I found a low mileage rebuilt, perfect running EFI 351w in a 1988 Bronco for less than I could even rebuild the heads on my weak '83 351w. I'm getting the engine next weekend, but out of curiousity I tried to find the engine specs and can't find much of anything. I believe this engine uses the same cam as the 84-86 351 HO (206/221@.050, 114 lsa, 115 ica), and maybe the E7 heads, but I'm not sure. Any idea on the factory rated compression ratio? I'm guessing about 9.0-1. I believe the factory power rating is 200hp/315tq...quite a step up from my 139hp/278tq monster
Also, I will be reusing my edlebrock 2181 performer intake and 600 holley carb and Mallory HEI ignition. Do you think this would bump the power output up any over the factory EFI setup? I also picked up a set of used hooker full length headers with 1 1/2" tubes and 2 1/2" collectors. Will these headers and a set of dual 2 1/2" exhaust make a significant difference on these things, with the weak factory heads? Has anybody ever tried advancing the stock cam 4*, and what was the result? I want to pull the heads and do some mild porting on them and remove that big bump out of the exhaust port too. With mild porting, the headers, performer, and 600 holley, what kind of output could I expect?
An all stock '88 EFI motor will have a puny little bumpstick not the 351HO cam, so if you have any plans to go inside the motor at all I highly recommend you change it. This motor will have E7TE heads and a nominal CR of 8.8-9:1. If you use a carb setup the Comp cams 35-234-3 or 34-238-3 are what you want, use the 238 if you have more gearing in the vehicle and the 234 with less gearing. If you stick with EFI you need the 35-255-5.
Simply swapping a carb onto the stock motor will make no difference at all, the EFI intakes are not restrictive it's all about the cam. The factory exhaust systems were a hugh cork too so headers will bring solid power gains for all combos.
Advancing the stock cam won't make any difference worth talking about and an aftermarket cam should be installed straight up. The EFI setup with the recommended cam and longtubes will make about 260-275hp with a big flat TQ curve up around 380ft/lbs from idle up, and the carb combos will make 275-300hp depending how good a porting job you do.
Ok...got the 351w home and started checking things out. I can't find the casting numbers on the heads (???)...they are just marked with a big "T" in several different places, with what I believe to be a casting date of 7K15 (November 15, 1987 ???). The stock cam measures about .280 on the intake lobe and .285 on the exhaust lobe, which figuring for the factory rated 1.6 ratio rockers equals .448 intake/.456 exhaust. Sounds pretty darn close to the 351HO cam to me. I haven't thrown a degree wheel on it yet, but everything I found shows that this engine should have the 351HO cam in it.
I haven't pulled the heads yet to check their condition as well as see what the bores and pistons look like, but one very notable difference for the much greater factory power rating over my '83 engine is the exhaust manifolds. Where the '83 stockers have a 1 3/4" (measured) outlet on them, these '88 factory bronco units have what appears to be an almost 2 1/2" outlet. The bronco downpipes where quite a bit bigger than my '83's, as well as the factory single exhaust on the bronco appeared to be a 3" system over my 2 1/2" factory single exhaust. Bigger cam, better heads, a bit more compression, and better exhaust...no wonder these things are rated at 70+ hp more than the '83 model.
Where can I fond some good info for porting the E7 heads? I am thinking seriously about using a comp cams retrofit roller cam, probably the 218/224 cam with a set of howards retro fit roller lifters. Any idea approx what pushrod length to start with to get me close?