LA 360 budget build ideas
What ^^^^ he said
The Scr we build to is to achieve a Dcr which is very much affected by the cam, and the whole thing has to run on pump gas, without pinging. It's no fun to take the engine back out to lower the compression, nor even just taking off the top.
This is why in an earlier post I wrote MINIMUM Ica of 61* for 9.5Scr IIRC. That 262 is the SMALLEST cam I would run in your combo with iron heads. It will make a good amount of pressure (was it 155psi?) for iron heads and pump gas. The Dcr that goes with that is ~7.8. You can run perhaps as high as 8.0 but yur gonna have to have all yur ducks in a row, and you may be stuck running best pump-gas ALL the time, which gets kindof pricey for a DD type of cruiser.
If you stay below 7.8 Dcr, you can vary your other engine parameters any way you want to and it should be fine with mid-grade gas at 800 ft elevation. As soon as you try to get over 8.0Dcr with open-chamber iron heads, yur looking for trouble.
When I ran that small cam at 11.3Scr, with closed-chamber alloy heads, the Q was ~.028, and the Dcr was 9.2 . That is the biggest, OK one of the biggest, advantages of the alloy heads. But IMO, that is overkill for a combo like what you are contemplating. Alloy heads will destroy your budget. and I question their use for a cruiser, that is seldom gonna see rpm because of the cruiser gears. You will likely be better off sticking to iron.
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But I suppose a closed chamber iron head might work, but getting the compression LOW enough with what's out there, to run with a cruiser-cam, well that's another can-O-worms.
the next bigger size cam would get you to a Dcr of 8.0 at about 10/1 Scr....... which would be a total chamber volume of
[email protected] bore. With 2.5cc in the decks and 5cc eyebrows and a tight-Q gasket of .028 being about 4.8cc, that totals 12.3cc leaving 70.4cc for the iron closed chamber heads. I don't think that's doable, so then the .028 gasket has to be sacrificed, in favor of the .039 Fellpro, and the new closed-chamber iron head comes to ~66.4cc . Doable maybe but the Q is borderline high at .051.... risky business.
So then if we add another cam size, we can make it work, but now the Dcr is down to 7.8 again, and the Ica is up to 67*, and the pressure is back to 155, and it just become very frustrating to find the sweetspot.
Easier it is with the stock iron heads and no Quench. And you can mill those to make whatever you want Scr, as long as the Quench remains over about .080, which should be doable.
Rumble said;
You’ll have to dial back the timing in order not to ping even with 93 octane and you’ll end up loosing a lot of power.
One of the fastest ways to lose power, especially between stall and ~3600, is having to compensate with retarded timing for too much pressure. Having to gas up with best gas, just to stay out of detonation in this tiny window really sucks. She might be fine until 80% throttle, and over 3600; but you gotta gas up with best gas ....... just in case you floor it at the wrong time. It's better to give up some pressure, and maybe delay the secondaries.
Part of the problem is the 3.23 or similar gear and the lo-stall, which will force your engine, even in First-gear, to not get to 3500 until ... what was it? I think 33mph? Sounds about right. And with a cruiser-car, your engine might spent 60/70/80% of it's life in that, stall to 3500rpm window, so you just gotta play it cool in the pressure department.
Hope that helps
Oh I guess I didn't finish the comparison; Zero to 3500/33 mph at WOT might be say 4 seconds. At an average rpm of 2800rpm, that would be say 188 revolutions . If she's detonating because of the load, and you can't hear it; firstly the power will be down, and secondly; the KBs are pretty tough, but they will eventually break.
But if you installed 4.30s, 3600 rpm becomes 24mph. Your new time from zero to 3600 might be a second faster, say 3 seconds at an average of 2800 is 140 revolutions, but the load will be reduced 21%. So maybe she escapes detonation. .
Or you could just install a 3000 stall convertor, ant the tires will light up reducing the load even with the 3.23s, and thus escape detonation in that way
Another thing you can do is to install a 2bbl, lol, and reduce the load in that way. But all/most, of these things cost money, destroying your engine budget.
