When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Don't worry about piston to valve clearance, you'll have plenty.
Plugs are 3/4 reach but require a 5/8 hex. Any of the NGK or similar will work.
Measure the pushrod length with a checker. Shoot for a slim pattern in the middle of the valve stem.
....The tank itself is great, I've ran it down to 2-3 gallons with zero fuel starvation with my EFI. I like that is has a "bucket" which the pump pulls from and the return line feeds into....
My experience too, have run it down to a gallon or so and not starved unless you 'slosh' it around hard.
I could never get the rubber seals to work right, they always leaked, grew, squished out, etc. What I did was ended up ordering the cork ones and used those. I brushed them with high tack, stuck it to the tank, and was able to work the sender and pump assembly in without incident.
One thing I don't particularly care for is the sending unit they offer, the swing arm for the float needs to be so short there's no granularity on the gauge. I ended up getting one from Classic Instruments, which has a flat float, and it works much better.
I run 5.25 backspacing on 18x9.5 with a 275 and there's no clearance issues on the rear. I could go bigger even, both tire and wheel, if I'm careful with the offset/backspacing.
I run the US Mag Bandits on my Pontiac, and there are folks who make an adapter for the center cap that allows you to use either the Pontiac or Olds center cap. Restore A Musclecar in Lincoln NE has the cap retainers to adapt, call them, tell them what you're doing, and they will ship them to you for like $45.
I could never get the rubber seals to work right, they always leaked, grew, squished out, etc. What I did was ended up ordering the cork ones and used those. I brushed them with high tack, stuck it to the tank, and was able to work the sender and pump assembly in without incident.
.
Same here! I cut an access panel in the trunk so I could get access to the fittings, and there is always a fresh film of gasoline around those dang seals. I used aviation form-a-gasket on them, not easy to work with!
Hey guys:
Well the engine assembly has been on hold up until today. I was rear-ended on the freeway which totaled my 4Runner and left me with an ugly black eye and a nasty concussion. Traffic stopped and the guy behind me came over the hill at full speed and hit me going 60-70 MPH. I'm just glad my kids were not with me and that I had those extra 5 feet of cargo space in the back to absorb the hit. But today I wasn't too dizzy to spend a few minutes in the garage, which leads me to my questions.
I noticed that one of the water jacket holes in the head gasket doesn't have a corresponding hole drilled in the block. There is a cooling passage hole in the head, but not in the block. Is this a problem? Should I drill a hole in the block to match the head gasket?
Also, can I open up the oil drain-back holes in the heads without hitting a water passage? The bottom leg of the oil return is a lot smaller than the top side of the head.
No hole in the block.
I could drill a hole in the block to match the gasket.
I decided against drilling out the oil drain back holes. I plan on using restricted push rods to limit how much oil gets pushed to the top of the head so these holes should be fine. Now I need to buy some spark plugs. How do you know what heat range plug is best? I'm looking at NGK 3/4-reach, 5/8 hex plug but there are way too many choices, I don't know how to narrow the field.
I would aim for a NGK with a heat range of 6 or higher. Higher the number, colder it is. Hopefully Mark will chime in on this, not as sure on aluminum heads.
Spark plug selection has got my head spinning - like the Billy Preston tune "Will it go round in circles"! According to the NGK application table, a 1972 350 engine uses an XR4 plug which has a heat range of 4. For modified engines, NGK recommends using the next cooler heat range plug for every 75-100HP added. My stock, low compression 350 made 180HP and my 10.3:1CR, 375 stroker should be around 375HP...so I should use a 6 heat range plug? Then there are 4 different style plugs to choose from: V-Power, G-Power, Iridium, & OE. Do I need an extended tip or a recessed tip??? Help!!
Disregard any reference to your stock 350, you're not even close to that in any way at this point.
Use a projected tip 3/4" reach 5/8" hex. I use an Accel 416s or 0784 I believe in most of the aluminum headed builds I do. I'd start with that or an equivalent.
Mark,
Thanks for the spark plug suggestions. I found the Accel 0784s on-line at S-K Speed shop. Most of the regular suppliers (Summit, Jegs, etc.) didn't have any in stock. I hope these don't become hard to find as this will be my daily driver.
I ordered pushrods from Smith Bros, 3/8" x 7-15/16" long. They're kind of spendy but they seem really well-made and they are available with restrictors to control oil flow to the rocker arms. I used a 5/16" adjustable pushrod to check the length, but the 3/8" pushrods are fatter and some are rubbing on the pushrod holes in the head. I'm not sure what is causing the problem, maybe this it's becaus the ProComp heads have been cut down to fit a small block? Is it OK to clearance the pushrod holes?
Did you measure them before ordering ? I guess what I mean is did you go through the whole process of using the adjustable pushrod to make sure it's what you needed.
Did you measure them before ordering ? I guess what I mean is did you go through the whole process of using the adjustable pushrod to make sure it's what you needed.
Yes, I used a 5/16" adjustable pushrod to get a good pattern on the valve stem. A length of 7-15/16" centered the rocker arm on the valve stem through the full travel of the rocker arm. I didn't have any interference problems with the narrower 5/16" adjustable pushrod, but the larger 3/8" ones from Smith Bros are hitting at the top of the holes on the block side of the head. Some of them rub and some of them don't.
I have no answer for your problem. What i can tell you is with two set of ebrock heads zero issues with 3/8 push rods! Thanks for posting pictures i have been following this thread and there is a lot of good info. I wish you best of luck with your project looks like you have done very well. It is nice to see this project as it proceeds.I can hardly wait to see it operational.Thanks for posting your build.
"Disregard Bills book for your build. Doesn't apply here.
.002 on the rods with .016-.018 side clearance along with .0025 or so on the mains is fine if you have main studs instead of bolts."
Dont' get me wrong, I know you are experienced builder and have a lot of knowledge about Olds engines. I am trying to learn from more experienced here, but would you please explain why wouldn't you want a bit more clearance for a performance build compared to stock? When stressed more than stock, parts tend to bend/twist/go out of round a bit. That's why you need a bit extra clearance, to make some room for these and still maintain the oil film.
Side clearance of 0,016-0,018" is huge. Even in worn out cores (sbo350) I have measured max 0,010, typically 0,008? So what do you get with side clearance of that big? I would be afraid to loose oil pressure when idling hot.
If changing main bolts to studs, would that affect to main clearance needed?
Rod side clearances have no impact on oil psi, just to point out, and the benefits of side clearances are that it has a 'cooling' effect on the rod big end and journal. Also, the added clearance allows for more splash on the piston pin, which helps with lubrication, especially desirable on floating pins.
Aftermarket rods are generally made from a more dense material, for strength, and from that respect, you would generally want larger clearances than OE.
Most of my builds, for Pontiacs, as a reference, I generally go .024-.026 side clearances, with aftermarket rods.
Main and rod clearances directly impact oil psi. Another factor is lifter bore clearance, but has less impact on oiling control.
Main studs help stabilize main caps, so theoretically you can run tighter clearances. Crank material and rotating mass is generally what dictates main clearances, with intended RPM being the variable.
One thing to note, is you want the align hone/boring done with the studs you plan to use. Because of the way they clamp, it can and usually does change the bore.
Rod side clearances have no impact on oil psi, just to point out, and the benefits of side clearances are that it has a 'cooling' effect on the rod big end and journal. Also, the added clearance allows for more splash on the piston pin, which helps with lubrication, especially desirable on floating pins. However that will also throw more oil on the cyl walls, possibly effecting the rings overall ability to control that. Wrist pins are typically fed oil thru the oil ring groove, not only splash.
Aftermarket rods are generally made from a more dense material, for strength, and from that respect, you would generally want larger clearances than OE. Incorrect. A stronger rod will flex less than a weaker one, therefore allowing you to run tighter clearances not loser.
Main and rod clearances directly impact oil psi. Another factor is lifter bore clearance, but has less impact on oiling control. Correct.
Main studs help stabilize main caps, so theoretically you can run tighter clearances. Crank material and rotating mass is generally what dictates main clearances, with intended RPM being the variable. A bigger issue however is the amount of flex the crank and block will experience. That, as much as studs, straps etc, will help dictate the amount of clearance needed. BBO stuff for instance isn't very rigid, therefore needing more clearance if you're going to be making any real power at all.
One thing to note, is you want the align hone/boring done with the studs you plan to use. Because of the way they clamp, it can and usually does change the bore. Correct
I don't run BTR type clearances, most guys don't. But I do run looser ones vs stock. The mods being done, (i.e straps studs etc) dictate my amount of needed clearances as well.
Last edited by cutlassefi; March 11th, 2016 at 05:19 AM.
Yeah, the BTR clearances are ridiculous, and you would see much lower operating oil psi.
On the rods, yes, less flex, but they retain more heat. And the comment was only from a side clearance perspective.
The crank flex is what I was pointing to, the OE cranks flex like heck. The lighter the rotating mass, and the lower RPM, the less flex. That was all I was trying to point out.
If you go with as light as possible rods, pistons, pins, and rings, and keep the RPMs down, you can go tighter on rod and main clearances.
Seems that opinions vary concerning clearances. My experience is that too tight of a clearance is more likely creating problems than a bit loose. I think BTR is definetely an Olds Guru. Maybe his toughts are a bit on a hardcore race minded for average Joe Anyhow he recommends bearing clearance for 200-400 hp engine to be minimum 0,0035"Also according to BTR rod side clearance has to do with oil pressure. And again according to him, less oil to cylinder walls is a good thing. Every one of us building our own engines has to decide what route to follow. I think I might experience a bit and go with bearing clearances on the loose side, exept rod side clearance on tight side. Add to that high volume oil pump to keep big clearances filled with oil.
Just a word of note regarding rod side clearance. You may want to see what some of the EMC guys are doing with piston guided rods. Some of them have .100 (yes .100) side clearance with no adverse effects. Kinda blows that oil pressure theory all to hell doesn't it.
Stroking Volvo B20 pushrod engine involves in biggest "easy" phase using Mitsubishi 4g63 rods. On those the width at bigger end is 26,5mm, and original Volvo rods are 29.5mm wide.
So there is 3mm side clearance ( 0,12"), and they run just fine, conrods quided just By piston. And thats some serious side clearance compared to ones depated here ( except Cutlassefi's example).
Last edited by Inline; March 11th, 2016 at 11:55 PM.
Not trying to hyjack this thread but a friend of mine locally just built a 375 cu in stroker using my old 350R from the first car I ever owned. He used a hydraulic flat tappet Cam (unknown specs) and C heads. It put down 434hp and 414 torque. The carb was a 750cfm carb shop Holley. They are going to try an 850 Holley today.
Piston guided rods are new thing to me. Never seen one. But if that's possible and they work, yea it kind of trashes the theory of side clearance affecting to oil pressure. Or does it? We don't have a glue if those engines would or would not have any difference in oil pressure with smaller rod side clearance.
Check out the EMC from brad wise a few years ago. The guy with him on that project is a friend of mine. That build had piston guided rods. They work, again with no adverse effects.
CP makes a 4.125" bore, 1.3cc dish stroker pistons that work with a 6" rod and come set up with the sbc .927" pin. BTR Performance brought them to market and they cost $680 with rings from him. Bill Travato is an Olds guy, wrote the High Performance Olds book and was a National record holder with Olds power.
Are these still available and I assume they use the stock compression height?
The crank needs ground on the bottom of the journal to increase stroke. If you have a block that will clean up with a hone to 4.065", CP makes a nice 2618 forged piston with a decent ring pack, Olds pin and stock stroke. Might be a very good piston for your service block.
The crank needs ground on the bottom of the journal to increase stroke. If you have a block that will clean up with a hone to 4.065", CP makes a nice 2618 forged piston with a decent ring pack, Olds pin and stock stroke. Might be a very good piston for your service block.
I am starting to understand the stack up of these pieces and the relation to deck height:-)
Just for my information what additional stroke would be ground into the crank for this to work?
Ryan
Just to clarify (or further confuse) it is really simple math that applies to all engines. Rod length, compression distance, and half of stroke added together should equal the deck height or very close to it. On a SBO, the deck height is 9.330".
Just to clarify (or further confuse) it is really simple math that applies to all engines. Rod length, compression distance, and half of stroke added together should equal the deck height or very close to it. On a SBO, the deck height is 9.330".
This I have figured out and have a spread sheet to work up various options.
Thanks, please continue to share, I am learning quickly:-)
October 28th, 2015, 06:06 PM
Anyhow he recommends bearing clearance for 200-400 hp engine to be minimum 0,0035"Also according to BTR rod side clearance has to do with oil pressure. And again according to him, less oil to cylinder walls is a good thing. 
