Mopar R1 block

-
When I freshen up the R1 in my Dart the lifter bores will be bushed.
 
SwedishViking said:
This is a new build with a new R block, i will bee doing bracket racing only so its a drag car.
I belive that the comp will get to about 13.5
The heads are not done yet, bought them of ebay and now they are being redone the plastic.
I am considering to have the lifte bores sleeved or not to do it. Calculating the cost vs horsepower gain would be my issue.


Mushroom lifters what is that? Do you still have to block of the oil to the lifters?
Click to expand...


A mushroom lifter has a .904 body and IIRC a 1.000 or 1.050 base on it. So it acts like you have a larger than .904 lifter.

I always block off the oil to the lifters with a tube or bushings. If you are going to run a SFT cam, the bushings probably won't do anything power wise.

If you are going to run a real agressive roller lifter, you may want to bush the lifters to make sure there are all on the same plane and axes.
 
Wyrmrider said:
we ran GK mushrooms in the AMC trans am car
they really work but are a real PITA during development
actually the increased acceleration is due to starting the sweep further from the center of the lifter
it can actually be less "agressive"
and a mopar size profile can be less agressive than a chevy and till have more acceleration
old wives tale that .904 profiles are harder on parts- but of course you can build a cam that you have to change spring on often with either size lifter- but with the mopar lifter you do not HAVE to to beat the chevies, who are also handicapped by their short rods
for example both Crane and Engle had 3 series of lobes god knows how many comp has
I'd call them streeet, street strip and trailer
Click to expand...


I'm hoping someone still has mushroom lifters. Maybe Jim at RB. I need to start making some phone calls. I may not be able to even get them any more.
 
yellow rose said:
I'm hoping someone still has mushroom lifters. Maybe Jim at RB. I need to start making some phone calls. I may not be able to even get them any more.
Click to expand...
I had one in a TA engine I never ran, had it 10 years, had a 3.466 8 bolt crank, Hemi footprint rods, dre under the pistons from Atlanta 4 bolt mains
 
Well short road trip south 4 1/2 hours to pick up the x block. Crossing my fingers it’s all good.
I have calipers and tape measure. No dial bore gauge. Supposed fresh 4.040 bore, as it was ran as a 318 bore size previously.
 
Ok got the X block.
It’s in nice shape, as in fresh bore of 4.040 new cam bearings. Clean.
I assume it’d be a good idea to install 4 bolt mains? It looks like it would favor a splayed 4 bolt cap setup?
I text my machinist and asked to sonic test this block, when he has time.
He of course responded are we gonna build a 440” small block? I said depends on the sonic test.

65FB4D9F-FC11-4EA4-8D99-BCABBE5AFAEA.jpeg


09958448-9DE5-46D5-8C1C-54432A760511.jpeg
 
Is 4.100 asking to much? Idk I’ve heard people have certain x blocks at 4.165 and would go 4.180
Or just leave it alone and take it from 4.040
 
What’s thick?
A bit depends on what you start with and what your OK with in how thin it gets but the least amount of overbore is where it is at for cylinder strength for a non flexing cylinder leading to better ring seal, ring life, piston life, cylinder life. More power is made and retained.

You gain little in terms of power and engine size with an over bore. If your racing the engine/car in heads up and that’s basically an unlimited type of class, build what ever, the only thing important is the win, then some excellent gains can be found with a larger bore.

A larger bore gets more air and fuel in the cylinder, unshrouds the valves more for better filling and exhaust.
The cylinder wall should be good enough to support the power intended. In this area, thicker is better all the way. If you can have a 4.180 bore and still have a nice thick cylinder wall of let’s just say, .300, your in good shape or sure.

What is thin? .030 Race at your own risk.
Is that a Addition to the line? Absolutely not!
I knew a fella running low 12’s in a heavy-ish Duster with a .030 thin spot cylinder.
Do I think it was a good idea? Nope!
But if you don’t care, have at it. When it blows up, laugh it off and carry on.
 
Probably a 4.060 bore would help in getting rings and maybe even pistons.
 
12swinger said:
Probably a 4.060 bore would help in getting rings and maybe even pistons.
Click to expand...


FABO member @Rocket has the caps you want for a great price. Splayed caps are overrated.

Nice pick up. If it sonics well 4.125 is a good starting point.

There is something to be said about ring seal, deck thickness and cylinder wall thickness. Try and not give up any more than you need.
 
12swinger said:
Ok got the X block.
It’s in nice shape, as in fresh bore of 4.040 new cam bearings. Clean.
I assume it’d be a good idea to install 4 bolt mains? It looks like it would favor a splayed 4 bolt cap setup?
I text my machinist and asked to sonic test this block, when he has time.
He of course responded are we gonna build a 440” small block? I said depends on the sonic test.

View attachment 1715463326

View attachment 1715463327
Click to expand...

Why go more overbore than you have to?
I did find nice pistons and rings for my R block. Going 4.04 bore.
Just trying to learn :)
 
SwedishViking said:
Why go more overbore than you have to?
I did find nice pistons and rings for my R block. Going 4.04 bore.
Just trying to learn :)
Click to expand...
I would think un shrouding the valve a win win. Those w5 heads we have need a big bore and stroke to work.
If you have the material why wouldn’t you?
I’m fairly conservative, and plenty of people have went much further, so I will error on the side of less.
It’s a caged street car, I want to live on 20-60 mile trips repeatedly and not get hot.
Maybe a half dozen trips to the drag strip a season.
The guy I’d like to wear out before he gets any more decrepit, has run a best of 10:17 usually runs around mid 10s doesn’t really drive it on the street though anymore. I will.
Gonna take something serious to get in the 10:00 range high 9s would be better.
 
parts availability and off the shelf rings
then enough for later rebuilds
mopar bore spacing is greater than sbc but the cylinders/ deck height is almost .600 taller so you get more flex at the same wall thickness
 
12swinger said:
I would think un shrouding the valve a win win. Those w5 heads we have need a big bore and stroke to work.
If you have the material why wouldn’t you?
I’m fairly conservative, and plenty of people have went much further, so I will error on the side of less.
It’s a caged street car, I want to live on 20-60 mile trips repeatedly and not get hot.
Maybe a half dozen trips to the drag strip a season.
The guy I’d like to wear out before he gets any more decrepit, has run a best of 10:17 usually runs around mid 10s doesn’t really drive it on the street though anymore. I will.
Gonna take something serious to get in the 10:00 range high 9s would be better.
Click to expand...

How much gain do one expect from unshrouding the valves gains?
I did buy the pistons some years earlier than the block.
Well i think if you have matrial why waste it? Save it for a rebuild was my mantra.
I do hear you about going as fast as you can
9 sec runs would be great.
 
yellow rose said:
FABO member @Rocket has the caps you want for a great price. Splayed caps are overrated.

Nice pick up. If it sonics well 4.125 is a good starting point.

There is something to be said about ring seal, deck thickness and cylinder wall thickness. Try and not give up any more than you need.
Click to expand...
My machinist is super conservative, so he won’t recommend anything near dangerously thin, or even thin. He’s a PIA
When he was honing my latest block, I said, I did this at a shop I helped at, so just clean it up. He calls me and starts this is at .008 in clearance already! I’m like take another thousands off if you have to, cause the pistons guys said 7-8 at least. He’s getting it more and more.
Guy I got the block from says it’ll only go 4.06 as that’s what the catalog said.
I heard these things are pretty thick.
Can’t wait to sonic check it.
 
too thin walls and you go slower and ring life goes away and you run hot
been there done that
let;s see what the sonic test shows
did you say whose pistons and cr?
how about a recap when your results come in
is this a siamese block?
chevy is siamese at 4.125 with a 4.40 bore spacing
 
Wyrmrider said:
parts availability and off the shelf rings
then enough for later rebuilds
mopar bore spacing is greater than sbc but the cylinders/ deck height is almost .600 taller so you get more flex at the same wall thickness
Click to expand...
At 4.100 you would have most like a good couple more bore jobs in it. Maybe 4.06-4.08 is a better start though I get it.
High nickel blocks, thicker decks, there pretty strong, much stronger bottom end probably than most sbc
 
Wyrmrider said:
too thin walls and you go slower and ring life goes away and you run hot
been there done that
let;s see what the sonic test shows
did you say whose pistons and cr?
how about a recap when your results come in
is this a siamese block?
chevy is siamese at 4.125 with a 4.40 bore spacing
Click to expand...
It’s a over next winter project, that I will be prepping the block for soon.
I’ll probably deal with BPE as he is 45 minutes from me. Ohio crank is close also.
 
I have this w2, roller cam 372 to keep me busy this season.
Should be a fun one.
 
You must log in or register to reply here.
-

Back
Top