Vortec 906 & 062 valve stem o.d. ?

[Returntrip]

Hello everybody, I am disassembling 2 sets of Vortec heads for inspection for my stroker build. One set of 906's & a pair of 062's. I am a little puzzled at the fact that the 906's have a valve stem o.d. of .332 & the 062's are .319. I thought the heads were supposed to be the same except for the exhaust valve seats. Could someone let me know why the difference? also can i install new guides in the 062's to run the beefier valves. the 062's are in much better shape, due to the fact the 906's sank in salt water boat with only 20 hours on the the new engine. Is it worth hours of wire brushing & sandblasting to save the almost new 906's that got rusty. Any help on at least the valve stem o.d. #s would be helpful, thanks.

 

[Scott Danforth]

casting numbers are only part of the equation.

they should be 0.341 or 0.343. the LS motors use 0.315

your heads could have been worked on prior.

I would talk to your local machine shop. you need to cut the seal seats, and I would seriously upgrade to better seals and screw in rocker studs anyway.

Brand new heads are $850 a pair. you tell us if its worth it for a $400 set of used heads. I personally wouldnt waste time on a rusty head. too many good heads out there with stainless over-sized valves, already modified for better seals, taller lift cam and screw in studs since the race guys abandoned the vortec heads a few years back.

 

[Returntrip]

casting numbers are only part of the equation.

they should be 0.341 or 0.343. the LS motors use 0.315

your heads could have been worked on prior.

I would talk to your local machine shop. you need to cut the seal seats, and I would seriously upgrade to better seals and screw in rocker studs anyway.

Brand new heads are $850 a pair. you tell us if its worth it for a $400 set of used heads. I personally wouldnt waste time on a rusty head. too many good heads out there with stainless over-sized valves, already modified for better seals, taller lift cam and screw in studs since the race guys abandoned the vortec heads a few years back.

 

[Returntrip]

Thank you for responding. Upon further inspection (with my glasses on) The 062's are .341. The 906's are close to.357, but the heads came off of a genuine mecruiser reman i purchased somewhere around 2009. I am a Diesel marine mechanic and use my boat for transportation from shipyard to shipyard. Ive never personally rebuilt a gas engine & I am extremely weary of purchasing a long block that is machined and assembled by someone I dont know. I have now problem doing the machine work myself to cut down the guides and drill and tap for studs. I also have no problem spending the money on a set of aluminum or cast iron heads. The reliability of the engine is my main concern because my primary trans. to make a living is my boat. IT is only a 23' boat, but heavily weighed down with tools & supplies. I would like to achieve a decent low rpm torque curve without having to re-power with a big block. I have a Mercruiser part # 429-863320 forged crankshaft (uncut) that i would like to use. Im not sure if it is a 3.75 stroke or 3.8? yet. I also have (2) 5.7 non bored blocks that i have checked with a taper bore gauge. I am very confused on which way to go with a build. would like to install a hydraulic roller cam with approx. .490 lift & slightly more onthe exhaust side and a decent lobe separation angle. Please, any info on your part would be helpful, ex. Forged rods & LCQ, "D" shaped pistons? Which camshaft to use? Which cylinder heads to purchase or modify my own 062's? Seems to be a lot of different info out there & you sound quite knowledgeable in your response & previous posts. Should i even bother with crank I have or purchase a complete lower end rotating assembly kit? Sorry for rambling on, just very confused & need to get my boat together for transportation. Thank you very much.

 

[Scott Danforth]

you need to simply talk to your local machine shop. especially if they supply the short track guys. plenty of machine shops have vortec heads on the shelf ready to rock (already set up with roller rockers, screw in rocker studs, etc) for cheap as they had them ready for the racers. however as I stated, the rule change helped the racers, however left machine shops with excess inventory.

I wouldnt run aluminum heads unless you have heat exchanged cooling

cam shaft, I would run comp cams XM264HR or XM270HR with 1.6:1 rockers

since you are going stroker, just buy the full rotating assembly. suggest competition products out of Oshkosh WI. stick with SCAT, stay away from Eagle. they can put together a kit with SCAT rods and crank and KB pistons along with the cam and clevite coated bearings.

 

[Returntrip]

you need to simply talk to your local machine shop. especially if they supply the short track guys. plenty of machine shops have vortec heads on the shelf ready to rock (already set up with roller rockers, screw in rocker studs, etc) for cheap as they had them ready for the racers. however as I stated, the rule change helped the racers, however left machine shops with excess inventory.
Of Course I’ll be installing a heat exchanger and roll water pump crankshaft ribbon I already have a cooling system designed.

I wouldnt run aluminum heads unless you have heat exchanged cooling

cam shaft, I would run comp cams XM264HR or XM270HR with 1.6:1 rockers

since you are going stroker, just buy the full rotating assembly. suggest competition products out of Oshkosh WI. stick with SCAT, stay away from Eagle. they can put together a kit with SCAT rods and crank and KB pistons along with the cam and clevite coated bearings.

Thank you. Wow I’m really disappointed that I shouldn’t use the forged crank I already have. It was a $1342.00 crankshaft from Mercruiser.

 

[Returntrip]

Thank you. Wow I’m really disappointed that I shouldn’t use the forged crank I already have. It was a $1342.00 crankshaft from Mercruiser.

sorry i couldnt finish my response. Is there a reason why I shouldnt use my crankshaft? It only has about 20 hours of use on it. I used a micrometer on it and it iis in spec. Never cut? the area I am in doesnt really support much auto racing & I dont really believe there is an over abundance of ready to go Vortec heads.I have time & a shop to do the minor work on my heads, but if it doesnt make sense financially I will buy some aluminum heads. Could you suggest a certain set, possibly AFR 195's maybe? Im looking to get in the 375 to 400 hp range, but having good torque curve is my most important issue. I will very rarely ever put the engine up to or over the 5000rpm range. And yes I am designing a fresh water closed cooling system, I would never invest money into a quality engine to run salt through it. Is it more cost friendly to buy the whole rotating assembly than to put together parts with my crank? and could you recomend a good set of heads (aluminum) if i dont use my Vortecs? I would like to deck the block and use the correct heads, pistons, head gaskets & so forth to achieve .38 quench with no more than 9.5 t0 1 compression. Sorry about all the questions, Im not very experienced building small gas engines. Thanks so much for your help so far.

 

[Scott Danforth]

Thank you. Wow I’m really disappointed that I shouldn’t use the forged crank I already have. It was a $1342.00 crankshaft from Mercruiser.

no, its a $300 GMPP (GM Performance Parts) cast crank that you bough from Mercruiser for $1342. you can use it, however need to have it inspected.

you still need new rods and slugs.

dont forget to get your rotating assembly balanced. for my BBC, I went zero balance which added about $400 of mallory metal to the crank, however Im spinning 6k

you can get to only about 350hp unless you go above the 5000 RPM. Even the 6.2 merc goes to 5100. you can get to 450hp at 5500 RPM.

the stock Champ Products built HX for the 6.2 is a 5" x 18" 6-pass shell and tube HX.

I would still use the iron heads over aluminum. flat top pistons are 9.4:1 compression

 

[Returntrip]

no, its a $300 GMPP (GM Performance Parts) cast crank that you bough from Mercruiser for $1342. you can use it, however need to have it inspected.

you still need new rods and slugs.

dont forget to get your rotating assembly balanced. for my BBC, I went zero balance which added about $400 of mallory metal to the crank, however Im spinning 6k

you can get to only about 350hp unless you go above the 5000 RPM. Even the 6.2 merc goes to 5100. you can get to 450hp at 5500 RPM.

the stock Champ Products built HX for the 6.2 is a 5" x 18" 6-pass shell and tube HX.

I would still use the iron heads over aluminum. flat top pistons are 9.4:1 compression

 

[Returntrip]

Wow! I feel more ignorant every time I post something. When I look up that part# on that crank it comes up anywhere between 1,300 & 1,700 dollars. I will definitely take your advice on the heads , I actually wanted iron heads before but was told there where better heads for the same money going to aluminum. Do you think assembled bowtie vortec small port heads would be a good choice? and you recommended flat top pistons, I thought the LCQ 'D' shape pistons were supposed to be a good match for the Vortec combustion chamber? I will definitely do the Scat rotating assembly wtih whatever pistons are recommended are good with the Vortec heads. I will definitely be going over the 5000 rpm range while in use, but hopefully not often. I do enjoy the benefits of more horsepower. Thanks for listening & dealing with my lack of knowledge on this build.

 

[Scott Danforth]

No i dont recommend flat tops. Just saying flat tops will give you 9.4:1 with a. 3.5" stroke.

I recommend propper d-shaped pistons. I believe 7cc dish is what you are looking at with 3.75" stroke, however look at the calculations

I also recommend talking to your machine shop before buying parts

 

[Returntrip]

No i dont recommend flat tops. Just saying flat tops will give you 9.4:1 with a. 3.5" stroke.

I recommend propper d-shaped pistons. I believe 7cc dish is what you are looking at with 3.75" stroke, however look at the calculations

I also recommend talking to your machine shop before buying parts

Thanks so much for your help. Definitely will do the machine shop. Im leaning heavily towards the gmperformance cast iron bowtie Vortec heads, I have a GM employee # and the heads would be discounted quite a bit. what do you think of those?

 

[Returntrip]

Thanks so much for your help. Definitely will do the machine shop. Im leaning heavily towards the gmperformance cast iron bowtie Vortec heads, I have a GM employee # and the heads would be discounted quite a bit. what do you think of those?

small port

 

[Scott Danforth]

Thanks so much for your help. Definitely will do the machine shop. Im leaning heavily towards the gmperformance cast iron bowtie Vortec heads, I have a GM employee # and the heads would be discounted quite a bit. what do you think of those?

same as the heads you have, however with GM's screw in studs and a slightly bigger chamber 66cc vs 64cc

you still need to knock the casting flash out of the combustion bowl.

talk to your local machine shop, bet he has a pair of vortec heads all modded up sitting on the shelf collecting dust you could get cheap.

 

[Returntrip]

I went to the machine shop today, unfortunately no heads on the shelf. You were right though, he usually has them. He said get the Bowties' better flowing, thicker casting, ex. valve set inserts,7/16 screw in studs, already machined guide bosses & will accept both Vortec & non Vortec intakes and valve covers. I ordered them, GM could only find three in stock, 2 of them being in Wisconsin & now coming my way. That crankshaft luckily also turned out to be a specially built forged crank for Mercruiser. Things are looking better. Now I have to figure out rods, pistons & valvetrain. I think your recommendation on the comp 264 or 270 is the way to go. Not sure on rocker arms, should I bother with roller rockers or are the stamped rockers good enough?

 

[Scott Danforth]

Let your machine shop figure out the rest

 

[Returntrip]

Let your machine shop figure out the rest

Yeah ok