Thread: camshaft for torque

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Originally posted by techinspector1
Erik, is that a nice way of saying you like the cam but everything else sucks?

NO I DO LIKE EVERYTHING ELSE.I WANTED HIM TO LOWER THE COMP. RATIO THAT WAY HE COULD RUN ANYTHING IN IT FOR GAS AND NOT WORRY ABOUT DETONATION.THE REASON I SAID TO GO WITH THE DART S/S HEAD WAS THAT WAY HE COULD ORDER THEN AND RUN UP .510 LIFT AND NOT DO ANYTHING BUT BOLT THEM ON.

That's why the tight squish. Should run fine on pump gas with no detonation.

Originally posted by techinspector1
That's why the tight squish. Should run fine on pump gas with no detonation.

I WAS THINKING THE GASOLINE OCTAIN RATING MIGHT NOT BE AS GOOD OVER THERE.

Tech1, while you are thinking about cams, let me ask a question. Unfortunately I did not take your short course until my 350 engine build was past the assembly point. Anyway I did not deck the block so I assume the deck height is about 0.025" and I have used the standard gasket for about 0.039" with shaved 882 heads to give 73 cc pockets and flat top eyebrow pistons as 4.030" bore. I am satisfied the C.R. will be low enough that even without much quench I will be able to run with 87 or 89 octane. My question is the cam I chose does not seem to be in the Crane catalog anymore (at least I can't find it online) and the box had two numbers on it. The old number on the box is #10010 but it has a pasted-on label marked "10010" AND in larger numbers "140072", 0.050 DUR I 194 X 204. The card that came with the cam says:

Intake @cam 0.265 @ valve 0.398"
Exhaust @cam 0.280 @ valve 0.420"

@0.005
Intake 22 BTDC 58 ABDC Adv. Dur. 260
Exhaust 71 BBDC 19 ABDC Adv. Dur. 270

@0.050
Intake 10 BTDC 24 ABDC Adv. Dur. 194
Exhaust 39 BBDC 15 ATDC Adv. Dur. 204

I realize this is a very conservative low rpm torque cam, but (!) when I run the rpm numbers for cruisin' on two lane black top roads in the local area with a 3.55 rear ratio and a 700R4 4th OD gear of 0.7, I get 1446 rpm at 50 mph and 1591 rpm at 55 mph (235/75/R15 rear tires). It seems to me that I need torque in the 1500 rpm range to avoid downshifting to 3rd or lugging in OD. I am hoping the low gear of the 700R4 will give a good launch since the 700R4 has a lower 1st gear than the TH350, so the problem is to maximize torque in the 1500 range. Now here is the question. I have both 1.5 and 1.6 roller tipped rockers of the simple type from Speedway. IF I RUN 1.6 ROCKERS ON BOTH INTAKE AND EXHAUST WITH THE 882 HEADS I WILL GET 0.424" INTAKE LIFT and 0.448" EXHAUST LIFT. This is still a very conservative lift and the 882 heads seem to offer little flow beyond 0.400" valve lift, so the question is whether it will help or hurt to use the 1.6 rockers? Will the extra lift and short duration and lack of quench lead to detonation on 87 octane? Bottom line, should I use the 1.6 rockers to get a little more torque or will this lead to worse detonation on cheap fuel? I have both a Performer RPM manifold which I am going to remove and a Performer EPS which I think is better for low rpm. I guess I can start out with the 1.5 roller-tip rockers and then experiment with the 1.6 rockers, but I wonder if the 1.6 rockers will help much with only 882 heads or lead to worse detonation on cheap fuel? It also would be easy at this point to replace the head gaskets for the thin set you mention above. Overall I wonder if most folks realize how low the rpm gets in OD? In retrospect I guess I should have gone to a 3.70 rear gear but I can't afford to make that change unless I find out the OD really bogs with the 3:55. I had a terrific ride recently with a guy about 3 miles away who has just finished a Gibbons '32 highboy and he seems to get good mileage over 20 mpg with a 3.23 rear and a TH350 which only has a 1.0 high gear. Maybe there is no way around expensive trial and error but maybe the light weight of the '29 will make this no problem after all? Sorry to test your patience. I just have to get the car on the road because all this speculation is uncertain, but you are the closest I know to a "brain dyno".

Don Shillady
Retired Scientist/teen rodder

Well in edit mode it was good for me at least to go over all of this and now I realize that I probably will not be in OD at 50 mph but in 3rd with a pretty zippy 3.55 overall gear so probably I should have installed a 3.7 rear gear but I am just going to have to live with the idea that the OD will only be useful for the Interstate! Still that leaves the question for Tech1 as to whether the 1.6 ratio rockers will do me any good on this setup?

Originally posted by Don Shillady
Tech1, while you are thinking about cams, let me ask a question. Unfortunately I did not take your short course until my 350 engine build was past the assembly point. Anyway I did not deck the block so I assume the deck height is about 0.025" and I have used the standard gasket for about 0.039" with shaved 882 heads to give 73 cc pockets and flat top eyebrow pistons as 4.030" bore. I am satisfied the C.R. will be low enough that even without much quench I will be able to run with 87 or 89 octane. My question is the cam I chose does not seem to be in the Crane catalog anymore (at least I can't find it online) and the box had two numbers on it. The old number on the box is #10010 but it has a pasted-on label marked "10010" AND in larger numbers "140072", 0.050 DUR I 194 X 204. The card that came with the cam says:

Intake @cam 0.265 @ valve 0.398"
Exhaust @cam 0.280 @ valve 0.420"

@0.005
Intake 22 BTDC 58 ABDC Adv. Dur. 260
Exhaust 71 BBDC 19 ABDC Adv. Dur. 270

@0.050
Intake 10 BTDC 24 ABDC Adv. Dur. 194
Exhaust 39 BBDC 15 ATDC Adv. Dur. 204

I realize this is a very conservative low rpm torque cam, but (!) when I run the rpm numbers for cruisin' on two lane black top roads in the local area with a 3.55 rear ratio and a 700R4 4th OD gear of 0.7, I get 1446 rpm at 50 mph and 1591 rpm at 55 mph (235/75/R15 rear tires). It seems to me that I need torque in the 1500 rpm range to avoid downshifting to 3rd or lugging in OD. I am hoping the low gear of the 700R4 will give a good launch since the 700R4 has a lower 1st gear than the TH350, so the problem is to maximize torque in the 1500 range. Now here is the question. I have both 1.5 and 1.6 roller tipped rockers of the simple type from Speedway. IF I RUN 1.6 ROCKERS ON BOTH INTAKE AND EXHAUST WITH THE 882 HEADS I WILL GET 0.424" INTAKE LIFT and 0.448" EXHAUST LIFT. This is still a very conservative lift and the 882 heads seem to offer little flow beyond 0.400" valve lift, so the question is whether it will help or hurt to use the 1.6 rockers? Will the extra lift and short duration and lack of quench lead to detonation on 87 octane? Bottom line, should I use the 1.6 rockers to get a little more torque or will this lead to worse detonation on cheap fuel? I have both a Performer RPM manifold which I am going to remove and a Performer EPS which I think is better for low rpm. I guess I can start out with the 1.5 roller-tip rockers and then experiment with the 1.6 rockers, but I wonder if the 1.6 rockers will help much with only 882 heads or lead to worse detonation on cheap fuel? It also would be easy at this point to replace the head gaskets for the thin set you mention above. Overall I wonder if most folks realize how low the rpm gets in OD? In retrospect I guess I should have gone to a 3.70 rear gear but I can't afford to make that change unless I find out the OD really bogs with the 3:55. I had a terrific ride recently with a guy about 3 miles away who has just finished a Gibbons '32 highboy and he seems to get good mileage over 20 mpg with a 3.23 rear and a TH350 which only has a 1.0 high gear. Maybe there is no way around expensive trial and error but maybe the light weight of the '29 will make this no problem after all? Sorry to test your patience. I just have to get the car on the road because all this speculation is uncertain, but you are the closest I know to a "brain dyno".

Don Shillady
Retired Scientist/teen rodder

Well in edit mode it was good for me at least to go over all of this and now I realize that I probably will not be in OD at 50 mph but in 3rd with a pretty zippy 3.55 overall gear so probably I should have installed a 3.7 rear gear but I am just going to have to live with the idea that the OD will only be useful for the Interstate! Still that leaves the question for Tech1 as to whether the 1.6 ratio rockers will do me any good on this setup?

IF THIS IS FOR YOUR( PARADE CAR) JUST PUT PREMIUM GAS IN IT AND DON'T WORRY ABOUT IT.

Well that may be the way it works out since my wife is not too keen on an open car anyway, but I wish I had joined the Forum 6 months earlier and then I could have built the engine Tech1 described for Lobster. So Erik what do you say about the 1.6 rockers? I guess for now I will use the 1.5s first for a slightly gentler break-in and then use the 1.6 rockers after everything is running OK, but even at 0.454" lift on the exhaust that is pretty mild, eh?

Don Shillady
Retired Scientist/teen rodder

Originally posted by Don Shillady
Well that may be the way it works out since my wife is not too keen on an open car anyway, but I wish I had joined the Forum 6 months earlier and then I could have built the engine Tech1 described for Lobster. So Erik what do you say about the 1.6 rockers? I guess for now I will use the 1.5s first for a slightly gentler break-in and then use the 1.6 rockers after everything is running OK, but even at 0.454" lift on the exhaust that is pretty mild, eh?

Don Shillady
Retired Scientist/teen rodder

YES,IT IS A VERY MILD CAM BUT IF YOUR WIFE IS LIKE MINE SHE WOULD NOT LIKE AN ENGINE IN A CAR WITH TO ROUGH AN IDLE MEANING A LARGER CAM.THE 1.6 CHANGE WILL GIVE YOU A LITTLE MORE LIFT.IF YOU DON'T LIKE IT YOU CAN ALWAYS CHANGE THE CAM TO A LARGER CAM DOWN THE ROAD.WHAT DID YOU SAY THE CAR'S WEIGHT IS?

I'm just guessing from other posts at about 2500 pounds. I plan to actually weigh it at a commercial scale when I get on the road. So you are implying I could use the 1.6 rockers and then if it pings, go to 93 octane? Again I guess I would try the 1.5s first and then play around with the 1.6 rockers. Originally I wanted something like a Comp Cam XE-252, but surprisingly my engine builder refused to use a Comp Cam so I picked a mild Crane cam with just a little more lift than the stock "929" 300 HP (flywheel) cam. Actually the whole reason behind this was I remembered a Nova my dad had with a 350 and to me that was wildest stock ride I had encountered and if I get back to that I will be content! I considered a Comp 268 with Rhodes lifters but as you say I doubt if my wife would have liked the extra clicking of the lifters, so now I don't want to change much except to just use the best combination for low rpm torque using parts I already have. Well thanks for listening. I am learning from the discussion although maybe slowly and talking myself into using the 1.5 rockers at first.

Don Shillady
Retired Scientist/teen rodder

Originally posted by Don Shillady
I'm just guessing from other posts at about 2500 pounds. I plan to actually weigh it at a commercial scale when I get on the road. So you are implying I could use the 1.6 rockers and then if it pings, go to 93 octane? Again I guess I would try the 1.5s first and then play around with the 1.6 rockers. Originally I wanted something like a Comp Cam XE-252, but surprisingly my engine builder refused to use a Comp Cam so I picked a mild Crane cam with just a little more lift than the stock "929" 300 HP (flywheel) cam. Actually the whole reason behind this was I remembered a Nova my dad had with a 350 and to me that was wildest stock ride I had encountered and if I get back to that I will be content! I considered a Comp 268 with Rhodes lifters but as you say I doubt if my wife would have liked the extra clicking of the lifters, so now I don't want to change much except to just use the best combination for low rpm torque using parts I already have. Well thanks for listening. I am learning from the discussion although maybe slowly and talking myself into using the 1.5 rockers at first.

Don Shillady
Retired Scientist/teen rodder

I WOULD TRY THE 1.5 ROCKERS AND IF YOU WANT LATER ON TRY THE 1.6 ROCKERS.I WOULD TRY AROUND 89 OCTANE FOR A STARTING POINT.I WOULD THINK IT WOULD RUN JUST FINE ON THE 89 OCTANE.

Don, I think you're worrying needlessly. Use the 1.5 rockers and fire it. For initial start-up and cam break-in, you want as little pressure on the lobes as possible and the 1.6 rockers would increase the pressure by squeezing the springs tighter. Change to the 1.6 rockers later after you have 200-300 miles on the motor if you want to.

Worst case scenario on the deck height is that the pistons are in the hole about 0.035" which would yield a c.r. of 8.65 with 7 cc's in the eyebrows and an 0.039" gasket. Your engine builder should have a record of the deck height.

Anyway, like I said, don't worry about it. The motor will make plenty of torque just off-idle to pull that lightweight little roadster. The cam you're using is just one notch off bone-stock and Chevy built millions of motors like this with excessive piston-head clearance and low static c.r. It's gonna be smooth as silk and pull hard.

Tech1, Thanks! You confirmed what I thought about starting out with the lower ratio rockers since Speedway even sells 1.3 rockers for break-in. I got the safety loop welded in for the driveshaft, the hand brake lines set up and the trans cooler on the side of the frame with a DeRale trans pan so I am getting ready to cut the holes in the floor for the gearshift and handbrake. I am impatient but making slow progress. I also got a custom stainless gas tank so I hope to get the floor-fenders on before the really cold February weather. I am sorry to work you on this question but now I am more confident about starting with the 1.5 rockers and then experimenting with the 1.6s later.

Don Shillady
Retired Scientist/teen rodder

The question is, who do i believe about the heads???

i was looking into some after market heads (such as the Dart and others) but they added up to be around $1000, where as the vortec are around $500.

is it worth the extra bucks, or would they be better spent else where?

The q-jets do sounds the best (just a pain to tune apparently) as the low torque is better. maybe i use the $500 i save by getting vortec heads, and put it towards a quad weber 2barrel stack. even though the initial cost of buying 4 weber si s high, ive heard you can get much better torque and marginally better fuel economy for the same top end power, when compared to an equivalent 4 barrel (thats if they are all tuned PROPERLY)

too many choises

oh and over here the pump gas is around 90, but for extra $$$ you can get 95 or so

Originally posted by lobster
The question is, who do i believe about the heads???

i was looking into some after market heads (such as the Dart and others) but they added up to be around $1000, where as the vortec are around $500.

is it worth the extra bucks, or would they be better spent else where?

The q-jets do sounds the best (just a pain to tune apparently) as the low torque is better. maybe i use the $500 i save by getting vortec heads, and put it towards a quad weber 2barrel stack. even though the initial cost of buying 4 weber si s high, ive heard you can get much better torque and marginally better fuel economy for the same top end power, when compared to an equivalent 4 barrel (thats if they are all tuned PROPERLY)

too many choises

oh and over here the pump gas is around 90, but for extra $$$ you can get 95 or so

THE DART S/S IRON EAGLE HEADS SELL FOR AROUND $570 WITH VALVE SPRINGS IN THEM GOOD TO .510. SEE COMPETIONPRODUCTS.COM OR 1-800-233-0199.

Lobster, here is an old thread on the Vortec heads. Keep in mind that the intake manifold is different for those heads but that is no big deal.

http://www.clubhotrod.com/forums/sho...2404#post72404

Don Shillady
Retired Scientist/teen rodder

.. Did this Range Rover mudder ever get built with Chevy 350"?