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340 stock cam question

John Hogan

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OK gang, I haven't built a motor in 30 years. And all the motors I built back then were for street/strip. I always ran Mopar Performance cams. Now I have a 1973 340 in a Road Runner I'm currently restoring and I plan on using it for cruising and possible road trips. This car won't be visiting the strip. Stock bore, stock compression ratio, stock heads. I am looking for a cam that will have good drivability and idle as well as lower RPM torque. I see Melling has a stock grind replacement cam (SPD-22) with the following specs:

Exhaust Duration - 289 deg
Intake Duration - 279 deg
Exhaust Duration at .050 Lift - 220 deg
Exhaust Valve Lift - .444
Intake Duration at .050 Lift - 209 deg
Intake Valve Lift - .429
Lobe Separation - not listed

They also offer a cam (MTD-1) with the following specs:

Exhaust Duration - 288 deg
Intake Duration - 278 deg
Exhaust Duration at .050 Lift - 214 deg
Exhaust Valve Lift - .443
Intake Duration at .050 Lift - 204 deg
Intake Valve Lift - .421
Lobe Separation - 112 deg

Your thoughts on if their MTD-1 (classified by Melling as a torque towing camshaft) would have any advantage over the stock cam for my intended usage? Or any other recommendations for a good cam? I have read there seems to be lots of quality issues lately. Thanks!
 
OK gang, I haven't built a motor in 30 years. And all the motors I built back then were for street/strip. I always ran Mopar Performance cams. Now I have a 1973 340 in a Road Runner I'm currently restoring and I plan on using it for cruising and possible road trips. This car won't be visiting the strip. Stock bore, stock compression ratio, stock heads. I am looking for a cam that will have good drivability and idle as well as lower RPM torque. I see Melling has a stock grind replacement cam (SPD-22) with the following specs:

Exhaust Duration - 289 deg
Intake Duration - 279 deg
Exhaust Duration at .050 Lift - 220 deg
Exhaust Valve Lift - .444
Intake Duration at .050 Lift - 209 deg
Intake Valve Lift - .429
Lobe Separation - not listed

They also offer a cam (MTD-1) with the following specs:

Exhaust Duration - 288 deg
Intake Duration - 278 deg
Exhaust Duration at .050 Lift - 214 deg
Exhaust Valve Lift - .443
Intake Duration at .050 Lift - 204 deg
Intake Valve Lift - .421
Lobe Separation - 112 deg

Your thoughts on if their MTD-1 (classified by Melling as a torque towing camshaft) would have any advantage over the stock cam for my intended usage? Or any other recommendations for a good cam? I have read there seems to be lots of quality issues lately. Thanks!
Lots of chatter on FABO about that. Just type 340 cam in the search box and hold on. Krazycuda sent a original 68 4 speed cam to Oregon Cams to be duplicated. Although it is more radical than the 73 cam, that's the grind everyone wants. Reproduction 340-4 Speed Cam The SPD22 is a good one. With your lower compression 340 (1973 vintage) I would use the MTD-1.
 
Lots of chatter on FABO about that. Just type 340 cam in the search box and hold on. Krazycuda sent a original 68 4 speed cam to Oregon Cams to be duplicated. Although it is more radical than the 73 cam, that's the grind everyone wants. Reproduction 340-4 Speed Cam The SPD22 is a good one. With your lower compression 340 (1973 vintage) I would use the MTD-1.
Thanks, that is what I am thinking as well.
 
By 73 the compression ratio was down (71 was the last year for decent compression) so the MTD cam might be a little better down low? Engine masters did a cam test with a motor home 440 and the motor liked the bigger cam better even though it lowered the PSI on a cranking test by nearly 20 lbs so you have to research what kind of dynamic compression might be between the two. The bigger cam can raise that. And yeah, FABO does have mostly small block guys on there....
 
By 73 the compression ratio was down (71 was the last year for decent compression) so the MTD cam might be a little better down low? Engine masters did a cam test with a motor home 440 and the motor liked the bigger cam better even though it lowered the PSI on a cranking test by nearly 20 lbs so you have to research what kind of dynamic compression might be between the two. The bigger cam can raise that. And yeah, FABO does have mostly small block guys on there....
Thanks Cranky. Back in the old days I would just grab a bigger Purple Shaft, throw it in a '69 or '70 motor and be really happy with it. Times have changed!
 
You can make the big cam work in a lower compression small valve engine but you may need headers, a converter, and/or higher rear gears. Spending all your street driving between idle and 4000 rpm isn't fun if your cam doesn't turn on until 5000 rpm.
 
You can make the big cam work in a lower compression small valve engine but you may need headers, a converter, and/or higher rear gears. Spending all your street driving between idle and 4000 rpm isn't fun if your cam doesn't turn on until 5000 rpm.
Had a .480 lift cam in a buddies 72 318 Demon that turned on at iirc 3000 (dang, getting old sucks) and turned on like a bad turbo lag and hauled butt to 6200 and shut off! Car had a stock converter but 4.88 gears turning 29" tires, headers, Torker intake intake, 650 DP, MP ignition.....13.50 @ 102. Terrible combo but that's what we had laying around. It surprised the snot out of us. Dang thing wanted LOTS of total timing to the tune of 50 degrees!
 
Had a .480 lift cam in a buddies 72 318 Demon that turned on at iirc 3000 (dang, getting old sucks) and turned on like a bad turbo lag and hauled butt to 6200 and shut off! Car had a stock converter but 4.88 gears turning 29" tires, headers, Torker intake intake, 650 DP, MP ignition.....13.50 @ 102. Terrible combo but that's what we had laying around. It surprised the snot out of us. Dang thing wanted LOTS of total timing to the tune of 50 degrees!
:rofl: Yep, there you go. 3-6200 but with 4.88's. Try that with a 2.76 or even a 3.23. Woof woof! You will be going 65 in low before the cam comes in. :lol:
 
Think the spd22 is 1968 4spd repop. The other is just a generic profile ground for all makes. I did put the generic in a 9:1 383 and it works great. Another friend put the generic in a low compression 350 Chevy and it worked good for him.
 
Looking in a 1969 service manual and the spd cam may actually have been used in automatic transmission cars. Whatever you do be sure and check the springs for coil bind. Stock springs won't take much lift.
 
Think the spd22 is 1968 4spd repop. The other is just a generic profile ground for all makes. I did put the generic in a 9:1 383 and it works great. Another friend put the generic in a low compression 350 Chevy and it worked good for him.
Interesting. The Melling website shows the SPD-22 as a stock?? replacement for anything from 1970 through 1981 small blocks. Obviously there were lots of different cams that Chrysler used during that time!
 
Looking in a 1969 service manual and the spd cam may actually have been used in automatic transmission cars. Whatever you do be sure and check the springs for coil bind. Stock springs won't take much lift.
Looks like Melling says the MTD cam requires different valve springs so possibly the SPD can use the stock springs. Decisions, decisions, guess I may be calling Melling tomorrow.
 
I have a 1973 road runner also with a 340, 40 thousand over, 10 to 1 compression, I run a comp cam XE 274, flat tappet and love it. Vacuum is still good for power brakes and has a rubble. In addition I run a 3200 stall and 3.90 gears. Just a Street car only. In addition double check your cam and lifters since too many horror stories wiping out cams.
 
Had a .480 lift cam in a buddies 72 318 Demon that turned on at iirc 3000 (dang, getting old sucks) and turned on like a bad turbo lag and hauled butt to 6200 and shut off! Car had a stock converter but 4.88 gears turning 29" tires, headers, Torker intake intake, 650 DP, MP ignition.....13.50 @ 102. Terrible combo but that's what we had laying around. It surprised the snot out of us. Dang thing wanted LOTS of total timing to the tune of 50 degrees!
Bet that was a pain to drive on the street!
 
You can make the big cam work in a lower compression small valve engine but you may need headers, a converter, and/or higher rear gears. Spending all your street driving between idle and 4000 rpm isn't fun if your cam doesn't turn on until 5000 rpm.
The biggest hangup was the super tight 318 converter that was in it....and to me, the cam was retarded. I had everything needed to degree it but my buddy decided to stick it in and use the 'dot' method to align it. The engine sounded louder than most other small blocks usually sound with open headers and that's usually another trait of a retarded cam along with the sluggish bottom end. The thing ran 102mph in the 1/4 with a super lousy 60' of 2.20. The only reason for 29's was because it was blowing off the 26" M/T's ET streets when it shifted into 2nd gear. Couldn't do a burnout because there was no torque to turn them in the water and going from a 4.10 to the 4.88 didn't help but it did trap good and pulled all the way through. The 29's were slicks and was all that we had between us.

Years later another buddy showed up at the track with a potent SB (or should have been) and it was really lazy off the line and....loud. Didn't ET very well and was lazy all the way down the track. He asked me what I thought might be wrong and I told him based on what it's doing and the way it sounded, the cam was retarded by a bunch. He too used the dot method and well, after doing a ton of work with the ignition, installing another converter, carb, and the list goes on he finally decided to check the cam. Forgot how much he said it was off but it was a bunch! That's why I'm such a stickler for degreeing in the cam....stock OR not.
 
Bet that was a pain to drive on the street!
Never did....it did drive around the pits without any issues but never ran it over 40 mph. We did have an area where lots of guys did their warming up where you could go faster but we never did that.
 
I have a 1973 road runner also with a 340, 40 thousand over, 10 to 1 compression, I run a comp cam XE 274, flat tappet and love it. Vacuum is still good for power brakes and has a rubble. In addition I run a 3200 stall and 3.90 gears. Just a Street car only. In addition double check your cam and lifters since too many horror stories wiping out cams.
That is one of the reasons I am looking at a Melling cam kit, haven't seen many horror stories about them compared with some other brands.
 
That is one of the reasons I am looking at a Melling cam kit, haven't seen many horror stories about them compared with some other brands.
Still check your parts before running, if not sure check out Mopar Joe on YouTube he got a lot of good info.
 
John,Please post your findings when you call Melling. Information is always good.
 
Cam design/knowledge has changed greatly since these engines were made. D.Vizard's 128 rule came from his testing of nearly 19,000+ cams for Crane Cams.

Also, factory cams were compromised by emissions. So a factory repro will give good performance, but not the best.

The Isky 264 Mega cam would be a good choice.

If you do not want a cam/lifter failure, have your factory lifters re-faced.
 
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