comp cams xe268 in a 305

[racerguy]

Hey everyone. I just bought a cam for my chevy 305. The cam is a comp cams xe268. I have an Edelbrock 650 carb, Edelbrock C3B intake, long tube headers, and I'm porting the heads. Just looking for some input on how this combo sounds. Thanks

[BlacK20]

i had that cam in my 350, sounds good, has a slight lope.

[dave89iroc]

thats a lot of cam for a 305

[96ImpSS]

That's a lot of cam for a 305 in a heavy vehicle.
What trans, TC, and rear gears are you running?

[SUBURBIAN]

Would have DEFINITELY been a good idea to ask about that cam BEFORE buying it. That cam is about as "big" as you'd want with stock converter and such in a 350" engine. Cams act larger in smaller engines, so you're probably going to wind up over-camming your 305 with it.

[racerguy]

Trans is a 700r4 with a stock converter, and the rear gears are 3.42:1. I plan on getting a 2000 stall for it. is there anything different I should do different with the gears?

[96ImpSS]

What do you plan to do with the truck? Any performance goals? Will you be looking for some good 1/4 mile runs.
Truck weight? 2 or 4WD? tire diameter?
For that cam, I have a feeling you're erring too much on the conservative side with TC and gearing.

[Dixie Normus]

so would that cam be good in a stock 350?

[racerguy]

my plan with the truck is to build it up from the motor back. I know 305's werent meant to produce that much power, but im looking to get as much as i can out of it. It is a 4wd truck with no lift or anything like that and its 31 inch tires. It's a short bed. I think it weighs somewhere around 4000 give or take. I'm young so mostly I'm doing this for fun and to experiment. Eventually I'd like to get it down to the strip and make a few runs. Mostly this is just for fun and learning so I'll take whatever advice you have for me.

[SBC305]

I put that exact cam in my 305 (in a 92 RCSB) and I'm pretty impressed with it. It doesn't over cam the engine at all, tons of horsepower improvements for sure. My 305 was a 1992 so it had the crap heads (Stock was rated at around 170 HP) so I swapped em for 97 vortecs. You won't be disappointed. I'm running a 15 second 1/4 mile and 95 mph trap speed with 3.08 gears and I'm having trouble with traction, I'm hoping for a 14.5 this summer with some minor traction improvements and better gearing.

What year is your truck?

[SBC305]

Oh and it peaks out at 6000 rpm :p

[racerguy]

wow thats awesome. thanks for the input. the truck I have is an 86. I was really surprised when I pulled the lifters out. They were in really, surprisingly good shape for being the original lifters. I got the truck a year ago and it was bone stock. So i decided to do what I can to see how much power I can get out of it. The only money I spent on the thing is the cam. Everything else was given to me. So I figured I might as well give the cam a shot seeing how I had a few extra dollars.

[SUBURBIAN]

I put that exact cam in my 305 (in a 92 RCSB) and I'm pretty impressed with it. It doesn't over cam the engine at all, tons of horsepower improvements for sure. My 305 was a 1992 so it had the crap heads (Stock was rated at around 170 HP) so I swapped em for 97 vortecs. You won't be disappointed. I'm running a 15 second 1/4 mile and 95 mph trap speed with 3.08 gears and I'm having trouble with traction, I'm hoping for a 14.5 this summer with some minor traction improvements and better gearing.

What year is your truck?



wow thats awesome. thanks for the input. the truck I have is an 86. I was really surprised when I pulled the lifters out. They were in really, surprisingly good shape for being the original lifters. I got the truck a year ago and it was bone stock. So i decided to do what I can to see how much power I can get out of it. The only money I spent on the thing is the cam. Everything else was given to me. So I figured I might as well give the cam a shot seeing how I had a few extra dollars.


Be careful of this. He put the cam in and CHANGED THE HEADS also. Changed them to vortecs. You cannot think that the results will be the same on your 305. Maybe with the "porting" you'll be fine. Me, I'd put a smaller cam in it...but that's just me.

[SBC305]

Yes, the Vortec heads are a major flow improvement. Not sure about 86 heads but the early 90's heads were all about fuel mileage, not power. thats why the horsepower numbers were so lame (170 HP for the 305's and 190 HP for the 350's), it wasn't till 96 that chevy smartened up :p 305's were rated at... 225HP and 350's at 255HP. Something like that anyway. Most of the gains were because of the Vortec heads.

On my 305 valvetrain wise, I replaced the lifters (bores were excellent, so I left them) kept the pushrods, upgraded the springs (which you will HAVE to do) go with the springs COMP recommends for that cam, they are cheap (65 bucks). NOTE: I had to buy a valve guide cutter so the heads would accept the springs (also from COMP, 50 bucks on Summit). It was an EXCELLENT tool that goes on the end of a drill, worked like a charm. You may not need to do this with your heads, I think the valve guides are larger in diameter on vortecs for some reason.

[racerguy]

thanks for all the advice guys. For now I'm on a tight budget so I'm gonna go with porting the heads for now. But I would like to get my hands on a set of those vortec heads. As far as springs and stuff goes, I bought the whole kit so I'm all set on all of that.

[SBC305]

One last thing: Compression ratio. Make sure it is AT LEAST 9.5:1. This cam needs it.

[racerguy]

Ok. I will make sure of that. I seem to have run into a problem while putting the motor back together. While cleaning up around the intake ports, I had a small amount of dirt fall into one of the ports. I had rags stuffed in the ports, but when I pulled the rag out, some dirt fell all the way back to the valve. Any ideas on how to get it out? should it be ok?

[SUBURBIAN]

Shop vac plus garden hose. If that's not small enough, get a smaller hose.

[racerguy]

perfect thanks

[Fast305]

Yes, the Vortec heads are a major flow improvement. Not sure about 86 heads but the early 90's heads were all about fuel mileage, not power. thats why the horsepower numbers were so lame (170 HP for the 305's and 190 HP for the 350's), it wasn't till 96 that chevy smartened up :p 305's were rated at... 225HP and 350's at 255HP. Something like that anyway. Most of the gains were because of the Vortec heads.


MOST of the HP gain of a Vortec chevrolet in 96 was NOT the heads. It was the switch to the way beefier roller cam, better flowing exhaust, freer flowing cats, port injection, better tuning, and free breathing MPFI setup.

[96ImpSS]

MOST of the HP gain of a Vortec chevrolet in 96 was NOT the heads. It was the switch to the way beefier roller cam, better flowing exhaust, freer flowing cats, port injection, better tuning, and free breathing MPFI setup.
Very valid points, although I have trouble calling that intake manifold "free breathing". It's a choke above 5000 rpm. The same cam, same head ports, headers, etc. makes ~40 more hp and peaks 500 rpm higher in the LT1. You won't see that 40 hp in factory advertised numbers, but it's there. 295 rwhp in my stock cammed ImpalaSS; 254 rwhp in my stock cammed pickup, same dyno, same tuner.