Jeff, you're planning to stay with the 1.5:1 ratio rocker arms... correct?
1..... I want torque and efficiency at cruise speed.
2..... The cam I posted was one of 2 the comp cam tech suggested but I am reconsidering
how little time he spent actually considering the details I was providing him with.
3..... So I guess in the end I will have to make a few other calls to other cam manufacturers and see what they come up with.
1.... Yes... so true! Your 3.750" stroke will give you the torque that you're after and at the correct RPM range for a Marine Cruiser SBC, but only to it's MAX if you get the LPCP where it must be.
The Q/E (as well as the cam profile) will give you the efficiency that you're after.
2.... If you spoke with the right person who has SBC Marine Engine knowledge, he may have enough experience to allow him to make his suggestion quickly. Just a thought!
3.... Agree..... asking your question of several companies is certainly a great idea!
As for the ignition system, I am going to stay with the stock TB5 for now and see how it performs. All of the reading I have done I cannot seem to find an actual curve but I do see that when the system is functioning properly it is quite good at timing correctly for good torque. I know it is a mystery exactly how it is done and it seems to be a closely guarded secret but IMO it actually had the stock 350 making good power that was not way underpowered for this boat. In the end I see no reason that it wouldn't time a better built engine properly and its built in protections and adjustment for changing conditions is something that I would like to keep. I know I could manually time it properly with a fairly inexpensive ignition system but I would be losing the protections and on the fly adjustments it provides. I just can't see spending extra money to "go backwards" in technology when I have a system that was functioning properly. The way I see it is I will use it for the season and if I hate it it is not a big deal to change out.
Jeff, my two cents on this would be to NOT look at nor use any Automotive Ignition Advance information .... not that you would..... Just an FYI!
As suggested..... a typical Marine Engine ignition advance curve (for use with the SBC which uses the GM full dished pistons), is going to be rather conservative. It will be conservative due to the increased Detonation Potential that this piston creates (of which you won't need to be concerned with).
While being conservative, it will affect the LPCP.... and since you are already versed on that, I won't continue with any redundancy!
As for the intake manifold. I have struggled here to but I think I may have found a solution. Given my normal use and conditions I have decided to go with a performer style manifold. This one
http://www.ebay.com/itm/Chevy-SBC-3...Parts_Accessories&hash=item2ed5bb5010&vxp=mtr
I have thought long and hard and I found that Dart Coatings DC8 is available for protecting against corrosion and I am going to look into it more to see if I can get it done locally and how much it would cost. If not I will simply monitor corrosion in the thermostat area and that should be a good indicator of any corrosion issues . I know a bit of a gamble here but 1999 fuel injected mercruiser engines use ....aluminum intake manifolds!!! Go figure! not saying it is best way to do it just en example of it being done.
Other than the potential for corrosion does anyone see anything that would not make this Intake a good choice?
Jeff, I fully understand the cost differences and the potential savings. If you keep a close eye on things, you may be OK with the manifold that you've shown. (I would have my suspcions that the Holeshot Vortec Intake Manifold is Chinese made)
Personally, I'd spend the extra money and go with the Edelbrock 2116 Performer Intake Manifold that Jack linked you to.
The Dual Plane is a great choice and will perform best for your Marine use.
Here's what Merc and other Marine Engine companies do to protect against galvanic corrosion when raw water cooled.
In this image, you can see that the coolant cross-over chamber is bronze lined.
If you were to turn this over, you'd see that the rear "would-be" cross-over areas are also bronze coated.
BTW I am going to heed the advice on the lifters and change them after ensuring they do indeed work well with the cam I end up selecting.
Jeff, I found an article by Jeff Smith in hopes of finding some information on the GM roller cam followers. I was hoping that he would comment on the roller diameter differences. I may be wrong in that all use the same diameter, which would mean that they are interchangeable.
http://www.hotrod.com/how-to/engine/ccrp-0710-chevy-small-block/
BTW, Jeff does suggest that these can be used or re-used on a different roller profile camshaft.
(FWIW.... the GM roller cam followers will often go 200+K miles in a car/truck engine, and will still be OK for re-use.)
I am close to nailing it down and locking it in so please hit me with all of your input on anything we may have discussed or may have overlooked.
Jeff, one last suggestion here.
When the time comes to adjust your cam followers, I'll suggest that you use the 8 stop procedure... (not the 2 or 3 stop that is often mentioned in the OEM service manuals).
You will be ultimately be setting the depth of the cam follower plunger.... (not rockers nor valves that is so often talked about).
Each plunger will offer approximately .100" to .130" of travel. Our goal is to place the plunger within it's proprociate travel range below zero lash.
If you chose this method, do this prior to installing the intake manifold and prior to any oil priming (plungers are free to move when not hydraulically locked).
You'd begin by setting/adjusting the #1 cylinder Int/Exh while the crankshaft is at #1 TDC C/S.
The follower plunger retainer will be visible, and will allow you to see the moment when the plunger begins to move downward.
Next... you'll rotate the crankshaft 90 degrees, and set/adjust #8 Int/Exh.
You'll continue rotating 90 degrees while you go right down the firing order, stopping a total of 6 more times (8 total).
If you do this, you'll be right at the cam lobe base circle low point during the adjustment, and you will not need to go back through them dynamically later on!
Your call!
