What is "bad" with mark 1?

[nilsenpeter63]

What is the worst "faults" of the mark 1?
The block is god , but could have used 4 bolt mains. It helps alot to have the 3 mains in the middle get 4 bolt caps like a smallblock. Can they be manufactured out of regular BB caps??

The heads are thin under the springs so the highest spring pressure of untouched heads stops "low" for inst. of "more" camshafts?
It seems to me that the problem of lack of springpressure/ instalation height is to go with longer valves/pushrods and thereby get higher pressure for more camshaft. Its a question of what the heads will tolerate at the springseat??
Probably will the valvecovers be to low, but that is not a problem. plenty of options to fix that.


Is it the heads or the intake that is the "brake" in breathing the engine? Original exhaust manifolds are of course no no in this matter.
The common remark is that it is the heads. what is the truth?

Then we have the weight of the pistons which are heavy. With new materials and technics shouldnt it be possible to get it somewhat better at that area to?
That is the case in camshaft/spring area.

Is there any tricks to improv waterflow like it is done on smallblocks? Does the block or heads need improvment at all?

 

[jim_ss409]

Go back a bit to a post titled " ???????On Building A Stroker" that will cover your first question about 4 bolt mains.
Yes you can install longer valves or different retainers to alow for more lift also the later 583 heads were cast thicker under the springs than the 690's but I don't think it's recomended that you cut the spring seat deeper.
I think the intake side of the high performance heads flow pretty well. About 260 cfm. But the exhaust side is a little weak. I think the intake manifold is a weak point also but there is no cheap solution to that problem. There is a nice manifold available but it costs about $1,200.00 or so.
You can get reasonably priced forged pistons that weigh 675 grams instead or the factory forged pistons that weigh over 1,000 grams. They are the ones that are designed for the stroker motors with the big block rods but they also work with the stock stroke and longer aftermarket rods.
I don't know about water flow changes except of course changing to a smaller pulley to increase flow. Also I've noticed that the holes in the block there the pump bolts on are a bit restricted, poor casting. I was going to clean mine up a bit with a die grinder.
With a bit of work and a good cam it's not a problem to make more than 500 hp with the stock heads and intake.
Maybe other members will add to or correct this information.

 

[nilsenpeter63]

Thanks for the answers Jim. I ´ll finish and refrace one of my questions in my original post so it make sense.

The heads are thin under the spring, so the highest spring pressure of untouched springseats would be? In 690 heads.

What is the story on the 18 headbolts on mk1. SB and mk4 has only 16. The Mystery engine also had more headbolts, but somewhere they got lost.

Another "weakspot" is the crankshaft snout isnt it? Best way to prevent failure on high perf. ++ engines are to install a fluidamper?? On stock engines the stock damper is sufficent?