Building a 331. Can I use late model factory hydraulic rollers and the spider? Can a Vortec head be successfully drilled for an early intake and do the ports match? Also can self aligning rockers work on early heads? Obviously without guide plates. I'll be trying to make about 475+ hp at about 63-6500 rpm. Motor will be run hard for long periods.
Tech questions
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If your talking about a .030 over 327 small block chevy if your block is an 86 and earlier style block with a two piece rear main seal then no you can't use the spider tray and roller lifters in the block as it does not have the provisions for them and some people have modified there blocks to use the spider tray but its not an easy everyday job that is easy to do for the average mechanic and I do believe you have to use a different lifter from a certain year v6 because of the oil hole location on the lifter in order for it to be in the correct range of the oil tunnels in the block when the lifter rides up and down but it has been over ten plus years since I have read on that part.
The vortec heads can't be drilled to accept the earlier style intake bolt pattern without perhaps having problems especially in the middle part where there are no provisions for bolts. Also the ports don't match as the vortec heads have higher intake runners vs the older styles and trying to seal one up is very hard to do with trying that conversion. I have heard of folks that have done it but its not the best option to spend any amount of money trying to do that mod.
Self align rockers can't be used on earlier heads unless you have the holes opened up enough to allow the pushrod to not be guided by the cylinder head as the earlier heads did not have the self align rocker arms. With the older heads the castings had the holes to guide the pushrod in the rocker arm I do believe as they did not use guide plates and you can't use a guide plate design with a self align rocker arm design as well.
You better get you some pretty strong stuff for a rotating assembly if you plan to beat on the engine and a regular bone stock old chevy parts won't last long and you will need to look at aftermarket heads if you want that kind of power and even with vortec heads that kind of power they don't support that range. Mostly around 400 or a hair over with a 350 and a decent sized roller cam and some head work done to the vortec heads to even get that much power.
I might be wrong on the earlier heads part with the self align rocker arms but I am pretty sure you have to open up the factory holes that normally guide the push rod if you want to run self align rocker arms.
The vortec heads can't be drilled to accept the earlier style intake bolt pattern without perhaps having problems especially in the middle part where there are no provisions for bolts. Also the ports don't match as the vortec heads have higher intake runners vs the older styles and trying to seal one up is very hard to do with trying that conversion. I have heard of folks that have done it but its not the best option to spend any amount of money trying to do that mod.
Self align rockers can't be used on earlier heads unless you have the holes opened up enough to allow the pushrod to not be guided by the cylinder head as the earlier heads did not have the self align rocker arms. With the older heads the castings had the holes to guide the pushrod in the rocker arm I do believe as they did not use guide plates and you can't use a guide plate design with a self align rocker arm design as well.
You better get you some pretty strong stuff for a rotating assembly if you plan to beat on the engine and a regular bone stock old chevy parts won't last long and you will need to look at aftermarket heads if you want that kind of power and even with vortec heads that kind of power they don't support that range. Mostly around 400 or a hair over with a 350 and a decent sized roller cam and some head work done to the vortec heads to even get that much power.
I might be wrong on the earlier heads part with the self align rocker arms but I am pretty sure you have to open up the factory holes that normally guide the push rod if you want to run self align rocker arms.
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to make 745 hp you will likely turn the engine 7,000 rpm.
You should have heads that flow north of 240 cfm if you are using pump gas. True roller rockers and a stud girdle or better rocker shafts for prolonged high rpm useage. This will not likely be a budget engine. Also getting better rods I think what Eric is hinting at
You should have heads that flow north of 240 cfm if you are using pump gas. True roller rockers and a stud girdle or better rocker shafts for prolonged high rpm useage. This will not likely be a budget engine. Also getting better rods I think what Eric is hinting at
I'm actually a retired machinist and engine builder. I was hoping to avoid some research, just haven't done much small block R&D. Valve tip length is a consideration when using self aligning rockers, I am aware no other form of alignment can be in place. Just wondered if there were other considerations.
Drilling and tapping for an early manifold isn't difficult, my concerns were intersecting existing bolt holes and or water jackets. Ports are ports, I'll deal with that as necessary.
Now, as for the roller lifters and spider. Mounting the spider isn't an issue. Lifter bore depth, lifter length, oiling intersection, and will the alignment blocks interfere with the valley walls or are the lifter bores too short/long to work without modifications.
I'm looking for 450-500hp, certainly not out of reality.
Drilling and tapping for an early manifold isn't difficult, my concerns were intersecting existing bolt holes and or water jackets. Ports are ports, I'll deal with that as necessary.
Now, as for the roller lifters and spider. Mounting the spider isn't an issue. Lifter bore depth, lifter length, oiling intersection, and will the alignment blocks interfere with the valley walls or are the lifter bores too short/long to work without modifications.
I'm looking for 450-500hp, certainly not out of reality.
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Yes they can be drilled but the port CL aren't inline that cause other issues to have to deal with. Unless class racing it's far easier and money/time ahead to buy a dedicated manifold. No worries about bolts holes or water jackets. The bolts go through to the intake valley. Watch for using too long of bolts as they could the pushrods.
Spider.....It's again better to use link bar lifters as the factory spider is limited in lift.
Can you do it? yeah I suppose you can but your have tons of time fabbing up what the aftermarket has available for about the same money as the time and materials it'll take you to fab it up.
If you have a decent mill and lathe big enough for the work than be my guest by all means go for it. I agree the V heads won't flow what that engine needs for 450hp at 7000. You cna get there, but you'll need extensive work done to the heads and your still limited to 450. For the same money you can get the imported alloy heads and NOT have to do the work OR be limited in the power. A nice entry level $1300 set of SBC heads can you in the 500hp at 7500 so it's just smart.
Spider.....It's again better to use link bar lifters as the factory spider is limited in lift.
Can you do it? yeah I suppose you can but your have tons of time fabbing up what the aftermarket has available for about the same money as the time and materials it'll take you to fab it up.
If you have a decent mill and lathe big enough for the work than be my guest by all means go for it. I agree the V heads won't flow what that engine needs for 450hp at 7000. You cna get there, but you'll need extensive work done to the heads and your still limited to 450. For the same money you can get the imported alloy heads and NOT have to do the work OR be limited in the power. A nice entry level $1300 set of SBC heads can you in the 500hp at 7500 so it's just smart.
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Just not going to happen below 7K rpm's. There is a documented build here with a set of AFR's, roller cam that dyno'd in this area - but rpm was king. The AFR's were the dealmaker on that build. I'm with johnsongrass, need link bars and all the cam that you can stand below 1500rpm's.
Think about what it takes to make 500hp with a 383, and now consider you have almost 15% less cubic inch - ouch - it will be a tall order. I don't want to be a downer with you plan, but I believe in being realistic as well. On the other hand, I'm confident it could be done with a good head, big cam and 7500-7800 rpm's.
Think about what it takes to make 500hp with a 383, and now consider you have almost 15% less cubic inch - ouch - it will be a tall order. I don't want to be a downer with you plan, but I believe in being realistic as well. On the other hand, I'm confident it could be done with a good head, big cam and 7500-7800 rpm's.
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On the issue of drilling Vortec heads for older conventional pattern...the end bolts do intersect the existing Vortec end bolt holes a bit, and the new bolt holes elsewhere on the intake face of the head are into very thing material, barely 1/4" thick so you don't get really good thread strength.
On the port location, Vortec port is about .120" higher roof that old school, so many old vintage intakes will have trouble making a good seal along the top of each port.
On the lifter deal, i believe it is the 3.4L V-6 lifter that gets you right for the early blocks...those earlier blocks have shorter lifter bores, that is why you cannot use later factory V-8 roller lifters, they are too tall.
You can drill the top of the center oil galley and using short spacers mount the factory spider. The lifter dogbones will require you to clearance grind the lifter valley wall and floor behind each pair of lifters for dogbone fit.
You've got an uphill battle shooting for 450+ Hp from 331 cubes w/Vortec heads....they are going to need some port work.
Factory hydraulic roller lifters are not going to like the rpm needed to get that much power....if you are familiar with machning, you can remove the lifter guts and make tubular spacers to limit plunger travel, making them work like the expensive aftermarket short travel high rpm roller hydraulics. Thin wall Chromoly tubing works well for this.
An alternative you may want to consider for endurance running is solid roller lifters on a hydraulic roller cam...popular with the marine endurance crowd, offshore boat racing.
The hydraulic cam profile lets the solid roller lifters live a ong life, you just have to tight lash them down around .005-.006" cold lash, in an effort to be as close to zero lash hot as possible without being too tight and holding the valve off the seat.
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First question is how are you getting to 331 ie destroke a 350 or stroke a 305?
A non roller block is difficult to modify to a factory roller set up. Not impossible but hardly worth the effort. The constraints are the lack of pads to bolt in the cam thrust plate, the lack of bosses to bolt the spider on the main oil galley (just happens the bolts fasten right over the number 2, 3, and 4 oil passages to those cam and main bearings, and the lifter blocks are to low to support the 90 degree V6 and V8 lifters while the shorter 60 degrees V6 roller lifter can be used the short barrel length really limits cam lift in terms of acceleration rate because of side loads on the lifter.
The Vortec L31 head uses an odd bolt pattern and the intake ports are located to the rocker cover rail by about .1 inch, this often makes for sealing problems along the top when adapting pre Vortec intakes. On the underside the L31 intake has proven to be problematic in sealing up the valley as well in manifold adaptions.
Really if your going to run the motor hard for long periods the Vortec heads should be adapted to screw in studs and pushrod guide plates. If you run steady at high RPM you should use a 7/16th stud, especially if you want to run self guided rockers as the 3/8ths stud is really struggling to control the rocker once you get around 6000 RPM’s and up. The Vortec head needs a lot of shortening of the upper guide to accept high lift cams.
The Vortec head is well known for cracking it does not tolerate running low on coolant.
For someone with an automotive machine shop at their disposal any of what you propose can be accomplished, but if you have to pay cash the cost of modifications quickly exceeds the benefits.
Bogie
Thank you all for your responses. Most of my questions were about using parts and pieces from around the shop. All this to build an inexpensive backup/testing mule.
Primary motor is a 355ci, .450 lift rule cam, small valve Vortec heads. 9.5:1 CR, 600cfm, with a Super Victor. Almost 420HP at 6250rpm.
This combination works well.
The 327(+.030) would be along the same vein, yet with a few 'exceptions'. A slightly larger cam, larger valves, about 12.6:1 CR, and a Smokey Ram intake. 830 cfm on alcohol.
I'd like to use the Vortec heads because they work well in the .450-.500 lift range. But if I can't adapt them to the intake I'll rethink that part. The factory roller was just another case of 'stuff' I've got. The rods are SJ Manley, pistons are JE with tool steel pins. The pieces are capable of sustained 7000rpm but experience suggests the powerband will not be that high. Probably 65-6800rpm would be a bit more realistic.
Questions about the rockers are for specific reasons. My experience says a stud girdle with stock long slot rockers is stronger and more stable than roller rockers regardless of stud diameter. Stock style Vortec valve covers will not accept a stud girdle and valve cover adapters will not work with roller rockers. It's all give and take. Screw in studs, no guide plates, that's the combo that works with stock long slot self aligning rockers. I've just never used them on early style heads. So I asked.
Tell me if I'm not seeing something.
Again thanks for responding.
Primary motor is a 355ci, .450 lift rule cam, small valve Vortec heads. 9.5:1 CR, 600cfm, with a Super Victor. Almost 420HP at 6250rpm.
This combination works well.
The 327(+.030) would be along the same vein, yet with a few 'exceptions'. A slightly larger cam, larger valves, about 12.6:1 CR, and a Smokey Ram intake. 830 cfm on alcohol.
I'd like to use the Vortec heads because they work well in the .450-.500 lift range. But if I can't adapt them to the intake I'll rethink that part. The factory roller was just another case of 'stuff' I've got. The rods are SJ Manley, pistons are JE with tool steel pins. The pieces are capable of sustained 7000rpm but experience suggests the powerband will not be that high. Probably 65-6800rpm would be a bit more realistic.
Questions about the rockers are for specific reasons. My experience says a stud girdle with stock long slot rockers is stronger and more stable than roller rockers regardless of stud diameter. Stock style Vortec valve covers will not accept a stud girdle and valve cover adapters will not work with roller rockers. It's all give and take. Screw in studs, no guide plates, that's the combo that works with stock long slot self aligning rockers. I've just never used them on early style heads. So I asked.
Tell me if I'm not seeing something.
Again thanks for responding.
Just a couple of points to consider...
I'll be giving up 25ci. But the gain side is 3 full points of compression. Some additional lift and duration on slightly larger valves. A substantially larger carburetor on Alcohol. I feel some noticable gains may be in this combination.
Agree?
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With you doing the wrenching and knowing what you are doing, you might consider the bolt pattern re-drill but use fine thread due to the thinner section. as long as you aren't ham fisted with the starting of the bolts during manifold install it could help with strength.
The Smokey Ram is going to be very close on sealing along the top edge...we tried to put one on Dart 215 Iron Eagles and it just barely seals, those a re a raised roof port also....owner wasn't wanting to lay a TIG bead along the tops of the manifold edge to help seal it.
Yeah, now that you've laid out that this is not a pump gas deal, you could get there....I still think it will need 7200 rpm to get it though.
IMO the hydraulic roller lifter is not the best place to be unless you pan to modify it...or run solid rollers on the hydro roller cam.
The Smokey Ram is going to be very close on sealing along the top edge...we tried to put one on Dart 215 Iron Eagles and it just barely seals, those a re a raised roof port also....owner wasn't wanting to lay a TIG bead along the tops of the manifold edge to help seal it.
Yeah, now that you've laid out that this is not a pump gas deal, you could get there....I still think it will need 7200 rpm to get it though.
IMO the hydraulic roller lifter is not the best place to be unless you pan to modify it...or run solid rollers on the hydro roller cam.
I'll probably end up running a flat tappet cam. As for the intake, it's actually the Offenhauser version of the Smokey Ram. It's brand new, never used, never even bolted down. I've had it for too many years to count, tired of looking at it so I want to try it. I'll need to set it in place and see the mismatch.
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The one a buddy is using is the Edelbrock SY-1, the real deal. His dad bought it new and never used it before he passed away. Looks great Jet-Hot coated ceramic silver!
12.5:1 solid lifter Dart 215's on a 355. On E85, 830 cfm Holley. It runs well. Street car, albeit "hot" street.
12.5:1 solid lifter Dart 215's on a 355. On E85, 830 cfm Holley. It runs well. Street car, albeit "hot" street.
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12:5 on a 3.25 stroke is hard to do without a dome piston that's very heavy. You can't cut the Vortec heads enough to get there either. You might be able to roll them over and get closer but then you'll need to spot the bolt holes and straighten the intake faces. A 750 on Alky is plenty. The alky will help the midrange power but it'll be real peaky and not very drivable.
You have a stroke that wants 7500
An intake that wants 7500 on 331"
A carb that wants 8500+ on 331"
Heads that won't flow 7000 period
Pistons capable of 8000 but VERY heavy up there
I don't like it.
I'd get a cheap Scat crank at 3.50 and go that route. It's a much better deal all the way around.
If dead set on a 331" I'd shoot for 16:1cr and turn it 9200.
You have a stroke that wants 7500
An intake that wants 7500 on 331"
A carb that wants 8500+ on 331"
Heads that won't flow 7000 period
Pistons capable of 8000 but VERY heavy up there
I don't like it.
I'd get a cheap Scat crank at 3.50 and go that route. It's a much better deal all the way around.
If dead set on a 331" I'd shoot for 16:1cr and turn it 9200.
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