SBC 5.7 Vortec cam & other bolt ons rebuild

[jaspers1]

Greeting fellow boaters. I am in the middle of a project and would like some expert opinions and advice. Thanks for all you help in advance. I have a 2004-05 volov penta GXi-F 5.7 block that I have bored .030 over and the bottom end freshened up. This motor was rated at 320 hp when new from vovlo with a 9.4:1 comp ratio and now has around 9.5:1 comp with new pistons. It is a vortec motor with the good 906 casting number 64 cc Vortec heads. The plan was to rebuild this motor and take all the accessories off my 87 5.7 260 Merc and drop it back in my boat. We are also going to install alum intake (vortec) and new carb. (fuel injection on the original Volvo was junk). We are to the point of reinstalling the cam but noticed some pitting and elected to replace instead. The vortec heads have comp cam 1.6 roller tip rockers already installed (should be stock parts). With not knowing the original cam specs here are my questions:
1. Can I reuse the roller lifters, this motor has very few hours on it?
2. What would be a good duration and lift cam to replace the stock cam or slightly better?
3. I have heard many talk about comp cams 256 extreme marine cam but I can?t seem to find that option in a hyd roller, roller cams from comp seem to be much more aggressive.
4. At what point do I need to worry about different valve springs with a cam?
5. Any suggestion on what to run for an intake and carb would be greatly appreciated, somebody has already done this.
6. With the 1.6 rockers how does that effect the cam specs and my choice?


As always, I am trying to stay on a budget and get the most from the least. I want to stick with a marine cam so we don?t need to go down that road. I would be tickled with the new motor if it made between 300-350 hp and gobs of torque so I am not wanting to go too radical.
Regards

 

[John_S]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Welcome to iBoats.

While there has been allot of info on the internals of Mercruisers, Volvo much less so. ie Volvo may have GM build or they build to slightly different specs. Given the stock 1.6 ratio roller rockers, I would assume either Volvo is using less lift for the cam or have modified the stock vortec heads for more lift. I suspect the latter. Is there a GM part number on the cam? Use a mic or caliper and measure the lobe lift.

If running in fresh-water or fresh-water cooled, an Edelbrock Performer or Performer RPM, or other good dual-plane manifold. If not, then will need a marine specific manifold which will usually have brass lined water passages.

A 600 cfm marine carb. Most like the Edelbrock 1409 for easy tuning. If you like spread bores, that will limit the intake selection.

If this is for an '87 boat, make sure your Merc is '87. It is common for an '87 boat to have a '86 engine. This was the transition year for the SBC and it may require some flywheel, starter, coupler changes if the older, pre 1pc oil seal.

 

[jaspers1]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Thanks for the info. The only number I can find on the volvo cam is ACR 12 144163 which I have done countless searches on and found no matches. Volvo says a 2001 and up 5.7 camshaft is volvo part# 3856119, also searched with no matches. Is there a way I can tell if the heads have been modified? I will try to have partner measure cam lobe lift tonight. It's 80 miles from here.

Great point on the year of my Mercruiser, is there an easy way to tell the difference? We already noticed that I will need an electric fuel pump because of no mechanical hole machined in the block.

The engine is fresh water and fresh water cooled.

I have looked at the edelbrock and was kind of intrigued by the RPM Air gap but didn't like the $$ spread. One more vote for an edelbrock carb and I will probably use one. I seem to get alot of mixed feed back on carburators. The old Holley vs. everyone else story. Thanks again

 

[John_S]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

If the cam lift (exhaust probably has higher lift) with 1.6 rockers is higher than 0.470 valve lift than they probably made some modification. There are numerous mods to accomplish this, including beehive springs, different seal, and machining guides, but which did volvo do? Don't know.

The '86-'87 change-over included single piece oil seal, roller cam capable, canted center intake bolts, and centerbolt valve covers. I believe the heads and block changed at the same time, but not 100% sure.

I believe you mean raw water cooled running in freshwater, which should not be a problem with aluminum intake. If it has a heat exchanger and run glycol in the engine, all the better.

Because the vortecs do not have an exhaust crossover, the intakes do not get that hot. The warm intake probably helps with driveability over trying to maximize a cold air charge. IMHO, the air-gap doesn't buy you much over the Performer RPM.

 

[jaspers1]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Thanks again guys. I will try to get a copy of Dennis's book if I can find one. Amazon doesn't list any available right now. My biggest fear is buying a cam that has less performance that what the stock cam has. I will have the lift measured off the cam tommorrow night but that will only give me lift not duration. Call me dumb, but is there an easy way to measure duration of a cam? With the odd ball 1.6 rockers I want to make sure what I get is going to work with what I have, roller lifters, valves, pushrods, and springs. Thanks again for all your help, I really appreciate it.

 

[John_S]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Thanks again guys. I will try to get a copy of Dennis's book if I can find one. Amazon doesn't list any available right now. My biggest fear is buying a cam that has less performance that what the stock cam has. I will have the lift measured off the cam tommorrow night but that will only give me lift not duration. Call me dumb, but is there an easy way to measure duration of a cam? With the odd ball 1.6 rockers I want to make sure what I get is going to work with what I have, roller lifters, valves, pushrods, and springs. Thanks again for all your help, I really appreciate it.

DM's book is a great marine SBC resource. Being out of print, has generated some rather high prices. It does cover the area of the '86-87 change-over well, but will not help you with any volvo specific data. Most of the book appears to be based on Mercruiser data. Even vortec heads, which had only come out before the last printing, are not covered in great detail. It is still a great book to have, it is just not going to answer all of your current questions.

If the cam is still in the engine, then get a degree wheel and you can map out the duration. To me, I wouldn't worry so much about that vs the LSA. For duration you can just pick something reasonable, but you need the right LSA such that you don't suck water back into the cylinders. Mfg specs are usually based on 1.5 ratio rockers. The 1.6 will slightly change LSA and duration. ie LSA is less, and duration is longer.

As far as HP, if the volvo was a MPI engine, you are going to take a 10-20hp hit by going to normally asperated 4brl. If it was throttle-body you can get about the equivelent hp.

 

[gbeltran]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

You can re-use the roller lifters. As for the cam, it's not so much the springs but you need to check for retainer to valve guide clearance when you go over .460 with the vortec heads if they still have the stock stuff on them. (I'd love to have that book also, but man, they are pricey)

 

[jaspers1]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

OK, I think we are getting closer. The cam lobe lift measued .287 I and .300 E. With a 1.5 rocker that comes out to exactly what I have found for specs on a Mercury marine roller cam at least for lift. My friend had another Mercury roller cam (junk too) and that measured exactly the same lift. Ignoring the duration for the moment these lift specs look extermely similar to the GM part# 14097395 which has marine applications and is also used in the GM RamJet motor as well as the truck 383 (LSA on this is 109?). So assume for a minute that the original cam in the boat was this GM 14097395 and I use my 1.6 rockers my valve lift would now be I .4597 and E .481. This would exceed what gbeltran stated of maximum lift for a Vortec head of .460 (I have read others that say .470 is max) but either way if it is the same cam as original it should work. Right? We can't really measure the retainer to valve guide clearance unit we put in the cam and assemble the heads.

So right now here is what I am thinking.

Performer RPM Vortec Intake
600 CFM 4160 marine Holley Carb
GM #14097395 Roller cam
Reuse Roller Lifters
Reuse Roller Rockers of 1.6/1
Summit Elec Fuel pump

Anyone see any glaring problems with this or any ideas to make it better?

Thanks again

 

[Bondo]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

but either way if it is the same cam as original it should work. Right?

Ayuh,... Sounds Good, as long as you don't get coil bind in the valve springs...

 

[bspeednut]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

has anyone done this recently - yes !!! you can read my posts and i just joined a few weeks ago.
My boat is a larson senza 210 lx
1990 in wich i wne t bcak with a vortec engine also. it was atruck engine - i used the 062 casting vortec heads with roller 1.6 rockers. Stock springs a and a ramjet camshaft is what the volvo 5.7gxi cam e with from fasctory - I found that ramjet cam at paceparts.com for 150bucks. used original roller lifters and all.
I built the engine last week and installed it - we ran it sunday. all i can say is wow. strong - fast and it sounds good too. i just chanced the lift being able to clear cause i got so many diff specs from diff places. it works and i had no prob at 5500rpm and 56mph..
Im tickeled to death.

got 1996 vortec truck short block
took a set of heads off a 1998 vortec
pushrods lifters and cam came out of a junk trailer in a 2001 5.0GL engine(same cam) ramjet - the engine was frose and busted the block. the guy gave it to me.
ordered an intake from kjm on ebay for 119bucks.
used the factory holley carb 650cfm
new gaskets and oil pump.
total this build project cost me less than a grand.
It sounds good and runs even better.

1990 larson senza 210 lxi - volvo penta duoprop system

 

[zbnutcase]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Found that book a year ago at Goodwill for $.50 Yes I snagged it. 'nutcase

 

[jaspers1]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Speednut, its nice to see that someone else has done this. It is pretty ironic that I was looking at KMJ intake maniflods before reading this. I live about 35min from KMJ so i think I may go pick it up myself.
I see they have a polished air gap model fairly reasonable to. Any reason you went with the one you did?
Even more ironic is this rebuild is going into an 87 Larson DC-230 BR. I love the look of the older Larsons, sound like yours is nice.
Bond-o -- I am a little concerned about that two. I have read up on the comp cams behive springs and that may be a good option to remidy the problem. Funny part on the springs is I have 2 sets -- the stock Volvo spring that came out of this engine (single spring) and a Mercury set that cam off the motor that we measure the junk cam from (double spring). Any idea on which one I should use. I hate to spend $180 on new springs it the old will work, but it is alot cheaper than blowing up a set of heads.

Thanks again to all, you have helped a bunch

 

[Tail_Gunner]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Im finishing a 4.3 as we speak...I accepted the mission... anyways here are some links that should help you

http://www.carcraft.com/techarticles/vortec_valve_spring_upgrade/index.html

I would not be so quick to judge mpi on a boat..The software program has been dumbed down a lot for saftey and longevity issues and can be improved on quite a bit...You may want to investigate these guys a bit...There very compitent...and informed..

http://www.mefiburn.com/

Custom tunes..On the water in real time if youd like....That generally cost thousands..with todays tech...its avaible for a fraction of the price..

http://www.obd2allinone.com/sc/details.asp?item=mefitune


We can tune your controller remotely, anywhere in the world, if you have purchased our MEFIburn software and you have a high speed internet connection while connected to the vehicle you want tuned. You will be able to watch your laptop's screen as the MEFI calibration parameters are changed and saved. Clear descriptions of what is being done will be explained as it is happening. Our price for remote tuning is $250. Call or email us for details.

Anyway have fun there are many ways to go...maybe a LT4 HotCam @ 112 LSA

 

[bspeednut]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

I only have one reason for going with the intake i went with.. It was the cheapest i found. I had one in my race trailer that went on a dirt modified a while back but every bolthole in it was stripped out and this one i found on ebay from kmj was the cheapest. I talked to some dirttrack buddies and the one they told me to get is one that a local machine shop was puttng on engines and said that the dyno numbers for it were exactly the same as the edlebrock.
I am now wishing i had more money when i was building this engine up - i would have had some machinework done and went a little more into the lower end.
this boat is super good condition and has never been in the weather.
I do know that valve springs are more important if your going to be running higher rpms but if you rjust going to run at the max rpm for the cam then the stock springs should work fine as long as they came off a roller cam.
I never heard so much as a tick or even a hint of valve float with mine - they are stock and they are with that ramjet camshaft.

 

[John_S]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

So right now here is what I am thinking.

Performer RPM Vortec Intake
600 CFM 4160 marine Holley Carb
GM #14097395 Roller cam
Reuse Roller Lifters
Reuse Roller Rockers of 1.6/1
Summit Elec Fuel pump

Anyone see any glaring problems with this or any ideas to make it better?

Thanks again

Is the Summit Fuel Pump marine rated? It also is required to wired in a specific way in boats. Should be info in old threads.

Regardless of how lucky someone else might have been, you had better check the clearance. Maybe they got by with minor seal damage or all the tolerance stack-up was in their favor. But, if you used everything stock from the volvo, yea you should be good.

Keep the push-rods and rockers matched.

Also, were the dual coil springs from another set of vortec heads or your '87 engine? Curious.

 

[jaspers1]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

Also, were the dual coil springs from another set of vortec heads or your '87 engine? Curious.

The dual springs were from a set of Vortec heads, and thanks for the tip on the fuel pump. They do have marine rated pumps just a few more $$. I will check the clearance once we get everything assembled and if it needs to be changed we will do so. What are you thinking with the matched roller rockers and push rods? I am pretty certain that we did not keep them matched.

I did pick up a knock off Alum Intake today from KMJ. Looks nice but I will know more once I put it to the test.

Tail Gunner -- Whoops, when I said the MPI was junk I meant that it was no longer useable, damaged, not that I didn't like it. I would have loved to kept it injection but thats way more than I want to spend right now. Thanks for the links. The car craft article was were I got my Bee hive spring info.

Any more Edelbrock or Holley carb lovers out there? Or like bspeednut I could reuse my Quadrajet. Any body know the CFM specs for a 260 1347 9662 carb?

Any one know where I can pick up a nice looking flame arrestor?

Thanks

 

[John_S]

Re: SBC 5.7 Vortec cam & other bolt ons rebuild

What are you thinking with the matched roller rockers and push rods? I am pretty certain that we did not keep them matched.

Or like bspeednut I could reuse my Quadrajet. Any body know the CFM specs for a 260 1347 9662 carb?

Any one know where I can pick up a nice looking flame arrestor?

Thanks

It is recommended in the service manual. The parts have worn into each other, and mixing them could cause excessive wear. I believe you can polish the rod and socket ends to eleviate the issue.

Q-jet is 750 cfm. If you purchased the low-rise dual plane than it will accept square or spread bore carbs. I didn't think the Edelbrock or equiv, Performance RPM vortec or RPM air-gap vortec, would take a spread bore.

K&N flame arrester can be ordered at most speed shops. a little pricey, especially with the breather hose fittings. Holley make some too. You need to know how much room you have in the doghouse/engine compartment.