BBC hyd roller conversion help pls
Thread Starter
Drifting
Joined: Apr 2004
Posts: 1,302
Likes: 36
From: Allen Park Mi
BBC hyd roller conversion help pls
hey all,
i know my way around SBC cam swaps way too well, but BBC i'm kindova noob.
basically, i'm working on my 1970 Monte which has its original LS5 in it - but the previous owner put flat tops in and its actual comp is more like 9:1
car has a th400 and original 3.31 gears.
the hyd roller cam i bought is a howards grind - 278-284 adv, 225-231 at .050 - .567-.578 lift on a 112.
Figured it should make plenty more than the LS5 stick -
it's probably 1/2 step too big, but i do plan (down the road) to go with a 700r4 and a slightly looser converter - so nevertheless.
This motor will not be living in the 5500rpm range all that frequently, and i have a set of original long slot rockers that i intend to use - and it seems that "retro-fit" roller push rods are plentiful in standard sizes -
as for using a retro-roller in a 70era block... is a thrust button the only thing I need, - or is the thrust plate a necessity? what about the thrust bearing on the timing gear? it seems i get different answers from som - so i'm curious what you guys that have done the bbc hyd roller swap did?
CHeers
A
i know my way around SBC cam swaps way too well, but BBC i'm kindova noob.
basically, i'm working on my 1970 Monte which has its original LS5 in it - but the previous owner put flat tops in and its actual comp is more like 9:1
car has a th400 and original 3.31 gears.
the hyd roller cam i bought is a howards grind - 278-284 adv, 225-231 at .050 - .567-.578 lift on a 112.
Figured it should make plenty more than the LS5 stick -
it's probably 1/2 step too big, but i do plan (down the road) to go with a 700r4 and a slightly looser converter - so nevertheless.
This motor will not be living in the 5500rpm range all that frequently, and i have a set of original long slot rockers that i intend to use - and it seems that "retro-fit" roller push rods are plentiful in standard sizes -
as for using a retro-roller in a 70era block... is a thrust button the only thing I need, - or is the thrust plate a necessity? what about the thrust bearing on the timing gear? it seems i get different answers from som - so i'm curious what you guys that have done the bbc hyd roller swap did?
CHeers
A
Team Owner
Joined: Feb 2003
Posts: 54,073
Likes: 9,398
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
Been a white since I did mine but I seem to recall about drilling and taping threads in front for a thrust barring retainer. And also drilling holes in the oil plugs to get oil into the timming chain. If I remember all this was available though my local GM dealer.
Melting Slicks
Joined: Jun 2001
Posts: 2,750
Likes: 724
From: Fountain Hills Arizona
2022 C2 of the Year Finalist - Modified
It is a very good practice to drill one of the front oil galley plugs on BBC to provide oil to the back of the timing gear, you really need a better supply of oil back there than just splashing around. You also at least need a cam thrust button between the front of the cam and timing cover, AND you absolutely need to check the clearance and machine the bearing down to have about .010 clearance. This thrust bearing will keep the cam from walking around. Remember, roller cams are ground flat on the lobes, flat tappet cams are ground at a slight angle to get the lifters to rotate and to also create a slight rear thrust on the cam.
Also,make sure you actually degree the cam to get your centerline where it needs to be relative to TDC. I just did a 66 427 and had to move the crank sprocket to get the cam lobe centerlines at proper location. Do it right the first time, you can make the engine run great and last a long time if you take care of the basics, AND the small details.
I just went through this with a hydraulic roller motor that was supposedly assembled by a BBC expert. Turns out the engine was a total mess and the guy didn't know his **** from a hole in the ground.
Also,make sure you actually degree the cam to get your centerline where it needs to be relative to TDC. I just did a 66 427 and had to move the crank sprocket to get the cam lobe centerlines at proper location. Do it right the first time, you can make the engine run great and last a long time if you take care of the basics, AND the small details.
I just went through this with a hydraulic roller motor that was supposedly assembled by a BBC expert. Turns out the engine was a total mess and the guy didn't know his **** from a hole in the ground.
Race Director
Joined: Feb 2004
Posts: 11,031
Likes: 2,587
From: Del Boca Vista FL
When you are installing the camshaft and have the degree wheel set up check at least two cylinders. One and six are the obvious choices. There have been instances where a camshaft has been improperly indexed during the grinding procedure.
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Joined: Feb 2003
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From: Sitting in his Nowhere land Hanover Pa
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Safety Car
Joined: Mar 2009
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From: Corpus Christi, TX
The cam you chose should have decent street manners. It is very close to the specs of a Comp Cams XE274H flat tappet hydraulic cam, which was the last hydraulic stick I had in my 427. A little bit of a lumpy idle, about 12" vacuum at 850 RPM, but it picks right up off idle and has really good mid range (3000-5000). You may want to consider a rev kit; the valve spring pressure you'd need otherwise might cause too much bleed down on hydraulic lifters.