cam and compression question
 

Well i purchased a baja 226 from a friend with a bad motor with 1 hour .so sad! ...the setup contained a eagle crank h beams and mahle pistons .060 over . The old owner had it built by some random mechanic which installed and folded the rings cause damage to the newly bored cylinder walls and damaging 2 pistons. The current setup was a 496. But now I have to bore over .70 and it will be raised to 498? My question after checking compression it would bring me up to 11.5 due to the L92 Heads with 100cc combustion. will it be safe or should i change the heads to lower compression. Also not sure what cam is in there but I will ask machine guy to tell me. I ordered the pistons already any suggestions to make this thing not blow? thanks

wont be safe unless you have top notch premium or race gas avail for use. First time you have to fill up on water and they only have 87/89 avail you will have problems :(

well since this boat is mostly for fun. I planned on putting premium gas before heading out or even avgas but ..I rather build it safe... I was thinking of having timing a bit retarded to avoid detenation...another set of heads is going to set me back..lol

Think twice before building something thats going to require expensive gas. Boats suck lots of gas and having to fill up with $7.00 a gallon fuel would end the fun in a hurry! In addition boring your block to .7 IMO is not a good idea. I think I would sleeve the two bad cylinders instead or find a new block.

About the only thing you can do now is install a camshaft that closes the intake valves very late. A long duration camshaft with a wide LSA and installed with zero advance on the intake lobe centerline. This will knock down cranking compression (running compression) to a point where you can use pump gas.

I would suggest a single pattern camshaft with 242 degrees intake and exhaust duration.
A LSA of 114-116 degrees and ground with split overlap (no advance on the intake lobe centerline).

Combined with your high static compression ratio this camshaft might work pretty good...ya never know!

The L-29 heads have an excellent heart-shaped combustion chamber and work very well with higher compression ratios as long as they have a tight quench.
Make sure the pistons come to the top of the cylinders, even with the deck. Ideally you want aproximately .040 inches between the flat of the piston and the flat of the cylinder head. Most head gaskets are around .040 inches thick.

Bring in the ignition advance very slowly with a maximum of 28 degrees total advance at 3500 rpm.

To keep the engine from detonating, make every attempt to run the engine very cool with a 140 degree thermostat. Keep the fuel and carburetor very cool also. Cool fresh air entering the carburetor will help a great deal.
Good Luck
Dennis Moore

I was reading about that. I will look it up any idea where i can order sux a cam?

Any of the camshaft manufacturers will sell you this camshaft. Call Comp Cams tech line.

ill be using a cometic head gasket but also unsure of which one i know they are all .51 thick . so many things plus I am justa newb with a limited budget so trying to get it right before I am like the guy who sold it to me..lol

called the comp cam line and they suggested between 112-113 lobe seperation. 218/224 ..no matter what would need high octane. part number XR270HR-13

i call cometic and they state i can go 120 thick to reduce the compression anyone think this is a bad idea? i was thinking of gettin the .98 thickness. below are my options
A = .027" to .051" (.69mm to 1.3mm) Thick
B = .056" to .075" (1.42mm to 1.91mm) Thick
C = .080" to .098" (2.03mm to 2.5mm) Thick
D = .120" to .140" (3.05mm to 3.56mm) Thick

One of my blocks has been 0.070" over for 12 years with no problems.

Yes that is a bad idea. You will probably be more prone to detonation with that large of a quench. I went 0.051" before but that was the limit. As Dennis stated earlier you want the smallest quench possible. If you have new pistons on the way I would send them back for different ones or different heads.
My $0.02

11.5:1 is race gas only territory.

No money for different heads but you have money to replace/fix the motor when it breaks ?

Don't take my post too harshly but here it goes anyway :
You are trying to talk yourself into, and have others agree, that somehow you will be okay. I'm here to firmly stand on two feet and say you won't be okay.

BTW: Reducing timing / crazy thick headgaskets / wrong cam / etc,etc to try to save a motor from too high compression running lower fuel quality than it should is not a fix...not even a crutch.

BTW#2: I dispise the word 'crutch.' Motors and 'crutches' never get a long.

Build a motor for how you are going to use it. All components should closely match each other. This is the cheapest and most fun combo.

Your welcome. From a Voice of reason. LOL.

i am not trying to have other agree . I am not fimiliar with a bbc checy so thats why I have all the questions. Now I am trying to save as much as possible without replacing parts that are good. If you would have read the begining post I purchased this BROKEN!!! I AM JUST TRYING TO PICK UP THE PIECES AND AVOID HAVING IT BREAK ON ME LIKE IT DID ON THE GUY THAT WAS GUIDED THE WRoNG DIRECTION.. if i am better of with different heads so be it. I would hate to buy new one but it is what it is!....

If i were you and you could fix this motor for cheap and get it running right on race gas then i would sell it to a street guy and go buy a stock marine engine :) Probably be best/easiest all around

checked everything and they gave me the wrong information along the lines had the wrong rotating assembly part from the old owner... I went and got all the parts on the broken short block and determines that infact my compression will be 9.7:1 so I assume all this was for nothing but thanks for everyone that chimed in! Now gotta check out what cam will work best in this.

L92 HEADS 100CC
Mahle forged 4032 -3.0cc flat top
4.2500" stroke lightweight 4340 steel
6.385" standard H-Beam

Call RMbuilder, (585) 654-8583 no need to call anyone else

I second that, RM Builder designed my 427 BBC in my 242. absolutely excellent motor. In addition Bob is a fantastic guy to work with!

Call bob.... designed my valvetrain for my 428 sbc...love it