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5.7/260 merc build

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Hemidoc

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Discussion starter · #1 · (Edited)
5.7/260 merc build ?s

Well I wouln't call this a ful "build" but looking for some more power since I'll have it out and torn down.
This is a new to me boat 21' (small around here) Invader bowrider. I've not had her in the water as I'm replacing the deck,stringers,mounts and recovering the interior so I don't know what she'll really run. PO said he got 60+ with the 23p ss prop that's on it .
The boat came from the factory with tru-transom exhaust which I'll keep. I'd like to make a bit over 300 hp and not overpower the Alpha and tear it up.
So here's a list of the adds I'm looking at.

Summit flat-tops http://store.summitracing.com/partdetail.asp?part=SUM-17350-00&autoview=sku

Comp Cams extream marine
http://store.summitracing.com/partdetail.asp?part=CCA-CL12-236-3&autoview=sku\

Edelbrock Performer w/stock qjet
http://store.summitracing.com/partdetail.asp?part=EDL-2101&autoview=sku

Stock heads 89 model year with maybe a mild port job

I'm not gonna throw too much cash at this.

Thoughts and ideas would be great.
Thanks
 
#2 ·
No No and No.

The piston design is good, but your adding power and going with cheap pistons. They may work but I'd invest in some better quality hypers or even forged. The cams duration is good but with the lift, your pushing the limits of the stock pressed in rocker stud in the heads. You would need better springs as well. As for the intake, the performer on a 350 is nothing to brad about. If your sticking with the 217 heads go with GM's bowtie intake. Its a far better design then the regular performer. You want the RPM at least for the 350 which edel doest make in the 87-95 head bolt pattern.
 
#3 ·
That cam would work best with a set of factory Vortec heads.I would not spend any time or $ on your stock heads. You can get about 320 hp with flat top pistons, the cam you referenced and a set of Vortec heads. You can pin the studs yourself instead of using screw in studs.

BTW: I have a used Lunati cam and lifters from a previous set up I will let go really cheap.
 
#5 ·
Pinning would work as I've done it in the past with good results. BUT I had one stud break and it was a PITA to get it out. I did a walk thoug hon converting to screw in studs in the comfort of your own home that you may want to check out
 
Discussion starter · #6 · (Edited)
Mkos1980 said:
Pinning would work as I've done it in the past with good results. BUT I had one stud break and it was a PITA to get it out. I did a walk thoug hon converting to screw in studs in the comfort of your own home that you may want to check out
Click to expand...
I work at a new car dealer(not GM) so I have plenty of tools and equiptment to do such a job. I should've mentioned oringinally that was planning on upgrading the valve springs but I figured that was a given with that cam.
I was wanting some vortech heads but I don't wan't to throw too much money at this thing but how bout these
vortechs
http://store.summitracing.com/partd...asp?autofilter=1&part=NAL-12558060&N=700+4294925232+4294838998+115&autoview=sku

A name brand piston
http://store.summitracing.com/partdetail.asp?part=STL-H345NP&autoview=sku

This manifold
http://store.summitracing.com/partdetail.asp?part=EDL-2116&autoview=sku or GMs http://store.summitracing.com/partdetail.asp?part=NAL-12496820&autoview=sku

A little less cam lift
http://store.summitracing.com/partdetail.asp?part=CCA-CL12-232-3&autoview=sku

You guys mention about pushing out rocker studs with too much cam lift. I have not built a Chevy for a long time but I never had a problem up to 4.90 lift(maybe I was just lucky)

Thanks and I'm open to suggestions that don't involve throwing a lot of dollars at this thing since it'll never be a Formula just an inexpensive boat to haul azz and ski and have fun.
 
#8 ·
Pistons are good. You want the Performer RPM Vortec intake. The regular performer is nothing to run home to mom about. Those heads are good but thats for 1 only. I paid 200 bucks for my used heads, converted them to screw in studs for a total cost of about 250 bucks for both heads. I upgraded the springs to beehives for about another 150 bucks. I now have a set of vortecs that can handle 550 lift for 400 bucks. I also said heck with the flat tappet cams and I upgraded to a roller cam. I got all my lifters and holddowns used from a 93 LT1. I'm also running the LT4 Hotcam. 218/228 525/525 with 1.6 Rockers. If your going this far, you might as well upgrade to a roller setup.
 
Discussion starter · #9 · (Edited)
Mkos1980 said:
Pistons are good. You want the Performer RPM Vortec intake. The regular performer is nothing to run home to mom about. Those heads are good but thats for 1 only. I paid 200 bucks for my used heads, converted them to screw in studs for a total cost of about 250 bucks for both heads. I upgraded the springs to beehives for about another 150 bucks. I now have a set of vortecs that can handle 550 lift for 400 bucks. I also said heck with the flat tappet cams and I upgraded to a roller cam. I got all my lifters and holddowns used from a 93 LT1. I'm also running the LT4 Hotcam. 218/228 525/525 with 1.6 Rockers. If your going this far, you might as well upgrade to a roller setup.
Click to expand...
I'll keep hunting for a set of heads but I can get these now and they are new. Also it looks to me the RPM series manifolds are square bore and I have to use my Q-jet for a while till I can jump off the $$ for a marine Holly. I like the LT4 cam( but dag that's a lotta lift. I have to do more hunting parts and research. But lake time coming up quick so I gotta move forward. I've just got the deck in(got greased by the weather alot) and most of the interier done.
 
Discussion starter · #10 · (Edited)
#11 · (Edited)
A better cam and intake will get you 300hp.
Something like 218,218 at .050" .468" lift and 110 or 112LSA will get you there. Should be drop in springs capable of handling this.

So..........Comp High Energy 268H (218,218, .468, .468) and GM Bowtie intake for 87+ heads. Can use the qudrajet that came on engine, just probably use DA secondary rods, rest should probably be fine.

Why new pistons ?

I have a used GM Bowtie 87+ intake you could buy cheap and ship expensive if outside of New England (45lbs).

Done deal. Have fun with it. Over and out. :D
 
Discussion starter · #12 · (Edited)
cfm said:
A better cam and intake will get you 300hp.
Something like 218,218 at .050" .468" lift and 110 or 112LSA will get you there. Should be drop in springs capable of handling this.

So..........Comp High Energy 268H (or whatever Comp Extreme Cam is that gives you 218 at .050) and GM Bowtie intake for 87+ heads. Can use the qudrajet that came on engine, just probably use DA secondary rods, rest should probably be fine.

Why new pistons ?

I have a used GM Bowtie 87+ intake you could buy cheap and ship expensive if outside of New England (45lbs).

Done deal. Have fun with it. Over and out. :D
Click to expand...
Thanks! Maybe I got cought up in the moment. But all the cyl head talk got me thinking. Those aluminium heads looked cool. But really I'm just trying to get 300+ hp. The reason for the pistons was since I'll have them out.... Why not go to a flat top?
I'd be interested in that intake(just shipped a set of OMC log manifolds with risers in two packages for $54)
So that manifold should ship to ATL Ga for about $30.
 
#13 ·
Why are the pistons coming out ? Give us some history and if that involves having to replace certain items. If you have to replace something, sure, get something better, but if you don't , then why ? 300hp is no sweat. 320+ gets a lot more wallet involved, but that's even relatively cheap in comparison to ......

BTW: Most expensive thing you can do is buy a $100 GPS that shows speed.
 
Discussion starter · #14 · (Edited)
cfm said:
Why are the pistons coming out ? Give us some history and if that involves having to replace certain items. If you have to replace something, sure, get something better, but if you don't , then why ? 300hp is no sweat. 320+ gets a lot more wallet involved, but that's even relatively cheap in comparison to ......

BTW: Most expensive thing you can do is buy a $100 GPS that shows speed.
Click to expand...
Turns out I didn't take into account the X gallons of fogging oil used by the PO's "mechanic' when they winterized the thing and bent a rod. I've got another block in the garage I'm going to use for parts. A set of flat tops is <$100.
Wouldn't be the first or last time I did something stupid that cost $$$
 
#19 ·
Hemidoc said:
I'd be interested what specs? How'd it work?
Click to expand...
Its is a Lunati 60101. It worked great and pulled up to 5000 rpm. The lifters were removed and numbered. This cam was used with stock 906 Vortec heads with no issues. I also ran a Q'Jet with an adapter on a RPM Airgap intake for a while and it did fine.
 
#20 ·
Part Number: LUN-60101LK
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,000-5,500
Intake Duration at 050 inch Lift: 213
Exhaust Duration at 050 inch Lift: 219
Duration at 050 inch Lift: 213 int./219 exh.
Advertised Intake Duration: 256
Advertised Exhaust Duration: 262
Advertised Duration: 256 int./262 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.454 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.468 in.
Valve Lift with Factory Rocker Arm Ratio: 0.454 int./0.468 exh. lift
Lobe Separation (degrees): 112
 
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Hemidoc
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