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New member here. I have a 78 Delta 88 Royale Coupe. It has a Rocket 350 with a Rochester 4 Barrel. I called Edelbrock to see what they have to help me build 400 HP. They don't have heads but they do have the cam and intake which helps, but without the better heads, I'm pretty sure I can't hit my HP goal. Can I use 69 or 70 heads?
Someone else will have to verify, but there's some picayune difference in head gaskets on the later windowed blocks vs earlier solid web blocks. So not sure if the earlier heads will work with your block without creating an external leak or blanking off a steam hole.
Nice Delta BTW👍🤙
Last edited by rocketraider; Sep 25, 2021 at 05:20 PM.
As said, get an earlier block to build. Edelbrock will have SBO heads by spring. Get something better than their cam as well. Cutlassefi is doing a pretty mild build, well over 400 hp, he is testing Edelbrock new heads, perfect for your heavy car. The TH350 will need upgrades to live and something better than the 1600 factory stall. Or build a 2004R if you want much deeper gearing. You have 4000+ pounds to move. You also need to see what rear gear ratio you have. Good luck. A gorgeous Delta 88, those Holiday 88 are the nicest big cars from those years.
The biggest issue with swapping heads from early to late blocks is that the 1964-76 blocks used 7/16" head bolts and the 77-90 blocks used 1/2" head bolts. Early heads need the bolt holes drilled out for the larger head bolts. This is not a show-stopper. E-brock is dangerously close to releasing their new SBO-specific heads, but the supply chain issues that have hit all businesses have delayed that release. As others have noted, unless you really care about the numbers-matching block, get a 1976-earlier 350 as a starting point for the solid main webs.
Yes, with the head bolt holes enlarged to 1/2". You do need a RPM intake due to the larger BBO sized ports. Another issue besides the block is the later cranks are questionable at the power level you are shooting for.
The new, pending E-brock SBO heads have SBO ports.
Currently the intake port size is the same as the previous head, essentially “big block” size. However I’m lobbying to change that before release but not sure how far that will go.
Currently the intake port size is the same as the previous head, essentially “big block” size. However I’m lobbying to change that before release but not sure how far that will go.
OK, my mistake. I thought the intended 403 T/A market would have dictated the smaller ports to allow retention of the stock intake and shaker hood.
Unfortunately a 1978 Olds 350 was an intentionally compromised engine and not ideal for build up. I'm assuming the quest for 400 HP is better accelerative performance inspired. If so plenty can be done before spending a small fortune building up an engine not suited for it.
18.1 @ 78 MPH at 4000 LBS in the 1/4 mile is your starting point. Your standard optioned rear gear of 2.41 and factory single exhaust is stifling performance. True dual exhaust with high flow cats, performance mufflers, and a 3.42 rear gear swap will make a world of difference. Potentially improving performance to a 15.7 @ 87 MPH. That's 200 flywheel HP performance at 4000 LBS.
Because your model was designed with MPGs in mind rather than performance its setup is very inefficient for quickness. So much so that the 30 HP gain in these simple exhaust modifications + gear swap is amplified to a 70 HP gain in performance results. ( 18.1 at 4000 LBS represents 130 flywheel HP while 15.7 at same weight represents 200 flywheel HP.) A far cry from 400 flywheel HP absolutely. But you will experience a night and day difference in performance, and your engine will handle the improvement with ease.
If more power is a must, as has been mentioned by fellow members I would look into earlier engines. 1965-1970 are the best candidates, closely followed by 1971-1976.
Currently the intake port size is the same as the previous head, essentially “big block” size. However I’m lobbying to change that before release but not sure how far that will go.
I wonder how that will hurt flow numbers? It will be interesting to see what Edelbrock decides for the final product.
I wonder how that will hurt flow numbers? It will be interesting to see what Edelbrock decides for the final product.
Still working on that.
Joe - that topic has come up, port size vs engine size etc. But right now we’re looking at a couple of different scenarios. One change I’m proposing is a reduction in not only port size, but also chamber size to 65-66 vs the current 68. I have reasons for it and Edelbrock has been willing to listen. I know it’s hard to believe, but they really just want to get this right, and make it good for as many as possible. Even if it takes another month or so.
