upgrading V6 cam

[mhamilton]

Anyone use an aftermarket cam in the V6?

I was talking with a friend who used to work at a cam company, said a very mild upgrade would improve performance and economy. The stock cam is very short duration with retarded timing for the OE emissions considerations.

Was looking at something like Comp Cams 15-115-4:
Dur @ 0.05" 192* Int. 200* Exh
Lobe lift 0.26"

That's verses the stock 176* 0.234" int, 194* 0.257" exh.

Just wondering what kind of real performance/economy gains it will see. Not expecting any miracles, but anything's better than the smog cam. For a driver, looking for the same power/torque curves as stock, just more of it LOL

-Michael

 

[George B]

Hi Mike :

Not to go too far off the subject of cams, but thought I would run a question by you. I'm getting ready to pull the 229 out of my '80 Bu for a rebuild. My goal is economy and reliability, not high H.P, etc. I'm not looking to dump a lot of $$ in the rebuild but I'm not going to cheap out either. I know you rebuilt yours a few years ago. Is there any thing in your opinion I should upgrade or go a different route other than stock?
Thanks for your assistance.

George

 

[Darwinskeeper]

mhamilton,

A mild aftermarket cam may help mpg but you have to be careful, it is easy to go too far and pay the price in vacuum and mpg. Darwin's 4.3 originally had a Comp Cams 252H (206/206 [email protected]; .425/.425 lift) which is one step beyond the cam you are talking about. I think its one of the reasons why my mpg and vacuum readings are a little low. I am currently having it swapped for a Crower Level 1 camshaft.

Remember that when one's displacement to weight ratio drops, the cam will seem "bigger" than it would be in a car with more cuin/lb. Thus, while a Comp 240H might be an excellent cam for a 262cuin V6 in a wagon, it might be a little big for a 229. You might want to see if Crower makes a level 1 cam for the 229 semi-even fire engine.

 

[mhamilton]

George,

I didn't do anything extra to my 229 when I rebuilt it. But, since it has issues from that 1st rebuild I'm going to have to do it again (wrist pin ticking). This time around I will at least clean up the heads so that the ports match. There's 1/8" of extra casting around the pushrod holes on the intake runners. Not sure if it's worth any more efficiency, but couldn't hurt.

Darwin,

I do agree with you that a cam can get way out of hand for a driver like this V6. That is one reason I was not sure I even wanted to change from a stock cam. I will take a look at the Crower catalog, I'm going to see what all my options are.

I have been looking at other cam specs for GM engines. That Comp 240H has specs just about the same as the L69 HO 305 cam. Actually, it falls between the stock B body LT1 cam and the HO 305. Not much more lift (0.26 vs 0.234/0.257) so stock springs can stay, but does have the 15* extra intake duration and 10* more exh.

The 240H is advertised as "designed for high gear ratios, with low end torque and economy" but I would like to see a power/torque curve for it.

Talking with a friend who does a lot of engine work, he was saying that Comp cam is what GM should have used, but they went with the short duration cam to reduce burn temp and keep NOx emissions down. Would be very interesting to see what it would do on a dyno, but don't think anyone has done anything like that.

 

[Darwinskeeper]

mhamilton,

It is very hard to find much in the way of information concerning what does or doesn't work on a V6 (particularly if it isn't the turbocharged Buick used in the GN). I've looked all over the internet, studied catelogs and even purchased a book on modifying V6 engines. Still, I'm forced to to do this mostly by guess, trial and error. ](*,) I guess that is one of the things that goes with the V6 territory.

 

[mhamilton]

I've been busy compiling more cam specs, I put together a little Excel worksheet: Cam Data

The one good thing about the 229 is that we can look to the 305 and see what GM did to that, then take 75% to get approximate 229 performance. I also just found the Comp Cams CamQuest software that lets you simulate the V6s (http://www.compcams.com/Camquest/).

Comp's 240H looks promising. The software seems a bit optimistic predicting 140 hp @ 4000 rpm, and 210 ft.lbs. @ 3000 rpm. Then again, that's only 20% more than the stock configuration. And, that cam is in line with stuff GM used in late truck 305s, while not as hot as the Camaro 305s (I'm sure those are for high rpm hp). But you're right, I do worry that I'd be trying something that would make things worse on the small engine.

I still have to take a look at the Crower catalog. I'm guessing if they offer a mild 229 cam it would be similar to the Comp and Schneider. But you said your Comp 252H resulted in low vacuum on the 4.3? Was the low end power worse than stock?

 

[Darwinskeeper]

I'm afraid I can't say because we swapped the Comp 252H into the 4.3 before it was put into the car. I would imagine that the stock cam would have had more low end torque, but that's just a guess