Cam choice?

[mm1077]

Curious what cam everyone would recommend for this engine to maximize bottom end torque?. I’m not super knowledgeable on engines but I’m learning : ).
Engine specs are listed in photo (this is what I was told when I bought the truck).
Also - new Edelbrock avs2 650, has full length headers, MSD 8362 Hei ignition (full recent tune up) Freshly rebuilt th350 w/ b&m 2400 stall and 3.07 gears. I run 93 octane gas.
Truck pulls good after about 2500 rpm but it’s seems really darn slow getting to that point. feel like I’ve got to give it a lot of throttle for minimal acceleration. I’m trying to get to where I have daily driver that’s super fun to drive and can still comfortably cruise on the interstate. I feel like the current cam is probably really holding back the power in the range that I actually drive it in

*I have reached out to comp/lunati for recommendations online but have not gotten a response yet
Posted via Mobile Device

[MySons68C20]

I don't see the specs.

[mm1077]

I forgot to hit the upload button lol - should be there now

[MySons68C20]

Lots of variables like total timing, when you achieve full advance plus those tall gears aren't helping.
I don't know the specs on that cam but the ones I've been around idle really choppy but seem to run fairly well.
How is the power once you get the revs up 4k plus?

[mm1077]

Power seems really good to me at higher rpm’s . If I really get on it taking off, it’ll pull good or if I’m on the interstate going 65 and gas it it will pull…but anything under about 60mph or just taking off at a light in regular traffic feels like a lot of sound and not a lot of go : )
timing set at 12 degrees (w advance disconnected), timing rose to 17 at about 2600rpm is where it stopped advancing. Plugged in the advance which added an additional 7 degrees. No hesitations or surging when driving

[MySons68C20]

With the vacuum advance disconnected you need to see 34-36 degrees total mechanical advance all in by 3000 rpm. Do you have a timing light?

[mm1077]

I do have a digital timing light. I was reading that higher compression sometimes requires a lower total timing, do you think that would factor in at all in my case? Tough to navigate all the conflicting info I read online trying to learn all this lol

[Getter-Done]

Hey there Neighbor.

From past experience a Cam labeled (Rv cam) is what you are looking for.

This all depends on what you are looking for from the truck.

Is this your Daily Driver or do you want a Redlight Racer Truck ?

Depending on what your expectations are ?

The stall is probably the issue of your current performance.

Is The 3.07 gears the reason for the 2500 stall?

If so the Use of your truck needs to factor in.

Redlight racer?

Daily Driver?

Highway Cruser?

I like a RV cam and Stock convertor and 3:73 gear myself.

This would not be an Interstate driver thou.

[MySons68C20]

If your total timing is only 17 degrees (a rise of only 5 degrees from your set point) you are leaving a lot of torque & horsepower on the table.

[mm1077]

The current cam was the reason for the stall choice. I just had that installed when the trans was rebuilt (they said the stall they pulled out was like a 3500!) I’m guessing that the previous owner may have switched out a much lower gear for the 3.07 before selling but idk?
I’d like it to ultimately be a daily driver that can also pull away from a 95 Honda accord at a red light if needed : ) . I’d also like to get better than like 8mpg on premium but im not expecting anything crazy in that regard. I was looking at the xe268 or 272 as a cam choice but I was reading they were only recommended for up to 9.5:1 cr (I don’t understand the why on those #s yet). I ran that xe268 cam on my 78 2wd blazer like 8yrs ago (my buddy helped assemble and I learned a lot but I’ve forgotten half of it since then) and I liked the driveability. I’d prob go with that again if my current cr wasn’t a real issue

[mm1077]

I’ll go back and check the timing #s again. I think I was pretty accurate in reading them but definitely possible that I didn’t : ). If those #s are accurate would that mean that the distributor is limiting the mechanical advance and I would need to rework it some?

[MySons68C20]

I would verify top dead center on #1 cylinder and see if the marks on the balancer line up before anything else.
Once you have established that then you can continue with the advance issue etc.

[Accelo]

A lot of options that have been covered by prior postings.
The cam you have it just too large for the gears.
I had a DZ 302 in a Camaro (not the original Z28) with 3:08 gears.
It was a slug, it would go almost 60 in first gear, with a Muncie 4 speed.

I pulled the motor out and installed it in a Corvette with 3.73.
You would not have believed it was the same motor.

Choices is to go down on duration or down in gear ratio.

Just one ides is this one by Comp Cams;
Factory Muscle 222/222 Hydraulic Flat Cam for Chevrolet Small Block
https://www.compcams.com/factory-mus...all-block.html
It's a modern reproduction of the 350hp factory cam. Not identical, as it has a modern computer aided design.

I almost always pick the cam I think I want then purchase the one under it in duration. Worked well over the years.

[GSP7]

Originally Posted by Accelo

Just one ides is this one by Comp Cams;
Factory Muscle 222/222 Hydraulic Flat Cam for Chevrolet Small Block
https://www.compcams.com/factory-mus...all-block.html
It's a modern reproduction of the 350hp factory cam. Not identical, as it has a modern computer aided design.

.

Their "factory muscle" series must be pretty new. They cam timing specs on that one is interesting .

My Elgin E1069P cam is similar to comps- magnum H270- H280 and simular to that 222/222 cam except the cam timing

Those "thumper" cams are for idle sounding "cool" at a car show

[MySons68C20]

I'm a bit stuck in the past, love the "old" Comp Cams 268H

[mm1077]

I went ahead and ordered a recurve kit for the distributor and I plan to just verify my initial timing numbers and then change a few things to see if it picks up any. My gut has told me that this cam is just more than I want in the truck (I’d much rather have performance over sound and I’ve read a lot of the posts verifying that about the big Thumpr cams). I knew there were things I’d want to change when I bought the truck, in fact I liked that about it as it’s more of an opportunity to learn this end of things. I’ve put A ton of time into it so far and it’s been a fun process. I’ll prob swap the cam even if recurving helps, just maybe put it off a little longer

What would the difference between the xe268 and 268h be? Any issue running those with 10.5:1 cr?
Posted via Mobile Device

[MySons68C20]

The XE is the modern version of the original 268H afaik.
Have you run a compression test to see where you are at right now?
It's tough to know what you really have based upon what someone did or said.
I agree, it is fun and you get to learn new stuff!

[mm1077]

Originally Posted by MySons68C20

The XE is the modern version of the original 268H afaik.
Have you run a compression test to see where you are at right now?
It's tough to know what you really have based upon what someone did or said.
I agree, it is fun and you get to learn new stuff!

I have not checked it yet but that’s a good idea for sure - adding that to my to-do list
Posted via Mobile Device

[GSP7]

Originally Posted by mm1077

I went ahead and ordered a recurve kit for the distributor .............

What and where? the recurve kit you mention?

I just moved from where I had to smog check my truck to a state where I can tune my truck properly.

I'm rebuilding and re-calibrating my quadrajet and I need to address my distributor advance and timing

Thanks

[mm1077]

Spoke with the reps at Summit today and they recommended the SUM-K1104 cam/lifter kit. He said there’s a chance I may want to swap to a lower gear after the cam swap but it would best to just see how it drives after the swap and decide from there.

[MySons68C20]

Link to kit

https://www.summitracing.com/parts/sum-k1104

[Accelo]

Remember the difference between a stock cam and the lowest one on the aftermarket list will be the largest difference in HP. Typically as you go up in duration you may only gain 10hp per jump in cam duration for every camshaft after than. Where from stock to the first (lowest duration) can be as much as 40hp.

Always use duration at .050 to compare camshafts. Advertised duration is just that, for advertising.

I looked up the specifications for the "Big Muta" 243 intake and 257 exhaust with a nominal .5" lift. That's a lot of camshaft.

The cam you picked out is: 224 intake and 224 exhaust at .050.
It is a popular cam, but on the edge for running a stock converter. I see you have a mild stall converter in your automatic. Likely will be fine if you decide to use this cam.

After reading your posts you may like a cam between 212 and 218 duration better.

Especially if you do not plan on changing the differential gears.
Gearing is a big deal and typically referenced as "lower numerically gears recommended."

I get your complaint. Your current gearing has to be dog slow from a dead start.
Your final drive ratio in first is 7.76

Typical performance ratios are in the 10.00 range.
You would have to have a 4.11 differential ratio to get into this range
2.52* 4.1=10.3572
2.52 is the THM 350 first gear ratio.
The current cam is certainly deep into the performance range.
Should be no surprise that it's falling on it's nose.
Cheers

[mm1077]

Originally Posted by Accelo

Remember the difference between a stock cam and the lowest one on the aftermarket list will be the largest difference in HP. Typically as you go up in duration you may only gain 10hp per jump in cam duration for every camshaft after than. Where from stock to the first (lowest duration) can be as much as 40hp.

Always use duration at .050 to compare camshafts. Advertised duration is just that, for advertising.

I looked up the specifications for the "Big Muta" 243 intake and 257 exhaust with a nominal .5" lift. That's a lot of camshaft.

The cam you picked out is: 224 intake and 224 exhaust at .050.
It is a popular cam, but on the edge for running a stock converter. I see you have a mild stall converter in your automatic. Likely will be fine if you decide to use this cam.

After reading your posts you may like a cam between 212 and 218 duration better.

Especially if you do not plan on changing the differential gears.
Gearing is a big deal and typically referenced as "lower numerically gears recommended."

I get your complaint. Your current gearing has to be dog slow from a dead start.
Your final drive ratio in first is 7.76

Typical performance ratios are in the 10.00 range.
You would have to have a 4.11 differential ratio to get into this range
2.52* 4.1=10.3572
2.52 is the THM 350 first gear ratio.
The current cam is certainly deep into the performance range.
Should be no surprise that it's falling on it's nose.
Cheers

After talking to a few more folks as well as the replies on this thread I’ve kind of re-evaluated for now on the cam swap idea- I think I need to step back and think more about gear swap first…we’ll first I’ve revisited my timing.

Yesterday I installed a recurve kit to the street fire distributor with a lighter combination of springs. This seemed to help bottom end a little and no detonation issues. I’ve been reading everything on timing that I can, and I seem to be having issues with keeping my carb on the idle circuit. I’m set at 12 degrees right now w total timing of 34 @ about 3200rpm. (No advance connected). I’m getting full vacuum at the timed port. If I adjust the idle down to where I lose vacuum on the timed port it will want to stall unless I add a lot more timing. If I add more timing my total mechanical advance goes up as well. I did try connecting the va to full manifold vacuum as well - with idle adjusted down i’m still getting full vacuum at the timed port. I’m now thinking the engine would like about 16-20 degrees initial timing and if I could lock out the mechanical advance at about at an additional 15-20 (whatever gets me 34-36) , with a v/a canister that adds in another 7-10 for efficiency I might be in good shape? I’m looking at the billet Msd distributors that use the advance stop bushings to limit mechanical advance (darn they’re $$ though lol) since I’m not wanting to mess around with modifying the street fire. I guess once I get this dialed in I could move on to gear swap and/or revisit the cam idea
Posted via Mobile Device

[geezer#99]

While a bump to 22 degrees initial would be my normal suggestion, you’ll likely encounter a lot of pinging. Mostly due to your first gear total ratio being so low. You’ll need to just add a couple degrees at a time to see what works best. Once you find that number you’ll need to limit the mechanical. Here’s a link on ways to do that.
I’d buy a cheap hei off eBay to experiment with.


http://www.crankshaftcoalition.com/w...EI_distributor

[Tom]

Originally Posted by Accelo

Advertised duration is just that, for advertising.

Not at all. The difference between advertised and .050" duration tells you the ramp rates. The farther apart the numbers are, the slower/lazier the ramps are. Closer is better when it comes to power.