Rapido Engine with Wrong Heads?

[FreeBeeTony]

I just received my 350 Vortec Long Block today...........

After inspecting it briefly I wasn't sure of the casting numbers on the heads.
The numbers on the heads were 12558059.........after a google search it looks like these are 305 heads.............Raul is telling me it doesn't matter but I know the valves are smaller on these heads......the block casting number is 10243880 which seems to be a 350.

Any thoughts on this?....

 

[FreeBeeTony]

Re: Rapido Engine with Wrong Heads?

Any opinions?

 

[John_S]

Re: Rapido Engine with Wrong Heads?

From "http://www.mortec.com/castnum.htm"

10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal

12558059...97......305..........Vortec, truck, 1.84"/1.5" valves


"http://www.donsautopages.co.nz/chevheadnumbers.htm"

12558059 1997 305 Vortec, truck, 1.84"/1.5" valves, 64cc chamber



Yep, I'd want the vortec heads for a 350.

 

[mikeneal]

Re: Rapido Engine with Wrong Heads?

I think there are big differences between the 305 and the 350 heads. I say throw the BS on him , this is 1st thing I have heard negative about Rapido.

 

[FreeBeeTony]

Re: Rapido Engine with Wrong Heads?

I am going to speak with him tomorrow.

 

[Mike_B]

Re: Rapido Engine with Wrong Heads?

That's a bit disconcerting. I better check my casting #s also.

 

[JustJason]

Re: Rapido Engine with Wrong Heads?

dump some oil in it, bolt on a starter and spin it... see what your compression is.... don't want a repeat of last time.

 

[Buttanic]

Re: Rapido Engine with Wrong Heads?

What I found
12558062...98......350..........L31 Vortec, truck, 64cc chambers, 1.94/1.5, 170cc intake port
or
10239906...96-up...350.........."Vortec 5700", "L31", 64cc chamber,170cc intake port, 1.94"/1.5" valves

12558059...97......305..........Vortec, truck, 1.84"/1.5" valves, 64cc chamber

Chamber size is not a problem but performance will be down with the smaller valves, but it is possible to put the larger valves in during the rebuild, so you may or may not be OK. If he says he put the bigger valves then you either believe him or tear it down and measure.

 

[John_S]

Re: Rapido Engine with Wrong Heads?

Outside of trying to confirm valve size, I'd try to measure the intake ports and make sure they are the same, as your 350 heads. Also look around the valve pockets to see if there any noticable differences. I saw some info on an auto forum that the 58cc version 305 vortec heads had smaller ports than 350. Might be mis-information. Don't know how else to confirm. There is not that much info on the 305 heads. ???


Here are some links I found this AM. Somewhat conflicting, but they indicate that upgrading the valves and a little port work, they may be same as L31:

"http://www.hotrodders.com/forum/12558059-305-vortec-heads-108643.html"

"http://www.sallee-chevrolet.com/Discus/messages/3418/5694.html"

"http://www.thirdgen.org/techboard/tech-general-engine/157529-keep-my-lt1s-305-a.html"

 

[FreeBeeTony]

Re: Rapido Engine with Wrong Heads?

I am going to speak with Raul today.............late yesterday he was leaning towards taking the engine back............will know more later.

 

[FreeBeeTony]

Re: Rapido Engine with Wrong Heads?

Rapido is going to send my "350" heads for me to replace............

 

[erikgreen]

Re: Rapido Engine with Wrong Heads?

Just out of curiosity, did you get a two bolt or four bolt main? Mine's two bolt.

I don't really care, but I think my block may have started life as a 305, then been remanned as a 350 (355, actually). I haven't checked the casting numbers, however.

Erik

 

[FreeBeeTony]

Re: Rapido Engine with Wrong Heads?

Don't know if it's a 2 or 4 bolt yet..........haven't uncrated it that far yet.

Will get it on the engine stand this w/e.

 

[John_S]

Re: Rapido Engine with Wrong Heads?

Erik, not much of a chance of them being able to bore a 305 to a 350. Given Tony's discovery, I'd run the block and head numbers just to be safe.

 

[MikDee]

Re: Rapido Engine with Wrong Heads?

I don't think it's possible to bore a 305 out that much to be a 350, we're talking about 1/2" difference here in bore sizes, although the stroke is the same.

 

[erikgreen]

Re: Rapido Engine with Wrong Heads?

Okay... I had just heard it was the same small block, so I figured same amount of metal.

I'll check what numbers I can see tomorrow.

Erik

 

[WETSPOT2]

Re: Rapido Engine with Wrong Heads?

"http://www.mortec.com/castnum.htm",The best website to check out all casting numbers for big block chevy or small block chevy HEADS AND ALL

 

[Buttanic]

Re: Rapido Engine with Wrong Heads?

The 305 could not be bored, not enought metal. The cylinder wall can not be so thich because heat transfer to the water jacket would be compromised.
Although the blocks are identical on the outside different core patterns are used for the internals depending on the displacement.

 

[delsol]

Re: Rapido Engine with Wrong Heads?

raul with stand behind it. i had a problem with my one head. i got extended watt. but raul told me no matter what he will stand behind it 100%
bob/philly

 

[Bondo]

Re: Rapido Engine with Wrong Heads?

Raul is telling me it doesn't matter but I know the valves are smaller on these heads......

raul with stand behind it.

That would be Cool,..........

I bet Raul really Hates selling motors to fellas who are Awear of things like Casting #s..............

'cause he's Right,.......
In this case that motor would probably perform just as expected by a Non-mechanical Boater........