Cam selection for my TP ?

[hdheritage97]

Anyone out here that has some TP experience ? I'm thinking of changing my cam to get a little more juice out of this thing. As it sits in the garage tonight it has a Crane Cam, .579/.605 lift, 280/290 duration. I don't really want to have to fly cut pistons or anything like that, I'd just like to simply change my cam without having to pulll the engine and all that hassle. While I have it apart I'm thinking that MAYBE I should have the heads looked at and maybe ported and polish the chambers...what do you think, or do I have enough/too much flow already from the TP heads ? How difficult is it to go to a roller cam ? And what are the REAL benefits ? I'd really like to get some better low end out of it...it just really comes to life at around 4800 RPM's and that's a bit late but it's also what the TP was made to do....run all out. I'm just trying to wring all I can out of it without TOO many hassles. Looking forward to seeing what you guys think.


Thanks,


Cliff

[Chuck Nickloy]

Cliff,

I'm not an engine builder or anything like that. I have not run a TP yet. I have had a number of 427's built.

I have a set of TP heads and the Intake I want to build one. I have been talking and conceptionering about the TP motor for some time.

You are seeing first hand what it takes to make a 427 TP run good. Mucho RPM. RPM costs in an FE. The TP motor was designed to run 7500 RPM all day. Street cars don't do that, but we want to!

This is what I think I know. . . . . . . . . .

The understanding I have at this time is " you need to get the velocity of the intake air up for the TP heads to work good". I'm not sure you can do that with a cam change. I really don't know if you can. That would be a good question for George at Gessford.

The way to increase velocity is RPM, or you can increase the cube's and draw more air through which will increase the intake velocity at lower RPM. This is the approach I am going to take to keep the RPM's down.

Hope you get an engine builder to chime in.

The Best
Chuck

[SFfiredog]

Cliff,
Tunnel port heads love cubic inches. The bigger the better if you are looking for low end torque. For tunnel ports that are under 450 ci (or engines with bore sizes smaller than 4.25) I like to reduce the valve sizes, 1.675" exhaust and 2.19" intake. This helps reduce valve shrouding and actually increases flow and low speed velosity with the smaller valves. The tunnel port already has machined combustion chambers so there really isn't much to be done there although it would be better if the chambers were smaller on 427ci to 450ci engines. A flat top or inverse dome piston will give you better combustion and help stave off detonation for the same given compression ratio. Leave the intake ports alone but some exhaust port work is desireable but make sure whoever does it is familiar with FE heads. I've seen plenty screwed up by Chevy head porters with the best intentions! On bigger (475ci and up) I run 2.20" intake and 1.71 exhaust valves. I'm finishing up a 483ci tunnel port at this time and will report the dyno results. as far as cams are concerned, the one you have doesn't sound bad although I would like to know what the duration is a .050" lift. You don't need a big intake/exhaust split in lift and duration on tunnel ports. I would run a mechanical flat tappet with high 240 to low 250 degree at .050" lift and in the .590s" lift. If you are looking for more low end torque go with duration in the low to mid 240s at .050"
HTH,
Mike

[bmalone]

Cliff, I run a .579 cam and am happy with the performance and streetability. Mike knows a lot about these engines and if he says stroke 'em, I believe him. It is something I have in the works for mine. I only have 427 cid.

[KobraKarl]

Mike , isnt the reason tunnel ports like a stroke is because it helps speed up the low rpm fuel velosity to that of a more "streetable " mid riser or dual plane set up?

KK

[SFfiredog]

Karl,
Yes TP's like big arms because the stroke helps promote cylinder filling. And, naturally more stroke equals more cubes which equals more torque and low end power.
--Mike

[Doc]

I also have a 427TP but I have had other 427, 428, and 390. All can be made to run strong but as you have heard from others by doing big thing and all with a price either $ or in drivability. Just like if you ask what kit is best some one will repply what are you going to do with it, and this is a question for you on building this engine. Theirnis definate power in cam changes but big cams sacrafice drivability. This may sound like crazy advise but if I had a sound engine and didn't want the expense of a rebuild or valve notching pistons and wanted alot more power for a quarter mile pass I would put a plate nitrous oxide system on the rather than a cam change for just a few hp. It is an easy install doesn't hurt your ability to drive the car and will give you a bunch of power. Their are many things to do and try If I can assist you in any way e-mail me at tpumpelly@woh.rr.com
Doc