SHP Block Clearance Questions

[BadSS]

I've built a number of engines but this is the first time dealing with the SHP block (4.125 bore SBC). It says it is clearanced for 3.75" stroke and steel rods, but the 6" Eagle rods my buddy has will not clear. It looks like it will take removing at least an 1/8" from the block to get them to clear. I've ported heads and intakes for years so I'm very comfortable with a grinder but more than a little uncomfortable grinding on a relatively expensive block without knowing how much one could safely remove before getting into a water jacket.

I've looked for cutaways and couldn't find one that would be helpful. I've also searched this site and the web trying to find more information on clearancing a SHP block. It seems most questions and comments are center around clearancing for a 3.875 or 4" stroke and from what I can tell there is enough material there to get the longer strokes in the blocks, but there's no mention of what rods are being used. One post gave measurements for machining the block for clearance, but also stated something along the lines of good luck trying to do this by hand.

Has anyone else had any issues with Eagle rods and a 3.75” crank in the SHP blocks (or any other rods for that matter)? If so, what did you end up doing? Also, if there are folks out there that have grinded on the SHP block, would your best guess be that I could safely grind out another 1/8"-5/32”? If I went slow and didn't put a lot of heat in the bolt, would grinding some off the head of the bolt be a viable option - I'd hate to do that and he have an issue as a result. I've searched for short head rod bolts and gone to the ARP website, but all with the length needed were the same height.

My buddy has spent a lot more on this build than he anticipated but he’s not opposed to taking it to a machine shop and having them do the clearancing if he has to (I’d like to save him some money if I can). However, if there is an H-beam rod with ARP2000 bolts that anyone out there has used that doesn’t require additional or very little clearancing with a 3.75” stroke, I believe he could sell what he has and the difference might be about the same as having a machinist clearance the block. That’s assuming something in the $600 range like the Compstar or Scat “Stroker” rods will work - from the pictures,,, they appear to have a reduced head bolt length but I can’t tell if the bolt pad on the cap is any different from the Eagle rods or not.

Any help will be appreciated.

[af2]

Stroker rods have shorter bolts to clear the block and......Cam

[pdq67]

Did you contact DART and flat ask them what rods clear using a 3.75" stroke crank?? Heck, a 3.75" stroked crank is a stock stroke jobber!!

I would think that they should know.

OR if the block is still new and untouched, send it back and buy one that WILL CLEAR!! I think a, "Little-M", comes to mind but please check me here???

And I don't know if it is possible, but stock type hi-po- 400 block short rod, rod bolts should clear fine IF they can be installed in your present rods?

All just food for thought and as always just trying to help.

pdq67

[randy331]

Is it the standard SHP or the Pro block ?
I've used Callies comp star H beam 2.100" journal rods at 3.75 stroke and they cleared the block and cam with no modifications, but it was the SHP pro block.
I got 3.875 stroke in a Pro block and here and everything clears, but it's 2" rod journal.

I thought they were the same casting with just machining for cam, lifters, and main caps.

I got both SHP and SHP Pro blocks here, I could do some measuring across the pan rail to see.

Randy

[BadSS]

I appreciate the replies.

It is a standard SHP block, 3.75" stroke, 2.10 rod journals. I called Dart and they were not a lot of help in that he said pretty much what I expected him to say - they couldn't guarantee all manufacture's rods would clear. Also, if they were keeping a knowledge bank of what would clear, he either didn't know or wouldn't/couldn't tell me. He did say there was enough room to clearance for a 4" stroke without hitting water, implying that there should be plenty there for me to work with. However, he didn't know what rod journals and rods were being used, saying,,, “that would be up to the builder to make those determinations".

This all started out with me helping a buddy by going through a newly purchased “good” engine with less than 20 passes on it to make sure it was OK. I’m thinking at most a quick hand-hone, re-ring, and freshening up. Ended up the block was cracked and the pistons were worn out – had the crank and rods checked by a local machinist and at least they were good. Or so I thought.

I did read a post from around 2005 where someone said Eagle changed some of the dimensions and older rods might have issues with clearancing, but I put together a 406 with 5.7” Eagle “3D” H-beams back around 1997 and they cleared. Surely these are no older than that, but who fricken knows. This is exactly why I never buy used parts.

For reference, the bottom cap on these measures 3.49” wide, 3.30” wide from outside of bolt head to outside of bolt head, and 1.33” tall from the bottom of the cap (parting line) to the top of the bolt head.

Leaning heavily towards him selling what he has now and buying new rods. Thanks Randy on the heads up with the Compstars, I was thinking they looked good for the money and was hoping they would clear. Not finding any similar measurements like above to compare to what he has – unfortunately there are no speed shops anywhere in the area.

[87v6bird]

I have a set of Compstars I can measure for you. 6" length 2.1" journals. If you'd like to compare to what he currently has.

[77cruiser]

This rod will give more clearance than the Eagles. They're not quite as good as the Compstars though.

https://www.summitracing.com/parts/sca- ... /overview/

[BadSS]

I have a set of Compstars I can measure for you. 6" length 2.1" journals. If you'd like to compare to what he currently has.

Man, that would be great and I would owe you one for sure. EKG

[BadSS]

This rod will give more clearance than the Eagles. They're not quite as good as the Compstars though.

https://www.summitracing.com/parts/sca- ... /overview/

Thanks Jim, but he's going to need something a little more substantial. He's probably pushing things going with the Compstars. EKG

[BILL-C]

I just went through this with a dart shp block. We had to grind block at least .125 to get enough clearance to clear Scat h beams with 3.75 stroke. No problems, just a little time.

[Carnut1]

Sonic it to be sure. I am no help with that block. GM 400 with 5.7" eagles some grinding, GM 350 3.825" 6" eagles a good amout of grinding and plenty of 383's. I would think there would be plenty material but sonic to be 100% sure.

[BadSS]

Yep, Dart didn't say clearanced for steel H-beams, just "steel rods". Sounds like I could man up and start grinding. However, based on what Randy said, it looks like the Compstars will clear if there's no difference in the clearanced area of the Pro and Standard SHP. Hopefully 87v6bird will have time to check the measurements on the Compstars so I can be sure. I'd hate to get him to order the Compstars and still have to grind on the thing. Thanks again for everyone's replies.

[87v6bird]

Here are those measurements I promised.
3.49" Wide Across the cap


3.44 From Bolt Head to Bolt Head


And lastly the document that Callies sent with the rods. I think the "clears with out modification" statement is specifically aimed at cam clearance.

[randy331]

I did some measuring and the SHP and SHP pro measure the same in the area they have relieved for the rods. Looks like they are the same casting.

Not sure what the eagle vs Comp star is, but the Comp star fit with 3.75 stroke, at least they did.

You could order the Comp Stars and compare to what you have before deciding what to do.

Randy

[BadSS]

Thanks Randy for checking on the block differences that's extremely helpful.

Also thanks 87 for the measurements and pictures. I put the picture to scale and made some best guess measurement from the parting line to the top of the bolt and it appears the Compstar is about 1.25" compared to 1.33" for the Eagles, but there is a slight cant to the picture and measuring that way is a little hokey to say the least. 87 I hate to ask after you've already done so much, but if I could ask you, without having to separate the cap from the rod, could you do a best guess measurement from the parting line to top of bolt? If it is close to 1.25", and with Randy's input, I'll be rather confident they'll work.