1993 Teal Cobra Rebuild Progress

[EHardy1971]

Originally Posted by Dale McPeters

What year model 351w blocks?

'69 and '70 model blocks are supposed to be the 2 best years,due to being thicker castings,especially in the main webbing.I noticed you have a '70 model,so you should be good to go.

[Dale McPeters]

Originally Posted by qkjuicedpony

I've seen many early 70's blocks and a few lightning blocks.

One combo has had a fogger and a plate on it with a jericho as well as a procharger blow thru setup and a glide.This motor has been together for a while too

Do any of the setups have any block fill in the block to stabilize the bottom end harmonics?

Actually I have a '69 std. bore with 2 bolt mains & a '71 std. bore with a 4 bolt main conversion....

I just want to make sure that I have at least a 20-25% safety factor between the rwhp goal and what the block will actually handle. The max hp goal at the track should be somewhere in the 750+ rwhp range. At about 7200rpm max. as that is where the solid roller that Jay ground for me is supposed to work the best.

On the street it can be dialed back to about 550-600rwhp. One of the biggest concerns is main cap walk/flexing due to rpm and the 3" mains.

Will just have to wait & see what Pete finds when he sonic tests the '71 model block.

[EHardy1971]

Dale,what are the casting #'s on those blocks?

[Dale McPeters]

Originally Posted by EHardy1971

Dale,what are the casting #'s on those blocks?

These are the casting numbers. What I thought was a '70 is in fact a '71 as it has the D1 at the beginning. Will have to check my date code chart.

'69 2 bolt= C9OE
'71 4 Bolt conversion = D1AE

[EHardy1971]

I'd go with the '69 myself,just my opinion from everything I've read.

[Italian LX]

Originally Posted by Dale McPeters

These are the casting numbers. What I thought was a '70 may be in fact a '71 as it has the D1 at the beginning. Will have to check my date code chart.

'69 2 bolt= C9OE
'71 4 Bolt conversion = D1AE (checking date code)

Yep. I've got a D2 block myself.

[Italian LX]

Originally Posted by Dale McPeters

At about 7200rpm max. as that is where the solid roller that Jay ground for me is supposed to work the best.

Wow, that seems awfully high for that big of a stroke. I'm thinking the high rod-ratio and 3" mains won't let that motor last very long at 7000+ rpm.

However, I'm sure you've done your research. Definitely sounds like a recipe for a mean power plant.

[Dale McPeters]

Originally Posted by Italian LX

Wow, that seems awfully high for that big of a stroke. I'm thinking the high rod-ratio and 3" mains won't let that motor last very long at 7000+ rpm.

However, I'm sure you've done your research. Definitely sounds like a recipe for a mean power plant.

Yep that is high for 3" mains that is the reason I am looking into the Dart block that has 2.75" mains. The shift point on the cam is about 6400-6800 with a max rpm of 7200. A lot of spring pressure on the AFR-225's.

There is one guy here that is turning 7000 rpm with 3" mains. It will live for a while....

[Dale McPeters]

Well 306 is rebuilt and ready to set in the cobra......had to buy more parts, new polly locks etc. to replace the existing ones. The existing ones had no way to lock them in place other than the girdle...

I have went way over budget on this little 306 rebuild just trying to get the green slip inspection completed.......although maybe it would now make a nice little motor for my wife's '65 coupe......hmmmm....that and a T5Z 5 speed conversion....

On a side note I may have sold my '93gt today as a completely stripped rolling chassis......maybe will have to see if the cash shows up....

'71 351w block will be dropped off at the machine shop tomorrow for sonic testing. This will determine if the following can or will be done.

See if the 4 bolt main caps can be dowled in anyway and 2.75" main bearing inserts installed. Hard block up to the freeze plugs. I have another stud girdle to be machined and set in on the 4 bolt main caps. Install 1/8" oil restrictors to keep more oil at the mains since I have a tight lash solid roller...

If the sonic test is no good then it will be a Dart block for the build...

[coupe]

3" mains at 7000 RPM have a linear velocity of 91 ft./second at the oil boundary. The 2.75" mains are running 84 ft./sec. Both are high but the difference is not that bad. Just lower the viscosity of the oil and/or use a high-end synthetic and you should be fine.