Hey guys, just a quick question from somebody thats done it before, got a sbc 355 stock deck height, nothing milled. Have 062 Vortec heads and plan on using .015 head gaskets to get my quench to .040. Running stock 1.5 stamped vortec rockers, lunati voodoo 268 cam. Can i get by with stock length pushrods given block is stock? If i have to ill buy the pushrod checker to check but was wondering if just by changing gasket thickness(from a .041?) would make it necessary for new pushrods?
jmiller1119
Pushrods are commonly sized in increments of .050, so I'd venture to say that you can just use your stock length ones... unless I'm superseded by one of the resident experts...
I'd seriously consider getting something like Comp Cams Magnum roller tip rockers though... seems like running a Voodoo cam with stock rockers is not optimal.
At least put that on your "bucket list", if cost is an issue at this time...
Make sure that you get the self-aligning rockers.
I'd seriously consider getting something like Comp Cams Magnum roller tip rockers though... seems like running a Voodoo cam with stock rockers is not optimal.
At least put that on your "bucket list", if cost is an issue at this time...
Make sure that you get the self-aligning rockers.
If you are using the stamped rockers your pushrods will be fine, however for best performance, a set of full roller rockers are recommended, along with hardened proper length pushrods. Do it right, do it once!
I dont know if id ever use rollertip rockers, kinda a waste of money for the same friction with stamped steel. A buddy of mine had bought a cheap set off summit and he had to replace a few due to galling of the valve, after he showed me it kind of made me steer clear.
Just trying to get an engine together for my 66 impala to get it rolling so i can start doing a little body work.
Just trying to get an engine together for my 66 impala to get it rolling so i can start doing a little body work.
Aftermarket cam grinders such as Comp Cams, Isky, etc., grind GM camshaft profiles on camshaft blanks with up to .460” valve lift with 1.5:1 ratio rocker arms without reducing the base circle of the cam lobes. That will permit the use of stock length pushrods and will sell more camshafts.
Check the base circle diameter of one or your cam lobes and if it is the same as a stock cam lobe base circle, you will be able to use stock length pushrods. If it is not the same diameter as a stock cam lobe, the difference will give you the difference in pushrod length.
I use that method to establish the pushrod length even with short travel hydraulic lifters that set at .004” preload. Short travel hydraulic lifters have a pushrod seat that is installed about .050” - .060” deeper in the lifter. That permits the use of stock length pushrods and short travel lifters with a camshaft that has less than .460” valve lift with 1.5:1 rocker arms. A camshaft with more than .460” valve lift will require slightly longer pushrods.
Measure the aftermarket cam lobe base circle and compare it to a stock cam lobe base circle if your aftermarket cam has less than .460” valve lift with 1.5:1 rockers.
Check the base circle diameter of one or your cam lobes and if it is the same as a stock cam lobe base circle, you will be able to use stock length pushrods. If it is not the same diameter as a stock cam lobe, the difference will give you the difference in pushrod length.
I use that method to establish the pushrod length even with short travel hydraulic lifters that set at .004” preload. Short travel hydraulic lifters have a pushrod seat that is installed about .050” - .060” deeper in the lifter. That permits the use of stock length pushrods and short travel lifters with a camshaft that has less than .460” valve lift with 1.5:1 rocker arms. A camshaft with more than .460” valve lift will require slightly longer pushrods.
Measure the aftermarket cam lobe base circle and compare it to a stock cam lobe base circle if your aftermarket cam has less than .460” valve lift with 1.5:1 rockers.
My 1968 Chevrolet 350 CI engine has a GM-3863151 (L-79, discontinued) camshaft with .447” valve lift with 1.5:1 rocker arms. My 1966 #3890462 double hump heads have stock GM-3911068 valve springs that were set up with 90 lb seat pressure at 1.700” and 270 lb at .447” valve lift and are equipped with the OE pressed in rocker studs.
My heads have stock ports, Ferrea SS valves and have a peak flow at .485” valve lift. They do not require hardened valve seats with only 90 lb seat pressure and light weight Ferrea stainless steel valves.
My heads have stock ports, Ferrea SS valves and have a peak flow at .485” valve lift. They do not require hardened valve seats with only 90 lb seat pressure and light weight Ferrea stainless steel valves.
You can very easily make your own adjustable push rod by cutting an old one in half, remove a half inch or so of the length and then tap each size and put in a piece of threaded rod. I believe for a Ford push rod the ID is almost the perfect size for a #10-24 tap.
You can purchase adjustable pushrods from most aftermarket cam grinders. I bought one but I did not use it. I have a GM camshaft with less than .460” valve lift so stock length pushrods will work or stock lift that are no more than + / - .050” with hydraulic lifters. Solid lifters are a whole different thing. Hydraulic lifters are more forgiving, but solid lifter valve train geometry must be more precise.
You can buy Comp Cams and other grinders chromoly .050” wall pushrods that vary in .050” length increments if you need them with a high lift, small base circle camshaft.
You must use a weak hardware store spring if you use a adjustable pushrod. A valve spring will break or bend the threads of an adjustable pushrod.
The last set of custom pushrod I purchased for my 455 Pontiac engine were Smith Brothers chromoly pushrods with a .050” oil feed hole in the lifter end. That restricts useless oiling in the valve cover areas at high RPM. . You must use roller rocker arms with restricted pushrod oiling. Restricted oiling to the rocker arm area will increase oiling to the main bearings where it is needed more.
You can buy Comp Cams and other grinders chromoly .050” wall pushrods that vary in .050” length increments if you need them with a high lift, small base circle camshaft.
You must use a weak hardware store spring if you use a adjustable pushrod. A valve spring will break or bend the threads of an adjustable pushrod.
The last set of custom pushrod I purchased for my 455 Pontiac engine were Smith Brothers chromoly pushrods with a .050” oil feed hole in the lifter end. That restricts useless oiling in the valve cover areas at high RPM. . You must use roller rocker arms with restricted pushrod oiling. Restricted oiling to the rocker arm area will increase oiling to the main bearings where it is needed more.
Well, looks like my unqualified advice has been overruled on all counts... 
I wasn't taking the cam into consideration on the pushrod issue, I was only considering the difference in gasket thickness that he was talking about.
As for the rockers, the reason I mentioned those was basically as an "upgrade" from stock rockers, without having to go with taller valve covers... full roller don't work with stock height valve covers, do they? Are there roller tip rockers like the Comp Magnum ones that do work well, or something like TI is describing? Just curious since I mentioned them...
I wasn't taking the cam into consideration on the pushrod issue, I was only considering the difference in gasket thickness that he was talking about.
As for the rockers, the reason I mentioned those was basically as an "upgrade" from stock rockers, without having to go with taller valve covers... full roller don't work with stock height valve covers, do they? Are there roller tip rockers like the Comp Magnum ones that do work well, or something like TI is describing? Just curious since I mentioned them...
The only thing I like about full roller rocker arms is the roller pivot. The stock rocker arms will burn out the pivot ball when you have restricted pushrod oiling. Even the grooved rocker balls will burn out in some cases.
Solid lifters eat a lot of oil at high RPM and the engine can spin-out rod bearings. Chevrolet tried to solve that problem with their edge orifice solid lifters that were introduced in 1965 for the “30-30” camshaft. I run those lifter in my 1956 Chevrolet with a “30-30” fuel injection solid lifter camshaft. I used stock rocker arms with grooved pivot balls and did not burn up the rocker arm pivot balls when using higher load valve springs with the “30-30” cam. High load valve springs in the sixties was 120 lb seat pressure and 300 lb open pressure. Mine were supplied by Crane Cams.
With the edge orifice lifters, the oil pump just spurting oil on the headers rather than over the fenders when I was adjusting the valve lash. That was in the days when the best oil pump to use in a high performance SB Chevrolet engine was the Chevrolet 409 oil pump.
Solid lifters eat a lot of oil at high RPM and the engine can spin-out rod bearings. Chevrolet tried to solve that problem with their edge orifice solid lifters that were introduced in 1965 for the “30-30” camshaft. I run those lifter in my 1956 Chevrolet with a “30-30” fuel injection solid lifter camshaft. I used stock rocker arms with grooved pivot balls and did not burn up the rocker arm pivot balls when using higher load valve springs with the “30-30” cam. High load valve springs in the sixties was 120 lb seat pressure and 300 lb open pressure. Mine were supplied by Crane Cams.
With the edge orifice lifters, the oil pump just spurting oil on the headers rather than over the fenders when I was adjusting the valve lash. That was in the days when the best oil pump to use in a high performance SB Chevrolet engine was the Chevrolet 409 oil pump.
When the roller tip rocker is adjusted by the optimum pushrod length for all the involved geometry, the roller tip makes what is nearly a point of nearly instant contact on the stem. There is no scrub or smudge to any extent just a line not much wider than a pencil lead width. The roller does not roll in any "conventional" sense as it isn't going anywhere.
A well shaped and adjusted sliding shoe can do the same thing in that it can have a point of instant contact like a roller, but usually doesn't from the factory as these are made to compensate for production range of acceptable tolerance in the geometry as the production line and even the rework line is stuffing parts that need to work first time very time, they don't need to be perfect just functional.
The advent of the Gen III engine, as much as anything, tells us how far the production shops have come in maintaining accuracy to where permissible part tolerance is being held in a much tighter range for all the pieces of the engine thus allows such things as an instant contact to the valve stem using a fixed end rocker incorporating a cooler running roller fulcrum. This is something of a compromise between wanted performance goals and imposed 'cost to make' goals that modern casting, forging, and machining make possible.
For the GenI and II engines on the production floor this was just an impossible thing to do while maintaining production rate with the tooling then in use, so the sliding shoe rocker was simply an inexpensive somewhat a one size fits all solution that didn't require every engine on the line to have a selective fit which takes time thus costs money either in having to add lines to meet rate or live with reduced rate for the lines you got. The roller tip rocker makes more or less a point of instant contact when adjusted optimally, but at worst it will make a narrow smudge contact where either the roller skates a little or rocks back and forth a tiny amount, it never did nor does roll in the same sense as a rolling element bearing's roller does in an axled situation.
One needs to appreciate the facility and tooling costs of the manufacturers as not only do factories and equipment need to be used to meet production rate but, but there also has to be excess capacity to cover line shut downs for maintenance and accidents. At the same time you just can't spend crazy amounts of money on production capacity simply because there is so much cost involved, so designing a high rate production system is a game of nothing short of betting the company on the outcome. So yourbetting the market is there to by the product, the product will be successfully accepted by the customer, that economic, technical, political and social events don't override your decisions. So this is the high stakes game these big companies are playing every day, a miscalculation is deadly and the business highway is strewn with the wreckage of those that miscalculated or were overwhelmed by outside events.
My view from a long career inside really big companies.
Bogie
A well shaped and adjusted sliding shoe can do the same thing in that it can have a point of instant contact like a roller, but usually doesn't from the factory as these are made to compensate for production range of acceptable tolerance in the geometry as the production line and even the rework line is stuffing parts that need to work first time very time, they don't need to be perfect just functional.
The advent of the Gen III engine, as much as anything, tells us how far the production shops have come in maintaining accuracy to where permissible part tolerance is being held in a much tighter range for all the pieces of the engine thus allows such things as an instant contact to the valve stem using a fixed end rocker incorporating a cooler running roller fulcrum. This is something of a compromise between wanted performance goals and imposed 'cost to make' goals that modern casting, forging, and machining make possible.
For the GenI and II engines on the production floor this was just an impossible thing to do while maintaining production rate with the tooling then in use, so the sliding shoe rocker was simply an inexpensive somewhat a one size fits all solution that didn't require every engine on the line to have a selective fit which takes time thus costs money either in having to add lines to meet rate or live with reduced rate for the lines you got. The roller tip rocker makes more or less a point of instant contact when adjusted optimally, but at worst it will make a narrow smudge contact where either the roller skates a little or rocks back and forth a tiny amount, it never did nor does roll in the same sense as a rolling element bearing's roller does in an axled situation.
One needs to appreciate the facility and tooling costs of the manufacturers as not only do factories and equipment need to be used to meet production rate but, but there also has to be excess capacity to cover line shut downs for maintenance and accidents. At the same time you just can't spend crazy amounts of money on production capacity simply because there is so much cost involved, so designing a high rate production system is a game of nothing short of betting the company on the outcome. So yourbetting the market is there to by the product, the product will be successfully accepted by the customer, that economic, technical, political and social events don't override your decisions. So this is the high stakes game these big companies are playing every day, a miscalculation is deadly and the business highway is strewn with the wreckage of those that miscalculated or were overwhelmed by outside events.
My view from a long career inside really big companies.
Bogie
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