Thread: Cam Advice Needed By Experts Please

Tweet

Hello again everyone.. Well, I have my car running okay, but I need another opinion..Have a modified 350 in a vette. When I say modified, I mean just that, not worked. Here it is.
Standard Bore 350 w/76cc chamber heads(smog)1981
I installed Headers, and true duals
I had the q-jet properly rebuilt by the Carb Shop
HEI ignition
and the cam.. COMP CAM #12-231-2
This Cam was picked because of the weight of the car and the slight mods
It is 432-452 lift and 206-214 at .050 and Lobe sep is 111
I also had 2.56 rear gears.. With this it ran okay
I installed 3.73 gears now, and there is a huge difference

Now my question it...Would it make a HUGE difference if I installed a set of
305 HO heads with 57cc chambers to increase the compression? I think the cam needs more compression, and I am not into spending big bucks on this car..Would it do anything, or is it a waste of money? I don't race the car, but I would like it to get up and go out of the hole. It is close, but not there yet.
Also, it is an automatic th350..Did I pick the wrong cam, or is it what it is?
With the stock heads, I thik the compression is something like 7.8-1
Please get back to me with some opinions. Thanks

you can get nice iron heads from pbm that would help at a very good price that would help on your cr i would try them before the 305 .but did a 350 with 305 heads for a customer that what he wanted to use them. the cr and dynamic cr was border line for prem fuel. what intake do you have on this engine?

The intake is just a alum dual plane vette intake for a q-jet. Stock with the engine. I guess the question I was getting at is would I notice the type of difference that I did with the rear gears by adding more compression to make the cam work with the 305 heads? Again, it isn't a race car. I doubt it goes above 4500 rpms ever, but I want it to come out of the hole.

well Cr would help but if you went to a cam like on a lsa of 108to106 and abit more dura@050 and CR with the smaller 305 heads i would do a bowl job and 3+angle valve job .but i would use the PPM heads much better heads with CR and cam should be a runner. and you would get more out of them then a 305 head.

What cam would you suggest? Do you think I picked the wrong cam? The cam I chose is a 4x4 cam. Reason being I wanted lots of bottom end and the range was 600-4600 rpm. I thought it made sense at the time, and It does get up and go, but I think it should have more balls than it does. I mean, I think I should be able to get it and nail it, and light up the tires. Right now if I nail it, it spins for about 1 second and that is it. I work for Lexus, and I would bet money that a IS350 would walk by it all day long. Now we can't have that..

low cr and heavy car . it will be tough to move it. the cam you have is ok have used one like your cam in a truck it was ok . you should work on the dist curve and see what that will do. try to re curve it

I did work with that a little. I have an HEI and I took it apart, cleaned it up and installed the lightest springs that came with the accel type kit. There were 3 types of springs. The vacuum advance works. Have it set at 10 btdc at idle, and it is all in around 2800 at 36 degrees. I have played with it, but it has been A long time since I really set up a HEI dist or timing for that matter. Do you think I should use a vacuum guage? Give me your input on how to correctly set up the timing if you don't mind.

I did work with that a little. I have an HEI and I took it apart, cleaned it up and installed the lightest springs that came with the accel type kit. There were 3 types of springs. The vacuum advance works. Have it set at 10 btdc at idle, and it is all in around 2800 at 36 degrees. I have played with it, but it has been A long time since I really set up a HEI dist or timing for that matter. Do you think I should use a vacuum guage? Give me your input on how to correctly set up the timing if you don't mind...Do you thin I am wasting money with my head idea? What do you suggest I do to help this heavy car along??

you are not that far off i think on the curve i could pick you a different cam on a 106 would make more low end and mid but you would need more cr you may want to give compcam a call

Hey Pat, can we get him to tell us whether that was 10 btdc with or with out vacuum hooked up. Something on the post didn't seem right. I like the suggestion of cam advice, it seems a little factor of timing he said he has wasn't quite right.

The timing is at 10 btdc at idle with the vacuum advance unhooked and plugged. Then when I plug it in and give it gas and dial the light to 36, at around 2500-2800 I am at 36 degrees. Does that help you out at all? I think I am in the ball park. The fact of the matter might be that it is a heavy car, and the engine just isn't worked enough. The cam might be too small, but I didn't want to go the other direction and over cam. I did that in the past(15 years ago) and it sure sounded great, but what a dog.ha ha. I guess as you get older you figure out that you should make the engine trans rear all work together, and also know what you want to do with the car.

i never said the cam was to small .you do want more ? then i would go a different way the heads and cr and different cam on a 106/108 lsa will make it run better. will you be happy with that ? that would be hard for me to say

What do you think you would do with the situation I just explained? If it were you, and you wanted to go faster, what parts would you put together. Also,thank you for the help, I am not trying to be difficult, I just don't want to do it wrong, so I need all the info I can get.