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My 1970 coupe has a tired base 350 in it. It is matching numbers so I ruled out a crate motor. I do not know if anyone has been inside of it in the past but cylinders 5 and 8 are heavily fouled. When we pull the engine for rebuilding, does anyone out there have suggestions for a lopey cam that won't mess up the vacuum wiper door and headlight doors? Still want it streetable but love the lope! It is an automatic and will have under body headers once done. I appreciate your suggestions.
From: At my Bar drinking and wrenching in Lafayette Colorado
If you want a car that runs terrible, will get spanked by a Honda Civic, has horrible vacuum making engine and carb tuning impossible, and has the "lope" you want, get a "Thump-Yo-*****" cam. The most horrible, suck-*** cams ever offered by a manufacturer. All sound and no go. Why don't you get a cam that makes your car run well...?? If you want lope, yank a couple of plug wires off of it.
My 1970 coupe has a tired base 350 in it. It is matching numbers so I ruled out a crate motor. I do not know if anyone has been inside of it in the past but cylinders 5 and 8 are heavily fouled. When we pull the engine for rebuilding, does anyone out there have suggestions for a lopey cam that won't mess up the vacuum wiper door and headlight doors? Still want it streetable but love the lope! It is an automatic and will have under body headers once done. I appreciate your suggestions.
Comp Cams has the Thumpr series of cams that advertise the sound you are looking for. They have the Thumpr, ***** Thumpr and Big ***** Thumpr camshafts in hydraulic flat tappet and hydraulic roller. All of these cams are ground on 107 degrees lobe separation so it gives they choppy idle but are designed to still work good on the street.
From: At my Bar drinking and wrenching in Lafayette Colorado
If you want a car that runs terrible, will get spanked by a Honda Civic, has horrible vacuum making engine and carb tuning impossible, and has the "lope" you want, get a "Thump-Yo-*****" cam. The most horrible, suck-*** cams ever offered by a manufacturer. All sound and no go. Why don't you get a cam that makes your car run well...?? If you want lope, yank a couple of plug wires off of it.
Streetable and lopey is an oxymoron in a carbureted motor. A cam with a tight LCA is going to bleed vacuum at idle, be hard to tune for low RPM drivability and you will eventually hate driving your car. Stick with the known formulas of cam and piston selection in any Chevy high performance book.
I totally agree with Lars and RocketJSquirrel.
Any lopey thumper cam will be terrible on the street and they aren’t all that great for most race applications.
I just had a big block 496 built for my build and during the dyno tune the builder did not like the performance of the cam we initially agreed on.
It was making torque/hp at a higher rpm than we wanted.
The builder swapped cams to a less aggressive cam which increased the torque/hp into the rpm range that is much better for street use.
The engine now makes more power at a lower and useable rpm than it did with the more aggressive cam.
You can also install an exhaust system that will give you a more lopey choppy sound at idle.
I'll jump in here as well now that a couple other well respected people have commented.
I thought about replying 12 hours ago.
To Josh, second post. ARE YOU OUT OF YOUR MIND!
Big ***** what ever cams are for total *******! They advertise they work in a street car? Yes they advertise because they want to sell their junk!
How about a cam that runs well and the heak with the rump rump. rump.
You actually have to drive it you know!
We all see them coming into the car show with the rump rump cam. Herking and jurking and basically undriveable trying to park. And although some may think that sounds tough. Most of us are laughing at them.
People love to stand at the fence on the main straight at our local track. I love to come out of that last corner in third gear. Shifting to fourth right about where the spectators stand. Full noise, wide F'in open. WOW! Does she fly.
Many times now I've had blokes come up to me in the pits just to say how glorious my car sounds at full noise.
Yes it always makes me smile. Yes I can drive on the esplanade at 10 K's an hour. And it runs smoothly.
Pick a cam that makes power! Not noise. The noise comes when the throttle is applied!
Last edited by 4-vettes; May 30, 2026 at 04:46 AM.
Very true statement Lars. They wiill have a car with no brakes since it's a auto and will suck up gas like canal water because of the stall converter that will be needed
Last edited by socal_tom; May 30, 2026 at 09:59 AM.
The base 1970 engine will make between 10 and 10.5 CR. If you pick a good set of pistons that are not too far down in the hole, you can use a thin steel shim head gasket and maintain good quench. Look at the pin height to make sure you have the highest piston tops.
The cam suggestion for a Corvette with vacuum requirements and an automatic transmission has been a Comp 268H for as long as I can remember. It has a bit of a lope and still works with your accessories. If you go bigger you risk loosing vacuum to the point where the wiper door and power brakes will be compromised.
Last edited by stingr69; May 31, 2026 at 11:43 AM.
Pick a sensible cam, use some loudish mufflers and lower the idle as much as you can. It will sound ferocious in the parking lot and still be pleasant to drive.
And watch what you say about cards in the bicycle spokes. I was one of the coolest kids in town!
2 1/2 hp Tecumseh tiller motor grafted into cradle; was brazing & welding by age 11. Lotsa failures; lotsa progress. Also had a good-running Maytag flat twin; thanks Papa.
Pick a performance cam as mentioned above, based on power, not sound
If it has decent duration, you can do two things to make it sound meaner, and much lopier:
Lower the idle speed
Pull the vacuum advance off, retarding the timing
The best thing is these changes are temporary and can quickly get restored back to where the cam actually runs well.
If you are tech savvy, you could retard the timing with a switch from inside the cabin.
Hook a switch up to some electric exhaust cutouts and you will have all the noise you want.
I'm going to be a bit of a contrarian. I fully understand what our forum members are saying, and agree for the most part. But........there's a part of me that is old school and likes a bit of a cammed up idle. Our stock L-71 is an example, but it does have a stick and 4.11's so it's very steetable when you get used to it. We've owned many cars, including new ones, that we modified the heck out of and enjoyed them a lot. You can have both within reason. I'll give a couple of examples.
We had a '72 Hurst/Olds convertible pace car. 455, auto. I completely restored the car and built the motor the way the actual pace car was built - W-30 heads, W-30 stick cam, etc. I put a loose converter in it and changed the gears from 3.23's to 3.42's. The car ran great, was very streetable, sounded super, and turned low 13's on street tires at several trips to Union Grove. Actually won the Muscle Car Nationals with that one.
We had 2 '75 Hurst/Olds - both 455/autos - one white (the wifes) and then I bought a black one. She drove mine and came back and said, 'it's nice but mine's faster'. Engine and trans were out that weekend. New heads (worked over too), aggressive cam (one 'step' more agressive than a W-30 stick cam), worked over W-30 aluminum intake, headers, looser converter and perf clutch packs in the auto, put in 3.73 gears, etc. Car sounded fantastic, ran great - even the wifey liked to drive it. Traction limited but got a 13.0 out of it on street tires.
All 3 of these cars weighed over 4,000 lbs and had plenty of vacuum to run pb, etc.
I guess my point is you can have both! If you like a cam with some sound bite, go for it. As long as you don't go too far it can still be VERY streetable and a lot of fun. You can work the heads over and still keep them stock looking if you want. Headers really help too if you want to go that route. The right converter, gearing, and tuning and you're golden. There are still a few of us old farts around that like a cam with a bit of lope. It can definitely be done as long as you take care of a few other items - and the car will be a great driver and very quick. Have fun, and do it your way. Best, Paul
Hopper has a point.
230* duration @ .050" is about the limit for a decent driving street performance cam.
And that is with a stock 110-112* LC.
They sound great, have a lope, and are right on the edge where they run better with more compression and gears.
Vacuum at idle should stay above 12-13" with this setup.
LT-1 and L71 / 72 are in this range.
More duration, or a tight lobe center, changes the "overlap" to the nasty side.
It sounds like a race car cam, and has the low end manners to go with it.
Some of these cams make 7" of vacuum at idle.
Not my idea of a streetable cam.
Overlap without the big race car duration doesn't make good power.
Last edited by leigh1322; Jun 2, 2026 at 09:26 PM.
My 1970 coupe has a tired base 350 in it. It is matching numbers so I ruled out a crate motor. I do not know if anyone has been inside of it in the past but cylinders 5 and 8 are heavily fouled. When we pull the engine for rebuilding, does anyone out there have suggestions for a lopey cam that won't mess up the vacuum wiper door and headlight doors? Still want it streetable but love the lope! It is an automatic and will have under body headers once done. I appreciate your suggestions.
Just curious, but why did you rule out a crate motor?
You could put an LS3 in there, and with long-tube headers it will sound better than anything that ever came in a C3. And you get EFI, distributor delete, and a roller cam for free. Not to mention the best aftermarket support of any engine ever.
You can put the matching numbers engine in the corner of your garage for the next owner to throw away. You won't miss it.
Lopey Cam Choice Suggestion Help
that's all you will ever need 
