY, GOOD UPPER R.P.M.
TORQUE & H.P., HIGH COMP. RATIO REQUIRED

INTAKE @CAM 4167 @VALVE 708
EXHAUST @CAM 4167 @VALVE 708

TIMING OPENS CLOSES ADV DURATION
@ .0195 INTAKE 45 BTDC 85 ABDC 310 °
TAPPET LIFT EXHAUST 88 BBDC 48 ATDC 316

@ .050 INTAKE 29 BTDC 63 ABDC 105 °ATDC 272 °
TAPPET LIFT EXHAUST 72 BBDC 26 ATDC 115 °BTDC 278

RECOMMENDED RPM
RANGE WITH MATCHING COMPONENTS
MINIMUM RPM 4400
MAXIMUM RPM 7800
VALVE FLOAT 8500


So not a street cam, but not a pro-stock cam either.

The valve spring recommandation:

Crane-99876

LOADS:
CLOSED 160 LBS @ 1.968 OR 1 31/32
OPEN 490 LBS @ 1.308

I have installed them on 1.950" which gives 160-180lbs seat pressure new. Few questions. Is this enought as the rpm at finish line is about 7000? Should I upgrade the springs? Spring recommadations for 1.55 size? Heads are with 2.19/1.88 stainless steel valves. I had about 50 runs on new springs and lifters when we took it apart. Springs are now 150-180lbs at the seat. Valve seats and lifters seems to be fine.

I would make sure the springs are AT LEAST at the specs on the cam card...you could lose the whole motor over a cheap (relatively speaking) part. Any doubt in your mind at all I would get new ones.

Is this a roller cam or flat tappet cam?

Zip.

http://cranecams.com/index.php?show=...01&lvl=2&prt=5

According to Crane's website, you don't have enough spring.

Your spring part # should be 99886, not 99876. Big difference. If it were me I would set the heads up with a PAC 1246 spring, but at least get the correct springs. If you are limited to a 1.55 spring, a PAC 1225 would work much better than what you have.

OneBadGMC, that's funny. I got exatly the same camcard from 90's which says exatly same things expect the springs are Crane-99876.

LOADS:
CLOSED 160 LBS @ 1.968 OR 1 31/32
OPEN 490 LBS @ 1.308

Maybe they figured out that it wasn't enough spring and revised the website and new cam cards?

If you can fit a 1.56" spring, go with a PSI CT1227

http://www.psisprings.com/index.php?...ask=view&id=17

This is copied from the original post, very confusing.


1967-UP CHEVROLET V-8 396 THRU 454 CU.IN.
MODERATE COMP. ONLY, GOOD UPPER R.P.M.
TORQUE & H.P., HIGH COMP. RATIO REQUIRED


Moderate comp only, then high comp required? wt?

I'd go with the springs recommended from crane they know whats best for their cams, or go with a comparriabled set with them same seat pressure, same installed height and coil bind.
Goodluck, Charles

Pretty sure that means "Moderate competition only" asw you see that a lot in the catalog descriptions. I could be wrong.

Yeah your probably right Todd, that didn't even occure to me.
Cp