hi i just purchased a set of 58cc alum vette heads that i intend to install on my l98. this should increase my c/r. i also want to change the cam to one that would benefit me most while staying with the stock tpi as well as installing headers. my question....what size cam do i need? also what about the chip? what do i need there as well? the motor is currently stock 245hp/350 and i would like to get 300+hp outta it with this mod. do yall think thats achievable with this mod? please any help at all would be appreciated. if you guys knew me you'd know that i need all the help i can get!

 

Just with the heads and headers you should be able to pull that much horse power. If you want some more then go and get your self one of comp cams XE cams. I had one in mind a while ago but don't remember the exact number.

 

i aint no expert but from what ive heard if i install to much cam the thing wont perform either. ive heard that these tpi engines are really vaccum sensitive. i just dont want to mess anything up and get the most bang for my buck in the process. gurus give me some insight please. thanks

 

Those heads are the stock Vette heads. That version of the motor was rated at the same HP as the F-body version, maybe 5 HP more in some years. There's no increased HP there. Any improvement will have to come from optimum cam choice and a good exhaust.

Look at Comp or Crane, for a cam specifically designed for TPI. The normal XE cams WILL NOT work well. TPI, because of how it enhances cylinder fill at around 3600 RPM, needs a cam that doesn't hurt that feature; otherwise it will slow the car down.

For an otherwise stock L98, look at Comp's "302" grind. If you really open up the exhaust, look at the "304" grind instead; that's about as far as you want to go with the stock unmodified intake system on it. http://www.compcams.com/Technical/Ca...L/128-169.html scroll down to page 146. The 304 will require the spring pockets on the heads cut to get larger springs on them; stock diameter (1.25") springs are inadequate.

 

thanks for that info on the cam. i was hoping for more than 5hp with those angle plug heads. would porting those heads help much? if i go with the "304" grind what will i need ina chip? any insight helps....just dont wanna waste $'s. any idea in how much compression difference these heads will make over my stock 64cc heads? thanks for responses so far!

 

It's my understanding that in your engine you will gain .1 CR for every CC. So you will be going from 64CC to 58CC. That is 6CC. Your stock ratio was 9:3 to one. I believe the CR will be 9:9 to one. Hope this has been of some help. By the way on my L98 I put on the Brodix street heads that had 67CC chambers. So my CR went down to around 9:1. I'am going to have flat-top pistons and a ZZ4 cam installed. Hope to get around 300RWHP with all the mods I have done. Allen

 

08502-8........ Anybody runnin this cam? How do you like it? What kinda performance did it give you? thats there XR269HR cam.

 

Those heads will respond great to porting.

For maximum effect:

You want to upgrade to larger LT-4 / fastburn valves.
2.00"x1.56" These are the largest that will fit on the stock valve seat inserts. A new valve job is required.
If you want 2.02x1.60 you have to replace the valve seats inserts.

the LT-4 valves are special light weight.

Linkenfelter and T.P.I.S. are just two companies that specialize in CNC porting these heads for tons more power.
You can do a fairly good job your self at home.

These heads are covered in David Vizards book on Budget builing a Small block chev.

 

Really appreciate the advice the F-bird. I'd be skeered that id mess the heads up if i tried to port them myself. I think that im fairly mechanically inclined ...lol..and up to doing it if only i had some knowledge and insight on the "do's and don'ts". Are there any good books, websites, etc., out there 'splaining the "how to's"? Im stilll wondering bout the chip too. Where do i need to get it and what kind? Also wondering bout that cam mentioned above too. Thanks in advance to any and all for helpin a ignorant red-neck.