Engine Rebuild???

[StreetHawk]

Well I am having to replace my front cylinder head due to stripped out spark plug threads. So I'm banging around the idea of doing a slight rebuild. I'm no looking to build it wild (82mm over bore vs 79mm stock) 696cc. Seems like all the kits are for 82mm. I'm thinking like 80mm 663cc. I can find Wiseco and JE 80mm pistons and wonder if I can use them and if so do I use the stock rods or find something aftermarket. I know Hord uses Carrillo H beam rods. JD Hord said the pistons were not available at this time.

Or do I just put on the new/used head and go on?

rob

[ParcNHawk]

It's all in how much you want to spend.

Upgrading the pistons means also having the cylinders machined to match the bore. That's extra work and money.

And that's rebuilding the whole top end instead of just ½ of it.

Then what's the point without getting a better matched set of cams and oversized intake valves.

So the parts and labor add up.

You are in for a replacement head and some gaskets right now. A used head is going to cost a fraction of what just the pistons are going to cost.

[StreetHawk]

Yeah the used head was 125

Got a full gasket kit coming 100

[Ziggy]

Have you considered using a HeliCoil thread insert.
This is a reliable alternative to replacing the cylinder head.

HeliCoil Catalogue.pdf

[StreetHawk]

I'm already down the rabbit hole!

I'm in night school learning performance engine building so I understand all the process involved in putting in over sized pistons and so on. It's just that every kit I see is for 82mm bore (696cc) and that makes it higher compression and less reliable. Im either gonna just hone the bore and put it back stock fresh or if I can get a smaller bore like 80mm which takes it to a 664cc and a mild cam for a small bump and not as highly strung.

20220627_210319.jpg

Found a slight issue with my stock cam too... looks like it's pitted or delaminated. So I will be looking for a replacement cam or... $$$ for 2 of Hords.

20220627_211252.jpg

Rob

[riot]

It's just that every kit I see is for 82mm bore (696cc) and that makes it higher compression and less reliable.

Within reason, higher compression is 100% all upside. Higher compression is directly related to Otto cycle efficiency and therefore power (which is really the point)!

The only reliability issue you might run into is detonation which:

• Is unlikely in the common CRs available 11:1 or 12:1
• Is easily mitigated by using premium fuel
• Should it arise, can be completely solved by altering timing

The stock hawk at 9:1 or something is quite off the mark for performance. Increasing the CR would be good if you're down the rabbit hole already

[6]

Within reason, higher compression is 100% all upside. Higher compression is directly related to Otto cycle efficiency and therefore power (which is really the point)!

The only reliability issue you might run into is detonation which:

• Is unlikely in the common CRs available 11:1 or 12:1
• Is easily mitigated by using premium fuel
• Should it arise, can be completely solved by altering timing

The stock hawk at 9:1 or something is quite off the mark for performance. Increasing the CR would be good if you're down the rabbit hole already

Throw some JB weld on them pistons and raise it right up