700+hp sbc 23 degree heads

[mdross1]

Gotta wonder all the problems with aluminum blocks comes from being run to the max and stripped out threads from the many times they are pulled apart.These problems should not bother the street engines once together and run hard occasionally or when need be.Shaving a 100 lbs off a motorcycle is a big deal.The motor would never truly be working hard.

[bigjoe1]

i THINK A LOT OF THE STRIPPED THREADS is because the do not like vibration ( alu VS iron )The problems I saw were NOT because they were taken apart too often. It has to do with the material


JOE SHERMAN RACING

[Orr89rocz]

Gotta wonder all the problems with aluminum blocks comes from being run to the max and stripped out threads from the many times they are pulled apart.These problems should not bother the street engines once together and run hard occasionally or when need be.Shaving a 100 lbs off a motorcycle is a big deal.The motor would never truly be working hard.

I guess if you'd like to save some weight, go with an LS aluminum motor, built a 427+ " motor with some LS7 heads and make 650+ hp fairly easily

[mdross1]

i THINK A LOT OF THE STRIPPED THREADS is because the do not like vibration ( alu VS iron )The problems I saw were NOT because they were taken apart too often. It has to do with the material


JOE SHERMAN RACING

Have to ask,why not use Helicoil's? The last set of aluminum heads I put on a 460 in a kit cobra did both intake and exhaust.Also I'm talking a street motor,it will see max rpm's no doubt but not like you guys run these things.

[CNC BLOCKS]

The biggest problem is always about stripped out threads every where. I have seen heads studs. bell housing bolt holes. motor mounts holes and so forth have the threads pull out. When one was used with NOS, the leak downs were terrible after just a few runs. They also seem to loose 4o or more Hp compared to a Dart cast iron block. The cost to save 100 pounds does not seem to be a good deal at all


JOE SHERMAN RACING

We have worked with aluminum blocks for years with out stripping bolt holes, But alot of guys don't use the correct lenth head studs the ones for aluminum blocks are appox. 1.250 thread depth that goes in the block., To many guys will try a .750 reach stud in an aluminum block and it does not work.

[mdross1]

Hear the same things from boys running big inch Harleys that don't use the correct fasteners.Biggest thing I have seen are so many people without a feel for correct torque and over tighten hardware shearing out the threads.It can happen the same way in cast iron over time.The reason I personally use studs in high stress areas,mains and heads.

[Dick Gazan]

The biggest problem is always about stripped out threads every where. I have seen heads studs. bell housing bolt holes. motor mounts holes and so forth have the threads pull out. When one was used with NOS, the leak downs were terrible after just a few runs. They also seem to loose 4o or more Hp compared to a Dart cast iron block. The cost to save 100 pounds does not seem to be a good deal at all


JOE SHERMAN RACING

We have worked with aluminum blocks for years with out stripping bolt holes, But alot of guys don't use the correct lenth head studs the ones for aluminum blocks are appox. 1.250 thread depth that goes in the block., To many guys will try a .750 reach stud in an aluminum block and it does not work.

I've had more than a few aluminum blocks apart over 30 years and have had to helicoil very few holes. I'll agree that the most of the problems come from improper stud or bolt depth. Also cheap welded oil pans with bolt holes offset and steel bellhousings that are not perfect, intakes bolt holes out of alignment all contribute to failure. One of the last engines I worked on had rocker studs for lower head studs. As far as power goes the builder has to take into consideration that the block grows between .006 to .012 which will effect compression and valve lash. Some of the tight lash cams have to be adjusted by just spinning the pushrod or at .0015. If the short block is assembled properly you need extra warm up time to stabilize the heat in the block or a engine heater. The other thing is they are subject to chassis flex, some builders never tie the front down solid but use hose clamps and some exotic swivel front mounts.

[mdross1]

Aside from all the known issues sounds to me like they can all be dealt with.In the end on a motorcycle that 100 lb savings is a lot when your talking having a 900 lb bike as apposed to a 1000+lb bike.