2.4 question for T-REX (and others)

[Bartman39]

Have a rather strange 2.4 powerhead I bought (supposed to be a 200hp)... Its for sure a 2.4 since the bore is 3 3/8ths and appears to be a chrome bore as well and is std. in all the bores also. But after looking at pic`s of a 2.4 block it is not a reg 2.4 block...? It looks just like my 2.5 block (after looking at the outside of cylinders)...? The heads are dowel pin type but are for sure 2.4 heads and the exhaust is a 1 piece just like my 2.5 motor... Also its a carbed motor with squirter carbs (have to recheck for the numbers)... It has the 16 amp charging system with red flywheel... I checked compression cold and its 110 on all... Also in the bores of the head I removed it look pretty good, almost new (has that dull appearance of chrome not steel)...?

Anyhow could T-REX or anyone else shed some like on this kinda strange powerhead...? BTW no numbers on the top freeze plug... :( I did alot of searching before posting but if any other questions about it please ask...

[Eagle One]

The later run of 2.4's around 1990 were "Fat Blocks" and had the dowel pin style head surfaces. Most came with the 2.5 style carbs. If it has a 1 piece tuner plate it has been changed as the stock engines had 2 piece units. Nothing strange just a late model. 110 compression sounds close to normal. Check your gauge It should be about 120 PSI with a hot battery.

[YELLOWSS]

post some pics!!!!!!!

[Way2slow on H2O]

Yup, like Noah said, 2.4 in a 2.5 block. We call em "crossovers" from the transition. Luckily it was a quick transition, lol...

Ronnie

[Bartman39]

Finaly had time here are a few...

http://thumb0.webshots.net/t/50/750/6/30/33/2357630330103339220adzOkw_th.jpg (http://good-times.webshots.com/photo/2357630330103339220adzOkw)
http://thumb0.webshots.net/t/65/765/3/99/68/2117399680103339220JjyadG_th.jpg (http://good-times.webshots.com/photo/2117399680103339220JjyadG)
http://thumb0.webshots.net/t/65/765/5/49/48/2313549480103339220usqnIb_th.jpg (http://good-times.webshots.com/photo/2313549480103339220usqnIb)

[Bartman39]

A few more... Also the compression was checked cold not warm and think my gauge is about 20 years old...

http://thumb0.webshots.net/t/50/750/9/82/81/2878982810103339220lxdojy_th.jpg (http://good-times.webshots.com/photo/2878982810103339220lxdojy)
http://thumb0.webshots.net/t/69/569/3/60/70/2251360700103339220nccrpB_th.jpg (http://good-times.webshots.com/photo/2251360700103339220nccrpB)
http://thumb0.webshots.net/t/50/750/6/91/29/2513691290103339220HPnFfz_th.jpg (http://good-times.webshots.com/photo/2513691290103339220HPnFfz)

[YELLOWSS]

i knew they were out there, but never seen one!!!! cool

roy

[dash]

does it have behind the liner boost and finger ports like a 2.5 or is it through the piston like a 2.4?

[T-REX]

Like a 2.4!!

[Bartman39]

T-REX or dash not sure what you mean...? But on the intake side its got ports like my 2.5 does...? Can take pic`s of that are as well since I havent put the head back on...

Also am I looking at this right that its a chrome bore motor...? The bore is real dull as compared to my 2.5 for sure steel bore motor...

[Hottrucks]

ok I was looking at the pics who's Stormi028 and Jamie!!! I clicked what i thought was an album called good time for more boat pics BUT!!!!!!!! WOW

[RONNIE]

get a new ruler and a magnet thats a steel bore motor 2.5. stocker with slots in the sleeves.

[tlwjkw]

XR4 (150) "fat block". Think it was built late '90 thru '91..............T

[Bartman39]

Ok I can go with the idea of a steel bore motor just it just looks rather different in the bores to my 2.5...? But no mistake its a 3 3/8ths bore on any ruler... Also not sure on the 150 XR4 idea either it was pushing a 21' liberator to around 74-78mph (heavy to light load) so dont think a 150 would do it...? I too noticed the slots and that does make for a strange setup (just like my 2.5 also)...

I`ll have better bore pic`s tomorrow...?

[tlwjkw]

Ckeck tha production date. Its gonna be late 90 or 91. All production 2.4
200's were chrome. First steel production 200 was a 2.5. in '91. Its not a an unusal motor . Its a pretty stout 'ole motor. Tha relief slots are a common thing with that motor, 150/175 2.5's and some 2.5 200's.
Sounds like you got one of tha good ones. Ya know how production motors are. One may be a stem winder and tha next one off tha line may be gutless.

T

[YELLOWSS]

i never had any 2.5 that were less than a 260...... had plenty of 2.4 though.. BUT how can a horizontal reed motor be a 150???????? it has to be atleast a 175 right??????

wasen't some of the mercs 175 and 200 that were marked 150 just for the tourney guys.... wasen't the the xr4 xr6 more hp??????
i was running bridgeport with 135 hp decals when i fished...LOL


roy

[T-REX]

in 90 & 91 Mercury wuz Make'in 2.5's, so they used up the 2.4 sleeves left over and put them in the 2.5 blocks(My way ov thank'in, never know what mercury wuz thank'in)...All the 2.5's haz horz fronts, so the lower port 2.4 sleeve's rated 150 would have horz fronts...I have found that on the smaller CI motas(I don't deel wit a lot ov big CI stuff, and no HP stuff) the horz front ain't a huge performance gain(and nun in sum cases)....

The Fat block iz CAPIBLE ov bekumm'in a top perform'in 2.4, but in stock form, it'z no more potient than a 83-89 2.4(and possiblly not az potient..)...BUT tha possibilities are there, with exstended time on the mill and Pincil grinder!!

[Bartman39]

Bore pic`s...

http://thumb0.webshots.net/t/65/765/7/21/89/2309721890103339220ezfPaH_th.jpg (http://good-times.webshots.com/photo/2309721890103339220ezfPaH)
http://thumb0.webshots.net/t/50/750/5/64/79/2877564790103339220zqnouc_th.jpg (http://good-times.webshots.com/photo/2877564790103339220zqnouc)
http://thumb0.webshots.net/t/72/72/1/9/32/2278109320103339220BRHJEU_th.jpg (http://good-times.webshots.com/photo/2278109320103339220BRHJEU)

[T-REX]

Looks like fingerport'd 2.4 ta me!!:thumbsup:

[Rodney Nance]

In it,s stock form they are no stronger than a normal 2.4. But let Junior and Del Eaves pull the liners out of one and chage it from a piston port to a behind the liner motor and you really have something. Back in the old days the rules said you could not decrease the bore size to make a 2.4 out of a 2.5. Junior saw these engines as a way around that rule. Untill the "Weenie Motor" got to be well known I had to show several inspectors the inside of it to prove that it wasn't a downsized 2.5.

[gmjim]

i would like to find out more on these modified fat block motors?
can you explain what they did to these 2.4/2.5 fat blocks in regard to changing out sleeves etc?

[Rodney Nance]

The first step is to pull the sleeves out and do the machine work behind the liners that Mercury didn't do to those blocks. Then you get six 2.4 blank sleeves and cut them to what ever specs you want. Junior put a extra intake port in ours and it worked pretty well. Cut the exhaust chest and modify a set of pistons to flow behind the liners. Put a lot of compression on it and good fuel and done right it will be a strong motor. When we did it any legal 2.4 had a really good weight break and we cleaned house for a couple of years. Every year the different drag boat associations kept putting weight on us until it was pretty much a wash between us and a 2.5. I don't know the rules in Australia but if they use a weight break formula and a 2.4 comes out ahead on pounds per cubic inch one of those motors will be a winner.

[T-REX]

Every year the different drag boat associations kept putting weight on us

Aw Hell...All this time I thunk it wuz them DONUTZ & SWEET TEA:eek::D:D




Tha "Weenie" wuz a lil badazz!!:thumbsup: