Rocker spacing

[plovett]

I think Edelbrock heads have their own spacing which is different than either factory 390/428 type heads or factory 427 heads.  I also think all the Edelbrock heads have the same valve spacing.   

paul

[Stangman]

Nobady on the oil pressure if i leave them alittle loose

[cjshaker]

Nobady on the oil pressure if i leave them alittle loose

Joe, loose (side clearance) won't affect pressure at all. The shaft-to-rocker clearance is the only thing that would affect it. I suppose if the rockers were so offset that the bushing covered the shaft hole, that could raise pressure by blocking the hole from the rockers groove, but that is a pretty unlikely scenario.

[plovett]

Nobady on the oil pressure if i leave them alittle loose

I never checked the actual spacing on my Harland Sharps,  like with a feeler gauge.  I just followed the instructions in their diagram and made sure they were as centered as possible over the valve stems.   Worked fine for years.

pl

[plovett]

Nobady on the oil pressure if i leave them alittle loose

Joe, loose (side clearance) won't affect pressure at all. The shaft-to-rocker clearance is the only thing that would affect it. I suppose if the rockers were so offset that the bushing covered the shaft hole, that could raise pressure by blocking the hole from the rockers groove, but that is a pretty unlikely scenario.

I think that is the answer.

pl

[cjshaker]

I think Edelbrock heads have their own spacing which is different than either factory 390/428 type heads or factory 427 heads.  I also think all the Edelbrock heads have the same valve spacing.   

paul

I believe you're right. A quick read showed that the intake valve was spaced out from center, allowing both to be bigger, but still allowing it to fit in the smaller 390 bore. Chambers and exhaust bolt patterns make up the other differences.

[Stangman]

Thanks I’m just going to go over them  better. Plus we will see what machine shop says. I don’t want to believe the cam tunnel is not straight. That’s gotta be rare.

[frnkeore]

The actual lifter spacing on a FE is 1.98 and the valve spacing on factory, LR type heads is also 1.98. I asked about this on this forum recently and didn't get a answer so, I had to research it, before finding the spacing. I verified it with my engine. So, if your rockers are 1" wide to be centered on factory valve stems, you need a distance of 2.98, from outside to outside of the pair of rockers.

Because Edel is using a .060 spacer, on the intakes, I would assume, that is the amount they moved the intake valve. The rockers don't have to be perfectly centered but, I wouldn't deviate more than +/- .015 for each rocker.

For reference, I believe the TP, HR & MR factory valve spacing is 2.10. I don't have one of the  blocks to check but, I think the lifter spacing of the large valve blocks is the same as the LR style at 1.98 but, I can't verify that.

If anyone has one of the above blocks, on hand a caliper measurement of a pair of lifter bores, outside to outside, would verify that. If it's 2.885, it's 1.98 C/C. If it's anything else, subtract .875 from your reading and that will be the C/C distance.

[e philpott]

The spacing difference is Medium, High Riser and Tunnel Port have wider spacing, Edelbrock only moves the intake position like a MR HR and TP but leaves the exhaust alone to clear small bores since the intake has plenty of room