Michigan Boarder Engine Blueprint and Build

[formulaben]

What is the thickness of the block between cylinders at .060 over?

[sgt1970-442]

What is the thickness of the block between cylinders at .060 over?

not exactly sure what your asking. is it how thick the cylinder wall is after you bore it to .060 over? or are you asking how much spacing is between the cylinders in the water jacket area?

[Woodski]

@formulaben: the SBC has a 4.40" bore spacing, in std 350cid guise, a 4.00" bore. The 400cid production SBC uses the same 4.40" bore spacing with a 4.125" bore. 0.340" will be the wall thickness for a 4.060" bore on 4.40" bore centers.

[formulaben]

Thanks! Just curious how thin that area between the cylinders gets.

[sgt1970-442]

after re-reading your post and woodski's reply, now I get exactly what you were asking. woodski is right on with the numbers and i'll measure the thickness

when its done and let you know.

[nuttyskier2002]

Remember though.......only the 400 CID SBC has siamese bores (meaning no water jakets between bores). All other SBC production blocks do have water jackets between bores.

[sgt1970-442]

I think he is talking at the deck surface. fyi, I've never had an issue boring a chevy block .060 over. if you choose to go more .060 over than I suggest a sonic check. we have two olds 455's that stock bore is 4.125 and we have taken them out 4.250. .125 is doable when you sonic check and also filled it with hard block about half way up to the water pump holes.

[sgt1970-442]

thought i'd throw out an update. not much to report except we might finally get the .060 over pistons from srp this week.

on another side, we sent back the cylinder heads to summit. the quality of the port work on the second head we pulled out

of the box was a hack job. I called dart direct because they are local and said I could bring them by so they could explain

to me how this would pass through quality control. they asked if I could email some pics, I did and here's what they said.

while we do everything to over see a tight quality control, we sometimes have an issue. my response was, did stevie wonder

work on this set. they agreed that they were a mess. we also pulled a set of valves from one cylinder. specs show

max.520 lift and 130psi closed seat pressure. only had 105psi spring seat pressure and went into coil bind at .500 lift.

this means that with a roller cam set up that valve float would be an issue at rpm and lift is not as advertised.

also dart shows these heads at 165cc intake runner. summit request them to be 175cc runner. this is the machining they do

to the intake port for the extra 10cc.

buyer beware, never think for one minute that you can buy new heads and pull them from the box and install them.

I am now trying to find the RHS 12410-02 heads. price might be an issue though.

http://s772.

Edited March 24, 2014 by sgt1970-442

[Michigan boarder]

Wow, I don't know squat about this stuff but know enough to look at that and say "This isn't right".

Thanks for keeping such a close eye on things Sgt!

[nuttyskier2002]

Sgt........I can send you pix of my Chevy Bowtie Vortecs that I bought bare from Summit. They are advertised at 185cc for intake runners and seam to have a much better looking runner opening than shown above. Summit has a price match guarantee si I got them for just a bit over $300.00 per head.

[Woodski]

A key reason to have an experienced eye look over the parts and perform a few critical functional checks. If the specs had been blindly accepted and they chose a high lift cam or one that was greater than .500" lift, serious engine damage would have ensued shortly after MB hit the water. Nice catch on Sgt.'s part. Those are not elegant ports!

[sgt1970-442]

Sgt........I can send you pix of my Chevy Bowtie Vortecs that I bought bare from Summit. They are advertised at 185cc for intake runners and seam to have a much better looking runner opening than shown above. Summit has a price match guarantee si I got them for just a bit over $300.00 per head.

yes please do along with the part number. thanks woodski, I can't stress enough to people about checking every piece twice with two different sets of eyes.

woodski, pm me your number. I have a couple quick questions for you. thanks steve

[sgt1970-442]

Thanks for keeping such a close eye on things Sgt!

john, not a problem. just what needs to be done.

[WheelerWake]

the quality of the port work on the second head we pulled out

of the box was a hack job. I called dart direct because they are local and said I could bring them by so they could explain

to me how this would pass through quality control. they asked if I could email some pics, I did and here's what they said.

while we do everything to over see a tight quality control, we sometimes have an issue. my response was, did stevie wonder

work on this set. they agreed that they were a mess. we also pulled a set of valves from one cylinder. specs show

max.520 lift and 130psi closed seat pressure. only had 105psi spring seat pressure and went into coil bind at .500 lift.

this means that with a roller cam set up that valve float would be an issue at rpm and lift is not as advertised.

This kind of nonsense is one of the reasons I bought GM vortecs. They have much more engineering, testing, quality control and production experience.

A pilot run for GM might be about the same as a production run for Dart.

But I still disassembled mine and check them.

[Roster man]

Wow! I can't believe dart would let this get out of the factory! Have they eliminated any qa/qc check and they are just hoping for the best? Aftermarket was supposed to be quality that the big 3 couldn't afford to produce. Looks like I am wrong!

Edited March 24, 2014 by Roster man

[sgt1970-442]

finally, after 3 weeks we have .060 pistons and rings.

[nuttyskier2002]

yes please do along with the part number. thanks woodski, I can't stress enough to people about checking every piece twice with two different sets of eyes.

woodski, pm me your number. I have a couple quick questions for you. thanks steve

Hey Sgt. Tried posting images of heads but received error msg. Seams I don't have privs yet perhaps because of membership dues. Just paid them and tried re-posting. I guess one of the admins has to approve first

[nuttyskier2002]

I sent the pix to Sgt.'s yahoo mail. From what I've seen the GM Bowtie Vortecs are a very good quality product. Could benefit from a little minor cleanup in the exhaust ports with a few cartridge rolls. I will be updating my 383 stroker build as soon as I get my block back from AZ Speed and Marine. Will post pix of everything including heads.

[WheelerWake]

I sent the pix to Sgt.'s yahoo mail. From what I've seen the GM Bowtie Vortecs are a very good quality product. Could benefit from a little minor cleanup in the exhaust ports with a few cartridge rolls. I will be updating my 383 stroker build as soon as I get my block back from AZ Speed and Marine. Will post pix of everything including heads.

The only place my non-bowtie vortecs needed any cleanup was your standard "pocket port" within .5" of the seat. Probably 20 minutes work total, both intake and exhaust. Quality was good on these also. The price of these has gone up recently to $350 each for complete heads (were $300 6 months ago).

[sgt1970-442]

yes after looking at the gn 25534351 castings, they are a nice head.

[sgt1970-442]

well I found the custom cam grind we will be using as long as john approves. for you gear heads, you won't believe the specs on it.

all I can say is it will be good from idle to 4800rpm.

[WheelerWake]

well I found the custom cam grind we will be using as long as john approves. for you gear heads, you won't believe the specs on it.

all I can say is it will be good from idle to 4800rpm.

Sounds pretty "mild"

[sgt1970-442]

yeah maybe, more of a different pattern than what your use to hearing.

[sgt1970-442]

finally going to be making some progress. cam is ordered, machining done, heads coming and soon to start the measuring and recording of sizes of all these goodies.

lots of pics coming soon.

[sgt1970-442]

ok so between the parking lot and paver jobs I've been able to get a few things done on john's engine.

rings are fit, cam bearings installed, freeze plugs installed, bearing clearances being checked.

block all deburred and crank sizes checked.