Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

I ran this cam (single pattern) years ago on a basically stock block L48 with headers, torqer, holley, untouched 64cc angle plug 2.02's, TH350 with 3000 stall, 4.11 gear. With a small squirt of nitrous, this car would run 12.7's every weekend thru the mufflers and stock radials.

I found this cam to be sensitive to valve timing. Advancing 4 degrees would make it idle like a sewing machine and have the torque of a big block but die out at 4000rpm. Retarding 4 degrees made it idle like a dragster. I ran 2 degrees retard and shifted at 6500.

http://www.sysmatrix.net/~jtreber/smokey.jpg

Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

FWIW

I have an XE256, Perf intake port matched to 882 heads with valve job and 2.02/1.6 valves, dual exhaust with custom made headers, Qjet, recurved dist, 3.08 diff, TH350 with 2500 stall. I ran 226 rwhp last dyno run.

I'm sure with better heads and a tad more compression over stock would give me a few more HP.

:cheers:

Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

Chris I have the XE268 on the stock L-82 heads with 1.6 roller tips true dual exhaust. The car feels like it has a v-tech engine after 3500 rpm it seems to down shift and boogies like bat out of hell to about 6000 grand where I back off. I run 13.8 on my G-Tech and 5.6 0 to 60 I was thinking of changing heads but here in Canada they are about $2000. plus install :confused: But i Love the lompy idle

Re: Those with a 268H comp cam or similar specs.... (silver79)
 

Silver, I hear ya about the cost for heads. I had the same problem so I decided to spend half and do up the stock ones. Mine only runs to about 5400 and starts around 2200. I haven't had time to play with my new 2500 converter but I'm going to the drags for the first time in Aug so hopefully I'll do a mid 14.

My idle is pretty smooth.

:cheers:

Re: Those with a 268H comp cam or similar specs.... (silver79)
 

feels like a v-tec? Is that a good or bad thing? I would think bad :confused:

Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

Chris, You know the set-up I have. I'm going back to Race-Related this Saturday; having fixed the inlet restriction. I'll post the dyno results on this thread.

Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

Here is an article with the XE268H cam 1.6 rockers and Vortec heads and 413hp.
http://www.chevyhiperformance.com/techarticles/46320/

It is an 8 part series, I only linked the first part. They tried many combos but this is the one that I chose execpt I went with the XE268H-14 due to my TPI setup.

Re: Those with a 268H comp cam or similar specs.... (mean8t)
 

I was considering a XE268H soon, but I have a chance to get a HE268H instead at a very very reduced cost. I'm willing to wait and spend the extra money if it's going to hurt me in the long run, but what are everyone's thoughts on the difference between the two varieties? How does split-duration affect things?

I have:
mostly stock 350
stock (rebuilt) QJet
performer intake
True dual 2inch exhaust
KBD Targa "non-mufflers"
Stock stall on stock TH350
Stock 3.08 gears

I plan to upgrade to either a Tremec 5-speed or Muncie M20 in the future, and Sportsman 2 heads (64cc, probably 180 runners) sometime sooner. Looking for a powerband no higher than 5500 (never rev above 4500 anyway!) What's going to be best for me now, and in the long run?

Thanks,
Chris

Re: Those with a 268H comp cam or similar specs.... (RUXperienced)
 

In my opinion, the XE252 or XE260 is the most I would go with stock components. The XE line has much more agressive cam lobes (quicker lift) and will impose increased where on the entire valve train.

Unless you are going 'extreme', I'd stay with the single-pattern HE260H or HE268H.

Just a quick comparison. My target is about 350hp/400 ft lbs at the flywheel. The Crane Energizer 272H is a close 'cousin' to the HE268H. I have 1800stall converter, 3.55 gears, heads, headers, duals, etc. This cam is supposed to be perfectly matched to my combination (and emissions legal).

If you want more, go with the Comp XE cam lines (or equivalent from Crane).


[Modified by TedH, 5:01 PM 4/2/2003]

Re: Those with a 268H comp cam or similar specs.... (Nomad78SA)
 

Neil, I think my problems are more related to my inability to tune carbs. :) I think if I had everything tuned with jetted properly for my heads, cam, etc, it would work fine.
-terry

Re: Those with a 268H comp cam or similar specs.... (terryrudy)
 

Terry,

I found out the same thing. Good vacuum signal (read no vacuum leaks) and properly tuned carb (rich/lean) make a world of difference not only with start/warm-up but also overall performance. With Lars' help and parts from Dr Rebuild and Bow-Tie Overdrives, I've stabilized alot of the vacuum/mixture issues that plagued my engine for the last 4 years since my engine rebuild in 1999.

Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

416 hp, 423 torque (flywheel)

holly 750, rpm intake, XE268, 1.6 ratio rockers, TFS 23# heads, and super comps.
http://www.73-87.com/chp/chp.htm

This takes the previous mentioned artical a few steps further. With dyno charts to show progress. Very good reading.

Hope it helps, Steve.

Re: Those with a 268H comp cam or similar specs.... (Chris@VetteFinders)
 

Chris,

Dyno results on 4/5. Not a vast improvement but more sustained power numbers. I'm going to take the car back to Race Related for a re-curve session to see if there is potential for improved timing.
http://forums.corvetteforum.com/zerothread?id=531018

Re: Those with a 268H comp cam or similar specs.... (terryrudy)
 

Terry,

Your idle and off-idle carb behavior can be improved with a carb rebuild by Lars (unless your heart is set on the TPI).