Team Chevelle banner

1999 Stock 350 Vortec compression ratio???

39K views 17 replies 7 participants last post by  BowtieAaron 
#1 ·
I just picked up a complete 350 vortec engine out of a 99 (old body style) Escalade. It is the same engine as the chevy trucks, tahoes and suburbans had in them from 96-99. The engine looks good inside so I'm just going to run it as is except for a cam upgrade. I'm just wondering what the compression ratio is on this engine? Thanks.
 
#3 ·
I have a set of Vortec heads that have machined guides already, 202 valves, oversized springs and screw-in studs and guideplates all ready to be slapped on this engine. The stock heads that came on the motor had some hairline cracks between the valves so I trashed them. I was just wondering if I should have the heads surface machined down a little in increase the CR. What do you think? We only have 91 octane out here in California.
 
#6 ·
thats all i run is pump gas.. i had 62cc '461 camel humps with stock 4valve pistons, probably somewhere about 9.8:1, maybe a little more. ran good. no ping.

i run just about 10:1 with aluminum heads and 38* timing with a large cam, and no ping.
my stock lt1 trans am has 10.4:1cr and alum heads, and only has slightest bit of ping when hot with stock crappy tune.


aaron
 
#9 ·
Brian,
Dont know what you are putting it in, but the one in my 99 Tahoe runs so good, I dont know if I would even do a cam change. It will spin right up to 5500 rpm and really pulls that 5000 lb brick around pretty good. It should haul arz in a 3600 lb car. And ... it got 21 mpg on a trip to Florida last December, probably averaging 75mph.

Its a shame you cant keep the fuel injection with it, I am pretty sure it is responsible for the awsome power and the fuel mileage.
 
#12 ·
I rebuilt the one in my Tahoe with Speed Pro hyper flat tops, compression is right at 10:1, maybe a tad higher since I zero decked the block. I run the lowest octane pump gas with no problem, plenty of power and just short of 20mpg. The computer helps, but so does the fast burn chamber of the vortec heads.
 
#13 ·
i also have speedpro hyper 4 valve flat tops. they are really close to the factory pistons, with zero deck and 64cc heads they claim 9.8:1cr, i think the part number is 345cp or something like that, i cant remember.

my dad had a 96 tahoe with the same motor, and it moved pretty good in that thing.
i have a 94 trans am with an lt1 in it. it is basically the same motor but reverse flow cooling and aluminum angle plug heads. the caprice lt1's had iron heads, and that is where gm based their vortec heads off of. my ta is rated at 275hp 325ftlbs and it runs damn good for a 3500lb automatic car. of course i have exhaust and some other bolt on/free mods, but 300fwhp is very fun.

aaron
 
#15 ·
i thought they were shut also.
i know for sure the 87+ truck motors are shut.

mine had a block off plate, but a hole for the pushrod.
i am running a 130gph holley fuel pump (mechanical) on my 880 block (vortec block).

no mods were done to it.

hope you can make out the hole in there...









aaron
 
#17 ·
About half of the ones I've found have the pushrod hole machined, the others just have the boss. It's no problem for a competent machine shop to drill the hole.
I found out the hard way that the boss on the front of the block for the timing cover is different for '96 up Vortec engines than the TBI's. The Vortec cover barely covers the TBI boss, we had a fun time getting ours to seal. That same vortec timing cover works like a champ on the '96 up blocks.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top