351w build help!
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351w build help!
Hi all, trying to finish a build on a 1988 351w 4x4 speed density efi, truck motor. I know Im limited because of the SD, but cant afford a conversion on top of the rebuild. will be used to tow 4-5000# travel trailer. The build.
Block is still out, may have to bore to .060 over.
Heads having the bumps in the exhaust ground smooth , very mild port clean up.
Comp RV cam everything I read points to a 260H, called comp they said it is to big to use the 252H, help here.
Torque converter matched to cam, higher stall.
Hedman shorty headers A.I.R. compatable
New flexplate and harmonic balancer.
Homemade K&M airbox,
wanted to use a noisy gear drive timing set, but was warned the noise may trigger the knock sensor, so prob double roller, but was also told their is no knock sensor on a 351w
The cam is troubling me, but I think the 260H will be okay.
if not seen a dual 56mm throttle body may help.
I'm losing sleep here, and maybe checkbook from wife. All help is appreciated. Jeff
Block is still out, may have to bore to .060 over.
Heads having the bumps in the exhaust ground smooth , very mild port clean up.
Comp RV cam everything I read points to a 260H, called comp they said it is to big to use the 252H, help here.
Torque converter matched to cam, higher stall.
Hedman shorty headers A.I.R. compatable
New flexplate and harmonic balancer.
Homemade K&M airbox,
wanted to use a noisy gear drive timing set, but was warned the noise may trigger the knock sensor, so prob double roller, but was also told their is no knock sensor on a 351w
The cam is troubling me, but I think the 260H will be okay.
if not seen a dual 56mm throttle body may help.
I'm losing sleep here, and maybe checkbook from wife. All help is appreciated. Jeff
Last edited by stressed; Mar 20, 2004 at 11:35 PM.
Elder User
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From: Miami
The cam is a very touchy subject wiyh the speed density system. I have heard that you need a minimum of 114 deg lobe sep. on the cam. The speed density computer will not regonize the icrease in air flow through the motor. Make sure the cam you do buy is compatible, or everything get's screwed up! I do not think the 351 has a knock sensor. There are aftermarket system's you can adapt to the speed density system to allow for changes! But they are not cheap!
Al
Al
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From: Fredericksburg, VA
The 252 RV type cam (206deg at 0.05" tappet lift) will give the most torque through 3000RPM. So you will need gears to use the 212deg or 218deg cams for towing.
The engine will respond very well to mild porting of the exhaust port. So good job on that. It also will let you minimize the exhaust lobe duration for better low speed performance and mileage without hurting the powerband (4000-5000RPM). Good tow cams for up to 3000RPM tow speed with the ported exhaust will look like 202I/208E with 105ILCA/113ELCA (109LSA). Overlap duration is very short, so you don't need the 114LSA like you would use with longer exhaust durations.
The engine will respond very well to mild porting of the exhaust port. So good job on that. It also will let you minimize the exhaust lobe duration for better low speed performance and mileage without hurting the powerband (4000-5000RPM). Good tow cams for up to 3000RPM tow speed with the ported exhaust will look like 202I/208E with 105ILCA/113ELCA (109LSA). Overlap duration is very short, so you don't need the 114LSA like you would use with longer exhaust durations.
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Gears
The truck has 4:10 gears, not an AOD tranny either, was looking for good highway tow speeds. Im a little fuzzy on the 105ILCA/113ELCA, what it means, Rodbuckler, but with the exhaust porting and 4:10 gears you think the 260H 110 LSA will be okay? yeah and I'm not happy about the .060 over half the shops in town wouldnt touch it, say it'll burn up or hot spots, this other guy said they do it all the time, ug. But the person I bought the truck from 500 miles ago and since developed a rod knock, said he had it bored 60 over, I watched him build it during several stages, when I brought it back he said what did you do to it? so maybe he lied about that too. Thanks All Jeff
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using 265/75/16, enough tread for the rest of this year, but probably 31 or 33x15's next year.
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As previously mentioned you need a camshaft with 114 lobe seperation. You will have idling problems with the 110 cam you want, not idling problems as in rough idle performance sound but surging, where the computer is trying to figure out what in the world is wrong with the engine, because it won't recognize the vacuum signal that that camshaft would produce. Call comp or crane cams they have a camshaft for speed density that will wake up your truck. Give'em a call and see what they can do for you, good luck
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there it is
after scouring comps catalog there it is the perfect cam, XE254H
dur@ .050 In. 210, EX. 214
LSA 114
Specific for speed density, I just needed to look closer. BUT when I called comp last week the tech said to use the 252H. go figure, and thats what would have went in without your guys help. alright on track again, should be running in a week, I'll let ya know. Thanks Jeff
dur@ .050 In. 210, EX. 214
LSA 114
Specific for speed density, I just needed to look closer. BUT when I called comp last week the tech said to use the 252H. go figure, and thats what would have went in without your guys help. alright on track again, should be running in a week, I'll let ya know. Thanks Jeff
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total seal rings
Hi all, I keep managing to srounge a little more money, was thinking about a total seal ring set, but it would probably raise compression, would this be an issue with the stock speed density? also decided better exhaust port clean up, I was just going to grind the bumps down, now sending them out to have the guides narrowed, raise the port and grind the bumps down. all feedback appreciated. Thanks Jeff
Last edited by stressed; Mar 23, 2004 at 11:09 AM.
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It would raise your compression psi slightly, not compresson ratio.
I would use regular rings or a cost effective performance ring, and put that additional money somewhere else...but thats my opinion...good luck. later
I would use regular rings or a cost effective performance ring, and put that additional money somewhere else...but thats my opinion...good luck. later
Last edited by jwtaylor; Mar 23, 2004 at 11:09 AM.
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
stressed, check out fordfuelinjection.com. there is a lot of info on this site that can explain this whole efi garbage. the guy running the site is very knowledgeable and is willing to answer all questions.
late
late
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Joined: Dec 2003
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From: tukwila
Please keep us updated - I too am considering pushing the limits of the stock efi on an 89 Bronco. Don't really want to tear it out and replace with Mass Air. Extra cost, price of gas etc. Good luck.
Tuned
Joined: Mar 2004
Posts: 281
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From: Petersburg, MI
No the 351 EEC does not have a knock sensor. The cam you want is either Comp cam part # 35-255-5(LSA 114) or Edelbrock part # 3782 (LSA 116 degrees) both designed specifically for our motors. I know a few guys that have these on their SD motors and they run GREAT!
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From: Fredericksburg, VA
Sorry, I gave the wrong advice in my post above. I was thinking of the cam specs for the carbureted intake. For the long-runner fuel injection intake you would retard the Intake Lobe Centerline angle to something like 110deg. The long intake runners pull the RPM range of the engine down and boost the midrange. Later ILCA is a natural match to the long runners.
My advice on the exhaust lobe and ELCA stands as is. The ported exhaust makes the 214deg exhaust lobe work as if it were larger than with the stock exhaust port. For example the Edelbrock cam uses a 216deg lobe on a 120ELCA! That lobe is designed for the stock untouched head. You won't need it after the port job.
Your gear and tire combo will do fine with a 210deg intake lobe for towing. Some guys don't have enough gear for their tire diameter, and end up needing a shorter cam.
My advice on the exhaust lobe and ELCA stands as is. The ported exhaust makes the 214deg exhaust lobe work as if it were larger than with the stock exhaust port. For example the Edelbrock cam uses a 216deg lobe on a 120ELCA! That lobe is designed for the stock untouched head. You won't need it after the port job.
Your gear and tire combo will do fine with a 210deg intake lobe for towing. Some guys don't have enough gear for their tire diameter, and end up needing a shorter cam.
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