Starting to assemble the BB

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schmitt

schmitt

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Probably going the have a few questions.

To start

70 383

How do I know what to set my initial and all in timing too? Comp xe 274H cam. I know most say 20 and 36 all in.

Also I took a bunch off the block to get 0-5 thousand piston to deck height. Will stock pushrods still work? Running stock rockers.

Thanks guys
 
The specs

383
30 over
KB 400 pistons with valve reliefs. 10:1
Block deck 9.960
Comp XE274H cam
Sidewinder aluminum cylinder heads with matching springs. (mopartsracing.com) 84cc
Wieand action plus intake
Pro systems Holley pro series 4150
2500 stal
dana 60 3:55 gears
 
Are you degreeing the cam when installing it or just dot to dot?

I would cut two pushrods and measure to see if they need to be shorter

As far as timing - when you're in final assembly mode, once you're done, turn the balancer to 15* BTDC cyl No.1 on the compression stroke, and stab the dist/oil pump gear, and line up No.1 plug right inline with No.1 position on the dist - that way it will already be 15* advanced at first start up - I did this but at 10* and mine fired right up
 
I asked the machine shop to degree the cam. Looks dot to dot. The lower timing gear has a -4 keyway, 0 keyway, and +4 I believe. It's using the 0 keyway.

Can you explain the cutting pushrods to figure length?

I know how to get the motor timed just didn't know if certain cams need to be set different timing wise.??
 
schmitt said:
I asked the machine shop to degree the cam. Looks dot to dot. The lower timing gear has a -4 keyway, 0 keyway, and +4 I believe. It's using the 0 keyway.

Can you explain the cutting pushrods to figure length?

I know how to get the motor timed just didn't know if certain cams need to be set different timing wise.??
Click to expand...
You could buy the tools to measure pushrods (adjustable pushrods basically)

BUT you can make them from the old pushrods by cutting them near either end, and find a rod that will fit tight inside them, and then fully extend the rod, get 0 lash, and mark it, pull it out, and measure, add .010"-.020" or so for lifter pre-load (ask your machinist what a good lifter pre-load is or maybe someone can chime in on it..)

Not sure on the cam's needed "advance", I would ask if it was degreed, and what it was degreed to, because they had to mock up a cyl. head, and 2 pushrods to effectively do it.. there is the chance that it was ground like it should have been and it only needed dot to dot, but doubtful..
 
schmitt said:
I asked the machine shop to degree the cam. Looks dot to dot. The lower timing gear has a -4 keyway, 0 keyway, and +4 I believe. It's using the 0 keyway.

Can you explain the cutting pushrods to figure length?

I know how to get the motor timed just didn't know if certain cams need to be set different timing wise.??
Click to expand...

Yes, certain cams do need different initial distributor timing. Here is a good beginners guide. Select your cam profile and the look for you carburetor and engine size and you will see the recommended initial distributor timing.

http://www.demoncarbs.com/Tech/DemonSelectionGuide.asp
 
Thanks IQ52

Im going to run Valoline VR1 10w-30. (high zinc synthetic)

Am I on the right track running comp cam's engine break in oil for cam break in (10w-30). Then change and run it again for the next 500 miles before going back to the VR1 synthetic>
 
I would set the initial at 18 (give or take slightly) for the breakin. The $25 FBO plate is the easiest/fastest way to set the slot amt for your total after breakin once you get the initial finalized & the best way is the vac gauge method after it is broken in. (have your dist man set it to 36 when it fires). I would JB weld the top lifter cup the distance below the retainer clip that you intend to run for preload (IE .020") in a pair of junk hyd lifters to make solids out of em & mockup & see what you have for preload with your pushrods then go from there. there is ALOT of prep that needs to be done for a good breakin. You have thousiands of $$$ invested plus your time/energy & you have ONE shot to get an excellent breakin (cam & rings) as opposed to an average one that will lose power (compression/leakdown numbers) years earlier than it could have.
 
often a cam is checked for degree and it is in the ballpark, then there would be no offset bushing. put a head on with the pushrods u have and see what the lifter preload is, check with comp cams on how much they like. full synthetic oil is not good for non roller lifters-too slippery-the lifters will not rotate like they need to
 
I used Comp 10/30 break in oil with success - I'm reusing my cam in the new motor..

A cam can be degreed with out installing a bushing in the cam gear.. that's why there are multi-tooth crank gears
 
Got a lot done today.
 

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I understand the multi slot lower cam gears as 7 to 9 slots you can degree on in but the "it's in the ballpark" is good enough just doesn't seem correct, but I guess some folks' millage does vary.
 
What is the bolt hole for on the drivers side of the block that goes down into the oil pan? You can see it in Zac's picture?
 
schmitt said:
Did the tube thread into that hole? I have a different pan so I don't use that.

Thanks
Click to expand...

No. Presses in. You could tap the hole and use a threaded plug. Or small expansion plug.
 
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