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Old 02-06-2013, 05:10 PM
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Cam help needed 327 with a TPI

I just got off the phone with Comp Cam tech line and I spoke to a tech from from Lunati yesterday. I was going to call Crower, but I figured why add to the confusion.

I'm looking for a a streetable cam for my setup. My questions relate to ICL, DCR, LSA, ramp rates and quench. They are as follows :

For a SBC what is the target ICL and what happens when you either increase it or decrease it?
Regarding DCR, I've read on many old threads here that the target for iron heads with pump gas is somewhere between 8.0 to 8.5, but how bad is to have it at 7.8 or 7.9? Am I going to be able to feel a difference in performance between 7.9 and, say, 8.2 or 8.3?
For LSA, how much will give enough vacuum, say 15-18 inches?
In terms of ramp rates, I understand that lower ramp rates are easier on most all of the valve train components, but how slow of a ramp rate do I need to make my cam/lifters and valve springs last and how much performance will I lose with a slower ramp rate?
And lastly, for quench I currently have .059", but with a swap of head gaskets I could get it to .046. How much of a benefit will I find by getting my quench to .046" or am I wasting my time swapping head gaskets?

My current setup is : 327 .030 over with 6.25" rods, SCR is 9.58, quench is .059", coil bind is at .540 of lift, 1.6 roller rockers, ported iron heads 1.94/1.50, Sanderson shorty 1.5" headers with 2.5 exhaust that is only 4' long(exits under the seats), 2004R with 2400 stall in a 2600lb car, and a stock TPI intake with a Megasquirt (hence the need for decent idle vacuum to maintain idle quality with a speed density system.)

Again, this for a STREETABLE car - drag racing is not a concern, and I've been told that a stock TPI is going to run out of air before 5400 rpm's. I, just like everyone else, want the best of both worlds - both streetable and great top end numbers, but I KNOW that I need a compromise.

I've read many old threads and I DO NOT want to create a p.....g match about DCR, but most of you guys have oodles more experience than I have and I'm interested in ALL opinions and advice.

As always, thanks in advance - Jim.

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Old 02-07-2013, 05:02 AM
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something like this.

Crower Power Compu-Pro Performance Level 2 Camshafts 00240 - SummitRacing.com
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Old 02-07-2013, 06:32 AM
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Cam help needed 327 with a TPI

Jim, IDK how much help I can provise. You are using 6.25" rods, what type pistons are you using? Piston head volume, and compression height. 1/2 stroke+rod length+compression height=parts stack. 9.025 is the stock factory deck clearance. 1.63+6.25+c.h.=? If it were me I would use a head gasket to get me close as possible for a .040 quench especially with iron heads. On the choosing the camshaft LSA and ICL on a TPI engine higher is better. The higher the LSA the more vaccuum you will have. The ICL is ground in with 4* advance for most manufacturers. An example would be 110 LSA and 106 ICL. For your engine I would pick a camshaft with a 112 LSA and a 108 ICL.
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Old 02-07-2013, 08:23 AM
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Use Crane cam H266-2 #113941
You can get a little more compression using a felpro 1094 shim gasket

Ignore the DCR. Pick the cam for where you want the power and the idle quality concern.

TPI does not like huge cams.

Last edited by F-BIRD'88; 02-07-2013 at 08:29 AM.
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Old 02-07-2013, 04:19 PM
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Thanks for the help guys. All of you recommended 'relatively' similar cams.

CD - .020 piston to deck clearance.

F-Bird - if I use the head gasket you recommend it give me .035" quench - is that too little?

Thanks for the help
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Old 02-07-2013, 04:26 PM
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Quote:
Originally Posted by 64nailhead View Post
Thanks for the help guys. All of you recommended 'relatively' similar cams.

CD - .020 piston to deck clearance.

F-Bird - if I use the head gasket you recommend it give me .035" quench - is that too little?

Thanks for the help
I have run the net quench clearance that tight before, with no piston head contact.
you an experiment with the installed C/L of the cam to find what the motor/TPI/ car likes the best.

Ignore the DCR crap. What matters is how the engine runs. Moving the cam will adjust the engine torque bias.
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Old 02-08-2013, 07:59 AM
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There are all good answers to your situation; If you feel like making another phonecall, Id call Mike Jones at Jones Cams in Denver, NC. I'm also a huge UDHarold fan as well.
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Old 02-08-2013, 06:49 PM
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Originally Posted by AutoGear View Post
There are all good answers to your situation; If you feel like making another phonecall, Id call Mike Jones at Jones Cams in Denver, NC. I'm also a huge UDHarold fan as well.

Who is UDHarold?
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