Hey all,
Has anyone out there stroked their 390 out to a 410 with a 428 crank? Looking at a complete rebuild for my Marauder and just wondering if I should consider this option or not. What do I need to know? Kind of new at this (as I’m sure you’ved all guessed). I’m not a racer…just an enthusiast looking to maximize HP for my '67 GT.
Thanks,
I have not done that swap, but I think you will have to get new 410 pistons because the 428 stroke is 3.984 and the 390 is 3.784 which would put the pistons 20 hundreds higher , so the new pistons would move the pins higher up in the pistons to compensate for this. Where is Royce when you need him?
I’m curious about this one too so I hope more info comes in on this one. I was interested in building either a 410, or replicating a 406, the seemingly forgotten FE displacement.
You do need 410 pistons, to get a quality performance piston you may need to have them custom made and you will need to have the engine balanced since the 428 is an external balance engine. You may want to look at one of the stroker kits for the FE. Survival Motorsport makes a few combos one is a 445 ci pump gas engine that makes about 450 hp from a 390 with a .030 overbore. They are internally balanced so you can use you balancer and flywheel. (looks stock) Complete kits cost about $1900. to $2400… There are a few quality kits out there now. Just search FE stroker and a few companies come up.
You can do this with 390 pistons. The extra stroke is 1/2 up and 1/2 down. If the block has not been decked in the past typically the pistons sit .040" in the hole. Add a 410 crank and now the pistons sit a little out of the hole. It is a very simple matter for a machinist to mill off the tops of the 390 pistons to use them with a 428 crank in a 390 block. Much cheaper than buying custom forged pistons. Plus you get the advantage of “zero decking” the pistons without having to mill the block.
BTW if you don’t have the 428 crank yet the option mentioned by Islracing is the way I would go. Barry’s kits are awesome.
This is what I was led to believe from other sources as well. Just wanted to confirm here on this forum. I never do anything without checking CCC first. Thank you Royce, and everyone else who took the time. I appreciate it.
Last question…is it worth it? I mean, is the return on investment there? $$ for horsepower…
It’s been probably 20 years, but we did a 428 to 410 conversion. The 428 block was shot, but the rotating assembly was usable. If I remember right, we swapped the 390 pistons onto the 428 rods. I don’t remember which 390 pistons they were, but I think they were just low compression production pieces out of a pickup and we didn’t have to do any modifications. One thing you have to be careful with is the balance. 428’s are not neutral balance like the 390’s are. They are all 28oz imbalance from the factory, and the SCJ version uses an extra “hatchet” weight on the front of the crankshaft, too. I’m just beginning my research into a 428 swap, so there are plenty of people out there that know quite a bit more about the differences.
Is it worth it? There’s actually a bit to getting it swapped over. It’s more than just swapping out the crank. If you take an optimistic (for a street engine) outlook of 1hp per cubic inch, you’re looking at a 20hp gain. I think what you would notice the most is an increase in low end torque. Monetarily, it depends on what your expectations of $/HP are.
…and yes, I’d want to do it!
Anthem75 what are the plans and budget for the car? There’s no replacement for displacement. General rule is 1hp/c.i. for a mild motor but both my brothers make about 1.3hp/c.i totally streetable just a little more money and need the proper setup and premium fuel. If it’s close to the same price I’d go with the 445 kit. You know it all works together and it’s more power. But you need to ask yourself how much power you really want and what the budget is. 2000$ could go a long ways towards alot of other parts if you are only looking to make 400hp anyways
Thanks for the insightful response Caleb. Your last point above is the one that I have to consider foremost. I appreciate your time and advice.
Cheers,
I would never build an FE for any car that I was going to keep without at least 3.98" of stroke. It is a major and noticeable difference in a 390 or a 427. The amount of fun per mile is what I worry about. Dollars take care of themselves. It is an invisible change that costs very little compared to many other things.
CJ heads and exhaust/maybe headers, 2.25/2.5 exhaust system, aluminum intake.
I have some Hooker Super Comp headers on hand that I plan to install already. A new exhaust system will naturally accompany them. The Cat currently has '68 GT heads and an original '68 S code intake. I know aluminum intakes are the way to go. I installed one on my '69 XR7 once upon a time and it ran like a dream. Difference in that case was the engine was a '74 cast, so I didn’t really care about originality. My '67 GT engine however, is a true 390 Marauder (even with the '68 heads and intake, in my opinion), so I am torn about putting an aftermarket intake on it. I am ok with making an exception for the headers (for whatever reason in my head). I even paid dearly to have a factory and date correct Holley carb restored to original condition for it. If I am making little or no sense to everyone, I understand. Just talking out my ass really, trying to figure out what the hell I actually want.
I truly appreciate everyone’s time and advice on this.
67 68 Ford PI aluminum intake or a 67 427 low riser single carb Ford aluminum intake.
The S code GT intake really isn’t very good. Even the 4-barrel truck intake is better. Plus, like all cast iron FE intakes, it weighs a runnin’ ton. Paint it blue if you want an original look, but the upgrade to aluminum is well worthwhile.
My two cents.
You’re absolutely right about the weight. When I took the old one off my XR7, I thought I was going to blow one of my own gaskets! I appreciate your time and input very much. Thank you…
I just checked out the FE stroker kits and was surprised at how low the prices were. Actually competitive with a GOOD small block stroker kit. Now I wish I had an FE in need of some tlc.