Erson Cam >> good with lots of compression ?

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toolmanmike said:
advancing the cam doesn't do too much. The HP stays pretty much the same and the torque increases from 283@4000 to 286@4000. Not enough to bother. Thats with stock 4 barrel intake and a 550 carb with stock manifolds and exhaust.
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That is only the effect on peak torque of cam advance so that is not the way to help the the OP's 'low end grunt' question.... peak torque is not what counts at low RPM's..

BTW, OP, 10.5 with the stock heads and original pop-up pistons is not likely. You need to measure the head's combustion chambers and know you head gasket thickness, but for production stuff, high 9's is more realistic for those pistons, and it will be lower for the Egge replacement L2222's. But that ain't awful either.. not like you will have a smog era 318 low compression!

Certainly it will have more low end grunt than with the flat tops. Probably will feel something like a stock late 60's 318 off idle, judging from the DCR results being in the low 7's. So it depends on what you are happy with...
 
toolmanmike said:
Headers and intake made a huge difference
0° advance HP 331@6000 TQ 339@4000
1° advance HP 329@5500 TQ 341@4000
2° advance HP 330@6000 TQ 344@4000
3° advance HP 330@6000 TQ 346@4000
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I guess my question is what is the torque curve from say 2000rpm to 4500rpm depending on where you install the cam. Just from my own seat of the pants feel I have found that advancing a cam will help the bottom end without killing the top end real bad. If its a drag only car the install per spec and gear accordingly but if street driven you can make a big cam a little more bottom end friendly by advancing it.. don't go to far 100*-101* seems to be about as low as they like it before causing other problems. AGAIN THIS IS JUST MY OPINION I HAVE NO DYNO TO BACK THIS UP.
 
mod5v said:
I guess my question is what is the torque curve from say 2000rpm to 4500rpm depending on where you install the cam. Just from my own seat of the pants feel I have found that advancing a cam will help the bottom end without killing the top end real bad. If its a drag only car the install per spec and gear accordingly but if street driven you can make a big cam a little more bottom end friendly by advancing it.. don't go to far 100*-101* seems to be about as low as they like it before causing other problems. AGAIN THIS IS JUST MY OPINION I HAVE NO DYNO TO BACK THIS UP.
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This is the 3° advanced chart. Looks like about 300 ft/lb at 2000.

Capture.JPG
 
nm9stheham said:
That is only the effect on peak torque of cam advance so that is not the way to help the the OP's 'low end grunt' question.... peak torque is not what counts at low RPM's..

BTW, OP, 10.5 with the stock heads and original pop-up pistons is not likely. You need to measure the head's combustion chambers and know you head gasket thickness, but for production stuff, high 9's is more realistic for those pistons, and it will be lower for the Egge replacement L2222's. But that ain't awful either.. not like you will have a smog era 318 low compression!

Certainly it will have more low end grunt than with the flat tops. Probably will feel something like a stock late 60's 318 off idle, judging from the DCR results being in the low 7's. So it depends on what you are happy with...
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I did a compression check on my other commando with 10.5 pistons .028 gasket and 920 closed chamber heads and the number was 150 psi.
 
I should show the non believers that chart when they say 273's don't have torque. The Chevy guys build 6" rod motors on purpose for more torque. Ours comes with 6 1/8" already.
 
stroker402 said:
I did a compression check on my other commando with 10.5 pistons .028 gasket and 920 closed chamber heads and the number was 150 psi.
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920's are a good 273 head. They used them late in 66 and 67.
 
your lift as nothing to do with piston to valve clearance
duration and lca has more
If that is a grind from the old Super Shop days it was well made but obsolete even then
Super shop did not want comebacks from treeshade ,mechanics so they were really gentle
which also meant that they wore well
grinds from that era are all obsolete given todays springs and computer generated masters or even CNC no master used grinders
so inspect carefully and give it a try- jack the timing around and see what it likes
 
lift before and after tdc matters
max lift at lca does not
max lift for piston clearance is not (usually) at TDC
I don't understand your comment toolguy
 
Lift has everything to do with valve to piston clearance. Valve timing can make it worse. If what you said were true, the op could put a 750 lift cam in his 273 without modification. There is physically not enough clearance without modifications..
 
toolmanmike said:
Lift has everything to do with valve to piston clearance. Valve timing can make it worse. If what you said were true, the op could put a 750 lift cam in his 273 without modification. There is physically not enough clearance without modifications..
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yes , you can only go sooooooo big .
 
stroker402 said:
yes , you can only go sooooooo big .
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maybe someone can tell us how big of cam I could go up to before mods would be needed. I bet someone has gone over 500 lift with 273 components . maybe they will chime in . I Think a 510 lift with 286 advertised duration would still be safe . something I would have to check for sure , before and after tdc.
 
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toolmanmike said:
Lift has everything to do with valve to piston clearance. Valve timing can make it worse. If what you said were true, the op could put a 750 lift cam in his 273 without modification. There is physically not enough clearance without modifications..
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Be careful with absolute statements with P-V clearance....if the ramp speeds changes, the answer is going to change. Actually a .750" lift could be done with adequate P-V clearance here .... the mid-lift ramps would be far steeper than anything we use and probably could not be run over 1 RPM LOL. But it would have adequate P-V clearance if the ramps were slow up to 40-50-60 degrees after intake closing or before exhaust closing and then got really, really steep.

So peak lift is at best a vague indicator for P-V clearance... that was the point. If you used cams with all the same ramps, then you can make better estimates/guesses, but once the ramps start changing, the "OK or not-OK vs. peak lift" answer changes completely.

A 286 cam with old style, slow ramps might be OK here, but a 286 like a VooDoo or a grind optimized for a .904 lifter would probably be in trouble. Being a solid grind makes this more potentially troublesome. With the older 273 2V flat tops, the pocket depths are pretty shallow (maybe .100" or thereabouts) and those pistons came up almost to zero deck... IF those were the pistons the OP used before. I would assume the hi-comp pistons' valve pockets are deeper. But that has a lot of assumptions being made so is really only a guess. Sorry I can't do better, OP.

BTW, OP, you cam number does not show in the present Erson catalog. PN E420306 shows up as being a very similar MFT cam. Is yours a re-grind?
 
stroker402 said:
maybe someone can tell us how big of cam I could go up to before mods would be needed. I bet someone has gone over 500 lift with 273 components . maybe they will chime in . I Think a 510 lift with 286 advertised duration would still be safe . something I would have to check for sure , before and after tdc.
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I think that's the biggest cam I have heard anybody run. Indicate the cam in, assemble a complete cylinder and measure the clearance. Read up on how it's done. I used clay but I didn't think I there would be an issue.
(Egge 10.5/1's and a Isky E4) Measure twice. Here's one of the many video's piston to valve clearance - Google Search
 
nm9stheham said:
Be careful with absolute statements with P-V clearance....if the ramp speeds changes, the answer is going to change. Actually a .750" lift could be done with adequate P-V clearance here .... the mid-lift ramps would be far steeper than anything we use and probably could not be run over 1 RPM LOL. But it would have adequate P-V clearance if the ramps were slow up to 40-50-60 degrees after intake closing or before exhaust closing and then got really, really steep.

So peak lift is at best a vague indicator for P-V clearance... that was the point. If you used cams with all the same ramps, then you can make better estimates/guesses, but once the ramps start changing, the "OK or not-OK vs. peak lift" answer changes completely.

A 286 cam with old style, slow ramps might be OK here, but a 286 like a VooDoo or a grind optimized for a .904 lifter would probably be in trouble. Being a solid grind makes this more potentially troublesome. With the older 273 2V flat tops, the pocket depths are pretty shallow (maybe .100" or thereabouts) and those pistons came up almost to zero deck... IF those were the pistons the OP used before. I would assume the hi-comp pistons' valve pockets are deeper. But that has a lot of assumptions being made so is really only a guess. Sorry I can't do better, OP.

BTW, OP, you cam number does not show in the present Erson catalog. PN E420306 shows up as being a very similar MFT cam. Is yours a re-grind?
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John at erson talked to me personally and told me the specs on the cam. It is old and he didn't say anything about being a custom regrind. I pullled the cam out of a 67 cuda with a 273. locked up, bad rod. that was almost 20 years ago.
as far as the p-v clearance with the domes , the dome pocket depths are pretty deep on the 10.5 's . but clearance still would need to be looked at for sure .
 
OK, I was just trying to find a way to compare the new pistons to the old pistons and make a judgement. Sounds like that is not possible now.
 
guys ... what about the d dart 273 that had almost Identical cam installed in it. same 920 heads and domes .
 
nm9stheham said:
Actually a .750" lift could be done with adequate P-V clearance here
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"could put a 750 lift cam in his 273 without modification."

Apparently you didn't understand my last 2 words.
 
stroker402 said:
guys ... what about the d dart 273 that had almost Identical cam installed in it. same 920 heads and domes .
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Those were bolt on parts and obviously worked. You can bet they checked the clearances out ahead of time though.
 
found this info on d dart cam >>>>>>>>
Camcraft Camshafts.

#P-820-B {1966 D-Dart}
.493"/.503" Lift ~ 284"/ 284" Duration ~ 60* Overlap
--------------------------------------------------------------------

#P-820-Bx {1966 D-Dart 'Optimal Race'}
.504"/.515" Lift ~ 288*/288* Duration ~ 70* Overlap
-------------------------------------------------------------------

#273 Max-Race {1967}
.510"/.515" ~ 296*/296* Duration ~ 80* Overlap ~ 108* Centerline

Exhaust = 76* BTDC ~ 40* ATDC
Intake == 41* BTDC ~ 75* ATDC
 
stroker402 said:
found this info on d dart cam >>>>>>>>
Camcraft Camshafts.

#P-820-B {1966 D-Dart}
.493"/.503" Lift ~ 284"/ 284" Duration ~ 60* Overlap
--------------------------------------------------------------------

#P-820-Bx {1966 D-Dart 'Optimal Race'}
.504"/.515" Lift ~ 288*/288* Duration ~ 70* Overlap
-------------------------------------------------------------------

#273 Max-Race {1967}
.510"/.515" ~ 296*/296* Duration ~ 80* Overlap ~ 108* Centerline

Exhaust = 76* BTDC ~ 40* ATDC
Intake == 41* BTDC ~ 75* ATDC
Click to expand...
Yep, yours is close. These cams are splits but still close ((((with what specs we have to look at. ))))
 
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