Do I need to change pistons from the TRW-L2465F30 ones I have now to accommodate this build? If so then to what? And yes I’m on a budget, so nothing to exotic ;) .

Also does 1ml = 1cc? If so then the heads are 122cc. If not have to do them again

454 +.30
781 heads 2.19 & 1.88 122cc
Lunati cam (402a3lun) +spring kit
Air gap intake 750 vac (have a 750double pumper as well)
HEI + MSD6AL and a blaster coil
Stock rods
Stock crank +.20 +.20
Cloyes true roller timing chain(trying another)
200r4 or 5spd (not sure yet)
3:73 gears (12 bolt posi)
28”tires
Exhaust is 3” to muffler and 2.5” mandrel bent tail pipes

Is there anything I have over looked trying to piece this together.

Goals are 14mpg and a 12.5 time slip in street trim (through the exhaust and street tires)

Originally posted by BLT4FN:

Lunati cam (402a3lun) +spring kit
Are you sure that's the part or is it 40203? It's so hard to look up parts on the Lunati site since it got changed....if it is 402a3, what are the specs of this cam, just out of curiosity?

276 284 243 251 0.586 0.600 0.345 0.353 110LSA 104ICL
402A3LUN

it is the UD Solid 276/284 110LSA

Shaun,

1cc=1ml.

Your piston will yield about 9.8 to 1, with those heads. They are closed chamber pistons though, which should be ok, but there can be interferance with the dome on the edge of the dome near the intake valve. You HAVE to check for this when you mock up the motor.

Oh yeah, forget the tranny choices. Not going to work for you.

I dont think 14 MPG is gonna happen, especially with the 3.73's. JMO

If you haven't installed rear gears or plan to re-do the rear, have you considered the Richmond 5/Doug Nash 4+1 transmission? You could get a good launching 1st gear, 2,3,4 gear spread to match your combo and something like a 3.08-3.31 rear gear so that when you're in 5th you'll have highway gears but still be able to haul a$$ in 1-4th.

i think you can do the mid 12's with a smaller and more friendly cam.....

454 .030 over
10 to 1 motor
233/239 @ .050 cam .548/.551 lift with 1.72 rockers,111 lobe center
rpm intake
750 VS
hei,msd6al
stock bottom end,windage tray
port the heads (clean up runners and short turn radius)

with 3.73 gears and th200 tranny

with a very good tune

look for mid 12's at 108-109 mph thru the exhaust using small tube headers and sticky tires. run at min. a 2500 stall.

with the overdrive look for about 15 mpg.

cruise rpm at 70 or so depending on tires will be around 2300 rpms.....

on a untuned run look for low 13's maybe high 12's at about 103- 104 mph.....get the carb right and timing and shift points,launch correct...with some type of cold air induction,oil splash shield,wrapped fuel lines synthetic oils and so on....you can achieve you goals....

jmo tho :D

TJC
Did not know they were closed chamber piston. Only time they came close was when the timing chain broke in half :mad: . Hence the rebuild.
Not sure I understand the thing about tranny choice. What’s not going to work? :confused:

Cmt454
Tranny will be an overdrive one. Either a tremec or a 200r4. I thought with one of those I should be able to get the mpg I’d like to get. I’m getting around 12 now with a 350th and 3:31’s. Interested in why you think I would not get what I’m trying for. :confused:

Slowpoke
I considered staying with the 3:31 that are in it now , but thought if I go overdrive I could go a little bigger gear. smile.gif

ddeennis
You must have posted while I was trying to type this.
Have the CC #XE268H-10 in there now (which is a little small than you have suggested) and have made high 12’s with it smile.gif , on a so so track (read no prep work). The heads have had the flashing taken out and that’s it.

Thanks for all the help so far. Trying to do it right this time.
graemlins/thumbsup.gif

Originally posted by TJC:

Your piston will yield about 9.8 to 1, with those heads. They are closed chamber pistons though, which should be ok, but there can be interferance with the dome on the edge of the dome near the intake valve. You HAVE to check for this when you mock up the motor.

Shaun,

TRW-L2465F30 pistons are not closed chamber pistons, they are for open chamber heads.

The TRW-L2349F30 pistons are closed chamber pistons (1970 LS-6 replacements). They have similar sized domes to the L2465's, but can be used with either head.

The L2465's should work with your 781's, but need to be careful when installing long duration camshafts with those pistons. I've heard that it's not unusual to have P-V clearance issues with those pistons and bigger camshafts. :(

Thanks Darren, I guess I looked at the dome shape and ASSumed they were CC.

Shaun, the trannies you have chosen will not last behind this motor.

With a 3.31 gear, I doubt you will see an increase in mileage with the OD, unless you are cruising over 110KMH.

No clearance issuse last year till the chain broke graemlins/angry.gif .
But I am now going from 510 & 520 lift to possibaly 586 & 600. smile.gif

Sounds like I may have to go and partly rebuild the motor to see how much I will be able to run. :(

Just thought I may need a little more compession to run the cam I was looking at, or the next one down (550 & 570), because from what I have read here and elsewhere it appears I do not have the compression I thought I had with these pistons.
Did not know much when I brought them, just saw the figure 10.5:1 and assumed thats what I was getting redface.gif .
You live and learn graemlins/beers.gif

Shaun,

Total valve lift of a camshaft has very little effect (if any) with piston-valve clearance.

The main things that determine P-V clearance is the duration, the LSA and where the cam is installed in the engine (adavanced or retarded).

Bump.