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If you dont want to change the heads all else is pointless.
Sorry that is just not true, the stock heads are undersized for this motor but the stock cam is even more restrictive. I installed the Crane cam mentioned earlier and a full exhaust system on an otherwise stock 5.8 in my '90 and the gains were impressive, and it also managed close to 18mpg cruising on the highway.
Sorry that is just not true, the stock heads are undersized for this motor but the stock cam is even more restrictive. I installed the Crane cam mentioned earlier and a full exhaust system on an otherwise stock 5.8 in my '90 and the gains were impressive, and it also managed close to 18mpg cruising on the highway.
Sorry that is just not true, the stock heads are undersized for this motor but the stock cam is even more restrictive. I installed the Crane cam mentioned earlier and a full exhaust system on an otherwise stock 5.8 in my '90 and the gains were impressive, and it also managed close to 18mpg cruising on the highway.
WELL , MAYBE NOT COMPLETELY POINTLESS......but
If you are into it for a cam ( labor wise ) I'd just do both. I wouldn't want huge ports or anything like that.
I'd at least take off some metal to increase the CR and port them a bit. I'd be after smooth flow , not necessarily high flow numbers
By the time you you have done all the work to swap the cam 70% of the work of swapping the heads is done .
If you dont want to spend the coin for Trickflow or AFR there are good flowing import( yes chinese ) heads that will flow better at ALL rpms, The misconception is that bad heads only bottleneck at higher rpms is not true they restrict flow at all rpms .
I dont discount your experience there is power to be had with a cam and better exhaust (I put shortys on my 1996 5.8 and feel I picked up 20 rwhp) but why do two thirds of the work and leave the real power on the table.
not my intention to start a pissing match just my opinion
I looked at alum heads
they have either 60 CC or 64 CC
60cc seems pretty small ,,,,
even the 64cc should give over 10 to1 CR ...aint that a little high for a 7000 lbs truck !
Standard longtube headers will give you 95% of the gains of tri-Y and you will have more options to pick from so if you were going to spend a little more on headers I'd suggest a standard set made from stainless steel over a tri-y painted set.
As for upgrading the heads I never said it was a bad idea but it is pretty much a waste of money if the stock cam remains. On a budget I suggest you look for a set of GT40s from a 5.0 Explorer or Gen1 Lightning, these castings flow 25% better than the stock E7TEs just as they are, come equipped with larger 1.84"/1.54" valves and are a bolt-in using the existing pedestal mount rockers and pushrods. Some of these GT40s were factory milled to a nominal 60cc chamber as well(stock is 64cc) so you would also get a compression bump. These heads, the cam and exhaust will make this a 300hp motor which is about all the stock EFI system and injectors can support, and it should not cost you more than $300-$500 to buy and refurbish a set.. assuming you don't just find a set that are ready to go.
I looked at alum heads
they have either 60 CC or 64 CC
60cc seems pretty small ,,,,
even the 64cc should give over 10 to1 CR
No... this motor produces 8.8:1 CR all stock with heads that have 64cc chambers, the stock pistons have a small dish. For truck uses and with the type of cams that will work with the EFI system you want to keep CR at 9.5:1 or less.
Here is a chart showing potential sources, casting numbers and other specs, check your local classifieds too. Note you want the regular GT40 heads ideally, the GTP heads will also bolt on but fitting headers is a little more difficult due to the spark plug angle.
You either have E5 or E7 heads which for all intents and purposes are the same, and yes they are too small for this displacement, GT40s are what all 351s should have come from the factory with IMO. But don't just look at valve size, GT40's flow 200cfm and the p version flows even more despite having slightly smaller valves.
The EFI system in your truck needs a rock solid vacuum signal because that is what all fueling is based upon(manifold vacuum), so that means intake/exhaust valve overlap is a bad thing and you're going to have to suffer through(settle for) a buttery smooth idle and a cam with no less than 114LSA and no more than 210deg duration at 0.050" lift. That is mild compared to what many hot rodders would use with a carb but compare it to the stock cam specs for your motor...
0.236"/0.246" lift(that is 0.379"/0.395" with 1.6 rockers)
244/256 advertised duration(0.050" duration is in the 180-190deg range)
115deg LSA
In terms of valve lift all these heads keep flowing more up to 0.500" lift so take advantage of it, but the stock springs are too weak for higher rpms(above 4k) and bind at a little over 0.500" so installing a little heavier single spring isn't a bad idea even for a truck application.
You either have E5 or E7 heads which for all intents and purposes are the same, and yes they are too small for this displacement, GT40s are what all 351s should have come from the factory with IMO. But don't just look at valve size, GT40's flow 200cfm and the p version flows even more despite having slightly smaller valves.
If I remember correctly the GT40P's had the spark plugs at a different angle or something like that. So just be aware if he goes with the GT40P cylinder heads then he will need different headers due to the spark plug arrangement.
