Need clearances and advice on first engine build.
Thread Starter
Racer
Joined: Mar 2001
Posts: 308
Likes: 0
Need clearances and advice on first engine build.
I'm going to assemble the shortblock of my new 408 either tomorrow or Monday. I need to know some clearances, torque specs, and general tips.
Here's what's in the motor.
400 block 2-bolt ARP studded .040 over
Eagle 3.75 4340 forged crank
Eagle H-beam 6in rods
SRP Forged pistons
SRP File-fit rings
Clevite bearings
I just need some tips and other info on building this. Everything is machined and clearanced already. It only lacks assembly. I won't be installing the cam until later next week.
Thanks,
Jay
Here's what's in the motor.
400 block 2-bolt ARP studded .040 over
Eagle 3.75 4340 forged crank
Eagle H-beam 6in rods
SRP Forged pistons
SRP File-fit rings
Clevite bearings
I just need some tips and other info on building this. Everything is machined and clearanced already. It only lacks assembly. I won't be installing the cam until later next week.
Thanks,
Jay
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
Re: Need clearances and advice on first engine build. (TeenagerWith74Vette)
The first thing you want to do, if it hasn't already been done, is get the rotating assembly balanced. You're using an aftermarket crank and rods. Getting them balanced will be money well spent with your pistons, flywheel
and dampner.
On assembling the engine, the first thing you want to do is slide the camshaft in to make sure the bearings all fit and the cam turns freely. You can then take it back out and re-install later if you want, but there's nothing worse that getting an engine assembled and then finding out a cam bearing is too tight. You'll have to disassemble everything to get that corrected.
Go with ARP recomendations on torque specs for the main studs, and use Eagle's torque specs for their rod bolts.
Does the crank have a large enough radius on the rod journals to require
chamfered bearings?
The rings have already been filed???
Have fun...
and dampner.
On assembling the engine, the first thing you want to do is slide the camshaft in to make sure the bearings all fit and the cam turns freely. You can then take it back out and re-install later if you want, but there's nothing worse that getting an engine assembled and then finding out a cam bearing is too tight. You'll have to disassemble everything to get that corrected.
Go with ARP recomendations on torque specs for the main studs, and use Eagle's torque specs for their rod bolts.
Does the crank have a large enough radius on the rod journals to require
chamfered bearings?
The rings have already been filed???
Have fun...
Thread Starter
Racer
Joined: Mar 2001
Posts: 308
Likes: 0
Re: Need clearances and advice on first engine build. (danno85)
The kit was is already internally balanced.
I've got the bearings that came with the kit. The piston rings aren't filed yet. I need to know what clearance I should run on them. Should I just run the reccommended clearance.
Thanks,
Jay
I've got the bearings that came with the kit. The piston rings aren't filed yet. I need to know what clearance I should run on them. Should I just run the reccommended clearance.
Thanks,
Jay
Racer
Joined: Jul 2002
Posts: 269
Likes: 0
From: Paris AR, USA
Re: Need clearances and advice on first engine build. (TeenagerWith74Vette)
Run the recommended gaps--Should be somewhere in the vicinity of .016" on the top ring and a little larger, maybe .022" or so on the second ring-- but definately go by the manufacturer's recommendation. After filing, smooth out any rough edges left on the end of the ring with a whet stone and remember to keep everything super-clean when you assemble the engine.
Good luck with your '74. My first car was a '74 Vette.
Jason
Good luck with your '74. My first car was a '74 Vette.
Jason
Racer
Joined: Jul 2000
Posts: 290
Likes: 4
From: Jax, FL
Re: Need clearances and advice on first engine build. (TeenagerWith74Vette)
I used snap guages and mics to measure the clearances. You will have to torque the bearings and caps in place, then measure with the snap guages and mic. It is time consuming, but worth it. My clearances are on the tight side compared to the magazine clearances, I'm at .0015-.0018 on the mains and rods, instead of .002-.0025.
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
Re: Need clearances and advice on first engine build. (89gta383)
Plastigage is actually not too bad for checking bearing clearances if you use it correctly. Get the green stuff, which I think is the .001 to .003 range stuff. Don't put any lubricant on the bearing you are checking and don't turn the crank either while torqueing and removing. If you check one main and one rod then you're in pretty good shape (don't have wrong bearings, etc.). The best thing to do of course is check them all.
Dan
Dan
