quadzillaracer
New member
I just wanted to pass this information along to the fellow members here @ vmax4.com that are rebuilding or modifying their Vmax-4 engines.
As many of you know, I put together and build some pretty bullet-proof Vmax-4 engines for my turbo sled (it's a necessity with crazy TQ/HP numbers)! I have spent the last decade trying to study, learn, and improve on these already incredible engines.
Over the past year, I have found some alarming casting flaws on the bottom side of both "stock" 800 and 750 cylinders. On the inside surface of the cylinder that sits on the basegasket, next to the bore on the bottom; I found (3) of my spare cylinders had a .008" -.012" casting lip (sag) on one side of the cylinder or the other. This was causing my cylinder to sit at an angle on the basegasket and created a .012" taper on my worst cylinder when we used the dial indictator across the head.
So essentially lets say in my case, the #4 cylinder had a .012" casting lip between #4 and #3, so #4 was actually tipped towards the recoil assembly on the case... when I placed the head on between #4 and #3 the head is tapered and not making contact on #3, because of the lip the cylinder. This will and would cause #3 to blow head-gaskets out. We use a Fidal CNC machine with a special surface ground fixture we made just for these Vmax-4 cylinders; I always like to make sure the total deck height between all 4 cylinders is .001" or less.
I just wanted to pass this on for you guys that may be in the market to have cylinders re-nicked, bored, ported, or whatever. You will never notice it with the naked eye until you use a quality dial caliper. My advise is to have your cylinders lightly cut a few thousands on the base to make sure you don't have this issue and you have a flat surface. It's not a good sign that 3 of my spare 16 cylinders had this casting flaw and I'm sure that I'm not the only one out there. I'm thankful that I caught it, considering I had this issue over the past couple seasons. Now my cylinders are "flat" and true, even used a feeler gauge and everything is around .001".
Take care,
Justin
As many of you know, I put together and build some pretty bullet-proof Vmax-4 engines for my turbo sled (it's a necessity with crazy TQ/HP numbers)! I have spent the last decade trying to study, learn, and improve on these already incredible engines.
Over the past year, I have found some alarming casting flaws on the bottom side of both "stock" 800 and 750 cylinders. On the inside surface of the cylinder that sits on the basegasket, next to the bore on the bottom; I found (3) of my spare cylinders had a .008" -.012" casting lip (sag) on one side of the cylinder or the other. This was causing my cylinder to sit at an angle on the basegasket and created a .012" taper on my worst cylinder when we used the dial indictator across the head.
So essentially lets say in my case, the #4 cylinder had a .012" casting lip between #4 and #3, so #4 was actually tipped towards the recoil assembly on the case... when I placed the head on between #4 and #3 the head is tapered and not making contact on #3, because of the lip the cylinder. This will and would cause #3 to blow head-gaskets out. We use a Fidal CNC machine with a special surface ground fixture we made just for these Vmax-4 cylinders; I always like to make sure the total deck height between all 4 cylinders is .001" or less.
I just wanted to pass this on for you guys that may be in the market to have cylinders re-nicked, bored, ported, or whatever. You will never notice it with the naked eye until you use a quality dial caliper. My advise is to have your cylinders lightly cut a few thousands on the base to make sure you don't have this issue and you have a flat surface. It's not a good sign that 3 of my spare 16 cylinders had this casting flaw and I'm sure that I'm not the only one out there. I'm thankful that I caught it, considering I had this issue over the past couple seasons. Now my cylinders are "flat" and true, even used a feeler gauge and everything is around .001".
Take care,
Justin
Last edited:
