Camshaft for 350
08-25-2011, 02:10 PM
#32
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With smaller duration camshafts you will have the SAME AMOUNT OF OVERLAP with a tighter LSA (108 degrees LSA for instance) as a larger duration camshaft with a wider LSA (112 degrees LSA). A smaller duration camshaft with a tighter LSA will be as powerful (or more powerful) than a large duration camshaft and a wider LSA. They will both have the same amount of overlap but the smaller cam will close the intake valve sooner and create more cylinder pressure at low speeds.
Really the point is silly because how much effect can 2-4 degrees of difference in crankshaft rotation have on the effect of the camshaft on an engine?
NOT MUCH!!
I only suggest that smaller camshafts with a tighter LSA will be as powerful as a larger camshaft with a wider LSA.
Dennis
08-26-2011, 10:59 PM
#33
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Of course the issue is not really LSA but valve overlap between the exhaust closing and the intake opening.
With smaller duration camshafts you will have the SAME AMOUNT OF OVERLAP with a tighter LSA (108 degrees LSA for instance) as a larger duration camshaft with a wider LSA (112 degrees LSA). A smaller duration camshaft with a tighter LSA will be as powerful (or more powerful) than a large duration camshaft and a wider LSA. They will both have the same amount of overlap but the smaller cam will close the intake valve sooner and create more cylinder pressure at low speeds.
Really the point is silly because how much effect can 2-4 degrees of difference in crankshaft rotation have on the effect of the camshaft on an engine?
NOT MUCH!!
I only suggest that smaller camshafts with a tighter LSA will be as powerful as a larger camshaft with a wider LSA.
Dennis
With smaller duration camshafts you will have the SAME AMOUNT OF OVERLAP with a tighter LSA (108 degrees LSA for instance) as a larger duration camshaft with a wider LSA (112 degrees LSA). A smaller duration camshaft with a tighter LSA will be as powerful (or more powerful) than a large duration camshaft and a wider LSA. They will both have the same amount of overlap but the smaller cam will close the intake valve sooner and create more cylinder pressure at low speeds.
Really the point is silly because how much effect can 2-4 degrees of difference in crankshaft rotation have on the effect of the camshaft on an engine?
NOT MUCH!!
I only suggest that smaller camshafts with a tighter LSA will be as powerful as a larger camshaft with a wider LSA.
Dennis
So did u right the books? If so was wondering if you knew how to find a copy, they are almost non existent
03-09-2018, 08:41 AM
#34
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I want to hang
Sounds like him with his cam info and rpm ranges.
Very good books Dennis !
I may not agree with everything you say/recommend/etc cam wise / power wise / etc but your books are really well done. Very good resources for most everyone. Wholly crap are they worth alot now since publishing has ceased.
That said, for shelf cams, the Hot Cam and Comp XM270HR (I'd rather the XM) have been time proven for power, idle, mileage, etc,etc for everyday driving 5.7's with Vortec and other typical performance heads. They idle great and pull to 5000-5200rpm.
383's will need a little more cam, like the 224,230 that DM mentions. Or bigger of course if a 'more juiced' build. More power than the typicals, a wise call would be to RMBuilder.
I experimented a little a few years ago and installed the Comp XM EFI cam with 218,224" at .050" , .575 lift, 113LSA on bone stock '91 Merc 5.7L , and installed BrodixIK180 heads/w beehives, etc,etc. 52-55 (55 was best)stockmph, 65-68mph
(68.1 was best) after. Idle like stock, brutal acceleration out of hole, and very good top end. Both Engine Versions used Eddie Marine exhaust.
Experimentation was really just the 113LSA. Normally I'm like Dennis where I like the tighter LSA's on small blocks, but I've found with good heads we don't have to run our chances of poorer idle, reversion chances, etc, etc that a tighter LSA will give. I still would not go wider than 112LSA for pretty much anybuild. Of course if building 'all out' we throw all compromises out the window and give the motor everything it needs. Alpha's need not apply. LOL.
Anyhow, if anyone wants to hang (online) with a big group of smaller deep vee I/O boats with single small block engines from 50mph's to 80+mph's, send me a PM and I'll direct you to where they are. Never any BS (weird I know) and always willing to help (with actual experiences) when they are around.
Very good books Dennis !
I may not agree with everything you say/recommend/etc cam wise / power wise / etc but your books are really well done. Very good resources for most everyone. Wholly crap are they worth alot now since publishing has ceased.
That said, for shelf cams, the Hot Cam and Comp XM270HR (I'd rather the XM) have been time proven for power, idle, mileage, etc,etc for everyday driving 5.7's with Vortec and other typical performance heads. They idle great and pull to 5000-5200rpm.
383's will need a little more cam, like the 224,230 that DM mentions. Or bigger of course if a 'more juiced' build. More power than the typicals, a wise call would be to RMBuilder.
I experimented a little a few years ago and installed the Comp XM EFI cam with 218,224" at .050" , .575 lift, 113LSA on bone stock '91 Merc 5.7L , and installed BrodixIK180 heads/w beehives, etc,etc. 52-55 (55 was best)stockmph, 65-68mph
(68.1 was best) after. Idle like stock, brutal acceleration out of hole, and very good top end. Both Engine Versions used Eddie Marine exhaust.
Experimentation was really just the 113LSA. Normally I'm like Dennis where I like the tighter LSA's on small blocks, but I've found with good heads we don't have to run our chances of poorer idle, reversion chances, etc, etc that a tighter LSA will give. I still would not go wider than 112LSA for pretty much anybuild. Of course if building 'all out' we throw all compromises out the window and give the motor everything it needs. Alpha's need not apply. LOL.
Anyhow, if anyone wants to hang (online) with a big group of smaller deep vee I/O boats with single small block engines from 50mph's to 80+mph's, send me a PM and I'll direct you to where they are. Never any BS (weird I know) and always willing to help (with actual experiences) when they are around.
03-14-2018, 11:50 AM
#35
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After reading and listening to the numerous suggestions on this forum, I built a a nice 355 for my 18 Donzi 2+3. I used a Vortec 350 roller block, bored .030 over and installed Sealed Pro hyper Pistons. I installed a set of Vortec heads, that had the rocker studs pinned and 8 new exhaust valve, along with a good valve job. I also installed a 300hp Merc roller cam ( same as GM Perf cam) and had P bearings installed throughout. I have an Airgap intake and a 750 vac secondary Holley to top it off. We figure the CR should be right around 9.5-1 and I will probably be around 350ish HP. I know I could install a bigger cam, but at the time the price was right. This should be a nice little engine in an 18 footer.
