Where should peak power be for a 302 with the stock cam and unworked heads/intake. Mine drops off dramatically after 6400 rpm, immediately after peak power. I'm going to adjust the valve lash hot tonight. How much of a power/rpm difference can be found in the correct lash? In other words can my power be down by 20+ rwhp due to an improper lash setting?

Can I move the power band up in the rpm range by dialing in the cam differently (retarding)?

How does McNeish (Old Reliable) get that little 302 to make peak power at 7600 rpm with unported stock heads and intake? I can't understand this. He's using a custom ground cam from Crane. He lists 426 horsepower at 7600 rpm which I assume is at the flywheel.

Open headers would help, along with a blue printed engine
That olso mayhave been with the 2-4s crossram, and the porcupine heads?

Where should peak power be for a 302 with the stock cam and unworked heads/intake. Mine drops off dramatically after 6400 rpm, immediately after peak power. I'm going to adjust the valve lash hot tonight. How much of a power/rpm difference can be found in the correct lash? In other words can my power be down by 20+ rwhp due to an improper lash setting?

Can I move the power band up in the rpm range by dialing in the cam differently (retarding)?

How does McNeish (Old Reliable) get that little 302 to make peak power at 7600 rpm with unported stock heads and intake? I can't understand this. He's using a custom ground cam from Crane. He lists 426 horsepower at 7600 rpm which I assume is at the flywheel.


Based on my experience, the 30-30 should start to sign off about 6,400rpm as yours does. MacNeish uses a much larger cam (272@.050).

67RS502-Thanks,
Does a blueprinted/balanced motor allow the 302 to spin past 6500?

Neil B- Thanks,
Would retarding the cam 4-8* allow me to move peak hp up into the 6600-6800 rpm range and still have good cylinder pressure or would I screw things up by doing that?

I really need to talk to someone that really knows about cams...any advice out there??

MacNiesh of course, or you might try UDHarold on chevelles.com, he's a cam engineer (forget what company...the one that does the voodoo cams) other than pushing his company's products hard, he really really knows his stuff.

Stock ignition points can float at that speed.

Where is PDQ ? He knows that cam and that motor !

Jim,
UdHarold was THE MAN and maker of Ultradyne Camshafts. He is now with Lunati as Ultradyne has now folded.

I'm no 302 expert but I've driven and ridden in stock DZ302 cars that pulled strong well past 7000rpm. Way back in the day I helped install a stock '68 302 in my friends camaro. His tattletale recorded 8000rpm shifts frequently, points and all. The little engines don't wake up until 4500rpm, I can't imagine anyone wanting to move the power band further up in the rpm range.

67RS502-Thanks,
Does a blueprinted/balanced motor allow the 302 to spin past 6500?

Neil B- Thanks,
Would retarding the cam 4-8* allow me to move peak hp up into the 6600-6800 rpm range and still have good cylinder pressure or would I screw things up by doing that?

I really need to talk to someone that really knows about cams...any advice out there??


Retarding the cam will shift the entire powerband upwards. You'll likely have to find out out much the powerband shifts through trial and error. I would recommend consulting with a camshaft professional before going this route. Don't forget that altering camshaft timing changes P-V clearance and you'll need to recheck. If you're going to all the trouble to re-degree the cam, you might as well put a cam in that matches your powerband requirements. If your peak hp is at 6,400rpm, your shift point should be around 7K as it is. If you really want to make peak hp around 7K, the -140 cam might do the trick.

I went to the Crane website and found the following:

PN3849346 30-30 blueprinted cam 4000-7000rpm range
PN3927140 Off-Road blueprinted cam 4200-7200rpm range

Retarding the cam will shift the entire powerband upwards. You'll likely have to find out out much the powerband shifts through trial and error. I would recommend consulting with a camshaft professional before going this route. Don't forget that altering camshaft timing changes P-V clearance and you'll need to recheck. If you're going to all the trouble to re-degree the cam, you might as well put a cam in that matches your powerband requirements. If your peak hp is at 6,400rpm, your shift point should be around 7K as it is. If you really want to make peak hp around 7K, the -140 cam might do the trick.

I believe for every 4° the cam is retarded the power band is bumped north approx 200 rpm. I'd rather dial in this cam and install better pushrods than go experiment with a new cam all over again.

As you maybe recall my friend had the -140 cam and his peak is no where near 7k, as a matter of fact we were both at the dyno last week and my peak was around 6400 and his was around 6k. Now I believe his valve lash may be the reason why though. We're going to take a looksee tonight.

What cam expert could I talk to?

Jim,
UdHarold was THE MAN and maker of Ultradyne Camshafts. He is now with Lunati as Ultradyne has now folded.

I read everything he rights, the man knows airflow lick I know my fingers...

Jim, have you been licking your fingers again?? :waving:

lmao....

Ignition (point bounce) and low valve spring pressure are the major limiters to higher RPM. The stock 302 valve springs are just regular production car items, I believe. If they're old and weak, you might want to change them out for something a little stiffer.

What does the rest of the combo look like...exhaust, heads, intake, ignition, etc? The 30-30 cam is 254@.050 on a 114 lsa...it should scream to 7K easily in a short stroke 302 if the rest of the system is up to the task. I have a 250@.050 cam in my much longer stroked 388 and it will rev to 7K too easily. Like others have said, it could be a valvespring, points, or fuel related issue...that cam should have no trouble pulling past 6400 rpms.

I finally got here.

I figure NEW points bounce between 7,000 and 7,500 rpm b/c mine did in my old junk 301 with no more than the great little old Duntov, -097 solid cam!!

It was 287/228/287/230, .110.5/108, .383"/.383" net lift!! Like I said, a little-bitty bugger but IMHO, one of the best all-around small motor SB solid cams, stock or otherwise, ever made for a street motor!!

Look to points bouncing as well as valve springs being weak. I put a set of cheap, good old, -142 springs on my heads!! They were designed to go with the -140 cam so are adequate for the 30-30 cam, imho..

The death of many an old 302 was some lead-foot rpm'ming it past it's spring's life and then floating and bending the valves!! The little motor doesn't like that at all above 7,000+!!

I'm not saying that the peak power points are going to be ALL that high, but rather that a fresh 302 should rpm up there until you get scared!!

I know my junk 301 would AND did...

pdq67

The 302's I've run with the 30-30 cam all pulled hard way past 6500. However not until I started using Blue Streak points in the stock distributor. They won't float or bounce as quickly as the other brands. But be fore warned that due to the increased spring pressure on this point set you will wear out the followers sooner. Once it got difficult to pull past 8,000 I knew it was time for a new set of points. The motor should easily climb to and beyond 8,000. But in stock form there's really no benefit to going beyond 8,000. I do know of many higher compression and modified 302 that frequently saw 9400 and 10,000 rpm. But these were at the strip. Your street/stock 302 should pull easily to 8,000 with good points, gas and the cam installed straight up. You need good valve springs as well and proper valvetrain components.

I learned like pdq said that you'll break valve components when frequenting the 8,000 rpm range and beyond. Screw in studs, guide plates and good hardened once piece pushrods and proper valve springs will keep things safer.

It makes no sense to me that your friends -140 cammed motor did not make as much power or peaked sooner than your 30-30 cammed motor. Unless he did not follow GM's guidelines for stronger springs and minimum 12:1 compression with this cam. Crane makes a single spring with damper that is good for up to .580 valvelift and uses the stock valve spring pocket sizes. That is what I've used with the -140 cam. I also ran 1.6 rockers, something you may want to consider with you 302, as long as you're considering checking the piston to valve clearance anyway if you end up retarding the cam.

I think Elgin's single w/damper spring PN RV 1943X that Midwest Motorsports sells is about the same spring SY1 is talking about. It has a 125# on the seat at 1.8" and 360# at 1.2" and about a 391 pound/in rate and is stock OD and they say good to a .600" lift...

I bought the kit, (springs, retainers and locks), for $55 + S&H for my 283 motor's 305HO, -601 heads so I can run the cheap PAW solid cam. It's spec's are 280(262?)/246, 108/108, .501 lashed with 1.6 ratio rockers! I figure it should rpm above 8,000 easy!!

Guys, the little 302 motor will go UP there if it is fresh!!

pdq67

I believe for every 4° the cam is retarded the power band is bumped north approx 200 rpm. I'd rather dial in this cam and install better pushrods than go experiment with a new cam all over again.

As you maybe recall my friend had the -140 cam and his peak is no where near 7k, as a matter of fact we were both at the dyno last week and my peak was around 6400 and his was around 6k. Now I believe his valve lash may be the reason why though. We're going to take a looksee tonight.

What cam expert could I talk to?

If I recall your friend's combo correctly, he put AFR210's on, dropped the compression ratio, and replaced the -140 cam with a small Crane solid roller. If it's peaking at 6K with the big AFR's and the -140, something's definitely amiss.

Since Crane sells the 30-30 Blueprint cam, I would recommend calling them.

I figure his heads are way too big and if he isn't up to at least 11 to 1 CR. the 30-30 won't run right as well as the -140 cam needing at least 12 to 1 CR. to run it's best.

Remember, the little motor stock, uses a 160+ cc head and is about 11 to 1 CR.

180 cc's is about max., imho and then stay with at least the 11 to 1 CR.

I wouldn't run much over a 280 solid cam say at 10 to 1 to below 11, then at 11 to 1, run at least a 290 solid cam minium like Isky's Z-30 or GM's 30-30..

BUT, as always, jmho..

pdq67

Ignition (point bounce) and low valve spring pressure are the major limiters to higher RPM. The stock 302 valve springs are just regular production car items, I believe. If they're old and weak, you might want to change them out for something a little stiffer.

I'm using MSD billet distributor with a 6AL box

What does the rest of the combo look like...exhaust, heads, intake, ignition, etc? The 30-30 cam is 254@.050 on a 114 lsa...it should scream to 7K easily in a short stroke 302 if the rest of the system is up to the task. I have a 250@.050 cam in my much longer stroked 388 and it will rev to 7K too easily. Like others have said, it could be a valvespring, points, or fuel related issue...that cam should have no trouble pulling past 6400 rpms.

1 3/4" hooker sc heades
flowmaster 2 1/2" system with 40 series mufflers
stock 291 heads untouched
MSD 6AL and billet distributor (40* all in by 3000)

If I recall your friend's combo correctly, he put AFR210's on, dropped the compression ratio, and replaced the -140 cam with a small Crane solid roller. If it's peaking at 6K with the big AFR's and the -140, something's definitely amiss.

Since Crane sells the 30-30 Blueprint cam, I would recommend calling them.

Neil, great memory! My friend got so ****ed off about the whole Scott Shafiroff fiasco that we pulled his motor out, put the -140 cam back in and put on stock heads and intake. His compression is back up around 12:1. But his power is only ~245 at the wheels and it peaks at 5900-6k.

I adjusted my valve lash hot yesterday after work. Out of 16 rockers, I'd say maybe about 6 were right on, 4 were slightly loose and another 6 were really loose. By loose I mean > .030 lash. I really wonder how much of an impact that made on my dyno and quarter mile passes. Did I lose top end power? I know some of my MPH loss was due to larger tire diameter but maybe some was due to valvetrain. I did go from 101.7 mph to 97.9 mph. The only other variable is that I added a phenolic carb spacer (and of course weather which was certainly hotter this year at the Old Time Drags at E-Town).

I adjusted my valve lash hot yesterday after work. Out of 16 rockers, I'd say maybe about 6 were right on, 4 were slightly loose and another 6 were really loose. By loose I mean > .030 lash. I really wonder how much of an impact that made on my dyno and quarter mile passes. Did I lose top end power? I know some of my MPH loss was due to larger tire diameter but maybe some was due to valvetrain. I did go from 101.7 mph to 97.9 mph. The only other variable is that I added a phenolic carb spacer (and of course weather which was certainly hotter this year at the Old Time Drags at E-Town).

IMO, 97-101mph is about all you're going to get out of a stock DZ302. It sounds like your combo is doing what it should be doing. Your friend's combo may be limited to 6k peak by the heads (if unported) and intake.

Just food for thought, my DZ with 254@.050 cam (Comp 12-673-4), 170cc intake runner aluminum heads, stock intake, stock compression, and 1 3/4 headers peaks between 5,900 and 6,000rpm. I've verified that on 2 different chassis dynos. It runs 104mph in the quarter mile with a 6,500rpm shift point.