1973 Rebuild

[Matthew Abate]

Everything I've read says stay below 10:1. If you guys are running higher and don't have any problems, what's the disconnect?

Madkaw, I want to be able to run 89 if I have to by will probably run 91 regularly. Who knows what's going to happen to gas prices next year, and we only have 89, 91, and 93 around here.

Regarding the cam, I'm so not there yet. Next month I should have the brain space to do that research, but right now we're looking at Stage 1.

[Zed Head]

"Stage 1" is a generic term that is only defined by the number "1".  seriously, one grinder's Stage 1 is another's Stage 3.2.  Leon was right I think, talk to a good grinder and tell him your plans.  The good ones have already blown engines up for you learning what works and what doesn't.

The 10:1 limit is another generic recommendation.  Pretty sure it comes from the guys that do just a head or piston swap (ending up with a shaved N42 or N47 with flat-top pistons, or an MN47 on flat-tops) but keep a stock a cam and combustion chamber.  The net result is just a higher CR on an already detonation-prone engine.  A good head porter/combustion-chamber-shaper can reduce the tendency to detonate.

You can spend a ton of study on the topic.  The key is to get the right combination of parts.  You can't pick just one parameter at a time.  It's a system.

[Matthew Abate]

Okay, I had some of my information a little out of whack. Apparently we had not finalized the compression ratio yet and I was using old assumptions. Everyone seems to think 9.85 to 9.9:1 is the way to go, rather than 9.75:1.

I have to figure out where we are going to get our cam, but I know we aren't going to just go big. We want to figure out the sweet spot for low and midrange gains, yes. But we are considering the limitation on valve speed that comes with a big cam and how a smaller cam with more duration can help with that on the top end without killing the dynamic compression. Gotta find the happy medium.

Next steps on this will be getting the head worked over.

[Patcon]

3 minutes ago, Matthew Abate said:

we are considering the limitation on valve speed that comes with a big cam

I would suspect that any street cam you would consider will not be a problem. I can't imagine you will be spinning the engine at high enough rpm's for it to be an issue. The head work necessary to spin above 7,000 rpm's can get pretty intensive. You should rely on some of the folks here like Dizeased who has built multiple engines. Many engine builders haven't built as many as he has...

[Matthew Abate]

Yeah, I tried sending a PM to him but that function seems to be down for me at the moment.

I hear what you are saying about the RPMs. Maybe in the end it won't be an issue, but being cautious until I understand more. Still tons of time and stuff to do before I have to commit.


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[Patcon]

@Diseazd

^^^previous posts

[Matthew Abate]

Thanks. The site wouldn't let me send anything to him for some reason but it is working now.

Read through those posts and don't have the explicit answers, but I'll continue combing through tonight.

Thanks guys.


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[charliekwin]

Back to color, there happens to be a guy in my area who just posted his car for sale.  It's painted an orange metallic, and looks pretty good.  I grabbed a couple screenshots:

[Patcon]

That's a good looking car. Wish the airdam was painted though

[siteunseen]

Those things are so bendable.  I've wondered if paint would stay on mine.  Acrylic maybe?

[Patcon]

If they are prepped properly and scuffed well, add some "Bulldog" adhesion promoter. I think some reinforcement behind them is necessary to keep they from flexing to the road at speed...

[madkaw]

Love everything but that spoiler - no pun intended - . It needs color.



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