1977 2F motor (1 Viewer)

[Squidly]

Good evening folks. It’s been a while since I’ve been on the forum and longer since I last posted.

I’ve recently retired and have more time available to spend on my truck and am looking for some information that I found here a couple of years ago but neglected to save or bookmark It and have been unable to find since.

Specifically I’m looking for factory head thickness on a 61030 casting and the points from which the thickness is measured and the maximum amount of machining the head can tolerate before it’s no longer useable. Allowable compression would be a bonus.

Background: the head was machined a few years back for the second time as part of an engine overhaul. Neither instance of machine work recorded the amount machined so I really don’t know what I have in terms of available head thickness/compression. The last rebuild installed MAF forged pistons at the max overbore. The engine will be compression checked next week prior to head removal.

The engine is running the Affordable TBI setup and the DUI distributor. Even with base timing retarded to stock (and less than stock), the engine detonates with 93+ octane. As you are aware, it’s kind of pointless to retard the timing to prevent detonation. Kind of defeats the purpose. The engine makes no power. Aside from the info I’ve requested does anyone have any thoughts on a solution?

Thanks for any help provided.

 

[Cruiserdrew]

So the '77 motor has an open chamber head, and is supposed to have domed pistons to compensate. Are the MAF pistons domed? What's your compression? If there's a mismatch between head and pistons, I think the compression test will reveal it.

If the pistons are flat, an FJ60 head will restore your compression and sanity.

 

[Squidly]

So the '77 motor has an open chamber head, and is supposed to have domed pistons to compensate. Are the MAF pistons domed? What's your compression? If there's a mismatch between head and pistons, I think the compression test will reveal it.

If the pistons are flat, an FJ60 head will restore your compression and sanity.

Yes the pistons are domed. Looking forward to getting this behind me.

 

[65swb45]

Something else doesn’t sound right here. If the engine isn’t making power AND it is detonating, I have to wonder if you even have good compression, or if the timing is over-advanced to make up for lack of compression.

I seldom do this, but I am going to answer your question with a question: what is your compression at stock timing?

 

[Squidly]

It’s going into a friends shop tomorrow. I’ll post compression numbers as soon as I get them. Much thanks!

 

[rflegal]

I would be interested to see a pic of your pistons. I have Manefre's, forged high-comp, 040 over from a 2002 rebuild. They ran great i my '76 before I lost some rod bearing and oil pressure. Like you I was also running Holley Projection 2-Di, but now 2300 sniper. DUI as well. Should run great, curious.
Stupid question, but is the dizzy set up right?

 

[Squidly]

Went to run the engine to warm it for cylinder pressures and heard a bad squeal. Found the alternator idler sheave cocked and the bolt finger tight.

The large diameter on the bolt is a slip fit in the inner race and it appears as though the spacer is meant to lock the inner race when the bolt is tight. A couple of questions: is the bearing supposed to be a slip fit or a press fit and I’m guessing the bolt needs to be Loctited and torqued. If slip fit is correct can someone provide the torque value? I ordered the engine FSM from SOR last week but it hasn’t arrived yet. I appreciate the help. Btw, the bearing is fine and the sheave is in good shape.

 

[Cruiserdrew]

I think that bearing normally has a cover over it that is fitted into little tiny clips on the inner pully. I know that I replaced that bearing by dremmling out the clips, and then tiny tack welds to put the cover back on. So you may be missing a bit of thickness. I don't really have time to go look, but I'm pretty sure about the set up.