Race Engine project planning

Ronnie Russell

Well Known Member
Supporting Member 2
With a grooved rear cam bearing, you could probably get away with no groove in the rear cam journal, however, I hate that word "probably". Call Comp and get their reasoning for sending out the cam without a groove. Personally, I would have the cam grooved at the local machine shop.
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1961BelAir427

Well Known Member
Supporting Member 3
When I ordered both my Comp and Lunati roller cams, both companies had me specify if I wanted the rear journal groove. :scratch.
I bought both second hand so I can't say as to how or why, but you would think that any cam company would put the groove their standard (since that is how all 348/409 cams are) and that you'd have to special order a cam without one if you didn't want it for some reason. I can see why they don't do it on 396-454 cams as the only ones of those that need it are the 65 & 66.
With a grooved rear cam bearing, you could probably get away with no groove in the rear cam journal, however, I hate that word "probably". Call Comp and get their reasoning for sending out the cam without a groove. Personally, I would have the cam grooved at the local machine shop.
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I guess I could call them Ronnie, but I trust everyone here's knowledge of the W a thousand times more than ANY of the parts manufacturers. There may be a couple guys at Comp (and at each company) that know 348/409's, but the chances of me getting one on the phone are zip I bet.

Instead of going with the CH5 cam bearings, I bought the CHP4's and had the oiling holes drilled to match the rear W bearing. Learned that one from ya'll since I will be running more spring pressure than is recommended on the stock replacement W cam bearings. I'm pretty sure that rear bearing in the CHP4 set is not grooved. Even if it is, I am with you on hating that word "probably". Better to do what we all know works than gamble.

I seem to recall another fix is to cut a groove in the journal in the block.
I saw that in an old post while researching this last night. I'm sure that would work, but it seems like it would be harder to do than to just groove the cam. Plus if the block gets grooved then a grooved cam was used in it later, it seems that would be an oiling nightmare.

:yup Chevrolet put that groove in the rear cam journal for a reason,I'm wouldn't try to reinvent the wheel in something as important as the oiling system.

My thoughts too Don.

I am shocked that I've ran into this with BOTH cams yet didn't find where anyone else had received one that wasn't grooved. (Although did see several posts recommending to check and make sure it is.)

At least I got them both at prices that I can have them grooved and still come out very good. I've been swapping a lot of late model Trans Am parts to my machinist for fab work out of his shop at home. The machine shop he is half owner with and out of respect for his partner he doesn't swap out machine shop labor. Maybe he'll fix them with no more $$ on his mill at home.
 

buildit

Well Known Member
Supporting Member 8
If you cut your own groove in the rear cam bearing housing of your 409 block, you can use SBC race style cam bearings. (More durable in mech. roller application) Since this bearing is narrower, you want to leave off the groove in the rear bearing journal to have adequate load bearing area. I have done this on a few engines, and I'm sure others have as well. Late style SBC rear cam bearing length is .740", versus 409 rear bearing length of .945". When you delete the groove in the rear journal, the bearing area is basically the same. Early SBC's had the longer rear cam bearing, but I am unaware of any race type bearing sets that have the longer rear bearing.
 
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1961BelAir427

Well Known Member
Supporting Member 3
Jim, the earlier sbc ( 327) has a length of .940 ( rear bearing)... The CHP-4 DuraBond works well with the holes drilled to match 409 block holes. Actually, I think it is adding only 1 hole to make a total of 3.
I've got those for both blocks. Haven't drilled the holes yet and haven't installed the bearings as we're waiting until all the block work is finished to do a final hot tank and then put them in. Still have to mock everything up, notch the chambers, deck (hopefully not much), and I still need to de-burr the oil drain back holes in the valley and the water pump holes. In case you see this Skip, I haven't forgotten you on the Isky fly cutter tool you loaned me. I sure hope we're through with it and I can get it shipped back soon. You haven't mentioned it once, but I feel bad for keeping it this long. Sorry my friend.
 

1961BelAir427

Well Known Member
Supporting Member 3
Hopefully the ball is rolling again. I dropped off more parts at my machinists' house this evening. We are supposed to start mock-up and valve relief notching next week.
I also took him both camshafts and the Isky Z55 flat tappet so he'd have it to use as a pattern to put the (missing) groove in the rear cam journal of the roller cams. He said he would probably get those done tomorrow as they are slow at the moment.

This part isn't an update for me on this build as much as it is an update for everyone:
It is such great news to hear that we are all going to once again have a chance to buy a great intake for these engines and they are going to be sold by someone with integrity.
Like so many others, I've been struggling with the complete lack of an off the shelf single plane dual quad intake. I honestly think it's been a big part of why my build has been dragging out so long. Maybe I just couldn't get into a rush to finish what should be a fairly stout street/strip engine only to top it off with an 881 that we all know will be at least 50HP down in the upper RPMs.

I'm also pretty excited that I'll have the option to use Holley carbs. I have a pair of Edelbrocks for each of my builds, but I am not at all familiar with the AFB design. I know the old double pumpers fairly well and will feel more at home with those.
 
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1961BelAir427

Well Known Member
Supporting Member 3
Nearly a month later than I thought I'd be updating. Seems to be the way it goes with car projects for me.

Randy took the Isky flat tappet cam along with the rollers for this and the other engine to the machine shop and grooved the rear journals of the roller cams. He also took the other block along with Dan's old pistons and bored it to match them (4.360").

We notched the passenger block for this build last night for exhaust valve clearance. We were surprised how much variation there was in the size of the notch from one cylinder to the other. #1 and #8 required the least. Before cutting the #1 cylinder the valve didn't hit the cylinder wall until .760". I was so shocked after always hearing .550" to .600" or so was it with a car block that I called Ronnie to talk about it before we started cutting anything. That was with the Edelbrock head snugged down with a couple head bolts and no head gasket. Stock edelbrock 1.72" valves.
We went ahead and set the drill stop on the arbor for .800" clearance just to make sure there was room for some lateral movement too. We measured each cylinder and have some variation, but all between .780" and .810" before the valve touches.
I would guess that the largest of the notches are still only 3 or 4 cc's at most so they shouldn't hurt compression a noticeable amount.

I'm going to do the other block as soon as he brings it from the machine shop to his home shop. That one will have 690 heads, but since the valves are the same size (double checked last night) I am just going to use the Edelbrock heads to notch it as well before we reinstall the exhaust valves.

Hopefully we are going to start mocking things up on this one Tuesday evening and then he can do the final machine work. (decking, cleaning again, and cam bearings are all that's left I think).

Crappy cell phone pictures of the block notching done last night to follow if I can get them downloaded.
 

1961BelAir427

Well Known Member
Supporting Member 3
I believe the Edelbrock valves are moved a bit from the 690-583 heads. Better check my friend.
Mr. HP is correct,valve angles are different.
You're both correct.... I remember now. Stock the angles are different from intake to exhaust and when Edelbrock designed theirs they split the difference and made them both the same. So neither angle matches the stock heads.
 
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