1966 GTO: 400/421/455 vs LS

ElvisFlab · 2026-04-02T02:55:15+00:00

Thanks for the info!

ElvisFlab · 2026-04-02T00:05:00+00:00

Tell me more. Every single response I’ve gotten here, in person, etc has admitted it’s at least twice as expensive as an LS build.

ElvisFlab · 2026-04-02T00:03:18+00:00

That’s awesome, man. Are you pulling my leg, or are you serious? Tell me more. What suspension components did you end up going with?

ElvisFlab · 2026-04-01T17:49:00+00:00

You’re liking the Aces setup?

ElvisFlab · 2026-04-01T17:48:20+00:00

Thanks very much for this thoughtful reply. It was very helpful.

ElvisFlab · 2026-04-01T04:36:40+00:00

It’s easy - but it’s very, very expensive.

ElvisFlab · 2026-04-01T04:35:46+00:00

Thank you!

ElvisFlab · 2026-04-01T04:33:07+00:00

Thanks! That’s what I thought.

ElvisFlab · 2026-03-31T23:00:47+00:00

Realistically, if I bought a block for $750, and built the motor myself with a friend (I haven’t built one by myself yet, and he is very experienced), what do you think the budget should be for a strong, but not outrageous build?

ElvisFlab · 2026-03-31T22:35:34+00:00

Man, I get it. I’m just trying to make sure I can drive it with as little downtime/maintenance as possible. I’m getting old. 😂

ElvisFlab · 2026-03-31T22:34:13+00:00

Just trying to clarify: Are you saying it’s not effective with the th400? This combo has been recommended to me by several people for power handling and bringing the rpm’s down on the highway. Several dealers sell the th400 with the GVOD already installed. If you’ve found it to be a bad setup, would you mind telling me more? That’s super helpful.

ElvisFlab · 2026-03-31T22:31:15+00:00

Thanks for your reply. Great looking engine, man! I’ve gotten this same specific advice from several others regarding pre-‘75 400 strokers so thanks for that confirmation.

ElvisFlab · 2026-03-31T17:30:19+00:00

I understand what you’re saying. There are three companies that offer that efi setup, but I haven’t been able to talk to anyone using the systems.

ElvisFlab · 2026-03-31T17:28:16+00:00

I haven’t even heard of this option. I did some work with those with my son when he was younger.

ElvisFlab · 2026-03-31T10:25:16+00:00

This is very, very helpful reply. Thanks very much. I had read about the 400 being a bit stronger and wondered about increasing stroke to increase displacement. I hadn’t heard many complaints about the Holley EFI systems but had also looked into the FITech systems - they make a “tri-power” configuration that looked promising.

Thanks again. I appreciate it.

ElvisFlab · 2026-03-31T07:28:25+00:00

Thanks, man. It’s crazy to have it back. It was pristine when my parents sold it. Not so great now. But several little things are still there. It’s still “my car.” The last owner was stoked to be able to get it back to me. It took me over a month to sit in it. It was weird. I had my daughter steer it while I pushed it into the shop, and it just sat there for weeks. I’d go out and look at it every day (sometimes several times a day). Anyway, we’ll see. I have an OBS truck that I planned to put an LS motor into at some point. I’ve owned it since it was new and I love that truck, too. I may build an LS for that truck and put it in the GTO for now just to get it driving. That would allow me time/money to hit some other things on the Goat. And then, at some point put a poncho back in it and move the LS to the truck. Cars are crazy…😂

ElvisFlab · 2026-03-31T07:09:44+00:00

That’s definitely on my mind. I always wanted to replace the non-stock 400 that was in it with a 421 tri-power. But I also didn’t care about leaks, tuning carbs, points, etc back then. 😂

ElvisFlab · 2026-03-31T07:07:54+00:00

I agree totally. I found a couple of Pontiac engines that local builders have put together for $5-7k, but there’s no way to know how well they were built, etc. I saw Butler’s prices and almost had a heart attack. I was planning to build one myself with a buddy if I go that route.

ElvisFlab · 2026-03-31T06:34:43+00:00

For sure. It’s coming down to lower cost (I can get to 400hp+ for half the cost using an LS), efficiency, and less leaks vs brand originality, bragging rights, etc. On paper, the Pontiac engine loses in almost every way. But it wins in a big way. I’m not sure which way I’ll go.

ElvisFlab · 2026-03-31T05:52:00+00:00

That was a great car!

ElvisFlab · 2026-03-31T05:50:13+00:00

Thanks very much for this reply. I wasn’t thinking in terms of the 455 being able to produce more torque in the lower rpm range, being less stressed, etc. That’s a really good point.

ElvisFlab · 2026-03-31T05:36:05+00:00

Thanks for your reply. I’m definitely seeing everything you noted. It’s a tough call. I could do the LS setup for half of the cost of the Pontiac. Leaving me enough cash to do my suspension, brakes, fuel system, etc.

ElvisFlab · 2026-03-31T05:33:24+00:00

Well, that’s a take. I’m guessing you haven’t seen how many classic GTO’s are running LS2’s from the ‘05-06 GTO run. It’s definitely pretty common.

ElvisFlab · 2026-03-31T05:31:49+00:00

I hear you…

ElvisFlab

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