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lsugymrat24 08-10-2018 08:32 PM

Low rpm 390 stroker advice
 
I was going to install a bunch of goodies on the 390 FE engine of my 1966 galaxie (heads, cam, intake, etc). However the car has around 140,000 miles and it sat unused for the last 15 years so I’m now worried about the bottom end of the engine as well (bearings, piston rings, seals, oil pump, etc). I would send the car to lykins or my427stang, but they’re too far away so I plan to pull theengine and send it to a local builder. Since I’m looking at new bearings and such, I’m now contemplating the jump to a stroker kit from Barry at survival motor sports. I’d like to get some feedback on which kit would be best for my application and why.

Here’s the info for my car...
1966 Galaxie 500xl 2 door convertible (4400lb car)
390 ci FE motor stock economy 2bbl listed at 9.5:1 compression
factory 3 speed cruiseomatic with factory stall converter
power brakes & power steering

New stuff...
edelbrock performer RPM dual plane intake
Summit racing 600cfm 4bbl carb with annular boosters
FPA shorty headers
2.5" mandrel bent exhaust with x pipe and dynomax free flowing mufflers
Edelbrock aluminum heads with CJ valves
Stock valve train with POPs heavy duty shafts
Carter street pump mechanical fuel pump
3.55 gears
Pertronix distributor with Flamethrower III coil, performance recurve, rev limited at 5500 RPM
Custom lykins flat tappet hydro cam. Without giving away too many details, the cam is around [email protected] lift, 108 lsa

GOALS…
Street/highway car that will never see the track
Low end grunt from idle to 5500 rpm
Run on supreme unleaded pump gas
hoping for 340hp if unstroked or 400hp if stroked
Snappy throttle response both up and down
Outperform 428 CJ specs

Everything was spec’ed for the engine to stay as a 390 so Does it make sense to stroke the motor given the rest of my specs?
If so, should I use a 4.125 or 4.25 stroke? Are there pros and cons to either?
If the cylinders aren’t scarred, is there any reason to overbore the cylinders? I’d like to stay away from this if possible.
Is there anything else to worry about if I decide to have the stroker kit installed?
I kinda like the sound of the 4.25 stroke and 4.06 bore to make a 440 stroker. Thoughts?

Yadkin 08-11-2018 10:10 AM

Re: Low rpm 390 stroker advice
 
I went through this with mine three years ago, similar goals. My car is also 4400# and I have 3.00 gears.

I went with an RV type hydraulic roller cam, PQ adjustable rocker set and custom length push rods. I went through several sets of lifters before finding one that worked- Lunati Voodoo. The roller gives faster valve lift so more area under the curve; basically turning a 390 into a much larger net displacement.

Compression is 9.7:1 and I use 93 octane pump gas with no problems whatsoever.

Follow Rabotnik's advice on oiling modifications. He says use 0.060 - 0.090" restrictors to the heads. Go on the low side.

I went with a FAST throttle body fuel injection setup which necessitated the single plane intake, so keep that in mind if that is on your future wish list.

I have Sanderson headers- the only brand I found that would fit my unibody car with the fat spring towers. With your full frame car you have more options. I also have 2.5" dual exhaust, H pipe, and Borla mufflers. I had Magnaflos but they droned at speed so I changed them out. I also have Hushpower glasspack style in the rear acting as resonators. The car is quiet at idle but roars when you push the throttle.

The car isn't a rocket ship with the 3.00 gear but it is still very quick off the line. My ass-dyno tells me I'm at about 50HP over the stock 300.

My most recent mod was an AOD. At 70MPH the RPMs drop from 2700 down to 1800 and I have plenty of torque to climb moderate hills without downshifting. On two lanes I can tool around at 1400 RPM which is great fun.

My427stang 08-12-2018 07:08 AM

Re: Low rpm 390 stroker advice
 
First, no reason not to go 4.25 stroke if you are spending the money. The pistons are very stable and no issues with balancing or longevity. In fact in one of my own builds, I have 12 years and climbing with no measurable leakdown or issues of any kind. I average a 100 mile drive every other weekend with the engine, the other stroker is not as "experienced" but behaves the same way

Second, no reason to bore if you have a good bore, however, nobody has a good bore unless you have taper checked with a torque plate and previously honed or bored with a torque plate. Many many guys get away without doing it, but it is the difference between knowing it's right and hoping the cylinder doesn't distort, and they all do distort

You don't have to go 4.08 though, I see you are working with Brent, he is one of my closest car buddies and he can set you up with a smaller overbore that gets you to a straight cylinder. If you don't believe me, ask him about using your current bore, but my guess is, he already recommended you didn't.

Of course the compression needs to match the cam and it will be a slightly different piston with a 4.25 stroke than it will with less stroke, but again, no reason to go stroker without going all the way

In fact, just trust Brent, he is real sharp, he will tell you exactly what will run on pump gas because he and I use the same techniques and BS daily, he knows what he is doing.

My recommended checklist
- 4.25 stroke, internally balanced
- square deck the block to the mains using a 10.160-10.155 deck height
- Run a 1020 gasket for good quench
- Spec piston based on cam events and deck clearance (Brent can do this in his sleep, but happy to help)
- fit desired piston to bore (hone or bore with torque plate)

I do think you should run a 750 carb though, but the 600 will do OK, just flatten out real quick on top, especially with the annular boosters, thats a very small carb even for a mild stroker

As far as your goals

Street/highway car that will never see the track - Easy

Low end grunt from idle to 5500 rpm - Also easy

Run on supreme unleaded pump gas - No need to go that fancy, talk to Brent, if DCR at about 8:1 using his method, it'll run on midgrade all day long and regular in a pinch

hoping for 340hp if unstroked or 400hp if stroked - 440+ stroker in that combo will likely exceed your goals and be nice and mellow (if you go more carb, will likely meet your goals with the 600)

Snappy throttle response both up and down - Snappy is an understatement, the 440+ inch FE will be light switch on and off, and chug down to where you can count cylinders

Outperform 428 CJ specs - Also easy, I would say "outperform any factory FE ever put in a production car (less a Cobra due to weight)" :)

lsugymrat24 08-12-2018 10:59 AM

Re: Low rpm 390 stroker advice
 
Thatís great info!

You are correct. I had sized the carb based on keeping the motor as a 390 and a 5500 rpm max. When I plug 440 cubes into the equation, the calculator says 700cfm on the nose. Unfortunately I bought the carb from summit over a year ago. Itís unused but thereís no returning it now. I guess if I look on the bright side, with an undersized carb, Venturi effect causes increased air intake speed and throttle response increases as well, correct?

My427stang 08-12-2018 11:31 AM

Re: Low rpm 390 stroker advice
 
Quote:

Originally Posted by lsugymrat24 (Post 1629569873)
Thatís great info!

You are correct. I had sized the carb based on keeping the motor as a 390 and a 5500 rpm max. When I plug 440 cubes into the equation, the calculator says 700cfm on the nose. Unfortunately I bought the carb from summit over a year ago. Itís unused but thereís no returning it now. I guess if I look on the bright side, with an undersized carb, Venturi effect causes increased air intake speed and throttle response increases as well, correct?

Well, sorta, with a annular booster and a small carb, you'll likely find it will go very rich on top because of those very reasons and it's tough to manage high speed air bleeds to respond in the mid range if you kill it for high end. It's a bit of a misnomer that a small carb will respond faster, that is only if the car has such a large carb that it cannot provide enough signal to the boosters. Anything less than a 750 you'll likely be chasing top end tuning problems and to a lesser extent may have a tough time adjusting the primaries to stay out of the transition circuit without a lot of secondary idle.

If you are doing a stroker, I'd put it for sale and get a 750 or call Summit and see if there is anything they are willing to do. I think that would be a desirable carb for a small block guy or stock 352, 360 or 390

FWIW, I run a 1000 cfm vac sec Holley on my 445 in a 4x4 truck (basically an 850 vacuum secondary with an HP chokeless body, Holley made them in the early 2000s) with 33 inch tall tires and 3.50 gears and it responds immediately and is very well behaved. That's a 4x4 truck, it's as heavy as anything else out there

lsugymrat24 08-12-2018 01:36 PM

Re: Low rpm 390 stroker advice
 
Bummer. I spent months reading articles and forums and sizing charts before deciding on that summit carb. Closest thing I could find to the famed autolites that the older guys rave about. Horizontal gasket above the fuel line so no leaks. Annulars to mix air to fuel ratio like fuel injection. Old Holley design with new bells and whistles.

Well if I decide to go with the 440+ stroker kit and the 750 cfm carb, should I stick with the summit annular type? Or should I look into something else?

My427stang 08-13-2018 06:23 AM

Re: Low rpm 390 stroker advice
 
Quote:

Originally Posted by lsugymrat24 (Post 1629569877)
Bummer. I spent months reading articles and forums and sizing charts before deciding on that summit carb. Closest thing I could find to the famed autolites that the older guys rave about. Horizontal gasket above the fuel line so no leaks. Annulars to mix air to fuel ratio like fuel injection. Old Holley design with new bells and whistles.

Well if I decide to go with the 440+ stroker kit and the 750 cfm carb, should I stick with the summit annular type? Or should I look into something else?

So, I really like the garden variety 3310s on a mild stroker, although I assume you'd want one with electric choke. I think people get way too caught up in the annular booster stuff and the leaking issue. I just don't see carbs leak like that. However, if you want to, you could go with the Summit 750 carb, Brent has great luck with Quick Fuel. I would just stay away from the Street Avenger series, I have seen issues with the transition circuits on the 670 and 770 cfm versions.

In the end, the carb decision is not that big of a deal, with a good ignition curve, a well-built engine, pretty much bolt the right sized quality carb on and go. I just think yours is too small for the planned build.

lsugymrat24 08-14-2018 03:29 PM

Would it be better to rebuild and stroke the 390 that’s in the car or purchase a 428 service block and stroke that guy? The 428 could easily stroke to a 460 which has me salivating but is the 428 service block like looking for a unicorn these days? If the 428 service block is the way to go, where would you suggest buying the block?

lsugymrat24 08-14-2018 04:37 PM

Re: Low rpm 390 stroker advice
 
I just stumbled on them on the Craft Performance website. $2000 for a block. Not sure what these services are worth but For that price the block is...
Baked
Tumbled
Crack Checked
Tapped
Bored and Diamond Honed w/ Torque Plates
Deck Height Blueprinted
Line Honed
Lifter Bores Honed
Oiling Modifications
New Cam Bearings and Freeze Plugs Installed
Prepped and Painted for Assembly

My427stang 08-14-2018 05:32 PM

Re: Low rpm 390 stroker advice
 
Quote:

Originally Posted by lsugymrat24 (Post 1629569939)
Would it be better to rebuild and stroke the 390 thatís in the car or purchase a 428 service block and stroke that guy? The 428 could easily stroke to a 460 which has me salivating but is the 428 service block like looking for a unicorn these days? If the 428 service block is the way to go, where would you suggest buying the block?

They are out there, I just picked up a 428 with a std/std 1UB crank and a std bore block, I am going to build a 462 out of it. One of these days I should sell the crank and rods LOL, I don't do much stock stroke stuff anymore

I wouldn't advise buying an overbore service block though, the service blocks were worked pretty hard and usually don't have a lot of cylinder wall to go over .030

lsugymrat24 08-16-2018 06:20 AM

Re: Low rpm 390 stroker advice
 
Went with the recommendations. Sent the 600cfm carb back to Summit and ordered a Quick Fuel 780cfm SS-series. better adjustability with dual billet metering blocks and adjustable secondary without having to swap springs. should cover top end performance. Should I be worried about dialing in at low 1800 rpm stall speed for the stock transmission and 108 lsa cam?

I've been thinking really hard about the stock transmission. the original plan was to mildly modify the 390 and rebuilding the 3 speed cruiseomatic. now that I'm going with a 440 engine and exceeding 400hp, will the old FMX be ok or should I be looking at a new C6? I would like to save some money by keeping the old FMX but does it make sense?

My427stang 08-16-2018 07:52 AM

Re: Low rpm 390 stroker advice
 
Quote:

Originally Posted by lsugymrat24 (Post 1629570015)
Went with the recommendations. Sent the 600cfm carb back to Summit and ordered a Quick Fuel 780cfm SS-series. better adjustability with dual billet metering blocks and adjustable secondary without having to swap springs. should cover top end performance. Should I be worried about dialing in at low 1800 rpm stall speed for the stock transmission and 108 lsa cam?

I've been thinking really hard about the stock transmission. the original plan was to mildly modify the 390 and rebuilding the 3 speed cruiseomatic. now that I'm going with a 440 engine and exceeding 400hp, will the old FMX be ok or should I be looking at a new C6? I would like to save some money by keeping the old FMX but does it make sense?

If it was my car, I'd likely do it in steps. The carb is smart, and a better match for a 445 or 462.

The tranny may not hold the power over time, but remember as a street car, the tires won't hold all the power. So I would say try it, worse thing, you don't like it and start a C6 conversion

As far as the converter, I also wouldn't worry about it, especially if there is a potential to go C6 later, the cam will likely idle low enough to live with it, and when you do want to horse around, the 1800 stall will be higher than that with a stroker behind it. Stall speed is affected by power, and the original rating was likely with a pretty anemic motor.

lsugymrat24 08-16-2018 07:05 PM

Thanks again Ross. So far you’ve talked me through dissy recurve, intake, headers, exhaust size, rear end gearing, heads, valve train, and now carb, stroker kit, and transmission ideas. The only thing better would be if you were in Baton Rouge so you could do the engine build. Lol. Thanks again!

lsugymrat24 08-24-2018 12:01 PM

1 Attachment(s)
Not sure if this will be popular or not but I may use this thread to track progress of the stroker. New carb. 780cfm. Vac secondary

My427stang 08-25-2018 06:27 AM

Re: Low rpm 390 stroker advice
 
Quote:

Originally Posted by lsugymrat24 (Post 1629570327)
Not sure if this will be popular or not but I may use this thread to track progress of the stroker. New carb. 780cfm. Vac secondary

That is certainly pretty huh?


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