250 build advise

Ok.... I'm finally grabbing parts.... but need help on good combo. I have a 78 250 with a 30 over bore and deep smog pistons. already have 3 angle job on a matching head and a 2 to 1 adapter at the moment with a 2100 1.08 autolite and dII ignition.. planing to get a 274/ 274 112* cam. What can I do internally to this w/o a machine shop..... theres not one localy any more. I'm just lost and don't wanna waste time with a bad combo. Car is auto trans and 3.00 rear gear

may B machining needs R done already (piston boars & valve needs)?
A higher ratio rocker?
I guess a direct mount of the 2100 is out of ur DIY ball prk?
Congrats on the DSII...

This is a DD? not "st/strip"?

It's a dd / street... I been trying to figure out the best way to direct mount I know brazing is too risky for a warp. I'm great with DIY just need to have advice so it works out.

U guys have lost pop since 2000, Clearlake (lrgest) only 15K. I think U need a twn of 100K for a machine shop...
Have U cked our 'refference forum' for that (local mechanics &/or machine shops)?

viewforum.php?f=50

Check out this post for some great 250 build ideas Mike is using to solve ths Comression height issue. https://fordsix.com/viewtopic.php?f=1&t=77057

Good luck on your build

I would look at a dual pattern cam since you have a log head. Also a smaller cam might do better. I am running a 274/274 110 on my 250 with alum head.

Howdy sixshooter Maverick:

What is the compression on this engine? Since the engine is buttoned up and you don't want to unbutton, carb and ignition are about all that's left. An adapter with a 2 barrel carb will be a clearance and linkage issue.

Again, depending on the compression ratio, select a cam in the 260 duration range, and a dual pattern, already suggested, is a good idea. BUT----

To install a cam and new lifters, and timing gear you will likely need to remove the head. IF so, check the critical dimensions on the head to determine CR. IF the CR is not at least, 9:1, I'd strongly recommend milling to gain it.

Good luck and keep us posted.

Adios, David

Not knowing the comp ratio is one reason I was thinking about opining it up .. since it's no where close to what it was supposed to be I was going to look at tightening the quench and ccing the head. Looking to run pump gas since its 3.70 a gal for regular here. Want to have it ready for a aluminium head for when the funds come in. I been looking at products to build up the log for a conversion but all the fails have me worried about doing it. I'd like to modify it myself but research and advise is needed

Knowing the head chamber volume is the key element. An OEM 250 would be @ 62 cc's IF it hasn't been milled already and likely at least been shaved flat with the head work that was done.

The 250 with DSII and compatible carb works well with the higher 70's 3.00:1 rear ratio and the grunt-torque of mild built 250. The 2X1 adapter and 2Bbl is good tuning start suitable for D/D and more. Maverick braking and handling may need same tuning attention ...



have fun

.

Howdy Back:

Tightening the quench on a 250 is a major issue on a 250 due to the huge deck height. It involves special pistons, possibly connection rods and block machining. Deck height, measured from the top part of the piston to the deck of the block is typically about .150". When you said the engine has "Deep dish" pistons, which dish, the stock dish with 6.5 to 7 cc volume, or the 13 cc Calif Emmission, low(er) compression pistons? While we are at it which head gasket was use on the assembly? Was the head milled to compensate for the additional thickness? I'm guessing you are getting a headache about now, but as always, the devil is in the details. When you pull the head to add the cam all will be revealed. Measure carefully and write it down.

By the way, the reason I suggest a 260 duration cam was to maintain some of the lower rpm torque and cylinder pressure.

Adios, David

As far as the car it's a 70 mav I did disk brakes and upgraded master Granada 8in with big drum brakes.

As far as the engine its ca smog pistons original 78 ca granada, felpro gasket. going to yank the head to cc the chambers I desperately wanna see this compression ratio. The rebuild was supposed to have flat tops main reason y I just wanna re work doesn't have the skinny pedal pop I want

While you're at it make sure and degree the cam. There's a good chance it's off or retarded if they just lined up the dots and used a later timing set. Could also be why the skinny pedal is limp.

There are a couple ways to fix the 250's excessive quench problem with swapping in different conecting rods and pistons. The Ford 300 / 4.9 rods and a set of custom forged pistons for a more serious performance build up. Or the more budget friendly street Performace build, then the E6 rods from the 2.5L HSC engine and set of off the shelf cast Pistons. see below link. Good luck on your 250 build up

E6 rods from 2.5L Ford
https://fordsix.com/viewtopic.php?f=1&t ... 50#p599153

Piston used with E6
https://fordsix.com/viewtopic.php?f=1&t ... 50#p597415

Would the USC rods be a good match wit the 13cc dish in case I get up the funds for the vi head

Yes assuming you could press off the Pistons and install to the replacement HSC Rods without damaging them, then it would certainly be a big improvement. My 1977 250 Maverick had even more than the earlier 250's (was about .180 down the bore with C.R. Of 8.0 to 1 or less). For an example I will do the math using the stock Ford specs, but you should measure yours when you pull the head. In many cases I have found that the actual measurements are usually considerably more (taller deck) than the stated minimum Ford specs. In talking with one of the Ford engineers FTF, this was done so that if a mistake was made or damage occurred from a bad cutter during its machining at the Ford engine plant there was still enough material left to clean it up without having to scrap the part.

The Ford spec block deck height of a stock 250 is 9.469", this measurement also won't account for I f there was any milling during an engines rebuild.

The Ford USA 250 4.1L Connecting Rod is 5.880" long
The Ford USA 2.5L HSC Taurus Connecting Rod is 5.990" long.
The Ford USA 200 / 250 Pistons have a (CH) Compression Height of 1.50 inches
The Ford Austrailan 200 / 250 Pistons have a Compression Height of 1.530 inches

So a 250 with stock rod and piston combo, the piston will end up about 0.134" down the bore.
250 Crankshaft has a 3.91"stroke, dived by / 2 = 1.955 + Rod length of 5.880" + a Piston CH of 1.50" = a combined total of 9.335 - the Block Deck Height of 9.469 gives us a piston .134 down the bore. Now with the tipical FelPro head gasket (excellent) of .050 thick plus the .134 down the bore we have Quench Distance of .184

When you substute the 5.990 2.5L rod (that's .110 longer) with your 250 piston, the piston will now only be 0.024" down the bore.This will help a lot with your quench, and increase the compression ratio, plus the stock 250 rod to stroke ratio changes from 1.504 to 1.532 also another slight benefit. Now we have a much better Quench Distance too, .050 plus .024 = .074. If you then were to use the Austrailan Spec Piston too with its 1.530 CH this would bring the Quence Distance smack dab in the middle (at .044) of the more ideal range for Quench distance (.035 to .050) which helps in the fight against detonation when you start raising the compression ratio of a US 250 engine. And if you wanted too you could also use the Victor head gasket at .045 thick to lose another .005 of Quench, good luck

Thanks for that run down took away 1/2 my migraine.... what's a good filler to DIY 2v conversion good with files and grinders... haven't seen a write up that's detailed enough for me to jump in

Back in the day I used the JB Weld to do some cast iron repairs and also Devcon. As to what's the best I think there are going to be some better Epoxy's available see below for a group of posts discussing this. There have been a couple site members that had trouble with there Epoxies coming loose on their DIY 2V conversions I didn't see how or what material they used or how they did the filling prep so can only speculate as to what happened. First off the part needs to be very very clean of all dirt, crud, oils, ect. The part may also need to be baked after it's been cleaned. And also prepping the cast iron so that the Epoxy can really grab to it (much like if you were doing auto body repair with filler, See below for more info on techniques to repair heads and blocks. I do think that much or all of this job can be done by a DIY with a minimum amount of tools and a good skill level.

Personally I like to weld things togeather such as the 2V direct mount you are wanting to do, but it's not for everyone and it takes quite a high skill level or from years of practice. I hope to do Log head mod (remove the log and then weld on a flange) to create a budget Austrailia 2V style head that can use the many available bolt on Austrailian or V.I. Aluminum intakes. That is once I able to acquire a suitable head core and an intake to work with. Good luck on your 250 build.

Epoxy' s for Head Repairs and Porting
http://www.speedtalk.com/forum/viewtopi ... y&start=30

Methods to Make Block and Head Repairs
https://www.enginebuildermag.com/2015/0 ... ad-repair/

I appreciate all the help. Sad part is the early 300 rods are just as hard as the 2.5hsc rods..... I'm prolly going to try and find more specs on the aussie pistons and crunch the numbers on 2 or 3 set ups I don't wanna build a engine that I can't upgrade later to the aluminum head. Thought about just swaping rods out mute there's a high chance of destroying a piston so who knows.

six shooter maverick":tysblg8t said:

I appreciate all the help. Sad part is the early 300 rods are just as hard as the 2.5hsc rods..... I'm prolly going to try and find more specs on the aussie pistons and crunch the numbers on 2 or 3 set ups I don't wanna build a engine that I can't upgrade later to the aluminum head. Thought about just swaping rods out mute there's a high chance of destroying a piston so who knows.

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If you can find someone with a Kent-Moore piston pin remover/installer. You can change rods without damaging the pistons. This tool supports the rod so the piston isn’t under any pressure or contact. I picked one up on eBay. A lot of GM dealers had them. Some machine shops too.

six shooter maverick":1sbrkdy6 said:

.... what's a good filler to DIY 2v conversion good with files and grinders... haven't seen a write up that's detailed enough for me to jump in

Click to expand...

U know its a fill, mill, fill, final mill process then..

If ur chuckin the head in a few mi/yrs Y not a log-ectomoy?
Done the right way (some total, some partial DIY) U may never go Ci/Vi alu...