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-   -   Cam suggestions for 383 build (https://www.offshoreonly.com/forums/general-q/309167-cam-suggestions-383-build.html)

SB 03-06-2014 09:48 AM


Originally Posted by MER Performance (Post 4085326)
6.2 MPI is 377 CID

x 2.

So2fast5u 03-06-2014 11:06 AM


Originally Posted by MER Performance (Post 4085326)
6.2 MPI is 377 CID

Stock bore 350 with 3.75 crank? I see.

38special 03-06-2014 11:19 AM


Originally Posted by ACrooks69 (Post 4085001)
I don't know what stock 325hp marine engine came with roller rockers. It really depends on the cam profile. Dual pattern really doesn't mean anything for practicality. My question would be are they self aligning rockers for vortec / centerbolt heads, or are they for heads with guide plates? What style do you need? $375 doesn't seem bad if they are full roller rockers. The way I would look at it, if it is some stock cam, you are taking it off his hands. You are only buying the lifter / dogbone / spider assembly (if OEM style) and roller rockers (roller trunion and tip). The pushrods / springs may not work for you if you depending on your machine work. If you can offer up more equipment details, we can better help.

I'm not sure about the roller rockers either. He asked what I had for rockers and I told him I had planned on buying Yella Terra shaft mount roller rockers. I'm an old Mopar guy and never had rocker issues running solid lift cams on the street and could go months with out needing to adjust the Harland Sharp shaft mounted roller rockers. A friend of mine who race's at the local dirt track said he had tried all kinds of roller rockers on his sbc finely tried the yella tarra shaft mount rockers which put an end to rocker problems he had fought.

I didn't take into consideration when I started this 383 build restrictions like the stock logs or how much I could exhaust out the prop and as I said earlier in the thread the good paying job I had when I started this project is gone. Un-less I can find some decent exhaust manifolds for a good price I guess I need to finish this build with more of a stock tone or camshaft in this case that's not going to choke the engine due to restrictive exhaust. I'm not a chevy guy so I couldn't tell you what the EQ 23degree heads require. Supposedly they are ready to bolt on right out of the box. They are the 180cc runner performance EQ head with 202 and 160 +.100 valves and fast burn 64cc combustion chambers. They used molds from ported ports on both intake and exhaust runners.

The bottom end is a 98 4 bolt vortec block bored .030 over. Mains line honed with new ARP main studs. I went with RaceTec forged D dish -21cc and valve reliefs for 570 lift cam on 5.85 Oliver steel connecting rods and coated ACL rod and main bearings.I decided on the coated bearings after looking at opened up bottom ends of drag motors run all season long. All the coating was still on the bearings. No steel on steel after being run hard all season. The bearings actually looked like they had not been run at all. The deck was cut down leaving the pistons .005 in the hole. The Crank is a 3.750 forged and nitride Kellogg for 1 piece 5.7 GM block. Block was ground and clearance checked and bottom end internally balanced. My machinist calculated compression to be 9.3.1

How much do the Kodiak manifolds cost that I read about in this thread?

I had talked to my machinist yesterday about the new take offs of the marine engine, roller cam new roller lifters the spider thing, another one of those Chevy things lol. He does mainly race engines is not a marine engine guy but I asked what he thought about the cam and he said likely lots more torque in the 383 and a loss of top end rpm's.

My boat is a Glastron gs205 and dry weight of 26 or 2800 lbs. I scored a Volvo SX duo prop off a 2007 sting ray to replace the single prop SX cobra that came with the boat. I have not bought props yet. Any idea what mph this boat might be good for?

It does concern me that the take off parts may not be mercruiser. Another idea I had was to look at mercruiser engine packages exhausting out the stock logs and buy the part number of the cam used in that app. I think I saw a 383 Mag rated at 370 H.P. I'd bet my heads are as good or better than what they used on that package.

So2fast5u 03-06-2014 11:30 AM

383 divided by 61.023 is 6.27 liters
377 divided by 61.023 is 6.17 liters. Close enough....

That's what I was going by. Had me thinking I lied to my friends about my last few 383 builds I done. I told them they were 6.2 liters!!

Captain YARRR 03-06-2014 01:58 PM

I just finished a 383 build and I am very familiar with this whole process. I shared all my info every step of the way and had some very good results. The idea of going to 383 for a performance gain but doing it through the prop seems beyond silly when I know the expense involved.

If you want performance from a 383...you can't go through the prop. I'd just find a cheap used 6.2 and call it a day.

38special 03-07-2014 08:51 AM


Originally Posted by Captain YARRR (Post 4085494)
I just finished a 383 build and I am very familiar with this whole process. I shared all my info every step of the way and had some very good results. The idea of going to 383 for a performance gain but doing it through the prop seems beyond silly when I know the expense involved.

If you want performance from a 383...you can't go through the prop. I'd just find a cheap used 6.2 and call it a day.

So dropping down to a 377cid will make all the difference weather a stroked small block will work or not? I have been talking about a more factory type cam just to be able to use the 383. Not what I had intended when I started this build but something I may have to do because of what I have learned in this thread about the stock restrictive exhaust.

38special 03-07-2014 09:01 AM

Question about GLM exhaust manifolds. I have read these are a Chinese knock off of the Kodiak manifolds. They claim a 10% increase in flow. Would these be an improvement over my stock logs? And if so could I run a tru hull exhaust with the ability to exhaust through the stock leg at times when wanted?
http://www.ebay.com/itm/Volvo-Penta-...198c5a&vxp=mtr

Captain YARRR 03-07-2014 10:04 AM

I was saying buying a stock 377 might be cheaper and perform better than going through all the expense of a 383 build where you don't do it right.

I have the GLM manifolds on my build, we used those and some taller stainless risers. Because of that Bob Madera was able to make a bigger cam and build some more power.

Think of it this way, you can put anything on those exhaust ports and it won't matter because you are choking it with the through prop exhaust. When I switched to my 383s, I got rid of my through prop exhaust because it restricted my power, I also got rid of my captain's call. I had to do both of those things to make the power I wanted. I'm so glad I did! I'm very pleased.

I think I have one of the stronger 383 builds on the board, if you want to read what "recipe" my engine builder and I developed, here's my thread:

http://www.offshoreonly.com/forums/d...d-project.html

38special 03-07-2014 10:14 AM


Originally Posted by Captain YARRR (Post 4085957)
I was saying buying a stock 377 might be cheaper and perform better than going through all the expense of a 383 build where you don't do it right.

I have the GLM manifolds on my build, we used those and some taller stainless risers. Because of that Bob Madera was able to make a bigger cam and build some more power.

Think of it this way, you can put anything on those exhaust ports and it won't matter because you are choking it with the through prop exhaust. When I switched to my 383s, I got rid of my through prop exhaust because it restricted my power, I also got rid of my captain's call. I had to do both of those things to make the power I wanted. I'm so glad I did! I'm very pleased.

I think I have one of the stronger 383 builds on the board, if you want to read what "recipe" my engine builder and I developed, here's my thread:

http://www.offshoreonly.com/forums/d...d-project.html


Thank you. That was exactly info I was looking for. How much will I hurt my performance running the captains call but still using the GLM's and tru hull exhaust? And can I run stainless risers with this set up? I'm checking your thread out now. Thanks for the link.

Captain YARRR 03-07-2014 10:20 AM

Tough to say, I think there's more experts on that question in this thread. But I can say when I was making my decisions, if I kept my captain's call Bob Lloyd pretty much laid it out for me that I wouldn't be able to get a big enough cam to make anywhere near my power goal. It was pretty much a foregone conclusion that we were ditching the captain's call.

C'mon, it sounds awesome :) I also don't feel like a jerk being loud anymore around the docks...because I have no option now!


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