Edelbrock top end problems
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
Edelbrock top end problems
hey guys,
I have a 75 corvette and I've owned it for about 4 years now. As you know, the stock 75 is the slowest v8 corvette ever. So I spent $1700 on the edelbrock e street top end kit. I really like the fact that it is claimed to be a "bolt on" kit with no modifications. Well the exhaust manifold hits the edge of the heads and do not allow a proper seal of the exhaust gasket. The result is an exhaust leak at the bottom of the manifold. Will require grinding to fix. Also, I want your guys opinion on this part: before the rebuild, my oil pressure was about 30psi at idle and 45ish around 2000-2500 rpm. Now after the top end swap, I'm at 20psi at idle and 35 at 2500 rp. If some old gasket material or excess sealant that got caught in the strainer cause this? Could wiping a lobe on the new cam shaft cause this? The bottom end stayed the same so I'm not sure why the oil pressure would change. Also now the car overheats at idle. Bummer. I suppose more horsepower means more heat.
I have a 75 corvette and I've owned it for about 4 years now. As you know, the stock 75 is the slowest v8 corvette ever. So I spent $1700 on the edelbrock e street top end kit. I really like the fact that it is claimed to be a "bolt on" kit with no modifications. Well the exhaust manifold hits the edge of the heads and do not allow a proper seal of the exhaust gasket. The result is an exhaust leak at the bottom of the manifold. Will require grinding to fix. Also, I want your guys opinion on this part: before the rebuild, my oil pressure was about 30psi at idle and 45ish around 2000-2500 rpm. Now after the top end swap, I'm at 20psi at idle and 35 at 2500 rp. If some old gasket material or excess sealant that got caught in the strainer cause this? Could wiping a lobe on the new cam shaft cause this? The bottom end stayed the same so I'm not sure why the oil pressure would change. Also now the car overheats at idle. Bummer. I suppose more horsepower means more heat.
The kit definitely improved the performance of the car but I'm not sure it was worth it. Opinions are welcome
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
It's a new radiator. Aluminum too. Timing is at 6 btdc. I haven't drained the oil yet. The rebuild has like 30 mins and 5 miles on it. Enough to drive it to the exhaust shop. That's when I noticed the lower pressures.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Oil Pressure is controlled by the force of the spring inside the oil pump. It doesn't care if you have cam lobes or not.
Oil volume is controlled by the size of the gears (impellers) inside the pump and somewhat the pickup screen.
I think a new oil filter will likely bring back "some" loss pressure. Could be full of rebuild RTV crap.
I suspect your timing is off a bit since the rebuild. Its flowing more air / fuel now than before, so, could use some additional timing. That could also reduce the extra heat now too.
Oil volume is controlled by the size of the gears (impellers) inside the pump and somewhat the pickup screen.
I think a new oil filter will likely bring back "some" loss pressure. Could be full of rebuild RTV crap.
I suspect your timing is off a bit since the rebuild. Its flowing more air / fuel now than before, so, could use some additional timing. That could also reduce the extra heat now too.
Last edited by HeadsU.P.; Dec 20, 2017 at 04:25 PM.
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
Oil Pressure is controlled by the force of the spring inside the oil pump. It doesn't care if you have cam lobes or not.
Oil volume is controlled by the size of the gears (impellers) inside the pump and somewhat the pickup screen.
I think a new oil filter with likely bring back some loss pressure. Could be full of rebuild RTV crap.
I suspect your timing is off a bit since the rebuild. Its flowing more air / fuel now than before, so, could use some additional timing. That could also reduce the extra heat now too.
Oil volume is controlled by the size of the gears (impellers) inside the pump and somewhat the pickup screen.
I think a new oil filter with likely bring back some loss pressure. Could be full of rebuild RTV crap.
I suspect your timing is off a bit since the rebuild. Its flowing more air / fuel now than before, so, could use some additional timing. That could also reduce the extra heat now too.
Ill change the oil and filter. I was thinking about pulling off the oil pan to look at the strainer. I set the timing based off the chiltons book. What would you set it at? Thanks.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
Time it like a 69 350 350. That 6 degrees was for emissions, not performance. Did you remove radiator to do cam swap? Did you put back every seal around the radiator? Did you put the shroud back? Did you drop the pan to do timing cover? Might be an idea to drop it, clean everything out and might even consider a new STOCK oil pump. Not this high psi-volume stuff. How many miles on the beastie? Can you post a pic of where exhaust hits head?
Last edited by derekderek; Dec 20, 2017 at 04:23 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Not going to answer about where to set timing. There is a w-h-o-l-e- bunch of info on that, through Lars. But at least bump it up a few for now.
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Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
hey guys,
I have a 75 corvette and I've owned it for about 4 years now. As you know, the stock 75 is the slowest v8 corvette ever. So I spent $1700 on the edelbrock e street top end kit. I really like the fact that it is claimed to be a "bolt on" kit with no modifications. Well the exhaust manifold hits the edge of the heads and do not allow a proper seal of the exhaust gasket. The result is an exhaust leak at the bottom of the manifold. Will require grinding to fix. Also, I want your guys opinion on this part: before the rebuild, my oil pressure was about 30psi at idle and 45ish around 2000-2500 rpm. Now after the top end swap, I'm at 20psi at idle and 35 at 2500 rp. If some old gasket material or excess sealant that got caught in the strainer cause this? Could wiping a lobe on the new cam shaft cause this? The bottom end stayed the same so I'm not sure why the oil pressure would change. Also now the car overheats at idle. Bummer. I suppose more horsepower means more heat.
I have a 75 corvette and I've owned it for about 4 years now. As you know, the stock 75 is the slowest v8 corvette ever. So I spent $1700 on the edelbrock e street top end kit. I really like the fact that it is claimed to be a "bolt on" kit with no modifications. Well the exhaust manifold hits the edge of the heads and do not allow a proper seal of the exhaust gasket. The result is an exhaust leak at the bottom of the manifold. Will require grinding to fix. Also, I want your guys opinion on this part: before the rebuild, my oil pressure was about 30psi at idle and 45ish around 2000-2500 rpm. Now after the top end swap, I'm at 20psi at idle and 35 at 2500 rp. If some old gasket material or excess sealant that got caught in the strainer cause this? Could wiping a lobe on the new cam shaft cause this? The bottom end stayed the same so I'm not sure why the oil pressure would change. Also now the car overheats at idle. Bummer. I suppose more horsepower means more heat.
The kit definitely improved the performance of the car but I'm not sure it was worth it. Opinions are welcome
As for the overheating I agree the first thing to check is the timing. I would set it to 12-14 BTDC as a starting point. Lots of info on this forum on how to set up the advance curve. Recommend you do it, if only so that you are certain about your timing. And grinding the manifold is hardly a major modification.
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
Couple of things come to mind. I assume you changed the cam as part of the kit. If the new cam is very slightly smaller in diameter than the previous cam you will have more clearance in the cam bearings which will result in lower oil pressure. Same applies to the lifters. I have heard some of the lifters coming out of China are smaller than the .842" spec. Regardless, you still have plenty of pressure.
As for the overheating I agree the first thing to check is the timing. I would set it to 12-14 BTDC as a starting point. Lots of info on this forum on how to set up the advance curve. Recommend you do it, if only so that you are certain about your timing. And grinding the manifold is hardly a major modification.
As for the overheating I agree the first thing to check is the timing. I would set it to 12-14 BTDC as a starting point. Lots of info on this forum on how to set up the advance curve. Recommend you do it, if only so that you are certain about your timing. And grinding the manifold is hardly a major modification.
I'll change the timing along with new oil and a filter. I agree grinding is not a major modification. My main point of this post was for why I lost 10# of pressure with a top end swap. I figured Id mention the clearance issue in case any other fellows here are looking to buy edelbrock e street heads.
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
Time it like a 69 350 350. That 6 degrees was for emissions, not performance. Did you remove radiator to do cam swap? Did you put back every seal around the radiator? Did you put the shroud back? Did you drop the pan to do timing cover? Might be an idea to drop it, clean everything out and might even consider a new STOCK oil pump. Not this high psi-volume stuff. How many miles on the beastie? Can you post a pic of where exhaust hits head?
It's got 100k miles. Which is why I left the bottom end alone for now. Pistons and rings looked great. I'll try to get a picture tomorrow. But it's hitting right at the outlet where the manifold becomes one pipe. The heads have a thicker edge/lip and that's what is hitting the manifold. Not a huge deal, but figured I mention it in case other guys where considering these heads.The radiator is new and has no leaks. I did drop the oil pan to put the timing cover on but I have to redo it because it's leaking. Also I put a lot of gasket sealant on the oil pan and timing chain cover. After doing some research here a lot of guys say only put gasket sealer on the corners. Makes me wonder if excess sealant has clogged the oil pump strainer.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
I use a thin smear of silicone. Just enough to make it stick a little. Maybe get the new type 1-piece pan gasket. Just make sure it is for the right year-thickness up front. There are a couple of recent threads on here about the diff. Grab each rod with pan off and see if any play whatsoever. 100k. I would put 8 rod bearings in if I had pan off.
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
on the overheating, you could simply have an air pocket in the cooling system. Is the thermostat opening? You can check that by seeing if the top radiator hose gets hot. If it doesn't you could have a stuck thermostat, or an air pocket. Stranger things have happened, if it's a stuck thermostat.
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
I use a thin smear of silicone. Just enough to make it stick a little. Maybe get the new type 1-piece pan gasket. Just make sure it is for the right year-thickness up front. There are a couple of recent threads on here about the diff. Grab each rod with pan off and see if any play whatsoever. 100k. I would put 8 rod bearings in if I had pan off.
Good idea
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
I use a thin smear of silicone. Just enough to make it stick a little. Maybe get the new type 1-piece pan gasket. Just make sure it is for the right year-thickness up front. There are a couple of recent threads on here about the diff. Grab each rod with pan off and see if any play whatsoever. 100k. I would put 8 rod bearings in if I had pan off.
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
I use a thin smear of silicone. Just enough to make it stick a little. Maybe get the new type 1-piece pan gasket. Just make sure it is for the right year-thickness up front. There are a couple of recent threads on here about the diff. Grab each rod with pan off and see if any play whatsoever. 100k. I would put 8 rod bearings in if I had pan off.
The one piece pan gaskets are the best invention since the Wright brothers. Every small block Chevy I ever built leaked oil until these things were invented. Nothing to do with your oil pressure or overheating, but if you're replacing the pan gasket, go one piece.Not sure I would try to replace rod bearings from underneath with the engine in the car, but then I'm almost 60. Maybe in my younger days.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
If the coolant temps are running noticeably hotter, that will explain the drop in oil pressure... Hotter oil = pressure.
6* of timing is not nearly enough and could contribute to it running hotter. You need to set the timing so that you have around 34-36* total at 3000 rpms or so, and around 15-20* initial timing without the vacuum advance connected. Ideally, with the VA connected, you want to be idling at around 30-35* of total timing. That will allow it to run more efficiently, and be more responsive. You may have to play with the weights/springs in the distributor to get that much initial timing in it, yet keeping the total timing at 34-36*...(without VA).
I would not bother with pulling the pan, changing bearings or any of that....
Tune it right, get the temps under control, and THEN monitor your oil pressure. As long as its holding at least 20 psi of HOT oil pressure at idle, I wouldn't worry about it. Now if you do see it start losing pressure over time, you could be eating the cam and the metal is going into the bearings, destroying them.
How did your camshaft break in procedure go? Valve train quiet now?
You would have to get a LOT of silicone/gasket material in the pick up to lose that much oil pressure.
6* of timing is not nearly enough and could contribute to it running hotter. You need to set the timing so that you have around 34-36* total at 3000 rpms or so, and around 15-20* initial timing without the vacuum advance connected. Ideally, with the VA connected, you want to be idling at around 30-35* of total timing. That will allow it to run more efficiently, and be more responsive. You may have to play with the weights/springs in the distributor to get that much initial timing in it, yet keeping the total timing at 34-36*...(without VA).
I would not bother with pulling the pan, changing bearings or any of that....
Tune it right, get the temps under control, and THEN monitor your oil pressure. As long as its holding at least 20 psi of HOT oil pressure at idle, I wouldn't worry about it. Now if you do see it start losing pressure over time, you could be eating the cam and the metal is going into the bearings, destroying them.
How did your camshaft break in procedure go? Valve train quiet now?
You would have to get a LOT of silicone/gasket material in the pick up to lose that much oil pressure.
Last edited by ajrothm; Dec 21, 2017 at 11:06 AM.